/* Cap Maturité — Bleu nuit & ivoire. Shared visual layer, same routes and interactions. */
:root{
 --brand-orange:#805d2b;--brand-orange-hover:#69491e;--brand-orange-ink:#fff;
 --brand-orange-tint:color-mix(in srgb,var(--brand-orange) 10%,var(--surface));--brand-orange-line:color-mix(in srgb,var(--brand-orange) 30%,var(--surface));
 --accent-action-fill:var(--brand-orange);--accent-action-hover:var(--brand-orange-hover);--accent-action-ink:var(--brand-orange-ink);
 --paper:#f8f7f3;--surface:#fff;--ink:#192b45;--navy:#14243c;
 --body:#43536a;--muted:#647286;--blue:#345d8f;--blue-hover:#254973;
 --tint:#edf1f7;--line:#dee3ea;--line-strong:#bdc9d8;--gold:var(--brand-orange);
 --shadow:0 2px 4px rgb(20 36 60 / 2%),0 10px 28px rgb(20 36 60 / 4%);--shadow-lift:0 5px 12px rgb(20 36 60 / 4%),0 18px 38px rgb(20 36 60 / 9%);
 --sans:"Segoe UI",Arial,Helvetica,sans-serif;--serif:"Iowan Old Style","Palatino Linotype",Palatino,Georgia,serif;
 --math:"Cambria Math","STIX Two Math",Cambria,Georgia,serif;
 --champagne:#e7d8b9;--champagne-soft:#f5efe2;--gold-ink:var(--brand-orange);
 --radius-card:14px;--radius-control:9px;--ease:cubic-bezier(.2,.7,.2,1);
}
html{color-scheme:light;scroll-padding-top:24px}
body,body.billing,body.account-page{background:var(--paper);color:var(--ink);font-family:var(--sans);font-size:1rem;line-height:1.65;-webkit-font-smoothing:antialiased}
button,input,select,textarea{font-family:inherit}
p{color:var(--body)}
h1,h2,h3{color:var(--ink);text-wrap:balance}
h1,.billing h1,.number-lesson h1,.account-story h1,.dashboard-heading h1{font-family:var(--serif);font-weight:500;font-size:clamp(2rem,3.3vw,2.9rem);line-height:1.16;letter-spacing:-.035em}
h2{font-weight:600;letter-spacing:-.025em}
h3{font-weight:600;letter-spacing:-.015em}
a,button,select,input,summary{transition:color .18s ease,background-color .18s ease,border-color .18s ease,box-shadow .18s ease,transform .18s ease}
a{text-underline-offset:4px}
a:focus-visible,button:focus-visible,summary:focus-visible,input:focus-visible,select:focus-visible{outline:3px solid #668bb7;outline-offset:4px}
::selection{background:#d9e4f1;color:var(--navy)}
.eyebrow,.navlabel,.school{font-family:var(--sans);font-size:.75rem;letter-spacing:.13em;color:var(--muted);font-weight:600}
/* Wordmark and unchanged persistent navigation */
.brand,.site-sidebar .brand{font-family:var(--serif);font-size:1.75rem;font-weight:600;letter-spacing:-.065em;color:var(--navy)}
.brand span{font-family:var(--sans);font-size:.7em;font-weight:400;color:var(--gold);margin-left:7px;vertical-align:middle}
aside.site-sidebar{background:var(--surface);border-color:var(--line);padding:34px 22px;width:250px}
.site-sidebar .school{line-height:1.9;margin:17px 0 32px;color:var(--muted);font-size:.7rem}
.site-sidebar .navlabel{font-size:.69rem;letter-spacing:.09em}
.site-sidebar .nav{border-radius:8px;color:#56657a;padding:11px 13px;font-size:.9rem}
.site-sidebar .nav.active{background:var(--tint);color:var(--navy);font-weight:600;box-shadow:inset 2px 0 0 var(--blue)}
.site-sidebar .nav:hover{background:#f3f5f8;color:var(--navy)}
.site-sidebar .years{margin-top:32px}
.site-sidebar nav .year{padding:7px 6px;font-size:.9rem;color:var(--muted);gap:12px;border-radius:8px}
.site-sidebar .year b{display:grid;place-items:center;width:31px;height:31px;padding:0;background:#fafbfc;border:1px solid var(--line);border-radius:7px;font-size:.83rem}
.site-sidebar .year.selected{color:var(--navy);font-weight:600}
.site-sidebar .year.selected b{background:var(--navy);border-color:var(--navy);color:#fff}
.site-sidebar .year:hover{background:#f6f7f9;color:var(--navy)}
.asidebottom{padding-top:25px;border-top:1px solid var(--line);font-size:.83rem;color:var(--body)}
.asidebottom span{font-size:.75rem;color:var(--muted)}
body:not(.billing):not(.account-page)>main{padding-left:clamp(28px,3.7vw,58px);padding-right:clamp(28px,3.7vw,58px)}
header{border-color:var(--line);color:var(--body)}
header .pill{background:transparent;border-color:var(--line-strong);color:var(--body);font-size:.78rem;padding:7px 14px;text-decoration:none}
header .pill:hover{background:#fff;border-color:var(--blue)}
.muted{color:var(--muted)}
.intro{margin:42px 0 34px;gap:24px}
.intro h1.brand-slogan{max-width:790px;font-size:clamp(2.1rem,3.5vw,3.05rem);line-height:1.13;letter-spacing:-.04em;margin:15px 0 18px}
.intro p{font-size:1rem;line-height:1.7}
.yearbadge{font-family:var(--serif);font-size:3.7rem;color:#899aaf;letter-spacing:-.08em}
.yearbadge span{font-family:var(--sans);color:var(--muted);font-size:.7rem;letter-spacing:.08em;line-height:1.6}
/* A quiet, editorial feature with the existing mathematical demonstration. */
.feature{background:var(--navy);border:1px solid var(--navy);border-radius:16px;padding:34px 38px;gap:32px;box-shadow:var(--shadow-lift)}
.feature h2{font-family:var(--serif);font-size:2.6rem;font-weight:400;color:#fff;line-height:1.1;letter-spacing:-.035em;margin:17px 0}
.feature p{color:#d0dae6;font-size:1rem}
.feature .eyebrow{color:#bbcadb;font-size:.7rem}
.featuremeta{font-size:.7rem;color:#adbed3;letter-spacing:.07em}
.white,.offer-cta{background:#f3eee3;color:var(--navy);border:1px solid #f3eee3;border-radius:8px;font-size:.9rem;font-weight:600;padding:12px 18px;box-shadow:0 3px 8px rgb(0 0 0 / 6%)}
.white:hover,.offer-cta:hover{background:var(--accent-action-hover);border-color:var(--accent-action-hover);transform:translateY(-1px)}
.formula-art{border-left:1px solid rgb(255 255 255 / 12%);background-image:linear-gradient(#ffffff06 1px,transparent 1px),linear-gradient(90deg,#ffffff06 1px,transparent 1px);background-size:30px 30px;border-radius:0 8px 8px 0;padding:18px 12px;gap:20px}
.formula-art .formula{font-family:Georgia,serif;font-size:1.65rem;letter-spacing:0;color:#f6f7fb;text-align:center}
.formula-art .square{transform:none;gap:3px;border:1px solid #ffffff30;padding:5px;border-radius:4px;width:190px;height:190px}
.square div{background:#dce5f1;color:#223b5e}
.square div:nth-child(2),.square div:nth-child(3){background:#9fb6d3;color:#192e4c}
.square div:last-child{background:#e8d9b9;color:#574426}
.formula-art>span{font-size:.78rem;color:#c0cddf}
/* Catalogue: consistent cards with clear chapter numbering and restrained lift. */
.course-picker{margin:42px 0 25px;gap:26px}
.course-picker h2{font-family:var(--serif);font-weight:500;font-size:2rem;letter-spacing:-.03em;margin:6px 0}
.course-picker p{color:var(--body);font-size:.95rem}
.picker-controls label{font-size:.875rem;color:var(--body);font-weight:600}
.picker-controls select{border-color:var(--line-strong);color:var(--ink);border-radius:8px;min-height:45px;padding:10px 35px 10px 14px;box-shadow:0 2px 5px rgb(20 36 60 / 2%)}
.catalogue-meta{color:var(--muted);font-size:.82rem;margin:30px 0 24px}
.chapter-group{margin-bottom:38px}
.sectionhead{margin-bottom:18px;gap:18px}
.sectionhead h2{font-size:1.23rem;font-weight:600}
.sectionhead span{font-size:.8rem;color:var(--muted)}
.cards{gap:20px;align-items:stretch}
.card{padding:25px 23px 21px;border:1px solid var(--line);border-radius:12px;background:var(--surface);box-shadow:var(--shadow);min-width:0}
.card:hover{border-color:#a6b8cf;box-shadow:var(--shadow-lift);transform:translateY(-3px)}
.cardtop{gap:12px;margin-bottom:23px}
.symbol,.card:nth-child(2n) .symbol{background:var(--tint);color:var(--blue);border:1px solid #e0e7f0;width:44px;height:44px;border-radius:9px;font-size:1.5rem}
.cardnum{color:var(--muted);font-size:.75rem}
.card h3{font-size:1.16rem;line-height:1.4;letter-spacing:-.015em;margin:0 0 12px}
.card p{font-size:.9rem;line-height:1.65;color:var(--muted);margin-bottom:24px}
.cardfoot{border-color:var(--line);gap:10px;flex-wrap:wrap;padding-top:15px;line-height:1.55}
.cardfoot span{font-size:.75rem;color:var(--muted)}
.cardfoot span:last-child{color:var(--blue);font-weight:600}
.secondary-link,.secondary,.dashboard-years a{background:#fff;border:1px solid var(--line-strong);border-radius:8px;padding:11px 16px;color:var(--blue);font-size:.875rem;font-weight:600;white-space:normal;line-height:1.55;text-decoration:none}
.secondary-link:hover,.secondary:not(:disabled):hover,.dashboard-years a:hover{background:#f3f6fa;border-color:#8da5c3;color:var(--navy)}
.topic-resource-links .secondary-link{font-size:.875rem}
#year-progress>.secondary-link{background:transparent}
.curriculum-note,.release-note,.planned-message{background:#eef1f5;border-color:#8da5c3;border-radius:9px;color:var(--body)}
.tutor-banner{background:#edf1f6;border:1px solid #dce3ed;border-radius:14px;padding:32px;margin-top:46px}
.tutor-banner h2{font-family:var(--serif);font-weight:500;font-size:2rem;line-height:1.2;letter-spacing:-.03em}
.tutor-banner p{font-size:1rem;color:var(--body)}
.offer{background:var(--navy);border:1px solid var(--navy);border-radius:14px;padding:32px 34px;margin-top:28px}
.offer h2{font-family:var(--serif);font-weight:500;font-size:1.9rem;color:#fff}
.offer .eyebrow{color:#c0ccdc}
.offer p,.offer small,.payment-brands{color:#cbd6e4}
.price{font-size:2.15rem;font-weight:600;font-variant-numeric:tabular-nums;letter-spacing:-.03em}
footer{border-color:var(--line);font-size:.78rem;padding-top:25px;margin-top:42px;color:var(--muted)}
footer p{color:var(--muted);line-height:1.75}
.footer-slogan{font-family:var(--serif);font-size:1.1rem;color:var(--ink);letter-spacing:-.015em}
.footer-links{gap:14px 24px}
.footer-links a{font-size:.83rem;text-decoration:none;color:var(--body)}
.footer-links a:hover{color:var(--blue);text-decoration:underline}
/* Courses, questions and worked examples share one calm reading surface. */
.billing-shell,.account-shell{max-width:1180px}
.billing-header,.account-header{border-color:var(--line);min-height:100px}
.return-link,.account-header nav a{color:var(--body);font-size:.875rem}
.billing .billing-main{padding-top:45px}
.number-lesson{max-width:900px!important}
.number-lesson h1{font-size:clamp(2rem,3.5vw,2.7rem);margin:16px 0 20px}
.number-lesson .billing-intro{font-size:1.13rem;line-height:1.75;margin-bottom:27px;color:var(--body)}
.number-lesson h2{font-size:1.5rem;font-weight:600;line-height:1.4;letter-spacing:-.02em}
.number-lesson h3{font-size:1.13rem;line-height:1.45}
.number-lesson p,.number-lesson li{font-size:1.0625rem;line-height:1.8;color:var(--body)}
.number-lesson .number-note,.number-lesson .suite-note,.cycle-allocation{font-size:.875rem;color:var(--muted)}
.foundation-links{gap:10px;flex-wrap:wrap;margin:23px 0}
.number-formula{font-family:Georgia,serif;background:var(--tint);color:#223d61;border:1px solid #dfe6ef;border-radius:10px;line-height:1.75;padding:23px 25px;font-size:1.5rem}
.math{color:#223d61;line-height:1.6}
.number-examples{color:var(--blue)}
.number-explorer,.foundation-card,.foundation-example,.number-question,.walkthrough,.suite-chapter-list>a,.account-card,.account-resource,.private-formats section,.checkout-content{background:#fff;border-color:var(--line);border-radius:12px;box-shadow:var(--shadow)}
.number-question{padding:27px;margin:22px 0}
.number-question legend{font-size:1.12rem;line-height:1.75;font-weight:600;color:var(--ink)}
.number-question legend>span{font-size:.75rem;letter-spacing:.12em;color:var(--blue);margin-bottom:6px}
.answer-options{gap:12px;margin:21px 0 4px}
.answer-options label{background:#fbfcfe;border-color:var(--line);border-radius:8px;padding:14px 16px;color:var(--body);font-size:1rem}
.answer-options label:hover{background:#f1f5fa;border-color:#a4b7ce}
.answer-options label:has(input:checked){background:#edf3fa;border-color:var(--blue);box-shadow:inset 0 0 0 1px var(--blue);color:var(--navy)}
.answer-options input,.payment-choice input,input[type=range],progress{accent-color:var(--blue)}
.exercise-summary,.foundation-summary,.theory,.cycle-toc{background:#edf1f6;border-color:#d9e2ed;color:var(--body)}
.cycle-toc{border-radius:12px;padding:25px 28px}
.cycle-toc a{color:var(--blue)}
.cycle-figure,.foundation-figure{background:#fff;border-color:var(--line);border-radius:12px}
.cycle-figure svg{border:0;background:transparent}
.cycle-figure figcaption{color:var(--muted);font-size:.9rem;line-height:1.7}
.cycle-section{border-color:var(--line)}
.walkthrough{padding:26px}
.walkthrough li{background:#eff3f8;border-radius:8px;padding:20px}
.walkthrough .step-math{color:#223d61;font-size:1.5rem}
.step-controls button{background:white;border-color:var(--line-strong);color:var(--blue);border-radius:8px;min-height:42px;font-size:.875rem}
.step-controls button:not(:disabled):hover{background:var(--tint);border-color:var(--blue)}
.step-controls output{color:var(--muted);font-size:.875rem}
.suite-formulas>div,.suite-decision>section,.course-total>span{border-color:var(--line);background:var(--tint);color:var(--body)}
.suite-formulas b,.suite-decision h3,.suite-chapter-list span{color:var(--blue)}
.suite-chapter-list{gap:22px}
.suite-chapter-list>a{padding:27px;text-decoration:none}
.suite-chapter-list>a:hover,.account-resource:hover{border-color:#a6b8cf;box-shadow:var(--shadow-lift);transform:translateY(-2px)}
.suite-chapter-list h2{font-family:var(--serif);font-size:1.65rem;font-weight:500;line-height:1.3}
.suite-chapter-list p{font-size:.95rem}
.course-total>span{font-size:.875rem;border:1px solid #dce4ee;border-radius:7px;padding:9px 14px}
.foundation-next{border-color:var(--line);gap:20px}
.foundation-next a{color:var(--blue);font-size:.9rem;line-height:1.6}
/* Keep dynamic tables readable before and after client-side decoration. */
table{border:1px solid var(--line);border-radius:8px;overflow:hidden;background:var(--surface);color:var(--ink)}
th{background:var(--tint);color:var(--ink)}
th,td{border-color:var(--line)}
.foundation-hero,.interval-hero{background:var(--navy);border-radius:12px;color:#fff}
.number-lesson .foundation-hero p,.number-lesson .interval-hero p{color:#d0dbea}
.foundation-hero h2,.interval-hero h2{color:#fff}
.foundation-hero .eyebrow,.interval-hero .eyebrow{color:#bccbde}
.foundation-hero .number-formula,.interval-hero .number-formula{color:#f1e9d9;background:#ffffff0c;border-color:#ffffff20}
/* Dialogs retain the original course and demo controls. */
dialog{background:var(--paper);color:var(--ink);border:1px solid var(--line);border-radius:16px;box-shadow:0 24px 80px rgb(8 23 43 / 22%);padding:32px}
dialog::backdrop{background:rgb(12 25 45 / 62%);backdrop-filter:blur(5px)}
.modalhead{color:var(--muted);font-size:.8rem}
.close{background:#e9edf3;color:var(--ink);width:40px;height:40px}
.close:hover{background:#dce4ef}
.lesson-title{font-family:var(--serif);font-size:2rem;font-weight:500;line-height:1.2}
.chapter-path section{background:var(--tint);color:var(--ink);border:1px solid var(--line);border-radius:10px;padding:22px}
.chapter-path .eyebrow{font-size:.75rem}
.chapter-path h3{color:var(--ink)}
.chapter-path p,.topic-list p{font-size:.9rem;color:var(--body)}
.topic-list>div{border-color:var(--line);padding:19px 0}
.topic-list>div>b{color:var(--blue);font-weight:500}
.topic-list strong{font-weight:600}
.check,.account-button{background:var(--blue);color:white;border-color:var(--blue);border-radius:8px}
.check:hover,.account-button:not(.secondary):hover{background:var(--blue-hover)}
.good,.number-question .good{color:#276448}
.bad,.number-question .bad{color:#a13d33}
summary{color:var(--blue)}
.tabs{border-color:var(--line);gap:9px}
.tabs button{background:#e9eef5;color:var(--body);border-radius:8px}
.tabs button[aria-selected=true]{background:var(--navy);color:white}
.visualstage{background:#edf2f7;border:1px solid var(--line);border-radius:12px}
.visualstage p{color:var(--body)}
.exercise p{color:var(--body)}
/* Supporting pages and the prepared subscription flow. */
.teacher-intro,.experience-panel,.account-art,.dashboard-course,.billing .order-summary{background:var(--navy);border-radius:14px}
.teacher-intro h2,.experience-panel strong,.dashboard-course h2,.order-summary h2{color:white}
.teacher-intro p,.experience-panel p,.dashboard-course p,.account-art p,.order-summary p,.summary-line>span{color:#cbd6e4}
.teacher-monogram{background:#e6dfcf;color:var(--navy)}
.experience-panel>span{font-family:var(--serif);color:#e6d5b4;letter-spacing:-.06em}
.about-lead{font-family:var(--serif);font-size:1.6rem;color:var(--ink)}
.price-pending{border-color:var(--line);color:var(--ink)}
.private-formats li{color:var(--body)}
.order-summary .eyebrow,.dashboard-course .eyebrow{color:#b9c9dd}
.subscription-price{font-size:3.5rem;font-weight:500;letter-spacing:-.04em;font-variant-numeric:tabular-nums}
.payment-choice{border-color:var(--line-strong);border-radius:10px}
.payment-choice:has(input:checked){background:#edf3fa;border-color:var(--blue)}
.payment-label>span,.method-explanation{color:var(--body)}
.choice-mark{color:var(--blue)}
.method-explanation,.subscription-account,.account-notice{background:#f0f3f7;border-color:var(--line);color:var(--body)}
.billing-faq summary{color:var(--ink)}
.subscription-account a,.account-row a,.account-card p a,.account-preview-link,.account-resource>span{color:var(--blue)}
.order-summary #pay-button{background:#d5dce5;color:#4d5b70;opacity:1}
.demo-link{color:#dfd2b7}
.account-fields input,.account-fields select{background:#f4f5f7;border-color:#d1d9e3;color:#59667a;-webkit-text-fill-color:#59667a}
.account-fields label{color:var(--body)}
.account-fields button{background:#e4e9ef;border-color:#cdd6e2;color:#5a687b}
.account-tabs{background:#eef1f6;border-radius:9px}
.account-tabs a{color:var(--muted)}
.account-tabs a[aria-current=page]{color:var(--navy);box-shadow:var(--shadow)}
.account-badge{background:var(--tint);color:var(--body);font-size:.78rem}
.account-badge::before{background:var(--blue)}
.account-art strong,.dashboard-course .course-symbols{color:#e6d5b4}
.account-art small{color:#b9c9dd;font-size:.75rem}
.account-price{color:var(--navy);font-weight:500}
.account-steps li,.account-status,.dashboard-help{border-color:var(--line)}
.account-steps li::before,.account-resource .resource-index{color:var(--blue)}
.account-button.secondary{background:white;color:var(--blue);border-color:var(--line-strong)}
.dashboard-course .account-button{background:#f3eee3;color:var(--navy)}
.dashboard-course .account-button:hover{background:white;color:var(--navy)}
/* Responsive refinements preserve the mobile menu and the existing content order. */
@media(min-width:721px) and (max-height:790px){aside.site-sidebar{padding-top:23px;padding-bottom:20px}.site-sidebar .school{margin-bottom:20px}.site-sidebar .years{margin-top:20px}.asidebottom{padding-top:15px}}
@media(min-width:721px){aside.site-sidebar{overflow-y:auto}.site-sidebar .asidebottom{margin-top:auto}}
@media(max-width:1100px) and (min-width:721px){aside.site-sidebar{width:210px;padding-left:18px;padding-right:18px}.site-sidebar .brand{font-size:1.48rem}.formula-art .formula{font-size:1.15rem}.formula-art{padding:16px 6px}.formula-art .square{width:160px;height:160px}.feature{padding:28px;gap:20px;grid-template-columns:minmax(0,1fr) minmax(0,1fr)}.feature h2{font-size:2.2rem}.card{padding:22px 19px}.intro .yearbadge{display:none}}
@media(max-width:720px){
 aside.site-sidebar{position:static;width:auto;inset:auto;padding:18px 20px 14px;border-right:0;border-bottom:1px solid var(--line);background:white}
 .brand,.site-sidebar .brand{font-size:1.6rem}
 .site-sidebar .school,.site-sidebar .years,.site-sidebar .asidebottom{display:none}
 .site-sidebar .brand{margin-bottom:13px}
 .site-sidebar>nav:not(.years){gap:4px 8px;flex-wrap:wrap;justify-content:flex-start}
 .site-sidebar .nav,.site-sidebar .nav:last-of-type{font-size:.875rem!important;line-height:1.6;min-height:38px;padding:8px 10px!important}
 .site-sidebar .nav[href="connexion.html"]{background:#edf1f7;color:var(--navy)}
 .site-sidebar .about-nav{font-size:.83rem!important;margin-top:8px!important;padding-left:10px!important}
 body:not(.billing):not(.account-page)>main{margin-left:0;padding-left:20px;padding-right:20px}
 header{height:auto;min-height:76px;gap:12px;flex-wrap:wrap;padding:17px 0;font-size:.83rem}
 header .pill{font-size:.75rem;padding:6px 10px}
 .intro{margin:30px 0 26px}.intro h1.brand-slogan{font-size:2.15rem;margin-top:13px}.intro p{font-size:1rem}
 .intro .yearbadge{display:none}
 .feature{padding:27px 24px;gap:22px;border-radius:13px}
 .feature h2{font-size:2.15rem}.feature p{font-size:1rem}.feature .eyebrow{font-size:.7rem}
 .formula-art{border-left:0;border-top:1px solid #ffffff20;padding:25px 5px 8px}.formula-art .formula{font-size:1.4rem}
 .course-picker{margin-top:33px}.course-picker h2{font-size:1.8rem}.picker-controls select{font-size:1rem}
 .catalogue-meta{font-size:.83rem;gap:6px;margin:24px 0}.cards{gap:15px}.card{padding:24px}
 .card h3{font-size:1.2rem}.cardtop{margin-bottom:20px}.cardfoot{font-size:.8rem}.cardfoot span{font-size:.78rem}
 .sectionhead{gap:12px;align-items:baseline}.sectionhead h2{font-size:1.15rem}
 .tutor-banner,.offer{padding:26px 24px}.tutor-banner h2,.offer h2{font-size:1.8rem}
 .billing-header,.account-header{min-height:90px;gap:12px;padding:18px 0}
 .billing .billing-main{padding-top:30px}.billing h1,.number-lesson h1{font-size:2rem;letter-spacing:-.035em}
 .number-lesson h2{font-size:1.4rem}.number-lesson p,.number-lesson li{font-size:1rem}
 .number-formula{font-size:1.27rem;padding:19px 18px}
 .number-question,.walkthrough{padding:21px}.number-question legend{font-size:1.05rem}.answer-options label{padding:13px;font-size:1rem}
 .suite-chapter-list{gap:16px}.suite-chapter-list>a{padding:23px}.suite-chapter-list h2{font-size:1.5rem}
 .secondary-link{font-size:.875rem}.foundation-next{flex-wrap:wrap}.foundation-next a{white-space:normal}
 .cycle-toc{padding:22px}.cycle-section .number-formula{font-size:1.25rem}
 dialog{padding:24px 20px;border-radius:13px}.lesson-title{font-size:1.8rem}.topic-resource-links .secondary-link{font-size:.875rem}
 .step-controls{flex-wrap:wrap}.step-controls button{min-height:44px}
 .footer-links a{font-size:.875rem}.footer-slogan{font-size:1.05rem}
}
@media(prefers-reduced-motion:reduce){html{scroll-behavior:auto}*,*::before,*::after{transition:none!important;animation:none!important;scroll-behavior:auto!important}}
@media print{body,body.billing,body.account-page{background:#fff}*{box-shadow:none!important}.number-question,.cycle-figure{break-inside:avoid}a{color:#192b45}.step-controls{display:none}.walkthrough li[hidden]{display:list-item!important}}

/* Selected logo: original uploaded image, framed without modifying its pixels. */
.brand,.site-sidebar .brand{display:block;position:relative;width:336px;max-width:100%;aspect-ratio:1184 / 288;height:auto;overflow:hidden;flex-shrink:0;line-height:0;letter-spacing:0;mix-blend-mode:multiply}
.brand .brand-image{display:block;position:absolute;width:129.72973%;max-width:none;height:auto;left:-14.864865%;top:-54.166667%;margin:0;border:0;border-radius:0}
.site-sidebar .brand{width:calc(100% + 24px);max-width:none;margin-left:-12px;background:var(--surface);mix-blend-mode:normal}
/* Lift the image background to white; multiply blends it into each page surface. */
.brand .brand-image{filter:brightness(1.04) contrast(1.08)}
@media(max-width:720px){.brand,.site-sidebar .brand{width:290px;max-width:100%}.billing-header .brand,.account-header .brand{width:min(290px,100%)} }
@media(max-width:720px){.site-sidebar .brand{width:290px;max-width:100%;margin-left:0}}

/* Pilot resource: a chapter formula sheet, currently available for I only. */
.chapter-with-formulary{display:flex;flex-direction:column;gap:9px;min-width:0}
.chapter-with-formulary>.card{width:100%;flex:1}
.chapter-formulary-link{display:flex;align-items:center;justify-content:center;gap:12px;border:1px solid var(--line-strong);background:var(--tint);color:var(--blue);border-radius:8px;padding:11px 14px;font-size:.9375rem;font-weight:600;text-decoration:none;line-height:1.5}
.chapter-formulary-link:hover{background:#e2eaf5;border-color:var(--blue)}
.chapter-formulary-link>span:first-child{font-family:var(--serif);font-size:1.35rem;line-height:1}
.chapter-formulary-entry{margin:20px 0}

.suite-chapter-list>.annual-formulary-card>a:first-child{display:block;flex:1;background:#fff;border:1px solid var(--line);border-radius:12px;padding:27px;text-decoration:none;box-shadow:var(--shadow)}
.suite-chapter-list>.annual-formulary-card>a:first-child:hover{border-color:#a6b8cf;box-shadow:var(--shadow-lift)}

/* Current lesson remains a working jump to the start of its theory. */
.foundation-links a[aria-current="page"],.interval-links a[aria-current="page"]{background:var(--tint);border-color:var(--blue);color:var(--navy)}
.number-lesson h2[id]{scroll-margin-top:24px}
/* Long lesson expressions must remain readable at narrow widths and larger text sizes. */
.number-lesson .math,.number-lesson .foundation-result,.number-lesson .proof-conclusion{overflow-wrap:anywhere}
.number-lesson .suite-formulas>div,.number-lesson .suite-decision>section{min-width:0}
.answer-options label:has(input:focus-visible){outline:3px solid #668bb7;outline-offset:3px}

/* Direct contact links on the main site pages. */
.billing-header .header-links{display:flex;align-items:center;justify-content:flex-end;gap:12px 22px;flex-wrap:wrap}
.billing-header:has(.header-links){height:auto;min-height:105px;gap:16px;flex-wrap:wrap;padding-top:18px;padding-bottom:18px}
.header-links a{font-size:.875rem;text-decoration:none}
.header-links a:hover{text-decoration:underline}
.footer-contact{font-size:.875rem;overflow-wrap:anywhere;margin:20px 0}
.footer-contact a{display:inline-block;max-width:100%;padding:12px 18px;border:1px solid var(--navy);border-radius:8px;background:var(--navy);color:#fff;font-size:inherit;font-weight:500;line-height:1.5;text-decoration:none}
.footer-contact a:hover{background:var(--navy);color:#fff;text-decoration:underline;text-underline-offset:4px}
.footer-contact a:focus-visible{outline:3px solid #668bb7;outline-offset:4px}

/* Visual refinement: shared by the existing lessons, catalogue and account pages. */
/* 1. Typography: a consistent reading rhythm and well-spaced headings. */
body{font-kerning:normal;text-rendering:optimizeLegibility}
h1,.billing h1,.number-lesson h1{font-weight:400;letter-spacing:-.025em;line-height:1.2}
.home-marketing .home-intro h1.brand-slogan{letter-spacing:-.03em;line-height:1.16}
.number-lesson h2{letter-spacing:-.015em;line-height:1.4}
.number-lesson h3,.card h3,.account-resource h3{letter-spacing:-.01em}
.card p,.suite-chapter-list p,.chapter-path p{font-size:1rem;line-height:1.7}
.cardfoot span,.cardfoot span:last-child,.cardnum,.sectionhead>span,.catalogue-meta{font-size:.875rem}
.price,.subscription-price,.progress-metrics strong,.exam-score,.error-score{font-variant-numeric:lining-nums tabular-nums}
.number-lesson p,.billing-intro,.home-lead{text-wrap:pretty}

/* 2–3. Navy surfaces and restrained champagne accents. Logo colors stay intact. */
.feature,.offer,.teacher-intro,.experience-panel,.account-art,.dashboard-course,.billing .order-summary{background:linear-gradient(135deg,#14243c 0%,#1d3553 100%);border:1px solid #2b415e;box-shadow:var(--shadow-lift)}
.feature .eyebrow,.offer .eyebrow,.account-art .eyebrow,.dashboard-course .eyebrow{color:var(--champagne)}
.method-number,.home-method .method-number{color:var(--champagne)}
.cardnum{color:var(--gold-ink);font-weight:600;letter-spacing:.06em}
.site-sidebar .nav.active{background:#edf1f7;box-shadow:inset 3px 0 0 var(--gold);color:var(--navy)}
.site-sidebar .year.selected b{border-color:var(--navy);box-shadow:0 0 0 3px var(--champagne-soft)}
.teacher-monogram{background:var(--champagne-soft);color:var(--navy);border:1px solid var(--champagne)}
.home-proof{border-top-color:var(--champagne);border-bottom-color:var(--line)}
.number-lesson>section>h2{border-left:3px solid var(--champagne);padding-left:16px}

/* 4. Breathing room, using the current sections and responsive grids. */
.number-lesson>section{margin-top:44px;margin-bottom:44px}
.number-lesson>section>h2{margin-bottom:20px}
.number-lesson>section>p{margin-top:16px;margin-bottom:16px}
.billing .billing-intro{line-height:1.8}
.chapter-group{margin-bottom:42px}
.sectionhead{margin-bottom:22px}
.foundation-links,.interval-links{gap:12px;margin-top:26px;margin-bottom:30px}
.account-card h2,.private-formats h2{line-height:1.3}

/* 5. A shared, lighter card treatment; mathematical content retains its meaning. */
body :is(.card,.foundation-card,.foundation-example,.number-question,.number-explorer,.walkthrough,.account-card,.account-resource,.private-formats section,.checkout-content,.progress-card,.progress-review,.exam-card,.sheet-section){border-color:var(--line);border-radius:var(--radius-card);box-shadow:var(--shadow)}
.card{padding:28px 25px 24px}
.cardtop{margin-bottom:24px}
.cardfoot{margin-top:auto;padding-top:18px;border-color:#e8ebef}
.foundation-example,.foundation-card,.number-explorer,.walkthrough{padding:28px}
.number-question{padding:30px;margin:26px 0}
.number-question fieldset{min-width:0}
.suite-chapter-list>a{border-radius:var(--radius-card);padding:30px}
.progress-page .progress-metrics article{border-radius:var(--radius-card);box-shadow:var(--shadow);border-color:var(--line)}
.progress-page .progress-sheet-list article{border-radius:var(--radius-control);border-color:var(--line)}
.exam-card.exam-good{border-left-color:#187148}
.exam-card.exam-bad{border-left-color:#b52b3d}

/* 6. Matching button dimensions and clear primary/secondary emphasis. */
body :is(.check,.account-button,.home-primary,.white,.offer-cta,.secondary-link,.step-controls button,.exam-btn,.sheet-tabs a,.progress-link.primary){min-height:44px;border-radius:var(--radius-control);font-weight:600;font-size:.9375rem;line-height:1.5;white-space:normal}
body :is(.check,.home-primary,.exam-btn:not(.secondary),.progress-link.primary){background:var(--navy);border-color:var(--navy);color:#fff}
.account-page .account-button:not(.secondary){background:var(--navy);color:#fff}
.account-page .dashboard-course .account-button:not(.secondary){background:var(--champagne-soft);border-color:var(--champagne);color:var(--navy)}
body :is(.secondary-link,.step-controls button,.sheet-tabs a,.exam-btn.secondary){background:var(--surface);border-color:var(--line-strong);color:var(--navy)}
.white,.offer-cta{background:var(--accent-action-fill);border-color:var(--accent-action-fill);color:var(--accent-action-ink);-webkit-text-fill-color:var(--accent-action-ink)}
.white:hover,.offer-cta:hover{background:var(--accent-action-hover);border-color:var(--accent-action-hover)}
.picker-controls select,.progress-filter select,.error-toolbar select,.number-explorer select{border-radius:var(--radius-control);min-height:44px}

/* 7. One stroke weight and one scale for navigation icons and math badges. */
.site-sidebar .nav{display:flex;align-items:center;gap:11px;min-height:44px}
.site-sidebar .nav .nav-icon{display:block;flex:0 0 19px;width:19px;height:19px;background:none;border:0;border-radius:0;color:currentColor}
.site-sidebar .nav>span{min-width:0}
.symbol,.card:nth-child(2n) .symbol{width:46px;height:46px;border-radius:11px;background:#f0f3f8;border-color:#dbe3ed;font-family:var(--math);font-weight:400;color:var(--navy)}
.course-total>span,.account-badge{border-radius:var(--radius-control)}

/* 8. Better mathematical typesetting and quieter frames around existing graphs. */
.number-formula,.math,.foundation-result,.proof-conclusion,.walkthrough .step-math,.number-examples,.formula-art .formula,.billing .formula-sheet .sheet-formula,.billing .formula-sheet .sheet-key{font-family:var(--math);font-variant-numeric:lining-nums;letter-spacing:0}
.number-formula{background:#f0f3f7;border:1px solid #dce4ed;border-left:3px solid #b7c6d8;border-radius:var(--radius-control);padding:24px 26px;line-height:1.9}
.foundation-result{background:#f0f3f7;border:1px solid var(--line);border-radius:var(--radius-control);line-height:1.8}
.number-lesson .foundation-hero .number-formula,.number-lesson .interval-hero .number-formula{background:#ffffff0c;border-color:#ffffff26;color:#f1e9d9}
.proof-conclusion{background:var(--navy);color:#f3eee3;border:1px solid #304660;line-height:1.65}
.cycle-figure,.foundation-figure{padding:26px;border-radius:var(--radius-card);box-shadow:var(--shadow);border-color:var(--line)}
.cycle-figure svg,.foundation-figure svg{display:block;background:transparent;border:0}
.number-lesson .cycle-figure figcaption,.number-lesson .foundation-figure figcaption{border-top:1px solid var(--line);padding-top:16px;margin-top:18px;font-size:.9375rem;line-height:1.65;color:var(--body)}
.formula-art .square{box-shadow:0 10px 26px #07132640;border-color:#ffffff30;padding:6px}
.proof-chain>li::before{background:var(--champagne-soft);color:var(--gold-ink);border:1px solid var(--champagne)}
.number-lesson .number-formula sup,.number-lesson .math sup{font-size:.72em;line-height:0}

/* 9. Small, optional transitions; no delayed content or animated layout changes. */
.card,.account-resource,.suite-chapter-list>a,.answer-options label,.exam-option{transition:border-color .2s var(--ease),box-shadow .2s var(--ease),background-color .2s var(--ease),transform .2s var(--ease)}
.answer-options label{background:#fcfcfd;border-color:#d8e0ea;border-radius:var(--radius-control);padding:16px}
.answer-options label:has(input:checked){background:#edf3fa;border-color:var(--blue);box-shadow:inset 3px 0 0 var(--blue)}
.billing .exam-option[aria-pressed=true]{box-shadow:inset 3px 0 0 var(--blue)}
.number-question .exercise-feedback{border-radius:var(--radius-control);border-left-width:3px}
@media(prefers-reduced-motion:no-preference){
 .number-question .exercise-feedback:not(:empty),.error-feedback:not(:empty){animation:feedback-appear .18s ease-out}
 @keyframes feedback-appear{from{opacity:.25}to{opacity:1}}
}
@media(hover:hover) and (pointer:fine){
 .card:hover,.account-resource:hover,.suite-chapter-list>a:hover{transform:translateY(-2px);border-color:#a4b6cd;box-shadow:var(--shadow-lift)}
 body :is(.check,.home-primary,.exam-btn:not(.secondary),.progress-link.primary):not(:disabled):hover{background:var(--blue-hover);border-color:var(--blue-hover);box-shadow:0 4px 12px #14243c18}
 body :is(.secondary-link,.step-controls button,.sheet-tabs a,.exam-btn.secondary):not(:disabled):hover{background:#f0f3f8;border-color:#96aac3}
 .white:hover,.offer-cta:hover{background:var(--accent-action-hover);border-color:var(--accent-action-hover)}
}

/* 10. A clean closing panel around the existing footer and navy email link. */
body footer{background:var(--surface);border:1px solid var(--line);border-top:3px solid var(--navy);border-radius:0 0 var(--radius-card) var(--radius-card);padding:28px 30px;margin-top:48px;box-shadow:0 8px 24px #14243c04;font-size:.875rem}
body footer .footer-slogan{font-size:1.3rem;color:var(--navy);line-height:1.5;margin-top:0;margin-bottom:16px}
body footer>p:not(.footer-slogan):not(.footer-contact){font-size:.875rem;line-height:1.8;max-width:85ch}
body footer .footer-links{display:flex;align-items:center;flex-wrap:wrap;gap:8px 24px;margin-top:18px}
body footer .footer-links a{display:inline-flex;align-items:center;min-height:36px;font-size:.875rem;color:var(--body)}
body footer>span{display:block;border-top:1px solid var(--line);padding-top:16px;margin-top:20px;line-height:1.7;color:var(--muted)}
body footer .footer-contact{margin:20px 0 10px}
body footer .footer-contact a{min-height:44px;padding:13px 20px;font-size:.9375rem;background:var(--navy);border-color:var(--navy);color:#fff;box-shadow:0 3px 10px #14243c12}

/* Keep the existing breakpoints, accessible focus and paper-friendly lessons. */
@media(max-width:1100px) and (min-width:721px){.card{padding:24px 20px}.site-sidebar .nav{gap:8px}}
@media(max-width:720px){
 .site-sidebar .nav,.site-sidebar .nav:last-of-type{display:flex!important;gap:8px;min-height:44px}
 .site-sidebar .nav .nav-icon{width:17px;height:17px;flex-basis:17px}
 .card,.number-question,.foundation-example,.foundation-card,.number-explorer,.walkthrough,.suite-chapter-list>a{padding:22px 20px}
 .number-lesson>section{margin-top:34px;margin-bottom:34px}
 .number-lesson>section>h2{padding-left:12px;margin-bottom:17px}
 .number-formula{padding:19px 17px;font-size:1.25rem}
 .cycle-figure,.foundation-figure{padding:19px 16px}
 .chapter-group{margin-bottom:32px}
 body footer{padding:24px 20px;margin-top:36px}
 body footer .footer-links{gap:6px 18px}
 body footer .footer-slogan{font-size:1.15rem}
 body footer .footer-contact a{padding:12px 16px;max-width:100%;overflow-wrap:anywhere}
}
@media(prefers-reduced-motion:reduce){*,*::before,*::after{transition:none!important;animation:none!important;scroll-behavior:auto!important}}
@media print{
 body :is(.card,.foundation-card,.number-question,.number-formula,.cycle-figure,.foundation-figure){box-shadow:none}
 body footer{background:#fff;box-shadow:none;border-color:#bbb}
}

/* Fifteen finishing details, keeping the existing lessons and navigation. */
/* 1. Four year accents; labels remain the primary identifier. */
:root{--year-accent:#345d8f;--year-wash:#edf3fa}
[data-academic-year="1"],.year[data-year="1"]{--year-accent:#345d8f;--year-wash:#edf3fa}
[data-academic-year="2"],.year[data-year="2"]{--year-accent:#356778;--year-wash:#edf5f7}
[data-academic-year="3"],.year[data-year="3"]{--year-accent:#4d5683;--year-wash:#f0f0f8}
[data-academic-year="4"],.year[data-year="4"]{--year-accent:#3e536a;--year-wash:#eef2f5}
.site-sidebar .year[data-year] b{border-color:var(--year-accent);color:var(--year-accent);background:var(--year-wash)}
.site-sidebar .year[data-year].selected b{background:var(--year-accent);color:#fff}
#catalogue .symbol{background:var(--year-wash);border-color:var(--line);color:var(--year-accent)}
#catalogue .card:focus-visible{outline-color:var(--year-accent)}
body[data-academic-year] .course-total>span,body[data-academic-year] .suite-chapter-list>a>span{color:var(--year-accent);background:var(--year-wash)}
body[data-academic-year] .suite-chapter-list>a{border-top:2px solid var(--year-accent)}
.progress-page #progress-root{--blue:var(--year-accent)}

/* 2–3. Chapter labels and short champagne rules. */
.cardnum{display:inline-block;padding:5px 9px;border:1px solid #e5dac4;border-radius:6px;background:var(--champagne-soft);color:var(--gold-ink);font-size:.875rem;line-height:1.5;letter-spacing:.02em}
.cardtop{align-items:flex-start}
.cardtop .cardnum{max-width:calc(100% - 60px);text-align:right}
.chapter-group>.sectionhead{border-bottom:1px solid var(--line);padding-bottom:15px;position:relative}
.chapter-group>.sectionhead::after,.sheet-heading::after{content:"";position:absolute;bottom:-1px;left:0;width:44px;height:2px;background:var(--gold)}
.sheet-heading{position:relative}
.billing-header,.account-header{border-image:linear-gradient(to right,var(--champagne) 0 48px,var(--line) 48px) 1}

/* 4. A faint mathematical grid on a few existing navy panels. */
.feature,.offer,.teacher-intro{background-image:linear-gradient(90deg,#ffffff04 1px,transparent 1px),linear-gradient(#ffffff04 1px,transparent 1px),linear-gradient(135deg,#14243c,#1d3553);background-size:32px 32px,32px 32px,100% 100%}

/* 5–6. Key rules, methods and worked examples have distinct surfaces. */
.number-lesson .foundation-summary,.number-lesson .exercise-summary{background:#f1f4f8;border:1px solid #d8e1ed;border-top:3px solid var(--blue);padding:26px 28px;border-radius:var(--radius-card)}
.number-lesson .foundation-summary h2,.number-lesson .exercise-summary h2{border:0;padding-left:0;color:var(--navy);font-size:1.4rem;margin-top:0}
.number-lesson .foundation-summary p:last-child{margin-bottom:0}
.number-lesson .foundation-summary strong{color:var(--navy)}
.billing .formula-sheet .sheet-key{border-left:4px solid var(--champagne);box-shadow:0 4px 16px #14243c0c}
.number-lesson .theory,.number-lesson .suite-decision>section{background:#f0f4f9;border-left:3px solid var(--blue);border-radius:var(--radius-control)}
.number-lesson .foundation-example,.number-lesson .walkthrough{background:#fdfbf7;border:1px solid #e7decd;border-top:3px solid var(--gold)}
.number-lesson .walkthrough>h2,.number-lesson .foundation-example>h3{border-left:0;padding-left:0}
.number-lesson .walkthrough li{background:#fffdf9;border:1px solid #e9e0d0}
.number-lesson .foundation-example .math,.number-lesson .walkthrough .step-math{color:var(--navy)}

/* 7. Numbered reasoning steps; no explanation or answer is rewritten. */
.number-question[id^="corrige-"]>ol{counter-reset:reasoning;list-style:none;padding:0;margin:22px 0}
.number-question[id^="corrige-"]>ol>li{counter-increment:reasoning;position:relative;padding:0 0 18px 46px;margin:0;min-height:38px}
.number-question[id^="corrige-"]>ol>li::before{content:counter(reasoning);position:absolute;left:0;top:1px;width:28px;height:28px;display:grid;place-items:center;background:var(--champagne-soft);border:1px solid var(--champagne);border-radius:50%;font:600 .875rem/1 var(--sans);color:var(--gold-ink)}
.number-question[id^="corrige-"]>ol>li:not(:last-child)::after{content:"";position:absolute;left:14px;top:34px;bottom:5px;width:1px;background:#e2d6bf}
.number-question[id^="corrige-"]>ol>li:last-child{padding-bottom:0}
.proof-chain>li{border-color:var(--line);box-shadow:var(--shadow)}
.number-question[id^="corrige-"]>a:last-child{display:inline-block;font-size:.9375rem;margin-top:6px;text-underline-offset:4px}

/* 8–9. Consistent graph text and legible numeric tables. */
.cycle-figure svg text,.foundation-figure svg text,.interval-figure svg text{font-family:var(--sans)}
.cycle-figure svg,.foundation-figure svg,.interval-svg{shape-rendering:geometricPrecision}
.number-lesson figcaption{font-size:.9375rem;line-height:1.7}
.number-lesson figcaption strong{font-weight:600;color:var(--navy)}
.number-lesson table,.formula-sheet table{font-variant-numeric:lining-nums tabular-nums;line-height:1.65}
.number-lesson th,.formula-sheet th{font-size:.9375rem;font-weight:600;letter-spacing:.01em;background:var(--tint);color:var(--ink)}
.number-lesson td,.formula-sheet td{padding:12px 16px;border-bottom:1px solid var(--line);vertical-align:top}
.number-lesson tbody tr:nth-child(even),.formula-sheet tbody tr:nth-child(even){background:var(--tint)}
.number-lesson caption,.formula-sheet caption{font-size:.9375rem;line-height:1.6;color:var(--body);text-align:left;padding-bottom:12px}

/* 10. Real answer completion, kept distinct from correctness and mastery. */
.progress-page .progress-metrics article{border-top:3px solid var(--year-accent)}
.progress-page .progress-metrics strong{font-family:var(--serif);font-size:2.35rem;line-height:1.2;color:var(--navy)}
.progress-page .progress-metrics article>span{margin-top:6px}
.progress-page .progress-chapter[data-completion]{border-left:3px solid transparent;padding-left:16px}
.progress-page .progress-chapter[data-completion="started"]{border-left-color:var(--year-accent)}
.progress-page .progress-chapter[data-completion="answered"]{border-left-color:var(--gold)}
.progress-page .completion-label{display:inline-block;width:fit-content;padding:3px 9px;border-radius:5px;font-size:.875rem;line-height:1.5;color:var(--body);background:#edf1f5}
.progress-page [data-completion="started"] .completion-label{color:var(--year-accent);background:var(--year-wash)}
.progress-page [data-completion="answered"] .completion-label{color:var(--gold-ink);background:var(--champagne-soft)}
.progress-page .progress-sheet-list article[data-completion="answered"]{border-top:3px solid var(--gold)}
.progress-page .progress-sheet-list article[data-completion="started"]{border-top:3px solid var(--year-accent)}
.progress-page progress{height:9px}
.progress-page progress::-webkit-progress-value,.progress-page .progress-bar i{background:linear-gradient(90deg,var(--year-accent),#718ba7)}
.progress-page progress::-moz-progress-bar{background:var(--year-accent);border-radius:9px}

/* 11. Active resource and account tabs, with a discreet underline. */
.account-page .account-tabs{background:transparent;border-radius:0;border-bottom:1px solid var(--line);padding:0;gap:20px}
.account-page .account-tabs a{border-radius:0;background:transparent;padding:12px 4px;border-bottom:2px solid transparent;margin-bottom:-1px}
.account-page .account-tabs a[aria-current="page"]{border-bottom-color:var(--gold);color:var(--navy);box-shadow:none;font-weight:600}
.foundation-links a[aria-current="page"],.interval-links a[aria-current="page"],.power-nav a[aria-current="page"],.sheet-tabs a[aria-current="page"]{box-shadow:inset 0 -2px 0 var(--gold);background:#f3f6f9;border-color:var(--line-strong);color:var(--navy)}
.tabs button[aria-selected="true"]{box-shadow:inset 0 -3px 0 var(--champagne)}

/* 12. Form finishing, including the live account form. */
#account-service input:not([type="checkbox"]):not([type="radio"]):not([type="hidden"]),.account-fields input:enabled,.account-fields select:enabled{background:#fff;border:1px solid #b7c5d7;border-radius:var(--radius-control);min-height:44px;color:var(--ink);-webkit-text-fill-color:var(--ink);font-family:var(--sans);font-size:1rem}
#account-service input:focus-visible,.account-fields input:enabled:focus-visible,.account-fields select:enabled:focus-visible{outline:3px solid #c5d5e8;outline-offset:2px;border-color:var(--blue);box-shadow:0 0 0 1px var(--blue)}
#account-service input[aria-invalid="true"],.account-fields input[aria-invalid="true"]{border-color:#a63c43}
#account-service label,.account-fields label{font-size:.9375rem;font-weight:600;line-height:1.6;color:var(--body)}
.account-fields input:disabled,.account-fields select:disabled{background:#f2f4f7;color:var(--muted);-webkit-text-fill-color:var(--muted)}

/* 13. Quiet loading and error notices; icons carry no additional meaning. */
:is(#progress-root,#error-root,#exam-root)>p[role="status"],:is(#progress-root,#error-root,#exam-root)>p[role="alert"],#account-status{position:relative;padding:18px 20px 18px 52px;border:1px solid var(--line);border-radius:var(--radius-control);background:#f1f5fa;color:var(--body);font-size:1rem;line-height:1.7}
:is(#progress-root,#error-root,#exam-root)>p[role="status"]::before{content:"";position:absolute;left:20px;top:23px;width:16px;height:16px;border:2px solid #c7d5e5;border-top-color:var(--blue);border-radius:50%}
:is(#progress-root,#error-root,#exam-root)>p[role="alert"]{background:#fff5f4;border-color:#e6c3bf;color:#803b35}
:is(#progress-root,#error-root,#exam-root)>p[role="alert"]::before,#account-status::before{content:"i";position:absolute;left:19px;top:21px;display:grid;place-items:center;width:21px;height:21px;border:1px solid currentColor;border-radius:50%;font:600 .875rem/1 var(--serif)}
:is(#progress-root,#error-root,#exam-root)>p[role="alert"]::before{content:"!"}

/* 14. Fit the same content comfortably on narrow screens. */
@media(max-width:720px){
 .number-lesson h1,.billing h1,.account-page h1{font-size:clamp(1.8rem,6.5vw,2.2rem);line-height:1.24;overflow-wrap:anywhere}
 .number-lesson>section>h2{line-height:1.4}
 .number-lesson .foundation-summary,.number-lesson .exercise-summary{padding:22px 20px}
 .number-question[id^="corrige-"]>ol>li{padding-left:39px}
 .number-lesson td,.formula-sheet td{padding:10px 12px}
 .progress-page .progress-chapter[data-completion]{padding-left:10px}
 .progress-page .progress-metrics strong{font-size:1.85rem}
 .account-page .account-tabs{gap:12px}
 .cardtop{gap:12px}.cardnum{padding:4px 7px;letter-spacing:0}
 .number-lesson .foundation-table,.number-lesson .sheet-table{max-width:100%;overflow-x:auto}
 .number-lesson :is(.number-formula,.step-math,.proof-conclusion){overflow-wrap:anywhere}
}

/* Editorial details: retain the established layout and original identity. */
.visually-hidden{position:absolute!important;width:1px!important;height:1px!important;padding:0!important;margin:-1px!important;overflow:hidden!important;clip-path:inset(50%)!important;white-space:nowrap!important;border:0!important}
.billing h1:has(.chapter-number){margin-top:22px;max-width:24ch}
.chapter-number{display:block;width:fit-content;margin-bottom:12px;padding:0 0 7px;border-bottom:2px solid var(--champagne);font:600 .875rem/1.5 var(--sans);letter-spacing:.12em;color:var(--blue)}
.chapter-heading-text{display:block;text-wrap:balance}
.billing-intro{max-width:76ch;text-wrap:pretty}
mark.concept-keyword{color:inherit;background:linear-gradient(transparent 48%,var(--champagne) 48%,var(--champagne) 92%,transparent 92%);padding:0 .12em;box-decoration-break:clone;-webkit-box-decoration-break:clone}
.number-lesson .definition-panel{margin:24px 0;padding:18px 24px;border-left:3px solid var(--navy);border-radius:0 8px 8px 0;background:#f1f5f9}
.definition-label{font:600 .75rem/1.6 var(--sans);letter-spacing:.12em;text-transform:uppercase;color:var(--blue)}
.number-lesson .definition-panel p{margin:8px 0 0;color:var(--ink)}
.formula-sheet .sheet-definitions>div{border-left:2px solid var(--line-strong);padding-left:18px}
.formula-sheet .sheet-definitions dt{color:var(--navy);letter-spacing:.01em}
.number-lesson .math-condition{margin:8px 0 22px;padding-left:16px;border-left:2px solid var(--champagne);font:400 .9375rem/1.7 var(--sans);color:var(--body)}
.number-question[id^="corrige-"]>.number-formula{width:fit-content;max-width:100%;margin:20px 0 24px;padding:16px 22px;border:1px solid #aebfd1;border-radius:8px;background:#f5f8fb;color:var(--navy);box-shadow:inset 3px 0 0 var(--navy);font-weight:500}
.typeset-formula{max-width:100%;overflow-x:auto;overscroll-behavior-x:contain}
.typeset-formula math{font-family:"Cambria Math","STIX Two Math",math;font-size:1.2em;math-style:normal;line-height:1.8;padding:6px 0;white-space:nowrap}
.formula-sheet .sheet-formula .typeset-formula{padding:8px 0}
.proof-end{display:inline-block;margin-left:.6em;color:var(--navy);font-family:var(--serif);font-size:1.25em;font-weight:600;vertical-align:baseline}
:where(.billing-main,.number-lesson,.account-page) :is(p,li,td,dd)>a:not([class]),.number-question>a:not([class]),.source-list>a{color:var(--blue);text-decoration:underline;text-decoration-thickness:1px;text-underline-offset:.22em;text-decoration-color:#aabacf;transition:text-decoration-color .16s ease}
:where(.billing-main,.number-lesson,.account-page) :is(p,li,td,dd)>a:not([class]):hover,.number-question>a:not([class]):hover,.source-list>a:hover{text-decoration-color:currentColor}
.billing-header .return-link{display:inline-flex;align-items:center;gap:8px;line-height:1.5}
.return-link .return-icon{display:block;flex:0 0 20px;width:20px;height:20px;padding:0;border:0;border-radius:0;background:none;box-shadow:none;transition:transform .16s ease}
.return-link:hover .return-icon{transform:translateX(-2px)}
.card h3,.course-card h3,.chapter-group h3,.account-resource h3{text-wrap:balance;hyphens:auto}
.card .optional-badge{align-self:flex-start;display:inline-block;width:fit-content;margin:-2px 0 14px;padding:3px 9px;border:1px solid #d8c69e;border-radius:4px;background:var(--champagne-soft);color:var(--gold-ink);font:500 .75rem/1.5 var(--sans);letter-spacing:.04em}
.editorial-price{display:flex;flex-wrap:wrap;align-items:baseline;column-gap:.35rem;row-gap:0;white-space:normal}
.editorial-price .price-amount{font:500 clamp(2.75rem,4vw,3.5rem)/1.1 var(--serif);letter-spacing:-.04em;color:inherit}
.editorial-price .price-currency{font:500 1rem/1.4 var(--sans);letter-spacing:.04em;color:#edf2f8}
.editorial-price .price-period{flex-basis:100%;margin-top:7px;font:400 .9375rem/1.5 var(--sans);letter-spacing:0;color:#cbd6e4}
.teacher-intro{padding:36px;gap:30px;align-items:center}
.teacher-intro .teacher-monogram{width:96px;height:96px;font:400 3.5rem/1 var(--serif);outline:1px solid #d8c69e66;outline-offset:6px}
.teacher-intro h2{font:400 clamp(1.9rem,3vw,2.5rem)/1.2 var(--serif);letter-spacing:-.02em;margin-bottom:16px}
.teacher-intro .teacher-experience{padding-bottom:16px;margin-bottom:16px;border-bottom:1px solid #ffffff26}
.teacher-intro .teacher-experience b{font-weight:500}
.teacher-intro .experience-years{color:var(--champagne);font-size:1.35em;font-variant-numeric:lining-nums}
.number-lesson p.teacher-tip{position:relative;margin:24px 0;padding:18px 22px 18px 26px;border-left:3px solid var(--gold);background:#fffaf0;border-radius:0 8px 8px 0;color:var(--body);font-family:var(--serif);font-size:1.125rem;line-height:1.75}
@media(max-width:720px){
 .billing h1:has(.chapter-number){margin-top:18px}.chapter-number{margin-bottom:8px}
 .teacher-intro{gap:20px;padding:26px;flex-wrap:wrap}
 .teacher-intro .teacher-monogram{width:68px;height:68px;font-size:2.5rem}
 .teacher-intro>div{flex:1 1 230px;min-width:0}
 .number-lesson .definition-panel{padding:16px 18px}
 .number-question[id^="corrige-"]>.number-formula{padding:14px 18px}
 .typeset-formula math{font-size:1.05em}
}
@media(prefers-reduced-motion:reduce){.return-link:hover .return-icon{transform:none}}

/* 15. A4 handouts: flowing sections, readable equations and intact worked steps. */
@page{size:A4;margin:17mm 16mm 18mm}
@media print{
 html{font-size:11pt;scroll-padding:0}
 body,body.billing,body.account-page{background:#fff!important;color:#182438!important;font-size:11pt;line-height:1.55}
 .site-sidebar,.billing-header,.account-header,body>main>header,.foundation-links,.interval-links,.power-nav,.sheet-tabs,.foundation-next,.step-controls,.graphcontrols,.foundation-controls,.home-actions,.exam-actions,.exam-nav,.account-tabs,.progress-filter,.footer-contact,.footer-links,#account-sync-status,body footer{display:none!important}
 .billing-shell,.account-shell,.billing .billing-main,.number-lesson,.formula-sheet,.exam-shell,body:not(.billing):not(.account-page)>main{width:auto!important;max-width:none!important;margin:0!important;padding:0!important}
 .number-lesson>section,.sheet-section,.cycle-section,.exercise-group,.walkthrough,.foundation-summary{break-inside:auto!important;margin:6mm 0!important;padding:0!important;border:0!important;box-shadow:none!important;background:#fff!important}
 h1,.billing h1,.number-lesson h1{font-size:22pt!important;line-height:1.2!important;margin:0 0 6mm!important}
 h2,.number-lesson h2{font-size:15pt!important;margin:6mm 0 3mm!important;break-after:avoid;page-break-after:avoid}
 h3,.number-lesson h3{font-size:12pt!important;break-after:avoid;page-break-after:avoid}
 p,li,.number-lesson p,.number-lesson li{font-size:11pt!important;line-height:1.55!important;orphans:3;widows:3}
 .foundation-cards,.sheet-grid,.suite-formulas,.suite-decision{display:block!important}
 .foundation-card,.sheet-grid article,.suite-formulas>div,.suite-decision>section,.number-question,.foundation-example{margin:4mm 0!important;padding:4mm!important;border:1px solid #c6cdd7!important;background:#fff!important;box-shadow:none!important;break-inside:avoid;page-break-inside:avoid}
 .number-formula,.math,.step-math,.sheet-formula,.sheet-key,.foundation-result,.proof-conclusion{font-size:13pt!important;line-height:1.65!important;overflow-wrap:anywhere}
 .number-formula,.sheet-key,.foundation-result,.proof-conclusion{padding:3mm 4mm!important;background:#f5f6f8!important;color:#182438!important;border:1px solid #c6cdd7!important;box-shadow:none!important}
 .foundation-hero,.interval-hero,.feature,.offer,.teacher-intro,.account-art,.dashboard-course{background:#fff!important;color:#182438!important;border:1px solid #c6cdd7!important;box-shadow:none!important}
 :is(.foundation-hero,.interval-hero,.feature,.offer,.teacher-intro,.account-art,.dashboard-course) :is(h2,h3,p,span,strong,small,.eyebrow){color:#182438!important}
 .cycle-figure,.foundation-figure{margin:5mm 0!important;padding:3mm!important;box-shadow:none!important;break-inside:avoid;page-break-inside:avoid}
 .cycle-figure svg,.foundation-figure svg{max-height:105mm;width:100%;height:auto}
 .walkthrough li[hidden]{display:list-item!important}
 .walkthrough li,.proof-chain>li,.number-question>ol>li{break-inside:avoid;page-break-inside:avoid}
 .number-question>ol>li{padding-bottom:4mm}
 .number-question>ol>li::before,.proof-chain>li::before{background:#fff!important;color:#182438!important;border-color:#a7b2c1!important}
 .foundation-table,.sheet-table{overflow:visible!important}
 .number-lesson table,.formula-sheet table{width:100%!important;min-width:0!important;table-layout:auto;font-size:10pt!important;border-collapse:collapse}
 .number-lesson th,.number-lesson td,.formula-sheet th,.formula-sheet td{font-size:10pt!important;padding:2.5mm!important;overflow-wrap:anywhere}
 thead{display:table-header-group}tr{break-inside:avoid;page-break-inside:avoid}
 a{color:#182438!important;text-decoration:none}
 *,*::before,*::after{animation:none!important;transition:none!important;text-shadow:none!important}
}