/* Shared Рядом shell. The legacy aliases keep course content independent. */
:root{--bg:#f8f7f3;--surface:#fffefa;--ink:#303638;--muted:#63696b;--line:#dedfdb;--soft:#eeefeb;--brand:#536b60;--paper:var(--surface);--text:var(--ink);--sidebar:var(--bg);--sans:-apple-system,BlinkMacSystemFont,'Segoe UI',sans-serif;--serif:var(--sans);--green:#416c55;color-scheme:light}
:root[data-theme=dark]{--bg:#191b1d;--surface:#222528;--ink:#ecebe7;--muted:#b0b3b5;--line:#3a3e42;--soft:#2b2f33;--brand:#b0c0b6;--paper:var(--surface);--text:var(--ink);--sidebar:var(--bg);--green:#a9cfb7;color-scheme:dark}
:root:has(.subject-finance),:root[data-course=black]{--accent:#955f70;--accent-hover:#7f4b5b;--tint:#f2e3e9}
:root[data-theme=dark]:has(.subject-finance),:root[data-course=black][data-theme=dark]{--accent:#d6acbb;--accent-hover:#e4c1cd;--tint:#3a2b32}
:root:has(.subject-stats){--accent:#765b92;--accent-hover:#63467f;--tint:#ebe5f3}
:root[data-theme=dark]:has(.subject-stats){--accent:#c5b0dd;--accent-hover:#d6c5e9;--tint:#322b3c}
.platform-page{font:15px/1.7 var(--sans);background:var(--bg);color:var(--ink)}
.platform-page h1,.platform-page h2,.platform-page h3{font-family:var(--sans);font-weight:550;color:var(--ink)}
.platform-page h1{font-size:clamp(40px,3.8vw,52px);line-height:1.1;letter-spacing:-.045em}
.platform-page h2{font-size:25px;line-height:1.3;letter-spacing:-.035em}.platform-page h3{font-size:16px;line-height:1.45;letter-spacing:-.02em}
.platform-page a,.platform-page button,.platform-page input,.platform-page select{touch-action:manipulation}
.platform-page :is(a,button,input,select,textarea,summary):focus-visible{outline:2px solid var(--brand);outline-offset:4px}
.platform-header{position:sticky;top:0;z-index:80;display:flex;align-items:center;justify-content:space-between;gap:24px;height:80px;padding:0 32px;border-bottom:1px solid var(--line);background:var(--bg);color:var(--ink)}
.platform-identity{display:flex;align-items:center;gap:24px;min-width:0}.platform-brand{display:inline-flex;align-items:center;gap:10px;flex-shrink:0;font:700 28px/1 var(--sans);letter-spacing:-.065em;min-height:44px}.platform-brand>img{width:36px;height:36px;display:block;flex-shrink:0}.platform-brand-dot{color:var(--brand)}
.platform-course{border-left:1px solid var(--line);padding-left:22px;font-size:12px;font-weight:550;line-height:1.3;color:var(--muted)}.platform-actions{display:flex;align-items:center;gap:12px;flex-shrink:0}
.platform-switcher{position:relative;font-size:12px}.platform-switcher>summary{display:flex;align-items:center;justify-content:center;gap:15px;min-height:44px;padding:10px 15px;border:1px solid var(--line);border-radius:12px;cursor:pointer;list-style:none;font-weight:550;white-space:nowrap}.platform-switcher>summary::-webkit-details-marker{display:none}.platform-switcher>summary:hover,.platform-switcher[open]>summary{background:var(--soft)}.platform-switcher>summary>span{color:var(--muted)}
.platform-course-list{position:absolute;right:0;top:calc(100% + 10px);z-index:90;width:290px;max-width:calc(100vw - 32px);padding:7px;border:1px solid var(--line);border-radius:16px;background:var(--surface);box-shadow:0 12px 30px #0000000d}
.platform-course-list>a{display:flex;align-items:center;justify-content:space-between;gap:20px;min-height:46px;padding:11px 13px;border-radius:10px;font-size:13px;color:var(--muted)}.platform-course-list>a:hover{background:var(--soft);color:var(--ink)}.platform-course-list>a[aria-current]{background:var(--tint);color:var(--accent);font-weight:600}.platform-course-list>a>span{font-size:15px}
.platform-page .platform-theme{display:grid;place-items:center;width:44px;height:44px;min-width:44px;padding:0;border:1px solid var(--line);border-radius:50%;background:transparent;color:var(--ink);font:20px/1 var(--sans)}.platform-theme:hover{background:var(--soft)}
.platform-page .sidebar{position:fixed;top:80px;bottom:0;left:0;width:232px;display:flex;flex-direction:column;gap:0;padding:25px 18px 22px;border-right:1px solid var(--line);background:var(--bg);overflow-y:auto;z-index:30}
.sidebar-heading{margin:0 11px 12px;font-size:9px;letter-spacing:.13em;font-weight:600;color:var(--muted)}.platform-page #navigation{display:grid;gap:3px}.platform-page .nav-item{min-height:44px;padding:10px 11px;gap:11px;font-size:12px;border-radius:10px;color:var(--muted);box-shadow:none}.platform-page .nav-item:hover{background:var(--soft);color:var(--ink)}.platform-page .nav-item.active{background:var(--tint);color:var(--accent);box-shadow:none}.platform-page .nav-icon{width:20px;flex-shrink:0}.platform-page .nav-line-icon{width:18px;height:18px}.platform-page .nav-count{margin-left:auto;color:var(--muted);font-size:10px}
.sidebar-section{padding-top:14px;margin-top:12px;border-top:1px solid var(--line);font-size:12px}.sidebar-section>summary{display:flex;align-items:center;justify-content:space-between;gap:12px;min-height:44px;padding:9px 11px;color:var(--muted);cursor:pointer;list-style:none;font-size:11px;font-weight:550}.sidebar-section>summary:after{content:'+';font-size:17px;font-weight:400}.sidebar-section[open]>summary:after{content:'−'}.sidebar-section>summary::-webkit-details-marker{display:none}.sidebar-section[open]>summary{margin-bottom:5px;color:var(--ink)}.sidebar-more{margin-top:7px;padding-top:7px}.sidebar-more .nav-item{font-size:11px}.platform-page #topics-nav>a{min-height:44px;display:flex;align-items:center;gap:9px;padding:9px 11px;border-radius:10px;font-size:11px;line-height:1.5;color:var(--muted)}.platform-page #topics-nav>a:hover,.platform-page #topics-nav>a.active,.platform-page #topics-nav>a[aria-current]{background:var(--soft);color:var(--ink)}.platform-page #topics-nav>a>span:first-child{font:10px ui-monospace,monospace;color:var(--accent);flex-shrink:0}.platform-page .sidebar-utility{display:flex;align-items:center;justify-content:space-between;gap:10px;min-height:44px;margin:16px 10px 0;color:var(--muted);font-size:11px;line-height:1.5}.sidebar-utility:hover{color:var(--brand)}
.platform-page .sidebar-bottom{margin:24px 10px 0;padding-top:20px;border-top:1px solid var(--line);font-size:10px;color:var(--muted)}.platform-page .sidebar-bottom p{font-size:10px;line-height:1.8;margin-top:10px}.platform-page .progress-label{display:flex;align-items:center;justify-content:space-between;gap:8px;font-size:10px}.platform-page .progress-track{height:4px;background:var(--line);margin:10px 0 0;border-radius:8px}.platform-page .progress-track>div{height:100%;background:var(--brand);border-radius:8px}
.platform-page .workspace{margin-left:232px;min-width:0}.platform-page .workspace>main{max-width:1160px;margin:0 auto;padding:30px 40px 66px;min-height:72vh}.platform-page footer{max-width:1160px;display:flex;justify-content:space-between;align-items:center;gap:12px 24px;flex-wrap:wrap;margin:0 auto;padding:22px 40px;border-top:1px solid var(--line);color:var(--muted);font-size:10px}.platform-page footer a{color:var(--brand)}.platform-page footer .local-status{display:inline;font-size:10px;color:var(--muted);white-space:normal}
.course-toolbar{max-width:1160px;display:flex;align-items:center;gap:20px;flex-wrap:wrap;margin:0 auto;padding:23px 40px 0;min-width:0}.platform-page .breadcrumb{font-size:11px;color:var(--muted);line-height:1.5;min-width:0}.platform-page .course-switch{display:flex;grid-template-columns:none;gap:3px;min-width:0;padding:3px;margin:0;border:0;border-radius:12px;background:var(--soft)}.platform-page .course-tab{display:flex;align-items:center;justify-content:center;min-height:44px;padding:8px 13px;border:0;border-radius:9px;background:transparent;color:var(--muted);font-size:11px;line-height:1.3;white-space:nowrap}.platform-page .course-tab:hover{background:var(--surface);color:var(--ink)}.platform-page .course-tab[aria-current]{background:var(--surface);color:var(--accent);box-shadow:none}
.course-mobile-navigation{display:none;position:relative}.course-mobile-navigation>summary{display:flex;align-items:center;justify-content:space-between;gap:13px;min-height:44px;padding:10px 13px;border:1px solid var(--line);border-radius:12px;list-style:none;font-size:11px;color:var(--muted);cursor:pointer;white-space:nowrap}.course-mobile-navigation>summary::-webkit-details-marker{display:none}.platform-page .mobile-nav{display:grid;grid-template-columns:1fr 1fr;gap:3px;position:absolute;right:0;top:calc(100% + 8px);z-index:50;width:290px;max-width:calc(100vw - 32px);padding:7px;margin:0;border:1px solid var(--line);border-radius:14px;background:var(--surface);white-space:normal;box-shadow:0 12px 30px #0000000d}.platform-page .mobile-nav>a{display:flex;align-items:center;min-height:44px;padding:10px 12px;border:0;border-radius:9px;color:var(--muted);font-size:12px;line-height:1.5}.platform-page .mobile-nav>a:hover{background:var(--soft)}.platform-page .mobile-nav>a.active,.platform-page .mobile-nav>a[aria-current]{background:var(--tint);color:var(--accent)}
.platform-page .button{display:inline-flex;align-items:center;justify-content:center;gap:20px;min-height:44px;padding:11px 19px;border:1px solid var(--brand);border-radius:12px;background:var(--brand);color:var(--bg);font:550 12px/1.5 var(--sans);box-shadow:none}.platform-page .button:hover{background:var(--brand);border-color:var(--brand);filter:brightness(.96)}.platform-page .button.secondary{background:transparent;border-color:var(--line);color:var(--ink)}.platform-page .button.secondary:hover{background:var(--soft);filter:none}.platform-page .text-link{color:var(--brand);font-size:12px;min-height:44px}.platform-page :is(input,select,textarea){border-color:var(--line);border-radius:12px;background:var(--surface);font-size:14px}.platform-page select{min-height:44px;font-size:12px}.platform-page textarea{line-height:1.75}
.course-overview{display:grid;grid-template-columns:minmax(0,1fr) 250px;align-items:start;gap:42px;padding:13px 0 35px;margin-bottom:32px;border-bottom:1px solid var(--line)}.course-overview-copy{min-width:0}.course-badge{display:inline-flex;align-items:center;gap:7px;padding:5px 10px;margin-bottom:22px;border-radius:8px;background:var(--tint);color:var(--accent);font-size:10px;font-weight:600;line-height:1.5}.course-overview h1{max-width:680px;margin:0 0 21px}.course-overview-copy>p{max-width:600px;margin:0;color:var(--muted);font-size:14px;line-height:1.9}.course-primary-actions{display:flex;align-items:center;gap:14px 23px;flex-wrap:wrap;margin-top:25px}.course-next-step{padding:22px;border:1px solid var(--line);border-radius:16px;background:var(--surface);min-width:0}.course-next-step .eyebrow{display:block;font-size:9px;letter-spacing:.11em;color:var(--muted);margin-bottom:14px}.course-next-step h2{margin:0 0 10px;font-size:18px;line-height:1.45;letter-spacing:-.02em}.course-next-step p{margin:0;color:var(--muted);font-size:11px;line-height:1.7}.course-progress-summary{display:flex;align-items:center;justify-content:space-between;gap:12px;margin-top:23px;font-size:10px;color:var(--muted)}.course-progress-summary strong{color:var(--ink);font-size:11px;font-weight:550}.course-next-step progress{display:block;width:100%;height:4px;margin-top:10px;border:0;border-radius:5px;overflow:hidden;background:var(--line);color:var(--brand);accent-color:var(--brand)}.course-next-step progress::-webkit-progress-bar{background:var(--line)}.course-next-step progress::-webkit-progress-value{background:var(--brand)}.course-next-step progress::-moz-progress-bar{background:var(--brand)}
.platform-page .section-heading{display:flex;align-items:baseline;justify-content:space-between;gap:16px;margin-bottom:21px}.platform-page .section-heading h2{font-size:23px;margin:0}.platform-page .section-heading .muted{font-size:10px}.platform-page .topic-grid{display:grid;grid-template-columns:repeat(3,minmax(0,1fr));gap:14px}.platform-page .topic-card{display:flex;flex-direction:column;min-width:0;padding:22px;border:1px solid var(--line);border-radius:16px;background:var(--surface);transform:none;box-shadow:none}.platform-page .topic-card:hover{border-color:var(--brand);transform:none}.platform-page .topic-card>.eyebrow{display:block;font-size:9px;letter-spacing:.11em;color:var(--muted);margin-bottom:17px}.platform-page .topic-card h3{font-size:16px;line-height:1.4;margin:0 0 10px;letter-spacing:-.02em}.platform-page .topic-card p{font-size:12px;line-height:1.85;color:var(--muted);margin:0 0 8px;flex:1}.platform-page .card-bottom{display:flex;justify-content:space-between;align-items:center;gap:12px;padding-top:14px;margin-top:16px;border-top:1px solid var(--line);font-size:10px;color:var(--muted)}.platform-page .card-bottom>span:last-child{color:var(--brand);font-size:17px}.course-followup{margin-top:40px}.course-followup>h2{font-size:23px;margin-bottom:20px}.course-support-grid{display:grid;grid-template-columns:1fr 1fr;gap:14px}.course-support-grid>a{display:block;padding:23px;border:1px solid var(--line);border-radius:16px;background:var(--surface);min-width:0}.course-support-grid>a:hover{border-color:var(--brand)}.course-support-grid strong{display:block;font-size:14px;font-weight:550}.course-support-grid span{display:block;font-size:12px;line-height:1.8;color:var(--muted);margin-top:9px}.course-source-note{font-size:12px;line-height:1.9;color:var(--muted);margin:25px 0 0}.course-source-note a{color:var(--brand);text-decoration:underline;text-underline-offset:3px}
.platform-page .page-title{margin:8px 0 30px}.platform-page .page-title h1{font-size:clamp(34px,3.5vw,46px);margin:14px 0 19px}.platform-page .page-title p{font-size:14px;color:var(--muted);max-width:760px;line-height:1.9}.platform-page .page-title>.eyebrow{font-size:9px;letter-spacing:.12em;color:var(--accent)}.platform-page .question-card,.platform-page .demo-card,.platform-page .exam-task,.platform-page .formula-card,.platform-page .symbol-card,.platform-page .term-card,.platform-page .note,.platform-page .lab-card,.platform-page .homework-card,.platform-page .setup,.platform-page .backup-panel{border-color:var(--line);border-radius:16px;background:var(--surface);box-shadow:none}.platform-page .question-title{font-family:var(--sans);font-size:20px;font-weight:500;line-height:1.75;letter-spacing:-.025em}.platform-page .formula-grid{gap:16px}.platform-page .formula-card h2,.platform-page .formula-card h3{font-size:15px;font-weight:550}.platform-page .formula-card p,.platform-page .article-section p,.platform-page .demo-step p{color:var(--muted)}.platform-page .article-section h2{font-size:25px}.platform-page .lesson-toc,.platform-page .article-toc{top:102px}.platform-page :is(.math-block,.case-table-wrap,pre){max-width:100%;overflow-x:auto;overscroll-behavior-x:contain}.platform-page .toolbar{gap:10px}.platform-page .toolbar>:is(input,select){min-width:0}.platform-page .practice-tabs{gap:20px}.platform-page .practice-tabs button{min-height:44px;color:var(--muted)}.platform-page .practice-tabs button.active{color:var(--accent);border-color:var(--accent)}
.platform-study .study-shell{max-width:1160px;margin:0 auto;padding:0 40px}.platform-study .study-shell>main{padding:38px 0 60px}.platform-study .study-shell h1{font-size:clamp(36px,4vw,49px);max-width:760px}.platform-study .study-plan{gap:16px}.platform-study .study-step{padding:25px;border-color:var(--line);border-radius:16px;background:var(--surface)}.platform-study .study-step h2{font-size:23px;line-height:1.35;margin:16px 0}.platform-study .study-step .eyebrow{font-size:9px;color:var(--accent)}.platform-study .migration-note{padding:19px 23px;background:var(--soft);border-color:var(--line);font-size:12px}.platform-study .migration-note>strong{font-size:12px;font-weight:550;color:var(--ink)}.platform-study .study-tabs button{min-height:44px;background:transparent;color:var(--muted);border-color:var(--line)}.platform-study .study-tabs button[aria-pressed=true]{background:var(--tint);border-color:transparent;color:var(--accent)}.platform-study .study-backup{background:var(--surface);border-color:var(--line);border-radius:16px}.platform-study footer{padding-inline:0}.platform-study .study-footnote{max-width:850px}
@media(max-width:1160px){.platform-header{padding-inline:24px}.platform-page .sidebar{width:218px;padding-inline:14px}.platform-page .workspace{margin-left:218px}.platform-page .workspace>main{padding-inline:28px}.course-toolbar{padding-inline:28px}.course-overview{grid-template-columns:minmax(0,1fr);gap:25px}.course-next-step{display:grid;grid-template-columns:1fr auto;column-gap:24px;align-items:center;padding:20px 23px}.course-next-step .eyebrow,.course-next-step h2,.course-next-step p{grid-column:1}.course-next-step h2{font-size:17px}.course-next-step .eyebrow{margin-bottom:10px}.course-progress-summary{grid-column:2;grid-row:1/3;margin:0;gap:18px}.course-next-step progress{grid-column:2;grid-row:3;width:120px}.platform-page .topic-grid{grid-template-columns:1fr 1fr}.platform-page footer{padding-inline:28px}}
@media(max-width:850px){.platform-header{height:72px;padding:0 20px;gap:14px}.platform-identity{display:flex;flex-direction:column;align-items:flex-start;gap:2px}.platform-brand{font-size:24px;gap:8px;min-height:32px}.platform-brand>img{width:30px;height:30px}.platform-course{border:0;padding:0 0 0 38px;font-size:10px;line-height:1.2}.platform-actions{gap:8px}.platform-switcher>summary{font-size:11px;gap:10px;padding:10px 12px}.platform-page .platform-theme{width:44px;height:44px}.platform-page .sidebar{display:none}.platform-page .workspace{margin-left:0}.course-toolbar{padding:16px 24px 0;gap:12px;justify-content:space-between}.platform-page .course-toolbar>.breadcrumb{display:none}.course-mobile-navigation{display:block;margin-left:auto}.platform-page .course-tab{padding:9px 12px;min-height:44px}.platform-page .workspace>main{padding:25px 24px 48px}.course-overview{padding-top:5px;padding-bottom:30px;margin-bottom:28px}.course-overview h1{font-size:42px}.course-badge{margin-bottom:19px}.course-next-step{padding:20px}.platform-page .lesson-toc{display:none}.platform-page footer{padding:20px 24px;font-size:10px}.platform-study .study-shell{padding:0 24px}.platform-study .study-shell>main{padding-top:30px}}
@media(max-width:560px){.platform-header{padding-inline:16px;gap:8px}.platform-switcher>summary{font-size:10px;padding-inline:10px;gap:8px}.platform-brand{font-size:23px}.platform-brand>img{width:28px;height:28px}.platform-course{padding-left:36px;font-size:9px}.platform-actions{gap:7px}.platform-course-list{width:265px;right:-51px}.platform-course-list>a{font-size:12px;min-height:46px}.course-toolbar{padding:14px 20px 0;gap:10px}.platform-page .course-switch{padding:3px}.platform-page .course-tab{min-height:44px;padding:8px 10px;font-size:10px}.course-mobile-navigation>summary{font-size:10px;padding-inline:10px;gap:8px}.platform-page .workspace>main{padding:25px 20px 42px}.course-overview{gap:23px;padding-bottom:27px}.course-overview h1{font-size:36px;letter-spacing:-.045em;line-height:1.14}.course-overview-copy>p{font-size:13px;line-height:1.85}.course-primary-actions{gap:6px 21px;margin-top:21px}.course-badge{font-size:9px;margin-bottom:17px}.course-next-step{display:block;padding:20px}.course-next-step h2{font-size:17px;margin-bottom:8px}.course-next-step .eyebrow{margin-bottom:12px}.course-next-step p{font-size:11px}.course-progress-summary{margin-top:18px;font-size:10px}.course-next-step progress{width:100%;margin-top:10px}.platform-page .section-heading h2,.course-followup>h2{font-size:22px}.platform-page .section-heading .muted{display:none}.platform-page .topic-grid{grid-template-columns:1fr;gap:12px}.platform-page .topic-card{padding:22px}.course-support-grid{grid-template-columns:1fr;gap:12px}.course-support-grid>a{padding:22px}.platform-page .page-title h1{font-size:32px;line-height:1.15}.platform-page .page-title p{font-size:13px}.platform-page .page-title{margin-top:0;margin-bottom:25px}.platform-page .question-title{font-size:18px}.platform-page .toolbar{flex-wrap:wrap}.platform-page .toolbar>select{width:100%;max-width:100%}.platform-page .practice-tabs{gap:18px}.platform-page .article-section h2{font-size:23px}.platform-page .article-section p,.platform-page .steps li{font-size:13px}.platform-page .exam-bar{padding:17px}.platform-page footer{padding:20px;gap:8px 20px;font-size:9px}.platform-study .study-shell{padding:0 20px}.platform-study .study-shell>main{padding-top:28px}.platform-study .study-shell h1{font-size:34px;line-height:1.16}.platform-study .study-plan{grid-template-columns:1fr}.platform-study .study-step{padding:23px}.platform-study .study-step h2{font-size:23px}.platform-study .migration-note{padding:19px}.platform-study .study-backup{padding:23px}.platform-study .study-tabs{gap:7px}.platform-study .study-tabs>button{font-size:11px;padding-inline:10px}}
@media(prefers-reduced-motion:reduce){.platform-page *{scroll-behavior:auto!important;transition:none!important}}
@media print{.platform-header,.platform-page .sidebar,.course-toolbar{display:none!important}.platform-page .workspace{margin-left:0}.platform-page .workspace>main{padding:0;max-width:none}.platform-page footer{display:none}.platform-study .study-shell{padding:0}.platform-page .math-block{overflow:visible}.course-overview{display:block}.course-primary-actions{display:none}}

.course-storage-status{display:none;max-width:1080px;margin:20px auto 0;padding:14px 18px;border:1px solid var(--line);border-radius:12px;background:var(--soft);color:var(--ink);font-size:12px}:root[data-storage=temporary] .course-storage-status{display:block}@media(max-width:1160px){.course-storage-status{margin-inline:28px}}@media(max-width:560px){.course-storage-status{margin-inline:20px}}@media print{.course-storage-status{display:none!important}}

/* Keep long inline mathematics scrollable without widening a reading column. */
.platform-page .math-inline{display:inline-block;vertical-align:middle;max-width:100%;overflow-x:auto}