:root{--navy:#0F172A;--ink:#0F172A;--paper:#F8FAFC;--surface:#fff;--line:#E2E8F0;--muted:#64748B;--gold:#D97706;--blue:#334155}body{background:#F8FAFC}body.dark{--ink:#E2E8F0;--surface:#152238;--paper:#0C1424;--line:#2C3B52;--muted:#A7B5C7;--blue:#CBD5E1}button,input,select,textarea{font-family:Inter,system-ui,sans-serif}.vip-top{background:var(--surface);border-bottom:0}.vip-top .top-inner{min-height:98px;max-width:1280px;gap:20px}.vip-brand{display:flex;align-items:center;gap:12px;color:var(--ink);font-size:20px;font-weight:700;letter-spacing:-.035em;white-space:nowrap;text-decoration:none}.vip-brand>svg{width:36px;height:40px;stroke-width:1.5}.vip-top .vip-nav{display:flex;gap:26px;flex:1;justify-content:center;font-size:13px}.vip-nav a{padding:12px 0;color:var(--ink);font-weight:500}.vip-top-actions{display:flex;align-items:center;gap:22px;flex-shrink:0}.vip-login{font-size:13px;font-weight:600;white-space:nowrap;text-decoration:none}.btn.vip-gold{background:linear-gradient(115deg,#D7AD50,#F0CE76 54%,#CDA24A);border:1px solid #D0AB54;color:#17202F;box-shadow:0 2px 3px #38280308;font-weight:700}.btn.vip-gold:hover{background:linear-gradient(115deg,#E2B849,#F7D47A 54%,#D9AD47);color:#0F172A}.vip-top-actions .btn{padding:10px 18px;min-height:42px;font-size:13px}.vip-menu-toggle{display:none}.vip-landing{max-width:1280px;padding-bottom:55px}.vip-hero{position:relative;display:grid;grid-template-columns:1.04fr 1fr;align-items:center;gap:42px;background:#0F172A;border-radius:24px;padding:76px 58px 112px;min-height:595px;overflow:hidden}.vip-hero:before{content:'';position:absolute;width:560px;height:560px;right:-300px;top:-260px;border:1px solid #FFFFFF0A;border-radius:50%;pointer-events:none}.vip-hero-copy{position:relative}.vip-hero-kicker{display:inline-flex;gap:8px;align-items:center;font-size:9px;color:#E2C276;letter-spacing:.08em}.vip-hero-kicker>span{width:5px;height:5px;border-radius:50%;background:#EBCB7F}.vip-hero h1{font-size:clamp(37px,3.5vw,52px);line-height:1.24;color:#fff;font-weight:750;letter-spacing:-.045em;margin:22px 0 22px}.vip-hero-copy>p{font-size:16px;line-height:1.85;color:#B5BECD;max-width:520px;margin:0}.vip-hero-buttons{display:flex;gap:16px;flex-wrap:wrap;margin-top:32px}.vip-hero-buttons .btn{font-size:15px;padding:15px 20px;min-height:53px}.btn.vip-outline{background:transparent;color:white;border:1px solid #D9E1ED}.btn.vip-outline:hover{background:#FFFFFF0D}.vip-hero-note{display:flex;align-items:center;gap:7px;color:#93A3B9;font-size:9px;margin-top:21px}.vip-hero-note svg{width:13px;height:13px}.preview-window{position:relative;display:grid;grid-template-columns:47px 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minmax(90px,1fr);gap:8px;padding:10px}.preview-question-column{display:flex;flex-direction:column;min-width:0;gap:8px}.preview-question-card{background:white;border:1px solid #E1E6ED;border-radius:8px;padding:11px;flex:1}.preview-test-head{display:flex;justify-content:space-between;gap:5px;color:#6B7280;font-size:6px;border-bottom:1px solid #EDF0F5;padding-bottom:9px;white-space:nowrap}.preview-test-head>span:last-child{display:flex;align-items:center;gap:4px}.preview-test-head svg{width:9px;height:9px}.preview-test-head time{font-size:10px;letter-spacing:.05em;color:#1E293B;font-variant-numeric:tabular-nums}.preview-q-count{font-size:6px;color:#94A3B8;margin:9px 0 4px}.preview-question-card h2{font-size:10px;line-height:1.65;letter-spacing:-.015em;margin:0 0 9px;min-height:33px;color:#263347;font-weight:650}.preview-question-card fieldset{border:0;padding:0;margin:0;min-width:0}.preview-question-card 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h3{font-size:8px;margin:0 0 10px;color:#263347;letter-spacing:-.01em}.preview-mini-score{display:flex;align-items:center;gap:6px}.preview-mini-score>span{background:#1E2D45;color:white;border-radius:5px;padding:7px;font-size:12px;line-height:1}.preview-mini-score p{font-size:6px;line-height:1.5;margin:0;color:#7A8799}.preview-stat-card dl{margin:9px 0 0}.preview-stat-card dl div{display:flex;align-items:center;justify-content:space-between;font-size:7px;color:#475569;margin:6px 0}.preview-stat-card dd{margin:0;background:#EFF2F6;padding:2px 5px;border-radius:3px;font-size:6px}.preview-stat-card dl div:last-child dd{background:#FFF1CB}.preview-chart-card{flex:1;min-height:105px}.preview-chart-card svg{width:100%;height:auto;display:block}.preview-chart-card svg text{font-family:Inter,sans-serif;font-size:7px;fill:#A3ADBC}.demo-grid{fill:none;stroke:#EDF1F6;stroke-width:1}.preview-chart-card p{font-size:5px;color:#94A3B8;margin:3px 0 0}.preview-desktop>footer{font-size:5px;text-align:center;color:#8692A4;padding:0 7px 8px}.vip-features{position:relative;z-index:1;display:grid;grid-template-columns:repeat(3,minmax(0,1fr));gap:22px;margin:-56px 49px 0}.vip-feature{background:var(--surface);border:1px solid var(--line);box-shadow:0 9px 17px #0F172A0C;border-radius:18px;padding:27px 25px;display:flex;flex-direction:column}.vip-feature-heading{display:flex;align-items:center;gap:14px}.vip-feature-heading>span{background:#F0F3F8;border-radius:12px;width:50px;height:50px;flex-shrink:0;display:grid;place-items:center;color:#1C2B43}.vip-feature-heading svg{width:28px;height:28px;stroke-width:1.6}.vip-feature h2{font-size:18px;line-height:1.3;letter-spacing:-.035em;margin:0}.vip-feature p{font-size:13px;line-height:1.85;margin:17px 0 18px;flex:1}.vip-feature>a{display:flex;align-items:center;justify-content:space-between;font-size:10px;text-decoration:none;color:var(--muted);font-weight:600}.vip-feature>a svg{width:15px;height:15px}.vip-feature-gold .vip-feature-heading>span{background:linear-gradient(110deg,#FFFBEB,#F2D58D);color:#B4882C}.vip-real-library{display:flex;align-items:center;justify-content:space-between;gap:50px;padding:65px 18px 10px}.vip-real-library h2{font-size:28px;margin:12px 0}.vip-real-library p{font-size:13px}.vip-library-counts{display:flex;gap:36px;flex-shrink:0}.vip-library-counts strong{display:block;font-size:30px;font-weight:700;color:var(--ink);line-height:1.5;letter-spacing:-.035em}.vip-library-counts span{font-size:10px;color:var(--muted)}.dark .vip-feature-heading>span{background:#263850;color:#C4D1E2}.dark .vip-feature-gold .vip-feature-heading>span{color:#6E4B0C;background:#E2BC62}
.notebook-page{padding:5px 0 30px}.notebook-header{display:flex;align-items:center;justify-content:space-between;gap:25px;margin-bottom:25px}.notebook-header h1{font-size:32px;margin:11px 0 12px}.notebook-header p{font-size:12px;margin:0}.notebook-shell{display:grid;grid-template-columns:235px minmax(0,1fr);gap:20px;align-items:start}.notebook-chapters{padding:23px 16px;border:1px solid var(--line);border-radius:14px;background:var(--surface)}.notebook-chapters>p{font-size:10px;line-height:1.8;margin:9px 0 18px}.notebook-chapters>button{display:flex;align-items:center;gap:9px;text-align:left;width:100%;padding:12px 8px;border:0;border-bottom:1px solid var(--line);background:transparent;border-radius:7px;color:var(--muted);cursor:pointer}.notebook-chapters>button.active{background:#EEF2F7;color:var(--ink)}.notebook-chapters>button>span{font-size:9px;align-self:flex-start;padding-top:3px;color:var(--gold)}.notebook-chapters>button>div{flex:1}.notebook-chapters strong{display:block;font-size:11px;font-weight:600;line-height:1.5}.notebook-chapters small{display:block;font-size:8px;margin-top:5px}.notebook-chapters>button>svg{width:12px;height:12px}.notebook-source{display:flex;align-items:flex-start;gap:9px;margin-top:22px;color:var(--muted)}.notebook-source>svg{width:16px;height:16px;flex-shrink:0;color:var(--gold)}.notebook-source p{font-size:9px;line-height:1.8;margin:0}.notebook-reader{background:#E9EEF4;border:1px solid var(--line);border-radius:15px;overflow:hidden;min-width:0;min-height:600px}.notebook-reader:fullscreen{border-radius:0;overflow:auto;min-height:100vh}.notebook-toolbar{display:flex;align-items:center;justify-content:space-between;gap:10px;background:var(--surface);border-bottom:1px solid var(--line);padding:11px;position:sticky;top:0;z-index:3;flex-wrap:wrap}.notebook-navigation{display:flex;align-items:center;gap:7px}.notebook-navigation form{display:flex;align-items:center;gap:7px;font-size:10px;color:var(--muted)}.notebook-navigation input{width:52px;min-height:33px;padding:5px;font-size:11px;text-align:center}.notebook-toolbar .icon-btn{width:32px;height:33px;border-radius:7px}.notebook-toolbar .icon-btn svg{width:15px;height:15px}.notebook-view-tools{display:flex;align-items:center;gap:5px}.notebook-view-tools output{font-size:9px;min-width:30px;text-align:center;color:var(--muted)}.notebook-state{font-size:10px;text-align:center;padding:13px;color:#64748B}.notebook-canvas{overflow:auto;max-height:820px;padding:0 20px 25px;min-height:450px;display:flex;align-items:flex-start}.notebook-canvas canvas{margin:auto;box-shadow:0 7px 30px #0F172A17;flex-shrink:0;max-width:none}.notebook-reader:fullscreen .notebook-canvas{max-height:none}.notebook-footer{padding:13px;display:flex;justify-content:space-between;align-items:center;gap:15px;background:var(--surface);border-top:1px solid var(--line);font-size:9px;color:var(--muted)}.notebook-footer>span:last-child{display:flex;align-items:center;gap:6px}.notebook-footer svg{width:13px;height:13px}.notebook-locked{padding:75px 30px;text-align:center;min-height:500px;align-content:center}.notebook-locked>svg{width:42px;height:42px;color:#C4A053;margin:auto auto 20px}.notebook-locked .eyebrow,.notebook-locked .actions{justify-content:center}.notebook-locked h2{font-size:25px;margin:15px 0}.notebook-locked p{font-size:12px;max-width:400px;margin:15px auto 25px}.notebook-canvas[hidden],.notebook-locked[hidden]{display:none!important}.dark .notebook-reader{background:#1C2A3E}.dark .notebook-chapters>button.active{background:#243950}
@media(max-width:1200px){.vip-top .vip-nav{gap:17px;font-size:12px}.vip-brand{font-size:17px;gap:9px}.vip-brand>svg{width:30px}.vip-top-actions{gap:15px}.vip-hero{padding:60px 38px 105px;gap:25px}.vip-hero h1{font-size:41px}.vip-hero-copy>p{font-size:14px}.vip-features{margin-left:30px;margin-right:30px;gap:15px}.vip-feature{padding:23px 20px}.vip-feature-heading{gap:10px}.vip-feature h2{font-size:16px}.vip-feature-heading>span{width:43px;height:44px}.vip-feature p{font-size:12px}.vip-real-library{gap:30px}.notebook-shell{grid-template-columns:210px minmax(0,1fr)}}
@media(max-width:1000px){.vip-top .vip-nav{display:none}.vip-menu-toggle{display:inline-grid}.vip-top .vip-nav.open{display:flex;position:absolute;left:20px;right:20px;top:83px;background:var(--surface);border:1px solid var(--line);box-shadow:0 12px 30px #0F172A14;border-radius:13px;flex-direction:column;gap:0;align-items:stretch;padding:10px 20px;z-index:50}.vip-nav.open a{padding:13px 0}.vip-top .top-inner{min-height:87px}.vip-hero{grid-template-columns:1fr;gap:35px;padding:50px 45px 112px}.vip-hero h1{font-size:48px}.vip-hero-copy>p{font-size:16px;max-width:620px}.preview-window{max-width:540px;width:100%;margin:auto;grid-template-columns:48px minmax(0,1fr)}.preview-question-card h2{font-size:12px}.preview-question-card label{font-size:9px;min-height:28px}.preview-next{font-size:10px;min-height:35px}.preview-live-label{font-size:7px}.preview-desktop>header>strong{font-size:12px}.preview-analytics h3{font-size:9px}.vip-feature-heading{flex-direction:column;align-items:flex-start}.vip-real-library{align-items:flex-start;flex-direction:column;gap:20px}.notebook-shell{grid-template-columns:1fr}.notebook-chapters{display:grid;grid-template-columns:repeat(3,minmax(0,1fr));gap:6px}.notebook-chapters>.eyebrow,.notebook-chapters>p,.notebook-source{grid-column:1/-1}.notebook-chapters>button{border:1px solid var(--line);align-items:flex-start}.notebook-source{margin-top:10px}.notebook-chapters>button>svg{display:none}}
@media(max-width:767px){.vip-top .top-inner{padding-left:20px;padding-right:20px;min-height:80px;gap:10px}.vip-brand{font-size:15px;gap:8px}.vip-brand>svg{width:27px;height:32px}.vip-top-actions{gap:9px}.vip-top-actions .btn{font-size:10px;min-height:34px;padding:7px 10px;gap:5px;border-radius:7px}.vip-top-actions .btn svg{width:13px;height:13px}.vip-login{font-size:10px}.vip-menu-toggle{width:31px;height:33px}.vip-menu-toggle svg{width:17px}.vip-landing{padding-left:15px;padding-right:15px;padding-bottom:30px}.vip-hero{padding:35px 24px 95px;border-radius:18px;gap:29px;min-height:0}.vip-hero h1{font-size:35px;line-height:1.25;margin:19px 0}.vip-hero-copy>p{font-size:13px;line-height:1.85}.vip-hero-kicker{font-size:8px;letter-spacing:.025em}.vip-hero-buttons{gap:10px;margin-top:25px}.vip-hero-buttons .btn{font-size:12px;min-height:45px;padding:11px 13px;gap:7px}.vip-hero-buttons svg{width:15px}.vip-hero-note{font-size:7px;gap:5px;margin-top:17px}.preview-window{grid-template-columns:30px minmax(0,1fr);border-width:5px;border-radius:14px}.preview-rail{gap:14px;padding-top:13px}.preview-rail>svg{width:20px;height:24px;margin-bottom:7px}.preview-rail span{width:25px;height:25px}.preview-rail span svg{width:11px}.preview-desktop>header{padding:10px 8px;min-height:40px}.preview-desktop>header>strong{font-size:9px}.preview-live-label{font-size:5px;padding:4px}.preview-body{grid-template-columns:minmax(0,1fr);padding:8px;gap:8px}.preview-question-card{padding:11px}.preview-test-head{font-size:7px}.preview-test-head time{font-size:10px}.preview-question-card h2{font-size:12px;min-height:0;margin-bottom:12px}.preview-q-count{font-size:7px;margin-top:10px}.preview-question-card label{font-size:10px;min-height:29px;margin:5px 0;gap:8px}.preview-question-card label b{font-size:8px;width:20px;height:20px}.preview-next{font-size:10px;min-height:35px}.preview-progress-card{font-size:7px;padding:9px}.preview-progress-card strong{font-size:7px}.preview-analytics{display:grid;grid-template-columns:1fr 1fr;gap:8px}.preview-analytics h3{font-size:8px}.preview-stat-card,.preview-chart-card{padding:10px}.preview-stat-card dl div{font-size:8px}.preview-mini-score p{font-size:7px}.preview-chart-card p{font-size:6px}.preview-desktop>footer{font-size:5px;line-height:1.6;padding:2px 8px 9px}.preview-demo-feedback{font-size:8px!important}.vip-features{grid-template-columns:1fr;margin:-55px 15px 0;gap:15px}.vip-feature{padding:25px;min-height:0}.vip-feature-heading{flex-direction:row;align-items:center;gap:14px}.vip-feature h2{font-size:18px}.vip-feature-heading>span{width:47px;height:49px}.vip-feature p{font-size:13px;line-height:1.85}.vip-feature>a{font-size:11px}.vip-real-library{padding:40px 10px 10px;gap:15px}.vip-real-library h2{font-size:25px;line-height:1.35}.vip-library-counts{gap:30px;flex-wrap:wrap}.vip-library-counts strong{font-size:27px}.vip-library-counts span{font-size:9px}.notebook-header{align-items:flex-start;flex-direction:column;gap:18px}.notebook-header h1{font-size:28px}.notebook-header p{font-size:11px;line-height:1.8}.notebook-header>.btn{width:100%}.notebook-chapters{grid-template-columns:repeat(2,minmax(0,1fr));padding:18px 13px}.notebook-chapters>button{padding:10px 8px}.notebook-chapters strong{font-size:10px}.notebook-chapters small{font-size:8px}.notebook-source{display:none}.notebook-toolbar{padding:10px 8px;justify-content:center;gap:8px}.notebook-view-tools{flex:1;justify-content:center}.notebook-navigation{justify-content:center;flex:1;white-space:nowrap}.notebook-navigation form{font-size:9px}.notebook-navigation input{width:45px}.notebook-footer{font-size:8px;align-items:flex-start;flex-direction:column;gap:8px}.notebook-reader{min-height:480px}.notebook-canvas{padding:0 12px 20px;min-height:350px;max-height:640px}.notebook-state{font-size:9px}.notebook-locked{min-height:360px;padding:40px 22px}.notebook-locked h2{font-size:22px}.notebook-locked .actions{flex-direction:column}.notebook-locked .btn{width:100%}}
@media(max-width:380px){.vip-brand{font-size:13px;gap:5px}.vip-brand>svg{width:24px}.vip-top-actions{gap:7px}.vip-login{font-size:9px}.vip-top-actions .btn{padding:7px 8px;font-size:9px}.vip-top-actions .btn svg{display:none}.vip-hero{padding-left:20px;padding-right:20px}.vip-hero h1{font-size:32px}.preview-live-label{display:none}}

.notebook-toc-toggle{display:none}@media(max-width:767px){.notebook-toc-toggle{display:flex;align-items:center;justify-content:space-between;border:1px solid var(--line);border-radius:12px;background:var(--surface);padding:15px;color:var(--ink);font-size:12px;font-weight:600}.notebook-toc-toggle>span{display:flex;align-items:center;gap:9px}.notebook-toc-toggle svg{width:16px;height:16px}.notebook-chapters{display:none}.notebook-chapters.is-open{display:grid}.notebook-shell{gap:12px}}

.question-subject-grid{display:grid;grid-template-columns:repeat(3,minmax(0,1fr));gap:20px}.question-subject-card{display:flex;flex-direction:column;gap:12px}.question-subject-card h2{font-size:20px;line-height:1.45;margin:0}.question-subject-card p{font-size:13px;margin:0 0 12px;flex:1}.question-subject-card .actions{margin-top:auto;gap:8px;flex-wrap:wrap}.question-subject-card .subject-icon{display:grid;place-items:center;width:42px;height:42px;border-radius:12px;background:#EEF2F7;color:#334155}.question-subject-card .subject-icon svg{width:23px;height:23px}.question-lesson-navigation{display:flex;align-items:center;justify-content:space-between;gap:12px;padding:25px 0;border-bottom:1px solid var(--line);margin-bottom:20px}.question-lesson-navigation .btn{font-size:13px}.dark .question-subject-card .subject-icon{background:#263850;color:#E2E8F0}@media(max-width:1100px){.question-subject-grid{grid-template-columns:repeat(2,minmax(0,1fr))}}@media(max-width:600px){.question-subject-grid{grid-template-columns:1fr}.question-lesson-navigation{gap:8px}.question-lesson-navigation .btn{font-size:11px;padding:11px 10px;gap:6px}.question-lesson-navigation .btn svg{width:14px;height:14px}}

.nk-product [data-demo-options] label.is-correct{background:#d7f6ec;border-color:#34b78b}.nk-product [data-demo-options] label.is-incorrect{background:#fef2f2;border-color:#ef4444}.nk-product [data-demo-options] label:has(input:checked):not(.is-correct):not(.is-incorrect){background:#eff6ff;border-color:#60a5fa}.nk-product .preview-demo-feedback{white-space:pre-line;line-height:1.5}