:root{
  --navy:#071c33;--navy-2:#0c2d4e;--navy-3:#113f66;--teal:#009e9a;--teal-2:#00b8b2;
  --cyan:#e9fbfa;--blue:#2563eb;--purple:#7c3aed;--ink:#102033;--muted:#66768a;
  --bg:#f4f7fa;--surface:#fff;--line:#dce5eb;--soft:#eef3f6;--success:#087a4b;
  --danger:#b42318;--warning:#a65006;--shadow:0 14px 40px rgba(7,28,51,.08);
  --radius:18px;--radius-lg:28px
}
*{box-sizing:border-box}html{scroll-behavior:smooth}body{margin:0;font-family:Inter,ui-sans-serif,system-ui,-apple-system,"Segoe UI",Roboto,Arial,sans-serif;background:var(--bg);color:var(--ink);line-height:1.55}button,input,select,textarea{font:inherit}button{cursor:pointer}a{color:var(--teal)}h1,h2,h3,p{margin-top:0}.hidden{display:none!important}
.shell{min-height:100vh;display:grid;grid-template-columns:278px minmax(0,1fr)}
.sidebar{background:linear-gradient(180deg,#06182d 0%,#08243f 100%);color:#fff;padding:22px 16px;position:sticky;top:0;height:100vh;display:flex;flex-direction:column;overflow:auto}
.brand{padding:4px 10px 24px;border-bottom:1px solid rgba(255,255,255,.12);margin-bottom:18px}.brand span{display:block;color:#5ee3dc;font-size:.72rem;font-weight:900;letter-spacing:.15em;text-transform:uppercase}.brand strong{display:block;font-size:1.12rem;margin-top:4px}.brand small{display:inline-block;margin-top:8px;background:rgba(94,227,220,.13);color:#b8fbf7;padding:3px 8px;border-radius:999px;font-weight:800}
.sidebar nav{display:grid;gap:5px;flex:1}.nav-button{display:flex;align-items:center;gap:12px;width:100%;border:0;background:transparent;color:#ccdae6;text-align:left;padding:11px 13px;border-radius:12px;font-weight:750;transition:.18s}.nav-button:hover{background:rgba(255,255,255,.07);color:#fff}.nav-button.active{background:linear-gradient(90deg,rgba(0,184,178,.24),rgba(0,184,178,.09));color:#fff;box-shadow:inset 3px 0 0 #43dbd4}.nav-icon{width:24px;text-align:center;font-size:1.05rem}
.sidebar-footer{border-top:1px solid rgba(255,255,255,.12);padding:16px 6px 0;display:grid;grid-template-columns:38px 1fr 34px;gap:10px;align-items:center}.avatar{width:38px;height:38px;border-radius:12px;background:#16a7a3;display:grid;place-items:center;font-weight:900}.user-meta{min-width:0}.user-meta strong,.user-meta span{display:block;white-space:nowrap;overflow:hidden;text-overflow:ellipsis}.user-meta strong{font-size:.86rem}.user-meta span{font-size:.72rem;color:#a9bdce;text-transform:capitalize}.logout-button,.icon-button{border:0;background:transparent;color:inherit;border-radius:10px;padding:8px}.logout-button:hover,.icon-button:hover{background:rgba(255,255,255,.1)}
.main{min-width:0}.topbar{height:67px;background:rgba(255,255,255,.95);backdrop-filter:blur(10px);border-bottom:1px solid var(--line);padding:0 28px;display:flex;align-items:center;justify-content:space-between;position:sticky;top:0;z-index:10}.topbar-title strong,.topbar-title span{display:block}.topbar-title strong{font-size:.92rem}.topbar-title span{font-size:.72rem;color:var(--muted)}.topbar-badge{font-size:.72rem;font-weight:900;letter-spacing:.1em;color:var(--teal);border:1px solid #9de7e3;background:#effcfb;padding:5px 9px;border-radius:999px}.mobile-menu{display:none;color:var(--navy)}
.content{max-width:1380px;margin:0 auto;padding:30px 32px 60px}.overline{display:block;color:var(--teal);font-size:.72rem;font-weight:900;letter-spacing:.14em;text-transform:uppercase;margin-bottom:7px}.page-heading{margin-bottom:24px}.page-heading h1{font-size:clamp(2rem,4vw,3.25rem);line-height:1.03;margin-bottom:10px;color:var(--navy)}.page-heading p{max-width:760px;color:var(--muted);font-size:1.03rem}
.btn{border:0;border-radius:12px;padding:11px 16px;font-weight:850;background:var(--teal);color:#fff;box-shadow:0 5px 12px rgba(0,158,154,.16);transition:.18s}.btn:hover{transform:translateY(-1px);filter:brightness(.96)}.btn.secondary{background:var(--navy)}.btn.ghost{background:#edf3f6;color:var(--navy);box-shadow:none}.btn.light{background:#fff;color:var(--navy);box-shadow:none}.btn.small{padding:8px 11px;font-size:.82rem}.btn.wide{width:100%}.btn:disabled{opacity:.65;cursor:default;transform:none}.text-button{border:0;background:transparent;color:var(--teal);font-weight:800;padding:7px}.back-link{border:0;background:transparent;color:var(--navy);font-weight:850;padding:0;margin-bottom:16px}
.grid{display:grid;gap:16px}.grid.cols-2{grid-template-columns:repeat(2,minmax(0,1fr))}.grid.cols-3{grid-template-columns:repeat(3,minmax(0,1fr))}.grid.cols-4{grid-template-columns:repeat(4,minmax(0,1fr))}.card,.section-block{background:var(--surface);border:1px solid var(--line);border-radius:var(--radius);padding:22px;box-shadow:0 5px 20px rgba(7,28,51,.035)}.section-block{margin-top:20px}.section-title{display:flex;gap:18px;align-items:center;justify-content:space-between}.section-title h2{margin-bottom:5px}.section-title p{margin:0;color:var(--muted)}
.dashboard-hero{background:linear-gradient(135deg,#071c33 0%,#0b3f58 72%,#0a6d70 100%);border-radius:var(--radius-lg);padding:34px;color:#fff;display:grid;grid-template-columns:1fr auto;gap:28px;align-items:center;box-shadow:var(--shadow)}.dashboard-hero h1{font-size:clamp(2rem,4vw,3.4rem);line-height:1.03;margin-bottom:12px}.dashboard-hero p{color:#d8e8f1;max-width:700px}.hero-actions{display:flex;gap:10px;margin-top:22px}.hero-score{width:150px;height:150px;border-radius:50%;border:12px solid rgba(95,230,223,.25);display:grid;place-items:center;text-align:center;background:rgba(255,255,255,.06)}.hero-score strong{display:block;font-size:2.1rem}.hero-score span{font-size:.74rem;color:#cfe7eb}
.metric-grid{display:grid;grid-template-columns:repeat(4,minmax(0,1fr));gap:14px;margin:18px 0}.metric-card{background:#fff;border:1px solid var(--line);border-radius:16px;padding:18px}.metric-card strong{display:block;font-size:1.8rem;color:var(--navy)}.metric-card span{color:var(--muted);font-size:.78rem;font-weight:800;text-transform:uppercase;letter-spacing:.05em}
.subject-grid{display:grid;grid-template-columns:repeat(2,minmax(0,1fr));gap:18px}.subject-card{position:relative;overflow:hidden;border-radius:22px;padding:26px;color:#fff;min-height:310px}.subject-card.physics{background:linear-gradient(140deg,#0b2e5e,#1456a2)}.subject-card.chemistry{background:linear-gradient(140deg,#33206d,#6a3db5)}.subject-symbol{font-size:2.3rem;margin-bottom:18px}.paper-tag{display:inline-block;background:rgba(255,255,255,.15);border:1px solid rgba(255,255,255,.2);padding:4px 9px;border-radius:999px;font-size:.7rem;font-weight:850}.subject-card h2{font-size:2rem;margin:10px 0}.subject-card p{color:rgba(255,255,255,.83);max-width:520px}.subject-stats{display:flex;flex-wrap:wrap;gap:8px;margin:20px 0}.subject-stats span{background:rgba(255,255,255,.1);padding:5px 9px;border-radius:999px;font-size:.75rem}
.subject-header{border-radius:var(--radius-lg);padding:30px;color:#fff;display:flex;align-items:center;justify-content:space-between;margin-bottom:22px}.subject-header.physics{background:linear-gradient(130deg,#082c59,#1762b2)}.subject-header.chemistry{background:linear-gradient(130deg,#35216e,#7649c0)}.subject-header h1{font-size:clamp(2rem,4vw,3rem);margin-bottom:8px}.subject-header p{max-width:720px;color:rgba(255,255,255,.82)}.subject-header-stats{display:grid;grid-template-columns:auto auto;gap:3px 10px;align-items:end;min-width:160px}.subject-header-stats strong{font-size:2rem}.subject-header-stats span{color:rgba(255,255,255,.75);font-size:.8rem}
.topic-grid{display:grid;grid-template-columns:repeat(3,minmax(0,1fr));gap:16px}.topic-card{background:#fff;border:1px solid var(--line);border-radius:18px;padding:20px;display:flex;flex-direction:column;min-height:280px;box-shadow:0 5px 18px rgba(7,28,51,.035)}.topic-card-top{display:flex;justify-content:space-between;align-items:center}.topic-index{width:42px;height:42px;border-radius:12px;background:var(--cyan);color:var(--teal);display:grid;place-items:center;font-weight:900}.topic-card .paper-tag{background:#edf3f7;color:var(--navy);border:0}.topic-card h3{font-size:1.12rem;margin:16px 0 8px}.topic-card p{color:var(--muted);font-size:.9rem;flex:1}.topic-meta{display:flex;gap:7px;flex-wrap:wrap;margin:12px 0}.topic-meta span{font-size:.72rem;font-weight:800;background:#f0f4f7;padding:4px 7px;border-radius:999px;color:#506174}.progress-line{height:7px;background:#e9eff3;border-radius:999px;overflow:hidden}.progress-line span{display:block;height:100%;background:linear-gradient(90deg,var(--teal),#55d8d3);border-radius:999px}.topic-card-actions{display:flex;gap:8px;margin-top:16px}
.topic-hero{background:#fff;border:1px solid var(--line);border-radius:var(--radius-lg);padding:30px;display:grid;grid-template-columns:1fr auto;gap:22px}.topic-hero h1{font-size:clamp(2rem,4vw,3rem);line-height:1.05;margin-bottom:8px}.topic-hero p{color:var(--muted);max-width:720px}.topic-hero-stats{display:flex;gap:12px;align-items:center}.topic-hero-stats div{min-width:82px;background:#f2f6f8;border-radius:15px;padding:13px;text-align:center}.topic-hero-stats strong,.topic-hero-stats span{display:block}.topic-hero-stats strong{font-size:1.5rem}.topic-hero-stats span{font-size:.7rem;color:var(--muted);text-transform:uppercase;font-weight:800}
.topic-action-grid{display:grid;grid-template-columns:repeat(3,minmax(0,1fr));gap:12px;margin:18px 0}.topic-action{border:1px solid var(--line);background:#fff;border-radius:16px;padding:16px;text-align:left;display:grid;grid-template-columns:34px 1fr;column-gap:10px}.topic-action span{width:34px;height:34px;border-radius:10px;background:#eaf6f5;color:var(--teal);display:grid;place-items:center;font-weight:900;grid-row:1/3}.topic-action strong{color:var(--navy)}.topic-action small{color:var(--muted)}.topic-action:hover,.topic-action.active{border-color:#8eddd9;box-shadow:0 5px 18px rgba(0,158,154,.08)}
.lesson-list{display:grid;gap:10px}.lesson-row{display:grid;grid-template-columns:44px 1fr auto;gap:13px;align-items:center;border:1px solid var(--line);border-radius:14px;padding:14px}.lesson-row.completed{background:#f5fcfa}.lesson-status{width:40px;height:40px;border-radius:12px;background:#edf3f6;display:grid;place-items:center;font-weight:900;color:var(--navy)}.lesson-row.completed .lesson-status{background:#dff8ee;color:var(--success)}.lesson-row-main h3{font-size:.98rem;margin-bottom:3px}.lesson-row-main p{margin:0;color:var(--muted);font-size:.8rem}
.lesson-layout{display:grid;grid-template-columns:minmax(0,820px) minmax(240px,320px);gap:22px;align-items:start}.lesson-reader{background:#fff;border:1px solid var(--line);border-radius:22px;overflow:hidden}.lesson-title-block{padding:32px 34px;background:linear-gradient(180deg,#f8fbfc,#fff);border-bottom:1px solid var(--line)}.lesson-title-block h1{font-size:clamp(2rem,4vw,3rem);line-height:1.05;margin-bottom:8px}.lesson-title-block p{color:var(--muted)}.objectives-box{margin:26px 34px;padding:20px;background:#eef9f8;border-left:5px solid var(--teal);border-radius:0 15px 15px 0}.objectives-box h2{font-size:1.05rem}.objectives-box li{margin:5px 0}.lesson-content{padding:0 34px 10px}.lesson-heading{font-size:1.55rem;margin:32px 0 12px;color:var(--navy)}.lesson-paragraph{font-size:1.03rem;line-height:1.82;color:#24364b}.lesson-list-block{padding-left:22px}.lesson-list-block li{margin:8px 0}.definition-box,.formula-box,.warning-box,.keypoint-box,.exam-tip,.practical-box,.lesson-summary{margin:22px 0;padding:18px;border-radius:15px}.definition-box{background:#f0f7ff;border:1px solid #c9def5}.definition-box>span,.formula-box>span{display:block;font-size:.68rem;text-transform:uppercase;font-weight:900;letter-spacing:.1em;color:#2464a3}.definition-box strong{display:block;font-size:1.15rem;margin:4px 0}.definition-box p,.formula-box p,.warning-box p,.keypoint-box p,.exam-tip p{margin:4px 0 0}.formula-box{background:#eefaf9;border:1px solid #b8e8e5}.formula-box>div{font-family:"Cambria Math",Georgia,serif;font-size:1.4rem;font-weight:700;color:#075c5a;margin:5px 0}.worked-example{margin:26px 0;border:1px solid #cfdce5;border-radius:18px;overflow:hidden}.worked-label{background:var(--navy);color:#fff;font-size:.7rem;font-weight:900;text-transform:uppercase;letter-spacing:.12em;padding:9px 18px}.worked-example h3,.worked-example>.problem{padding:0 18px}.worked-example h3{margin-top:18px}.worked-example ol{list-style:none;padding:0 18px;counter-reset:none}.worked-example ol li{display:grid;grid-template-columns:31px 1fr;gap:10px;margin:10px 0;align-items:start}.worked-example ol li>span{width:28px;height:28px;border-radius:9px;background:#eaf6f5;color:var(--teal);display:grid;place-items:center;font-weight:900}.worked-example ol li p{margin:2px 0}.final-answer{display:flex;justify-content:space-between;gap:15px;background:#eef9f8;border-top:1px solid #cfe7e5;padding:14px 18px}.warning-box{background:#fff6e8;border:1px solid #f0d2a4;color:#7b3c00}.keypoint-box,.exam-tip{background:#edf8ff;border:1px solid #cce4f4}.practical-box{background:#f7f5ff;border:1px solid #ded3fb}.lesson-summary{background:#071c33;color:#fff}.lesson-summary .overline{color:#65e1db}.lesson-summary li{margin:6px 0}.visual-placeholder{display:flex;gap:15px;align-items:center;background:#f3f7fa;border:1px dashed #b8c8d4;border-radius:15px;padding:18px}.visual-icon{font-size:2.1rem;color:var(--teal)}.visual-placeholder p{margin:3px 0;color:var(--muted)}.table-wrap{overflow:auto;margin:20px 0}.data-table{width:100%;border-collapse:collapse}.data-table th,.data-table td{padding:11px;border-bottom:1px solid var(--line);text-align:left}.data-table th{background:#f1f5f7;color:var(--navy);font-size:.78rem;text-transform:uppercase}.inline-check{margin:20px 34px 30px;padding:22px;border-radius:18px;background:#f7fafc;border:1px solid var(--line)}.lesson-footer{padding:22px 34px;border-top:1px solid var(--line);display:flex;justify-content:space-between;gap:12px}.lesson-sidebar{position:relative}.sticky-panel{position:sticky;top:92px;background:#fff;border:1px solid var(--line);border-radius:18px;padding:20px}.sticky-panel>strong{font-size:.85rem}.sticky-panel ul{padding-left:18px;color:var(--muted);font-size:.84rem}.sticky-panel li{margin:7px 0}.lesson-progress{margin:8px 0;height:8px;background:#eaf0f3;border-radius:999px;overflow:hidden}.lesson-progress span{display:block;height:100%;background:var(--teal)}
.exercise-form{display:grid;gap:14px}.question-card{background:#fff;border:1px solid var(--line);border-radius:16px;padding:19px}.question-card h3{font-size:1rem;margin:10px 0 16px}.question-head{display:flex;justify-content:space-between;color:var(--muted);font-size:.72rem;font-weight:850;text-transform:uppercase;letter-spacing:.05em}.choice-grid{display:grid;gap:8px}.choice-grid.two{grid-template-columns:repeat(2,minmax(0,1fr))}.choice input{position:absolute;opacity:0}.choice span{display:flex;align-items:center;gap:10px;border:1px solid #cdd9e1;border-radius:12px;padding:11px 12px;transition:.15s}.choice span b{width:28px;height:28px;border-radius:8px;background:#edf3f6;display:grid;place-items:center}.choice input:checked+span{border-color:var(--teal);background:#effbf9;box-shadow:0 0 0 2px rgba(0,158,154,.1)}.answer-line{display:flex;align-items:center;border:1px solid #cdd9e1;border-radius:12px;overflow:hidden}.answer-line input{flex:1;border:0;padding:12px;outline:none}.answer-line span{padding:10px 12px;background:#f1f5f7;font-weight:800}.question-feedback{display:none;margin-top:13px;padding:12px;border-radius:11px}.question-feedback.show{display:block}.question-feedback.correct{background:#e5f8ef;color:#075e3b}.question-feedback.incorrect{background:#fff0ee;color:#8f2018}.question-feedback p{margin:4px 0}.memo-answer{margin-top:6px;font-weight:750}.result-panel{display:grid;grid-template-columns:auto auto 1fr;gap:12px;align-items:center;padding:18px;border-radius:15px}.result-panel strong{font-size:1.5rem}.result-panel span{font-size:1.2rem;font-weight:900}.result-panel p{margin:0}.result-panel.pass{background:#e8f8f0;color:#075f3c}.result-panel.retry{background:#fff4e7;color:#884200}.assessment-header{background:#fff;border:1px solid var(--line);border-radius:22px;padding:26px;display:flex;justify-content:space-between;align-items:center;margin-bottom:18px}.assessment-header h1{font-size:clamp(1.8rem,4vw,2.8rem);margin-bottom:5px}.assessment-header p{color:var(--muted);margin:0}.assessment-badge{border:2px solid var(--navy);color:var(--navy);font-weight:900;padding:9px 12px;border-radius:12px;letter-spacing:.08em}
.practice-guide{display:grid;grid-template-columns:repeat(3,minmax(0,1fr));gap:14px;margin-bottom:20px}.practice-guide article{background:#fff;border:1px solid var(--line);border-radius:16px;padding:18px}.practice-guide strong,.practice-guide span{display:block}.practice-guide span{color:var(--teal);font-size:.78rem;font-weight:900;margin:4px 0}.practice-guide p{color:var(--muted);margin:0;font-size:.87rem}.practice-topic-list{display:grid;gap:10px}.practice-topic{display:flex;justify-content:space-between;align-items:center;gap:18px;background:#fff;border:1px solid var(--line);border-radius:15px;padding:16px 18px}.practice-topic h3{margin-bottom:3px}.practice-topic p{margin:0;color:var(--muted);font-size:.85rem}.practice-topic>div:last-child{display:flex;gap:7px;flex-wrap:wrap;justify-content:flex-end}.paper-grid{display:grid;grid-template-columns:repeat(2,minmax(0,1fr));gap:18px}.paper-card{position:relative;overflow:hidden;display:grid;grid-template-columns:100px 1fr;gap:18px;border-radius:24px;padding:26px;color:#fff;min-height:300px}.paper-card.physics{background:linear-gradient(140deg,#0b2e5c,#1f67b0)}.paper-card.chemistry{background:linear-gradient(140deg,#38216f,#794ec0)}.paper-number{font-size:4.5rem;font-weight:950;opacity:.18;line-height:1}.paper-card p{color:rgba(255,255,255,.82)}
.progress-topic-list{display:grid;gap:12px}.progress-topic-list article{display:grid;grid-template-columns:minmax(180px,1fr) minmax(200px,2fr) 50px;gap:14px;align-items:center}.progress-topic-list strong,.progress-topic-list span{display:block}.progress-topic-list span{color:var(--muted);font-size:.78rem}.support-layout{display:grid;grid-template-columns:280px minmax(0,1fr);gap:18px}.support-info{background:#fff;border:1px solid var(--line);border-radius:18px;padding:20px}.prompt-chip{width:100%;text-align:left;border:1px solid var(--line);background:#f7fafc;border-radius:11px;padding:10px;margin:5px 0;color:var(--navy)}.usage-note{margin-top:16px;padding:14px;background:#eef9f8;border-radius:12px}.usage-note strong,.usage-note span{display:block}.usage-note strong{font-size:1.5rem;color:var(--teal)}.chat{display:grid;grid-template-rows:minmax(420px,1fr) auto}.messages{overflow:auto;display:flex;flex-direction:column;gap:10px;padding-bottom:14px}.message{max-width:82%;padding:12px 14px;border-radius:14px;white-space:pre-wrap}.message.user{align-self:flex-end;background:var(--navy);color:#fff}.message.assistant{align-self:flex-start;background:#e9f7f6}.chat-form{display:grid;grid-template-columns:1fr auto;gap:10px;border-top:1px solid var(--line);padding-top:14px}.chat-form textarea{min-height:76px}
.form-grid{display:grid;gap:14px}.field label{display:block;font-size:.78rem;font-weight:850;margin-bottom:6px;color:var(--navy)}.field input,.field select,.field textarea{width:100%;border:1px solid #becdd7;border-radius:11px;padding:11px 12px;background:#fff;color:var(--ink)}.field input:focus,.field select:focus,.field textarea:focus{outline:3px solid rgba(0,158,154,.13);border-color:var(--teal)}.fine-print{font-size:.78rem;color:var(--muted)}.alert{padding:11px 13px;border-radius:11px;margin:10px 0;font-weight:700}.alert.error{background:#fee9e7;color:var(--danger)}.alert.success{background:#e3f8ed;color:var(--success)}.alert.info{background:#eaf5fd;color:#145d8e}.status-pill{padding:5px 9px;border-radius:999px;background:#edf3f6;font-size:.74rem;font-weight:850}.status-pill.done{background:#e4f8ee;color:var(--success)}.status-pill.pending{background:#fff3e3;color:#925000}.learner-summary{display:grid;grid-template-columns:1fr auto;gap:2px 12px;padding:12px 0;border-bottom:1px solid var(--line)}.learner-summary strong{grid-column:1}.learner-summary span{color:var(--muted);font-size:.82rem}.learner-summary b{grid-column:2;grid-row:1/3;align-self:center}.empty-state{text-align:center;background:#fff;border:1px dashed #bbcbd5;border-radius:16px;padding:32px;color:var(--muted)}
.auth-page{min-height:100vh;display:grid;grid-template-columns:minmax(0,1.1fr) minmax(420px,.9fr)}.auth-visual{background:radial-gradient(circle at 80% 10%,rgba(0,184,178,.23),transparent 35%),linear-gradient(145deg,#06182d,#0a3553);color:#fff;padding:clamp(32px,6vw,82px);display:flex;flex-direction:column}.auth-brand span{display:block;color:#59e4dd;font-size:.72rem;font-weight:900;text-transform:uppercase;letter-spacing:.15em}.auth-brand strong{font-size:1.15rem}.auth-copy{margin:auto 0}.auth-copy h1{font-size:clamp(2.7rem,6vw,5.3rem);line-height:.95;max-width:820px;margin:10px 0 22px}.auth-copy p{font-size:1.08rem;color:#d5e7f0;max-width:690px}.auth-features{display:flex;gap:8px;flex-wrap:wrap;margin-top:24px}.auth-features span{border:1px solid rgba(255,255,255,.18);background:rgba(255,255,255,.07);padding:6px 10px;border-radius:999px;font-size:.75rem;font-weight:800}.auth-panel{display:grid;place-items:center;padding:28px}.auth-box{width:min(460px,100%);background:#fff;border:1px solid var(--line);border-radius:24px;padding:28px;box-shadow:var(--shadow)}.tabs{display:flex;background:#edf2f5;padding:4px;border-radius:12px;margin-bottom:20px}.tabs button{flex:1;border:0;background:transparent;padding:10px;border-radius:9px;font-weight:850;color:var(--muted)}.tabs button.active{background:#fff;color:var(--navy);box-shadow:0 2px 8px rgba(0,0,0,.07)}
.loading{min-height:70vh;display:grid;place-items:center;text-align:center;color:var(--muted)}.spinner{width:38px;height:38px;border:4px solid #dce7ec;border-top-color:var(--teal);border-radius:50%;animation:spin .8s linear infinite}@keyframes spin{to{transform:rotate(360deg)}}
@media(max-width:1100px){.topic-grid{grid-template-columns:repeat(2,minmax(0,1fr))}.lesson-layout{grid-template-columns:1fr}.lesson-sidebar{display:none}.metric-grid{grid-template-columns:repeat(2,minmax(0,1fr))}}
@media(max-width:900px){.shell{grid-template-columns:1fr}.sidebar{position:fixed;left:0;top:0;width:278px;z-index:30;transform:translateX(-102%);transition:.22s}.sidebar.open{transform:translateX(0)}.mobile-menu{display:block}.topbar{padding:0 16px}.content{padding:22px 18px 50px}.auth-page{grid-template-columns:1fr}.auth-visual{min-height:46vh;padding:34px 24px}.auth-copy h1{font-size:clamp(2.5rem,10vw,4.5rem)}.subject-grid,.paper-grid{grid-template-columns:1fr}.dashboard-hero{grid-template-columns:1fr}.hero-score{display:none}}
@media(max-width:650px){.topic-grid,.topic-action-grid,.practice-guide{grid-template-columns:1fr}.metric-grid{grid-template-columns:repeat(2,minmax(0,1fr))}.subject-header,.topic-hero,.assessment-header{display:block}.subject-header-stats,.topic-hero-stats{margin-top:18px}.topic-hero-stats{display:grid;grid-template-columns:repeat(3,1fr)}.lesson-title-block,.lesson-content{padding-left:20px;padding-right:20px}.objectives-box,.inline-check{margin-left:20px;margin-right:20px}.lesson-footer{padding:18px 20px;flex-direction:column}.practice-topic{display:block}.practice-topic>div:last-child{justify-content:flex-start;margin-top:12px}.support-layout{grid-template-columns:1fr}.choice-grid.two{grid-template-columns:1fr}.progress-topic-list article{grid-template-columns:1fr 50px}.progress-topic-list .progress-line{grid-column:1/3}.paper-card{grid-template-columns:1fr}.paper-number{font-size:3rem}.auth-panel{padding:16px}.auth-box{padding:22px}}