:root{--bg:#0b1020;--card:rgba(13,24,44,.82);--line:rgba(129,246,255,.18);--text:#f5fbff;--muted:#9bb4c6;--cyan:#22d3ee;--green:#5cffb1;--gold:#f6c453;--amber:#f59e0b;--red:#fb7185;--shadow:0 24px 70px rgba(0,0,0,.35);--sans:Inter,system-ui,sans-serif;--mono:'JetBrains Mono',monospace}*{box-sizing:border-box}html{scroll-behavior:smooth}body{margin:0;min-height:100vh;background:radial-gradient(circle at top left,rgba(34,211,238,.16),transparent 35%),radial-gradient(circle at bottom right,rgba(246,196,83,.15),transparent 33%),var(--bg);color:var(--text);font-family:var(--sans);overflow-x:hidden}button{font-family:inherit}.hidden{display:none!important}.ambient{position:fixed;inset:0;pointer-events:none;opacity:.2;background-image:linear-gradient(rgba(92,255,177,.06) 1px,transparent 1px),linear-gradient(90deg,rgba(34,211,238,.05) 1px,transparent 1px);background-size:44px 44px;mask-image:radial-gradient(circle at center,#000,transparent 80%)}body.maths{background:radial-gradient(circle at top left,rgba(246,196,83,.23),transparent 35%),radial-gradient(circle at bottom right,rgba(245,158,11,.16),transparent 32%),#141006}body.programming{background:radial-gradient(circle at top left,rgba(34,211,238,.18),transparent 35%),radial-gradient(circle at bottom right,rgba(92,255,177,.14),transparent 30%),#08111f}.update-banner{position:sticky;top:0;z-index:40;text-align:center;padding:10px;background:linear-gradient(135deg,var(--gold),var(--cyan));color:#061522;font-weight:900}.update-banner button{border:0;border-radius:999px;padding:6px 12px;margin-left:8px;background:#061522;color:#fff;font-weight:900;cursor:pointer}.topbar{position:sticky;top:0;z-index:20;display:flex;align-items:center;justify-content:space-between;gap:20px;padding:18px 26px;background:rgba(8,17,31,.82);backdrop-filter:blur(18px);border-bottom:1px solid var(--line)}.brand{display:flex;align-items:center;gap:14px}.brand-mark{width:50px;height:50px;display:grid;place-items:center;border-radius:18px;background:linear-gradient(135deg,var(--green),var(--cyan));font-size:26px;box-shadow:0 0 28px rgba(92,255,177,.25)}body.maths .brand-mark{background:linear-gradient(135deg,var(--gold),var(--amber))}.brand h1{margin:0;font-size:clamp(22px,3vw,34px);letter-spacing:-.04em}.brand p{margin:3px 0 0;color:var(--muted);font:600 13px var(--mono)}.top-actions{display:flex;gap:10px;flex-wrap:wrap;justify-content:flex-end;align-items:center}.primary-btn,.ghost-btn,.section-btn,.chapter-btn{border:0;cursor:pointer;border-radius:999px;font-weight:900;transition:transform .18s ease,opacity .18s ease,background .18s ease}.primary-btn{background:linear-gradient(135deg,var(--green),var(--cyan));color:#05202a;padding:12px 18px;box-shadow:0 14px 34px rgba(34,211,238,.22)}body.maths .primary-btn{background:linear-gradient(135deg,var(--gold),var(--amber));color:#241600}.primary-btn.small{padding:10px 14px}.ghost-btn{background:rgba(255,255,255,.04);color:var(--text);border:1px solid var(--line);padding:11px 16px}.primary-btn:hover,.ghost-btn:hover,.section-btn:hover,.chapter-btn:hover{transform:translateY(-2px)}.reminder-setting{display:inline-flex;align-items:center;gap:8px;color:var(--muted);border:1px solid var(--line);background:rgba(255,255,255,.04);border-radius:999px;padding:8px 12px;font:800 12px var(--mono)}.reminder-setting input{color:var(--text);background:transparent;border:0;font:800 12px var(--mono);outline:none}.app-shell{display:grid;grid-template-columns:360px minmax(0,1fr);gap:22px;padding:22px;max-width:1600px;margin:0 auto}.sidebar{position:sticky;top:96px;align-self:start;max-height:calc(100vh - 116px);overflow:auto;padding-right:3px}.profile-card,.progress-card,.hero-panel,.course-card,.chapter-detail,.modal-card,.section-card,.module-card{border:1px solid var(--line);background:var(--card);backdrop-filter:blur(18px);box-shadow:var(--shadow);border-radius:28px}.profile-card{display:flex;align-items:center;gap:14px;padding:16px;margin-bottom:14px}.avatar{width:52px;height:52px;border-radius:18px;display:grid;place-items:center;background:rgba(92,255,177,.13);color:var(--green);font:900 24px var(--mono);border:1px solid rgba(34,211,238,.38)}body.maths .avatar{background:rgba(246,196,83,.16);color:var(--gold);border-color:rgba(246,196,83,.45)}.profile-card h2,.profile-card p{margin:0}.profile-card p,.progress-card 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span:last-child{display:block;font-size:13px;color:var(--muted);margin-top:3px}.content-area{min-width:0;display:grid;gap:22px}.hero-panel{padding:clamp(22px,4vw,42px);position:relative;overflow:hidden}.eyebrow{color:var(--green);text-transform:uppercase;letter-spacing:.14em;font:900 12px var(--mono)}body.maths .eyebrow{color:var(--gold)}.hero-panel h2{margin:0;font-size:clamp(38px,6vw,76px);letter-spacing:-.07em;line-height:.92}.hero-panel p{color:#c9e7ef;font-size:17px;line-height:1.75;max-width:900px}.course-grid{display:grid;grid-template-columns:repeat(auto-fit,minmax(280px,1fr));gap:18px}.course-card{padding:24px;cursor:pointer;transition:transform .18s ease,border-color .18s ease}.course-card:hover{transform:translateY(-4px);border-color:var(--cyan)}.course-card h3{font-size:30px;margin:8px 0;letter-spacing:-.04em}.course-card p{color:var(--muted);line-height:1.6}.course-card strong{font-family:var(--mono);color:var(--green)}.chapter-detail{padding:clamp(20px,3vw,34px)}.chapter-header{display:flex;justify-content:space-between;gap:18px;align-items:flex-start;border-bottom:1px solid var(--line);padding-bottom:18px;margin-bottom:20px}.chapter-detail h2{margin:0;font-size:clamp(26px,4vw,46px);letter-spacing:-.05em}.chapter-meta{margin:8px 0 0;color:#c3dce5;line-height:1.65}.stage-badge{color:#05202a;background:linear-gradient(135deg,var(--green),var(--cyan));border-radius:999px;padding:7px 12px;font:900 12px var(--mono);white-space:nowrap}body.maths .stage-badge{background:linear-gradient(135deg,var(--gold),var(--amber));color:#241600}.section-stack{display:grid;gap:14px}.section-card{padding:18px}.section-card h3{margin:0 0 9px;color:var(--green)}body.maths .section-card h3{color:var(--gold)}.section-card p,.section-card li,.module-card p{color:#d6e9ef;line-height:1.7;white-space:pre-wrap}.section-card.locked-section{opacity:.58;filter:grayscale(.2)}.section-card.completed{border-color:rgba(92,255,177,.55)}body.maths .section-card.completed{border-color:rgba(246,196,83,.55)}.section-btn{margin-top:12px;padding:11px 15px;color:#05202a;background:linear-gradient(135deg,var(--green),#b6ff5c)}body.maths .section-btn{background:linear-gradient(135deg,var(--gold),var(--amber));color:#241600}.section-btn:disabled{cursor:not-allowed;opacity:.55;transform:none}.code-block{background:#050d18;border:1px solid var(--line);border-radius:18px;padding:15px;overflow:auto;color:var(--green);font:600 14px/1.8 var(--mono);white-space:pre-wrap}.video-frame{aspect-ratio:16/9;width:100%;border:0;border-radius:18px;background:#050d18;box-shadow:0 18px 40px rgba(0,0,0,.22)}.exercises{display:grid;gap:10px;padding-left:0;list-style:none}.exercises li{border:1px solid var(--line);background:rgba(255,255,255,.04);border-radius:16px;padding:13px 15px}.modal{position:fixed;inset:0;z-index:60;display:grid;place-items:center;background:rgba(0,0,0,.62);padding:24px}.auth-modal{backdrop-filter:blur(12px)}.modal-card{max-width:720px;width:min(100%,720px);padding:42px;position:relative;border-color:rgba(92,255,177,.34)}.auth-card{text-align:left}.auth-card h2{margin:6px 0 10px;font-size:clamp(32px,5vw,58px);letter-spacing:-.06em}.auth-card label{display:grid;gap:8px;margin:14px 0;color:var(--muted);font-weight:900}.auth-card input{width:100%;border:1px solid rgba(34,211,238,.38);border-radius:16px;background:rgba(3,10,18,.78);color:var(--text);padding:14px 15px;font:700 16px var(--mono);outline:none}.auth-card input:focus{border-color:var(--green);box-shadow:0 0 0 4px rgba(92,255,177,.12)}.auth-step{display:grid;gap:10px}.auth-message{min-height:22px;color:var(--gold);font-family:var(--mono)}.auth-note{color:var(--muted);font-size:13px;line-height:1.6}.course-choices{display:grid;grid-template-columns:repeat(2,1fr);gap:12px}.choice-card{border:1px solid var(--line);background:rgba(255,255,255,.05);border-radius:20px;padding:18px;cursor:pointer}.choice-card.selected{border-color:var(--green);box-shadow:0 0 0 2px rgba(92,255,177,.18) inset}.choice-card h4{font-size:24px;margin:0 0 8px}.certificate{text-align:center}.modal-close{position:absolute;right:18px;top:14px;background:none;border:0;color:var(--text);font-size:34px;cursor:pointer}.cert-kicker{color:var(--green);font:900 13px var(--mono);text-transform:uppercase;letter-spacing:.2em}.certificate h2{font-size:clamp(32px,6vw,62px);margin:6px 0 12px;letter-spacing:-.06em}.cert-signature{margin:28px auto;padding-top:18px;border-top:1px solid var(--line);color:var(--muted);font-family:var(--mono)}.warning{color:var(--gold);font-family:var(--mono)}@media(max-width:1050px){.app-shell{grid-template-columns:1fr}.sidebar{position:relative;top:0;max-height:none}.course-choices{grid-template-columns:1fr}}@media(max-width:720px){.topbar{align-items:flex-start;flex-direction:column}.app-shell{padding:14px}.chapter-header{flex-direction:column}}@media print{body{background:white;color:#111}.topbar,.app-shell,.modal-close,#printCert{display:none}.modal,.modal.hidden{display:grid;position:static;background:white}.modal-card{box-shadow:none;color:#111;border:2px solid #111}}
/* multi-course checkbox polish */
.choice-card label{display:flex!important;grid-template-columns:none!important;align-items:center;gap:10px;margin:0!important;color:var(--text)!important;font-size:20px}.choice-card input{width:22px!important;height:22px!important;accent-color:var(--green);padding:0!important}.choice-card span{font-weight:900}


/* Mobile/touch reliability fixes for hosted app */
html,body{overflow-x:hidden;overflow-y:auto;-webkit-overflow-scrolling:touch;touch-action:pan-y;max-width:100%}.topbar,.app-shell,.modal{max-width:100vw}.modal{overflow-y:auto;align-items:start}.modal-card{margin:auto 0}@media(max-width:720px){.topbar{position:relative;padding:14px 16px}.brand{align-items:flex-start}.brand-mark{width:44px;height:44px;border-radius:15px;flex:0 0 auto}.top-actions{width:100%;justify-content:stretch}.top-actions>*{flex:1 1 100%;justify-content:center;text-align:center}.ghost-btn,.primary-btn{min-height:46px}.app-shell{padding:14px;gap:14px}.profile-card{align-items:flex-start}.chapter-btn{grid-template-columns:26px 1fr}.hero-panel h2{font-size:clamp(34px,12vw,48px)}.chapter-header{gap:12px}.stage-badge{white-space:normal}.modal{place-items:start center;padding:14px}.modal-card{width:100%;padding:24px 18px;border-radius:22px}.auth-card h2{font-size:34px}.course-choices{grid-template-columns:1fr}.choice-card{padding:15px}.reminder-setting{min-height:46px}}

.video-section{order:-1;border-color:rgba(34,211,238,.5)}body.maths .video-section{border-color:rgba(246,196,83,.55)}

.force-update-modal{z-index:1000;background:rgba(0,0,0,.88);backdrop-filter:blur(18px)}.force-update-modal .modal-card{border-color:rgba(246,196,83,.5);text-align:center}.update-now-btn{display:inline-flex;text-decoration:none;margin-top:18px}.update-blocked{overflow:hidden}


/* Critical real-device layout fixes */
.topbar{min-height:86px}.content-area{align-content:start}.hero-panel{overflow:visible;display:grid;gap:16px;margin-top:0}.hero-panel .eyebrow{display:block;margin:0 0 4px}.hero-panel h2{line-height:1.06;margin:0;overflow-wrap:anywhere}.hero-panel p{margin:0}.cta-row{display:flex;flex-wrap:wrap;gap:12px;margin-top:8px}.auth-modal{overflow-y:auto;place-items:start center}.auth-card{max-height:calc(100dvh - 32px);overflow-y:auto;-webkit-overflow-scrolling:touch;touch-action:pan-y}.course-choices{max-height:min(54dvh,520px);overflow-y:auto;-webkit-overflow-scrolling:touch;touch-action:pan-y;overscroll-behavior:contain;padding-right:4px}.choice-card{min-height:116px}.primary-btn,.ghost-btn,.section-btn,.chapter-btn{min-height:44px}@media(max-width:720px){.topbar{min-height:auto}.content-area{gap:16px}.hero-panel{padding:24px 18px}.hero-panel h2{font-size:clamp(32px,10.5vw,44px);letter-spacing:-.045em;line-height:1.08}.auth-card{max-height:calc(100dvh - 28px)}.course-choices{max-height:46dvh}.choice-card{min-height:112px}.modal-card{margin:0}}