:root{--bg:#070b18;--card:rgba(255,255,255,0.05);--border:rgba(255,255,255,0.1);--text:#eef1fb;--muted:#98a2c3;--a:#7c5cff;--b:#22d3ee;--easy:#34d399;--medium:#fbbf24;--hard:#f87171}*{box-sizing:border-box}html{scroll-behavior:smooth}body{margin:0;background:var(--bg);color:var(--text);font-family:system-ui,-apple-system,Segoe UI,Roboto,sans-serif;line-height:1.6;min-height:100vh}a{color:var(--b);text-decoration:none}h1,h2,h3{line-height:1.15;margin:0 0 12px}h1{font-size:clamp(2.2rem,6vw,4rem);letter-spacing:-.03em}h2{font-size:1.7rem}.container{max-width:1040px;margin:0 auto;padding:0 20px}.grad{background:linear-gradient(90deg,var(--a),var(--b));-webkit-background-clip:text;background-clip:text;color:transparent}.lead,.muted{color:var(--muted)}.lead{font-size:1.1rem;max-width:620px;margin-bottom:28px}.bg-orbs{position:fixed;inset:0;z-index:-1;overflow:hidden}.bg-orbs:after,.bg-orbs:before{content:"";position:absolute;width:520px;height:520px;border-radius:50%;filter:blur(120px);opacity:.35;animation:float 14s ease-in-out infinite alternate}.bg-orbs:before{background:var(--a);top:-120px;left:-120px}.bg-orbs:after{background:var(--b);bottom:-160px;right:-120px;animation-delay:-7s}@keyframes float{to{transform:translate(60px,40px) scale(1.15)}}.nav{position:-webkit-sticky;position:sticky;top:0;z-index:10;-webkit-backdrop-filter:blur(14px);backdrop-filter:blur(14px);background:rgba(7,11,24,.6);border-bottom:1px solid var(--border)}.nav-inner{display:flex;align-items:center;justify-content:space-between;gap:16px;height:64px}.logo{font-weight:800;font-size:1.5rem;color:var(--text)}.logo span{color:var(--b)}.nav-links{display:flex;gap:6px}.nav-links a{color:var(--muted);padding:8px 14px;border-radius:999px;font-weight:500;transition:.2s;white-space:nowrap}.nav-links a.active,.nav-links a:hover{color:var(--text);background:var(--card)}.btn{display:inline-block;border:0;cursor:pointer;color:#fff;font-weight:600;font-size:1rem;padding:13px 24px;border-radius:12px;background:linear-gradient(135deg,var(--a),var(--b));box-shadow:0 8px 30px -8px var(--a);transition:transform .2s,box-shadow .2s}.btn:hover{transform:translateY(-2px)}.btn:disabled{opacity:.6;cursor:wait}.btn.ghost{background:var(--card);border:1px solid var(--border);box-shadow:none}.btn.small{padding:9px 16px;font-size:.9rem}.hero{padding:90px 0 50px}.hero p{color:var(--muted);font-size:1.2rem;max-width:600px}.cta{display:flex;flex-wrap:wrap;gap:12px;margin-top:28px}.pill{display:inline-block;padding:4px 14px;border-radius:999px;font-size:.8rem;background:var(--card);border:1px solid var(--border);color:var(--b);margin-bottom:16px}.section{padding:36px 0}.page-top{padding-top:56px}.section-head{display:flex;justify-content:space-between;align-items:baseline}.toolbar{display:flex;flex-wrap:wrap;gap:12px;margin:16px 0}.search{flex:1 1;min-width:200px;padding:11px 16px;border-radius:12px;color:var(--text);font-size:1rem;background:var(--card);border:1px solid var(--border);outline:none}.search:focus{border-color:var(--a)}.chips{display:flex;flex-wrap:wrap;gap:8px}.diff.day{color:var(--b);background:rgba(34,211,238,.1)}.chip{cursor:pointer;padding:9px 16px;border-radius:999px;color:var(--muted);background:var(--card);border:1px solid var(--border)}.chip.on{color:#fff;background:var(--a);border-color:var(--a)}.progress{position:relative;height:26px;border-radius:999px;background:var(--card);border:1px solid var(--border);overflow:hidden;margin:12px 0}.progress-bar{height:100%;background:linear-gradient(90deg,var(--a),var(--b));transition:width .4s}.progress span{position:absolute;inset:0;display:grid;place-items:center;font-size:.8rem}.problems{list-style:none;margin:0;padding:0;display:grid;grid-gap:10px;gap:10px}.problems li{display:block;border-radius:14px;background:var(--card);border:1px solid var(--border);transition:.2s}.row-link{display:flex;align-items:center;gap:14px;padding:14px 18px;color:inherit}.problems li:hover{transform:translateX(4px);border-color:var(--a)}.problems li.solved .p-main strong{text-decoration:line-through;opacity:.5}.problems input{width:20px;height:20px;accent-color:var(--a)}.watch-mark{flex:none;width:22px;height:22px;border-radius:50%;border:2px solid var(--border);display:grid;place-items:center;font-size:.8rem;color:#fff}.watch-mark.on{background:var(--easy);border-color:var(--easy)}.splash{min-height:60vh}.p-main{flex:1 1;display:flex;flex-direction:column}.p-main small{color:var(--muted)}.diff{font-size:.8rem;font-weight:600;padding:3px 10px;border-radius:999px}.diff.easy{color:var(--easy);background:rgba(52,211,153,.12)}.diff.medium{color:var(--medium);background:rgba(251,191,36,.12)}.diff.hard{color:var(--hard);background:rgba(248,113,113,.12)}.p-link{flex:none;display:inline-flex;align-items:center;gap:6px;white-space:nowrap;font-weight:600;font-size:.85rem;color:#fff;padding:8px 14px;border-radius:999px;background:linear-gradient(135deg,var(--a),var(--b))}.empty{padding:20px;text-align:center;color:var(--muted)}.card.center,.plus-teaser,.yt{text-align:center;border-radius:22px;border:1px solid var(--border);background:var(--card);padding:40px 20px;margin:24px 0}.plus-teaser{background:linear-gradient(135deg,rgba(124,92,255,.18),rgba(34,211,238,.12))}.card{background:var(--card);border:1px solid var(--border);border-radius:18px;padding:24px;-webkit-backdrop-filter:blur(10px);backdrop-filter:blur(10px)}.course-grid{display:grid;grid-gap:20px;gap:20px;grid-template-columns:repeat(auto-fill,minmax(300px,1fr));margin-top:24px}.course{display:flex;flex-direction:column;gap:8px;transition:transform .25s}.course:hover{transform:translateY(-4px)}.perks{list-style:none;padding:0;margin:6px 0;color:var(--muted)}.price{font-size:1.8rem;font-weight:800;margin:6px 0}.note{padding:14px 18px;border-radius:12px;background:rgba(251,191,36,.1);border:1px solid rgba(251,191,36,.3)}.error{color:var(--hard);margin:6px 0 0}.upi{display:flex;flex-wrap:wrap;gap:16px;padding-top:14px;border-top:1px solid var(--border)}.qr{background:#fff;border-radius:12px;padding:4px;height:-moz-fit-content;height:fit-content}.upi-body{flex:1 1;min-width:180px}.utr-row{display:flex;gap:8px}.lessons{display:grid;grid-gap:8px;gap:8px;margin-top:8px}.lesson{width:100%;text-align:left;cursor:pointer;padding:10px 14px;border-radius:10px;color:var(--text);background:var(--card);border:1px solid var(--border)}.player{width:100%;aspect-ratio:16/9;border:0;border-radius:12px;margin-top:8px}.site-footer{padding:40px 20px;color:var(--muted);text-align:center}.table{display:grid;grid-gap:10px;gap:10px;margin-top:12px}.table .row{display:flex;justify-content:space-between;align-items:center;gap:12px;flex-wrap:wrap;padding:14px 18px;border-radius:14px;background:var(--card);border:1px solid var(--border)}.table .row small{display:block;color:var(--muted)}.row-actions{display:flex;gap:8px}.login{max-width:440px;margin:0 auto}.legal{max-width:760px}.legal h2{margin-top:28px;font-size:1.3rem}.legal ul{padding-left:20px}.legal p,.legal ul{color:var(--muted)}.login form{display:grid;grid-gap:14px;gap:14px}.btn.google{width:100%;background:#fff;color:#1f1f1f;box-shadow:none;display:inline-flex;align-items:center;justify-content:center;gap:10px}.alt-qr{margin:10px 0;color:var(--muted)}.alt-qr summary{cursor:pointer;color:var(--b)}.alt-qr img{display:block;margin:10px 0 6px;border-radius:10px;background:#fff}.upi-id{margin:8px 0 0;font-size:.9rem}.upi-apps{flex-wrap:wrap;gap:8px;margin:8px 0}.only-phone{display:none}@media (pointer:coarse){.only-phone{display:block}.upi-apps.only-phone{display:flex}.only-desktop,.qr{display:none}}.or{color:var(--muted);font-size:.85rem;margin:14px 0}.code-input{text-align:center;font-size:1.6rem;letter-spacing:.5em}.link-btn{background:none;border:0;color:var(--b);cursor:pointer;font-size:.9rem}.lesson-form{display:grid;grid-gap:10px;gap:10px;grid-template-columns:repeat(auto-fit,minmax(200px,1fr));align-items:center}.watch{display:grid;grid-gap:24px;gap:24px;grid-template-columns:minmax(0,1fr) 340px;align-items:start}.player-box{width:100%;aspect-ratio:16/9;background:#000;border-radius:16px;overflow:hidden;box-shadow:0 20px 60px -20px var(--a)}.player-box iframe{width:100%;height:100%;border:0;display:block}.watch-title{font-size:clamp(1.4rem,3vw,2rem);margin:18px 0 6px}.controls{display:flex;flex-wrap:wrap;align-items:end;gap:10px;margin-top:14px}.controls label{display:grid;grid-gap:2px;gap:2px;font-size:.75rem;color:var(--muted)}.controls select{padding:8px 10px;border-radius:10px;color:var(--text);background:#151b33;border:1px solid var(--border)}.btn.on{background:var(--a);border-color:var(--a)}.shortcuts{margin-top:12px;padding:16px}.shortcuts ul{margin:8px 0;padding-left:18px;color:var(--muted)}kbd{background:#232b4d;border-radius:6px;padding:1px 7px;font-size:.8rem;color:var(--text)}.dim{position:fixed;inset:0;z-index:30;background:rgba(0,0,0,.92)}.stage{position:relative}.stage.lifted{z-index:40}body{overflow-x:hidden}.watch.is-theater{grid-template-columns:1fr}.stage.theater{width:100vw;margin-left:calc(50% - 50vw);background:#000}.stage.theater .player-box{max-width:min(100vw,calc(82vh * 16 / 9));margin:0 auto;border-radius:0;box-shadow:none}.watch-actions{display:flex;flex-wrap:wrap;align-items:center;gap:10px;margin-top:14px}.toggle{display:inline-flex;align-items:center;gap:8px;color:var(--muted);font-size:.9rem}.toggle input{accent-color:var(--a)}.watch-side{background:var(--card);border:1px solid var(--border);border-radius:16px;overflow:hidden}.side-head{display:flex;justify-content:space-between;padding:14px 16px;border-bottom:1px solid var(--border)}.side-list{list-style:none;margin:0;padding:6px;max-height:70vh;overflow-y:auto;position:relative}.side-list a{display:flex;align-items:center;gap:10px;padding:10px;border-radius:10px;color:var(--text)}.side-list a:hover{background:rgba(255,255,255,.06)}.side-list li.current a{background:rgba(124,92,255,.25)}.tick{width:16px;color:var(--easy);text-align:center;font-size:.85rem}.s-title{flex:1 1;font-size:.9rem;line-height:1.3}.side-list small{color:var(--muted)}@media (max-width:960px){.watch{grid-template-columns:1fr}.side-list{max-height:50vh}}@media (max-width:720px){.nav-inner{height:auto;flex-wrap:wrap;padding:10px 20px}.nav-links{order:3;width:100%;overflow-x:auto}.hero{padding-top:50px}.row-link{gap:10px;padding:12px}.diff.day,.p-cta{display:none}.p-link{width:40px;height:40px;padding:0;justify-content:center;font-size:1rem}}@media (prefers-reduced-motion:reduce){*{animation:none!important;transition:none!important}}