:root{
  --bg:#f6f8fc;--bg-soft:#eef2f8;--panel:#ffffff;--panel-soft:#f8fafc;
  --text:#101828;--muted:#667085;--border:#e4e7ec;--border-strong:#d0d5dd;
  --primary:#4f46e5;--primary-2:#7c3aed;--primary-soft:#eef2ff;--success:#15803d;
  --shadow:0 10px 30px rgba(15,23,42,.07);--shadow-hover:0 18px 45px rgba(15,23,42,.11);
  --radius:18px;--radius-sm:12px;
}
*{box-sizing:border-box}html{scroll-behavior:smooth}body{margin:0;min-height:100vh;background:radial-gradient(circle at 10% 0%,rgba(99,102,241,.08),transparent 28rem),var(--bg);color:var(--text);font-family:Inter,ui-sans-serif,system-ui,-apple-system,BlinkMacSystemFont,"Segoe UI",sans-serif}body.dark{--bg:#0b1020;--bg-soft:#111827;--panel:#111827;--panel-soft:#0f172a;--text:#f8fafc;--muted:#98a2b3;--border:#253047;--border-strong:#344054;--primary:#818cf8;--primary-2:#a78bfa;--primary-soft:#1b2140;--success:#4ade80;--shadow:0 12px 35px rgba(0,0,0,.22);--shadow-hover:0 20px 48px rgba(0,0,0,.3)}
a{color:inherit}button,input{font:inherit}button{cursor:pointer}
.topbar{position:sticky;top:0;z-index:50;background:color-mix(in srgb,var(--panel) 88%,transparent);backdrop-filter:blur(16px);border-bottom:1px solid var(--border)}
.topbar-inner{max-width:1240px;margin:auto;padding:13px 20px;display:flex;align-items:center;gap:14px}
.brand{display:flex;align-items:center;gap:11px;min-width:235px;cursor:pointer}.logo{width:38px;height:38px;border-radius:12px;background:linear-gradient(135deg,var(--primary),var(--primary-2));color:#fff;display:grid;place-items:center;font-size:13px;font-weight:800;box-shadow:0 7px 18px rgba(79,70,229,.25)}.brand strong{font-size:15px;letter-spacing:-.01em}.brand small{display:block;color:var(--muted);font-size:11px;margin-top:2px}
.search{flex:1;max-width:590px;position:relative}.search input{width:100%;height:42px;border:1px solid var(--border);background:var(--panel);color:var(--text);border-radius:12px;padding:9px 42px 9px 39px;outline:none;transition:.18s}.search input:focus{border-color:var(--primary);box-shadow:0 0 0 4px rgba(79,70,229,.12)}.search .icon{position:absolute;left:13px;top:10px;color:var(--muted);font-size:19px}.kbd{position:absolute;right:9px;top:8px;border:1px solid var(--border);border-radius:7px;padding:2px 6px;color:var(--muted);font-size:10px;background:var(--panel-soft)}
.icon-btn{width:40px;height:40px;border:1px solid var(--border);background:var(--panel);color:var(--text);border-radius:11px;display:grid;place-items:center;transition:.18s}.icon-btn:hover{border-color:var(--primary);transform:translateY(-1px)}
.container{max-width:1240px;margin:0 auto;padding:36px 20px 70px}.hero{position:relative;padding:36px 0 30px;overflow:hidden}.hero:after{content:"";position:absolute;width:300px;height:300px;border-radius:50%;right:-90px;top:-90px;background:radial-gradient(circle,rgba(124,58,237,.11),transparent 68%);pointer-events:none}.eyebrow{display:inline-flex;align-items:center;gap:7px;font-size:11px;font-weight:800;text-transform:uppercase;letter-spacing:.1em;color:var(--primary)}.eyebrow:before{content:"";width:7px;height:7px;border-radius:50%;background:currentColor;box-shadow:0 0 0 4px rgba(79,70,229,.1)}h1{font-size:clamp(32px,5vw,54px);line-height:1.04;margin:11px 0 13px;letter-spacing:-.045em;max-width:900px}h2{font-size:25px;margin:0 0 6px;letter-spacing:-.025em}h3{font-size:15px;line-height:1.35;margin:0}.lead{font-size:15px;line-height:1.7;color:var(--muted);max-width:760px}
.stats{display:flex;gap:9px;flex-wrap:wrap;margin-top:22px}.stat{background:var(--panel);border:1px solid var(--border);border-radius:11px;padding:9px 12px;color:var(--muted);font-size:12px;box-shadow:0 3px 12px rgba(15,23,42,.03)}.stat b{color:var(--text);margin-right:4px}
.section-head{display:flex;justify-content:space-between;align-items:end;gap:16px;margin:23px 0 14px}.count{font-size:11px;color:var(--muted)}
.grid{display:grid;grid-template-columns:repeat(4,minmax(0,1fr));gap:14px}.card{background:var(--panel);border:1px solid var(--border);border-radius:var(--radius);box-shadow:var(--shadow);transition:.2s transform,.2s box-shadow,.2s border-color}.card:hover{transform:translateY(-3px);border-color:color-mix(in srgb,var(--primary) 30%,var(--border));box-shadow:var(--shadow-hover)}
.subject-card{padding:19px;min-height:172px;display:flex;flex-direction:column;justify-content:space-between;cursor:pointer;position:relative;overflow:hidden}.subject-card:after{content:"";position:absolute;width:110px;height:110px;right:-42px;bottom:-42px;border-radius:50%;background:var(--primary-soft)}.subject-icon{width:43px;height:43px;border-radius:13px;background:linear-gradient(135deg,var(--primary-soft),var(--bg-soft));color:var(--primary);display:grid;place-items:center;font-weight:800;font-size:13px;position:relative;z-index:1}.card-top{display:flex;justify-content:space-between;align-items:flex-start;gap:10px;position:relative;z-index:1}.card-meta{display:flex;gap:7px;flex-wrap:wrap;color:var(--muted);font-size:11px;margin-top:7px;position:relative;z-index:1}
.course-grid{display:grid;grid-template-columns:repeat(2,minmax(0,1fr));gap:12px}.course-card{padding:18px;cursor:pointer}.course-card.empty{cursor:default;background:var(--panel-soft);box-shadow:none}.course-card.empty:hover{transform:none;border-color:var(--border)}
.badge{display:inline-flex;align-items:center;border:1px solid var(--border);border-radius:999px;padding:4px 8px;font-size:10px;font-weight:700;color:var(--muted);background:var(--panel-soft);white-space:nowrap}.badge.green{color:var(--success);border-color:color-mix(in srgb,var(--success) 25%,var(--border));background:color-mix(in srgb,var(--success) 7%,var(--panel))}.badge.purple{color:var(--primary);border-color:color-mix(in srgb,var(--primary) 25%,var(--border));background:var(--primary-soft)}
.breadcrumb{display:flex;gap:7px;align-items:center;color:var(--muted);font-size:12px;margin:6px 0 24px;flex-wrap:wrap}.crumb{cursor:pointer}.crumb:hover{color:var(--primary)}
.chapter-list{display:flex;flex-direction:column;gap:10px}.chapter{background:var(--panel);border:1px solid var(--border);border-radius:14px;overflow:hidden;box-shadow:0 3px 14px rgba(15,23,42,.035)}.chapter summary{list-style:none;cursor:pointer;padding:15px 17px;display:flex;justify-content:space-between;align-items:center;gap:12px}.chapter summary::-webkit-details-marker{display:none}.chapter summary:hover{background:var(--panel-soft)}.chapter summary .chev{color:var(--muted);transition:.18s}.chapter[open] summary .chev{transform:rotate(180deg);color:var(--primary)}.chapter-body{border-top:1px solid var(--border);padding:10px 12px}
.topic-group{padding:8px 5px}.topic-title{font-size:10px;font-weight:800;color:var(--muted);text-transform:uppercase;letter-spacing:.075em;margin:4px 7px 7px}.video-list{display:flex;flex-direction:column;gap:5px}.video{display:flex;align-items:center;justify-content:space-between;gap:12px;padding:10px 10px;border:1px solid transparent;border-radius:10px}.video:hover{background:var(--panel-soft);border-color:var(--border)}.video-info{min-width:0}.video-name{font-size:13px;font-weight:700;line-height:1.4}.video-topics{font-size:11px;color:var(--muted);margin-top:3px;line-height:1.45}.watch{text-decoration:none;border:1px solid color-mix(in srgb,var(--primary) 22%,var(--border));background:var(--primary-soft);border-radius:9px;padding:7px 10px;font-size:11px;font-weight:800;color:var(--primary);white-space:nowrap;transition:.18s}.watch:hover{border-color:var(--primary);transform:translateY(-1px)}
.results{display:flex;flex-direction:column;gap:8px;margin-top:18px}.result{background:var(--panel);border:1px solid var(--border);border-radius:12px;padding:13px 15px;display:flex;justify-content:space-between;gap:12px;align-items:center}.result small{color:var(--muted);display:block;margin-top:4px;font-size:11px}.empty-search{text-align:center;padding:55px;color:var(--muted);background:var(--panel);border:1px dashed var(--border);border-radius:14px}
.footer{border-top:1px solid var(--border);padding:24px 20px;color:var(--muted);font-size:11px;text-align:center}.loading{display:grid;place-items:center;min-height:70vh;color:var(--muted)}.loader{width:28px;height:28px;border:3px solid var(--border);border-top-color:var(--primary);border-radius:50%;animation:spin .7s linear infinite}@keyframes spin{to{transform:rotate(360deg)}}
@media(max-width:1000px){.grid{grid-template-columns:repeat(3,minmax(0,1fr))}.brand{min-width:205px}}
@media(max-width:800px){.grid{grid-template-columns:repeat(2,minmax(0,1fr))}.course-grid{grid-template-columns:1fr}.topbar-inner{flex-wrap:wrap}.brand{min-width:auto}.search{order:3;max-width:none;flex-basis:calc(100% - 54px)}.icon-btn{order:2}.search .kbd{display:none}}
@media(max-width:560px){.container{padding:22px 13px 48px}.topbar-inner{padding:10px 13px}.grid{grid-template-columns:1fr}.subject-card{min-height:145px}.hero{padding:23px 0 25px}.section-head{align-items:flex-start;flex-direction:column}.video{align-items:flex-start}.watch{padding:7px 9px}.brand small{display:none}.stats{gap:7px}}