:root{--bg:#070b14;--panel:#101827;--panel2:#131f33;--text:#eef5ff;--muted:#9fb0c8;--primary:#1577ff;--green:#36d399;--danger:#ff4d6d;--line:rgba(255,255,255,.09);--radius:18px}*{box-sizing:border-box}body{margin:0;font-family:Inter,Segoe UI,Arial,sans-serif;background:radial-gradient(circle at top left,#16345f 0,#070b14 35%,#05070c 100%);color:var(--text)}a{color:inherit;text-decoration:none}.app-page{display:flex;min-height:100vh}.sidebar{width:260px;position:fixed;inset:0 auto 0 0;background:rgba(7,11,20,.88);border-right:1px solid var(--line);backdrop-filter:blur(12px);padding:24px}.brand,.auth-logo{font-size:24px;font-weight:800;letter-spacing:-1px}.brand span,.auth-logo span{color:#fff}.brand b,.auth-logo b{color:var(--primary)}.sidebar nav{display:grid;gap:10px;margin-top:30px}.sidebar a{padding:13px 14px;border-radius:14px;color:var(--muted)}.sidebar a:hover{background:var(--panel2);color:#fff}.content{margin-left:260px;width:calc(100% - 260px);padding:22px}.topbar{display:flex;justify-content:space-between;align-items:center;margin-bottom:20px}.topbar h1{margin:0;font-size:26px}.card,.auth-card,.course-card,.hero,.player-card{background:linear-gradient(180deg,rgba(19,31,51,.92),rgba(12,18,30,.92));border:1px solid var(--line);border-radius:var(--radius);box-shadow:0 22px 60px rgba(0,0,0,.28);padding:22px;margin-bottom:18px}.grid{display:grid;gap:16px}.cards{grid-template-columns:repeat(4,minmax(0,1fr))}.metric span{color:var(--muted)}.metric b{display:block;font-size:34px;margin-top:8px}.section-head{display:flex;justify-content:space-between;align-items:center;gap:12px}.btn,button{display:inline-flex;align-items:center;justify-content:center;gap:8px;border:1px solid var(--line);background:#17243a;color:#fff;border-radius:12px;padding:10px 14px;cursor:pointer;font-weight:700;margin:3px}.btn.primary,button.primary{background:linear-gradient(135deg,var(--primary),#0ed3ff);border:0}.btn.danger{background:rgba(255,77,109,.16);color:#ff9bad}.alert{margin:0 0 14px;padding:13px 16px;border-radius:14px;background:#17243a;border:1px solid var(--line)}.alert.error{background:rgba(255,77,109,.14);color:#ffc3ce}.alert.success{background:rgba(54,211,153,.13);color:#a8f5d9}.alert.info{background:rgba(21,119,255,.13)}table{width:100%;border-collapse:collapse}.table-wrap{overflow:auto}th,td{padding:12px;border-bottom:1px solid var(--line);text-align:left;vertical-align:middle}th{color:#b9c8df;font-size:13px}.badge,.pill{display:inline-flex;border-radius:999px;padding:6px 10px;background:rgba(21,119,255,.14);border:1px solid 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8px}.course-grid{display:grid;grid-template-columns:repeat(auto-fill,minmax(260px,1fr));gap:16px}.course-card{overflow:hidden;padding:0}.course-card>div:last-child{padding:18px}.cover{height:150px;background-size:cover;background-position:center;background-color:#17243a}.course-detail{display:grid;grid-template-columns:300px 1fr;gap:22px}.course-cover-large{width:100%;border-radius:16px}.progress{height:8px;background:#0b1322;border-radius:99px;overflow:hidden;margin:12px 0}.progress.big{height:14px}.progress span{display:block;height:100%;background:linear-gradient(90deg,var(--primary),#0ed3ff)}.lesson-list{display:grid;gap:10px}.lesson-row{display:flex;justify-content:space-between;gap:14px;padding:14px;border:1px solid var(--line);border-radius:14px;background:rgba(255,255,255,.03)}.video-layout{display:grid;grid-template-columns:1fr 280px;gap:18px}.player-card{padding:0;overflow:hidden}.player-wrap{background:#000;min-height:420px;display:grid;place-items:center}.player-wrap video,.player-wrap iframe{width:100%;height:520px;background:#000}.player-info{padding:20px}.valid-box{border:1px solid rgba(54,211,153,.45);background:rgba(54,211,153,.10);border-radius:16px;padding:15px;margin-top:15px}@media(max-width:900px){.app-page{display:block}.sidebar{position:relative;width:100%;height:auto}.content{margin-left:0;width:100%;padding:14px}.cards{grid-template-columns:repeat(2,1fr)}.course-detail,.video-layout{grid-template-columns:1fr}.form-grid{grid-template-columns:1fr}.span2{grid-column:auto}}@media(max-width:560px){.cards{grid-template-columns:1fr}.topbar{display:block}.hero h2{font-size:25px}.player-wrap video,.player-wrap iframe{height:300px}}