:root{--primary:#4361ee;--primary-dark:#3a53cc;--bg:#f4f6fb;--surface:#fff;--text:#1e2433;--text-soft:#5c6577;--border:#e3e7f0;--success:#16a34a;--danger:#dc2626;--warning:#d97706;--radius:12px}*{box-sizing:border-box;margin:0;padding:0}body{background:var(--bg);color:var(--text);min-height:100vh;font-family:Segoe UI,system-ui,-apple-system,sans-serif}button{font-family:inherit}.btn{background:var(--primary);color:#fff;cursor:pointer;border:none;border-radius:8px;justify-content:center;align-items:center;gap:8px;padding:10px 20px;font-size:15px;font-weight:600;transition:background .15s;display:inline-flex}.btn:hover{background:var(--primary-dark)}.btn:disabled{cursor:not-allowed;background:#a5b0c8}.btn-danger{background:var(--danger)}.btn-danger:hover{background:#b91c1c}.btn-ghost{color:var(--text-soft);border:1px solid var(--border);background:0 0}.btn-ghost:hover{background:var(--bg)}.card{background:var(--surface);border:1px solid var(--border);border-radius:var(--radius);padding:20px}.input{border:1px solid var(--border);background:var(--surface);width:100%;color:var(--text);border-radius:8px;padding:11px 14px;font-family:inherit;font-size:15px}.input:focus{outline:2px solid var(--primary);outline-offset:-1px;border-color:#0000}.badge{border-radius:999px;padding:3px 10px;font-size:12px;font-weight:700;display:inline-block}.badge-approved{color:var(--success);background:#dcfce7}.badge-pending{color:var(--warning);background:#fef3c7}.badge-rejected{color:var(--danger);background:#fee2e2}.error-text{color:var(--danger);font-size:14px}.login-wrap{justify-content:center;align-items:center;min-height:100vh;padding:16px;display:flex}.login-card{flex-direction:column;gap:14px;width:100%;max-width:400px;display:flex}.login-logo{text-align:center;margin-bottom:8px}.login-logo h1{color:var(--primary);letter-spacing:-.5px;font-size:26px}.login-logo p{color:var(--text-soft);margin-top:4px;font-size:14px}.topbar{background:var(--surface);border-bottom:1px solid var(--border);justify-content:space-between;align-items:center;height:60px;padding:0 24px;display:flex}.topbar .brand{color:var(--primary);font-size:19px;font-weight:800;text-decoration:none}.topbar .user-area{color:var(--text-soft);align-items:center;gap:14px;font-size:14px;display:flex}.page{max-width:860px;margin:0 auto;padding:28px 16px}.page h2{margin-bottom:18px;font-size:21px}.lesson-list{flex-direction:column;gap:12px;display:flex}.lesson-card{flex-wrap:wrap;justify-content:space-between;align-items:center;gap:12px;display:flex}.lesson-card .info{flex:1;min-width:220px}.lesson-card .title{font-size:16px;font-weight:700}.lesson-card .sub{color:var(--text-soft);margin-top:3px;font-size:14px}.empty-note{text-align:center;color:var(--text-soft);padding:40px 16px}.room{background:#0f1117;height:100vh;display:flex}.room-video{flex-direction:column;gap:12px;width:340px;min-width:280px;padding:12px;display:flex}.video-box{background:#1a1e29;border-radius:10px;flex:1;min-height:140px;position:relative;overflow:hidden}.video-box .label{z-index:5;color:#fff;background:#00000073;border-radius:6px;padding:3px 9px;font-size:12px;font-weight:600;position:absolute;bottom:8px;left:10px}.video-box .placeholder{color:#5c6577;justify-content:center;align-items:center;font-size:14px;display:flex;position:absolute;inset:0}.video-el{width:100%;height:100%}.room-controls{justify-content:center;gap:10px;display:flex}.ctrl-btn{cursor:pointer;color:#fff;background:#ffffff1f;border:none;border-radius:50%;justify-content:center;align-items:center;width:46px;height:46px;font-size:19px;display:flex}.ctrl-btn.off,.ctrl-btn.leave{background:var(--danger)}.room-board{flex:1}.room-board iframe{border:none;width:100%;height:100%}.room-status{color:#8b93a5;text-align:center;font-size:13px}@media (width<=800px){.room{flex-direction:column}.room-video{flex-direction:row;align-items:stretch;width:100%;height:170px}.video-box{flex:1}.room-controls{flex-direction:column;justify-content:center}}