.preview-c .lecture-player{--lp-blue:#005da8;--lp-navy:#18354e;--lp-ink:#253c50;--lp-muted:#63788b;--lp-line:#d6e2ec;--lp-wash:#f3f7fa;display:grid;grid-template-columns:minmax(0,1fr) 302px;gap:22px;padding:24px;border-top:5px solid var(--lp-blue);background:#fff;color:var(--lp-ink);color-scheme:light;font-size:14px;line-height:1.6}
.preview-c .lecture-player-header{grid-column:1/-1;padding-bottom:16px;border-bottom:1px solid var(--lp-line)}
.preview-c .lecture-player-header small{color:var(--lp-blue);font-size:12px;letter-spacing:.04em}
.preview-c .lecture-player-header h3{margin:5px 0;color:var(--lp-blue);font-size:clamp(20px,2vw,28px);font-weight:600;line-height:1.4}
.preview-c .lecture-player-header p{margin:0;color:var(--lp-muted);font-size:12px}
.preview-c .lecture-player *{box-sizing:border-box}
.preview-c .lecture-player [hidden]{display:none!important}
.preview-c .lecture-player button,.preview-c .lecture-player input,.preview-c .lecture-player select{font:inherit}
.preview-c .lecture-player button{border:1px solid var(--lp-line);border-radius:4px;background:#fff;color:var(--lp-ink);padding:7px 11px;cursor:pointer}
.preview-c .lecture-player button:hover{border-color:var(--lp-blue);color:var(--lp-blue)}
.preview-c .lecture-player button:disabled{opacity:.45;cursor:not-allowed}
.preview-c .lecture-player :focus-visible{outline:3px solid #e3a84e;outline-offset:3px}
.preview-c .lecture-main{min-width:0}
.preview-c .lecture-screen{width:100%;aspect-ratio:16/9;background:#102438}
.preview-c .lecture-screen video{display:block;width:100%;height:100%;object-fit:contain;background:#102438}
.preview-c .lecture-toolbar{display:flex;align-items:center;flex-wrap:wrap;gap:8px;padding:13px 0;border-bottom:1px solid var(--lp-line)}
.preview-c .lecture-toolbar label{color:var(--lp-muted)}
.preview-c .lecture-toolbar select,.preview-c .lecture-page-form input,.preview-c #course-page-filter{border:1px solid var(--lp-line);border-radius:4px;background:#fff;color:var(--lp-ink);padding:7px 8px}
.preview-c .lecture-time{margin-left:auto;color:var(--lp-muted);font-variant-numeric:tabular-nums;white-space:nowrap}
.preview-c .lecture-current{margin:15px 0 6px;color:var(--lp-navy);font-size:18px;font-weight:600}
.preview-c .lecture-status{min-height:1.7em;margin:0;color:var(--lp-muted);font-size:13px}
.preview-c .lecture-status.is-notice{color:#8a5916}
.preview-c .lecture-status.is-error{color:#b23830}
.preview-c .lecture-discussion{margin-top:17px;padding-top:14px;border-top:1px solid var(--lp-line)}
.preview-c .lecture-discussion label{display:flex;align-items:center;gap:8px;width:fit-content;cursor:pointer}
.preview-c .lecture-discussion input{width:18px;height:18px;margin:0;accent-color:var(--lp-blue)}
.preview-c .lecture-discussion small,.preview-c .lecture-discussion p{color:var(--lp-muted);font-size:12px}
.preview-c .lecture-discussion p{margin:6px 0 0;line-height:1.6}
.preview-c .lecture-keyboard{margin:18px 0 0;color:var(--lp-muted);font-size:12px;line-height:1.8}
.preview-c .lecture-keyboard kbd{display:inline-block;padding:0 5px;border:1px solid var(--lp-line);border-bottom-width:2px;border-radius:3px;color:var(--lp-ink);font:inherit}
.preview-c .lecture-support{display:flex;flex-wrap:wrap;gap:8px 18px;margin:14px 0 0;font-size:12px}
.preview-c .lecture-support a{color:var(--lp-blue);text-decoration:underline;text-underline-offset:3px}
.preview-c .lecture-support span{color:var(--lp-muted)}
.preview-c .lecture-navigation{min-width:0;padding-left:20px;border-left:1px solid var(--lp-line);scroll-margin-top:20px}
.preview-c .lecture-nav-title{display:flex;align-items:center;justify-content:space-between;gap:10px;margin-bottom:12px}
.preview-c .lecture-nav-title h3{margin:0;color:var(--lp-blue);font-size:19px;font-weight:600}
.preview-c .lecture-tabs{display:flex;margin-bottom:12px;border-bottom:1px solid var(--lp-line)}
.preview-c .lecture-tabs button{flex:1;border:0;border-bottom:3px solid transparent;border-radius:0;padding:9px 5px}
.preview-c .lecture-tabs button[aria-selected="true"]{border-bottom-color:var(--lp-blue);color:var(--lp-blue);font-weight:700}
.preview-c .lecture-nav-list{max-height:min(64vh,760px);margin:0;padding:0;overflow:auto;list-style:none;scrollbar-gutter:stable}
.preview-c .lecture-nav-list li{border-bottom:1px solid #e6edf3}
.preview-c .lecture-nav-list .lecture-jump{display:flex;width:100%;gap:10px;padding:12px 8px;border:0;border-radius:0;background:none;text-align:left;line-height:1.5}
.preview-c .lecture-nav-list .lecture-jump:hover{background:var(--lp-wash)}
.preview-c .lecture-nav-list .lecture-jump.is-active{background:#eaf3fb;color:var(--lp-blue);box-shadow:inset 3px 0 0 var(--lp-blue)}
.preview-c .lecture-number{min-width:28px;color:var(--lp-blue);font-weight:700;font-variant-numeric:tabular-nums}
.preview-c .lecture-item-body{min-width:0;flex:1}
.preview-c .lecture-item-title{display:block;overflow-wrap:anywhere}
.preview-c .lecture-item-detail{display:block;margin-top:4px;color:var(--lp-muted);font-size:11px;font-variant-numeric:tabular-nums}
.preview-c .lecture-chapter-file{display:block;margin:0 8px 9px 46px;color:var(--lp-blue);font-size:11px;text-decoration:underline;text-underline-offset:3px}
.preview-c #course-page-filter{width:100%;margin:0 0 10px}
.preview-c .lecture-page-form{display:flex;align-items:center;gap:7px;margin-bottom:11px;font-size:12px;white-space:nowrap}
.preview-c .lecture-page-form input{width:60px;min-width:0;padding:5px 6px}
.preview-c .lecture-page-form button{padding:5px 9px}
.preview-c .lecture-empty{padding:12px 8px;color:var(--lp-muted);font-size:12px}
@media(max-width:1080px){.preview-c .lecture-player{grid-template-columns:1fr}.preview-c .lecture-navigation{padding:18px 0 0;border-left:0;border-top:1px solid var(--lp-line)}.preview-c .lecture-nav-list{max-height:420px}}
@media(max-width:650px){.preview-c .lecture-player{padding:14px;gap:17px}.preview-c .lecture-toolbar{gap:7px}.preview-c .lecture-toolbar button{padding:6px 9px}.preview-c .lecture-time{width:100%;margin-left:0}.preview-c .lecture-current{font-size:16px}.preview-c .lecture-nav-list{max-height:360px}}