:root{
  --ink:#002047;
  --blue:#00aaff;
  --green:#5da913;
  --yellow:#ffcc00;
  --pink:#ff4589;
  --violet:#ad61e0;
  --line:#d9e2ec;
  --muted:#5d6b7a;
  --bg:#fff;
  --soft:#f7fafd;
  --danger:#b91c1c;
  color-scheme:light;
}
*{box-sizing:border-box}
html,body{margin:0;min-height:100%;background:var(--bg);color:var(--ink);font-family:system-ui,-apple-system,BlinkMacSystemFont,"Segoe UI",sans-serif}
body{font-size:16px;line-height:1.35}
a{color:inherit;text-decoration:none}
button,input,select,textarea{font:inherit;color:inherit}
button{background:#fff;border:1px solid var(--line);min-height:42px;padding:0 12px;cursor:pointer}
button:active{transform:translateY(1px)}
.app-shell{width:min(100%,980px);margin:0 auto;background:#fff;min-height:100dvh;border-left:1px solid var(--line);border-right:1px solid var(--line)}
.topbar{position:sticky;top:0;z-index:20;background:#fff;border-bottom:1px solid var(--line);display:flex;align-items:center;gap:10px;min-height:56px;padding:8px 12px}
.brand{display:flex;align-items:center;gap:10px;min-width:0;user-select:none}
.logo-img{width:38px;height:38px;object-fit:contain;display:block}
.logo-fallback{width:38px;height:38px;border:1px solid var(--line);display:grid;place-items:center;font-weight:800;color:var(--blue)}
.brand-text{display:flex;flex-direction:column;min-width:0}
.brand-title{font-size:18px;font-weight:800;letter-spacing:.2px}
.brand-subtitle{font-size:12px;color:var(--muted);white-space:nowrap;overflow:hidden;text-overflow:ellipsis}
.main{padding:0 12px 24px}
.filters{position:sticky;top:56px;z-index:15;background:#fff;border-bottom:1px solid var(--line);padding:10px 12px;display:grid;grid-template-columns:1fr;gap:8px}
.search-row,.select-row{display:grid;gap:8px}
.select-row{grid-template-columns:1fr 1fr}
.input,.select{width:100%;height:44px;border:1px solid var(--line);background:#fff;padding:0 10px;border-radius:0}
.input:focus,.select:focus,textarea:focus{outline:2px solid color-mix(in srgb,var(--blue) 35%,transparent);outline-offset:-2px}
.section-head{display:flex;justify-content:space-between;align-items:end;border-bottom:1px solid var(--line);padding:14px 0 8px;gap:10px}
h1,h2,h3,p{margin:0}
h1{font-size:22px}
h2{font-size:18px}
.count{font-size:13px;color:var(--muted)}
.catalog{display:grid;grid-template-columns:1fr;gap:0}
.card{display:grid;grid-template-columns:6px 1fr;min-height:76px;border-bottom:1px solid var(--line);background:#fff}
.card-stripe{background:var(--blue)}
.card:nth-child(6n+2) .card-stripe{background:var(--green)}
.card:nth-child(6n+3) .card-stripe{background:var(--yellow)}
.card:nth-child(6n+4) .card-stripe{background:var(--pink)}
.card:nth-child(6n+5) .card-stripe{background:var(--violet)}
.card-body{padding:12px 8px 12px 12px;display:grid;gap:4px}
.card-title{font-weight:750;font-size:16px}
.card-meta{font-size:13px;color:var(--muted)}
.empty{padding:24px 0;color:var(--muted)}
.lesson-layout{display:grid;grid-template-rows:auto 1fr;min-height:calc(100dvh - 57px)}
.lesson-actions{display:flex;gap:8px;align-items:center;border-bottom:1px solid var(--line);padding:8px 12px;background:#fff;position:sticky;top:56px;z-index:10}
.lesson-title{font-weight:750;overflow:hidden;text-overflow:ellipsis;white-space:nowrap}
.lesson-frame{width:100%;height:calc(100dvh - 108px);border:0;display:block;background:#fff}
.admin-page .main{padding-top:10px}
.panel{border-bottom:1px solid var(--line);padding:14px 0}
.form-grid{display:grid;gap:8px;margin-top:10px}
label{font-size:13px;color:var(--muted);display:grid;gap:4px}
textarea{width:100%;min-height:120px;border:1px solid var(--line);padding:10px;border-radius:0;background:#fff}
.admin-list{display:grid;border-top:1px solid var(--line);margin-top:10px}
.admin-item{display:grid;gap:4px;border-bottom:1px solid var(--line);padding:10px 0}
.admin-item strong{font-size:15px}
.row{display:flex;gap:8px;flex-wrap:wrap}
.primary{border-color:var(--blue);background:var(--blue);color:#fff}
.danger{border-color:var(--danger);color:var(--danger)}
.notice{font-size:13px;color:var(--muted);padding:8px 0}
.hidden{display:none!important}
@media (min-width:680px){
  .main{padding:0 18px 30px}
  .filters{grid-template-columns:1fr 360px;align-items:center}
  .select-row{grid-template-columns:1fr 1fr}
  .catalog{grid-template-columns:1fr 1fr}
  .card:nth-child(odd){border-right:1px solid var(--line)}
  .card-body{padding:14px}
  .brand-title{font-size:20px}
  .lesson-frame{height:calc(100dvh - 112px)}
}
@media (min-width:980px){
  body{background:#f8fafc}
}