:root{
  --primary:#4f46e5; --primary-dark:#4338ca; --accent:#10b981;
  --bg:#f4f5fb; --card:#fff; --text:#1f2937; --muted:#6b7280;
  --danger:#ef4444; --border:#e5e7eb; --shadow:0 1px 3px rgba(0,0,0,.08),0 1px 2px rgba(0,0,0,.04);
}
*{box-sizing:border-box}
html,body{margin:0;padding:0}
body{font-family:system-ui,-apple-system,"Segoe UI",Roboto,"Microsoft YaHei",sans-serif;
  background:var(--bg);color:var(--text);line-height:1.5}
a{color:var(--primary);text-decoration:none}
button{font-family:inherit}

.topbar{display:flex;align-items:center;gap:12px;padding:14px 22px;
  background:linear-gradient(135deg,var(--primary),var(--primary-dark));color:#fff;
  box-shadow:var(--shadow);position:sticky;top:0;z-index:10}
.topbar h1{font-size:18px;margin:0;font-weight:600}
.topbar .spacer{flex:1}
.topbar .sub{opacity:.85;font-size:13px}

.btn{display:inline-flex;align-items:center;gap:6px;border:none;cursor:pointer;
  padding:9px 16px;border-radius:8px;font-size:14px;font-weight:500;transition:.15s}
.btn-primary{background:var(--primary);color:#fff}
.btn-primary:hover{background:var(--primary-dark)}
.btn-ghost{background:transparent;color:#fff;border:1px solid rgba(255,255,255,.4)}
.btn-ghost:hover{background:rgba(255,255,255,.15)}
.btn-light{background:#fff;color:var(--primary);border:1px solid var(--border)}
.btn-light:hover{background:#f9fafb}
.btn-danger{background:#fff;color:var(--danger);border:1px solid #fecaca}
.btn-danger:hover{background:#fef2f2}
.btn-sm{padding:5px 10px;font-size:13px}
.btn:disabled{opacity:.5;cursor:not-allowed}

.container{max-width:1100px;margin:0 auto;padding:24px}

.card{background:var(--card);border-radius:14px;box-shadow:var(--shadow);
  border:1px solid var(--border);padding:20px}

/* landing */
.landing{min-height:100vh;display:flex;flex-direction:column;align-items:center;
  justify-content:center;padding:24px;text-align:center;
  background:linear-gradient(135deg,#4f46e5,#7c3aed 60%,#2563eb)}
.landing h1{color:#fff;font-size:34px;margin:0 0 6px}
.landing p{color:rgba(255,255,255,.85);margin:0 0 36px;font-size:16px}
.role-grid{display:flex;gap:24px;flex-wrap:wrap;justify-content:center}
.role-card{width:240px;background:#fff;border-radius:16px;padding:32px 24px;
  box-shadow:0 10px 30px rgba(0,0,0,.18);transition:.18s;cursor:pointer;text-decoration:none;color:inherit}
.role-card:hover{transform:translateY(-4px)}
.role-card .ico{font-size:42px}
.role-card h2{margin:14px 0 6px;font-size:20px}
.role-card span{color:var(--muted);font-size:14px}

/* layout */
.layout{display:grid;grid-template-columns:280px 1fr;gap:20px;align-items:start}
.sidebar .card{padding:14px}
.sidebar h3{margin:0 0 12px;font-size:15px}
.content-item{display:flex;align-items:center;gap:8px;padding:10px 12px;border-radius:8px;
  cursor:pointer;border:1px solid transparent}
.content-item:hover{background:#f3f4f6}
.content-item.active{background:#eef2ff;border-color:#c7d2fe}
.content-item .ttl{flex:1;font-size:14px;overflow:hidden;text-overflow:ellipsis;white-space:nowrap}
.content-item .cnt{font-size:12px;color:var(--muted)}

.empty{color:var(--muted);text-align:center;padding:40px 10px;font-size:14px}

/* editor */
.editor-head{display:flex;align-items:center;gap:12px;margin-bottom:16px;flex-wrap:wrap}
.title-input{font-size:20px;font-weight:600;border:1px solid transparent;border-radius:8px;
  padding:6px 10px;flex:1;min-width:200px;background:transparent}
.title-input:focus{outline:none;border-color:var(--border);background:#fff}

.dropzone{border:2px dashed #c7d2fe;border-radius:12px;padding:30px;text-align:center;
  color:var(--muted);cursor:pointer;transition:.15s;margin-bottom:18px}
.dropzone:hover,.dropzone.drag{background:#eef2ff;border-color:var(--primary);color:var(--primary)}
.dropzone strong{color:var(--primary)}
.upload-progress{background:#eef2ff;border:1px solid #c7d2fe;border-radius:12px;padding:16px 18px;margin-bottom:18px}
.upload-progress .upload-head{display:flex;justify-content:space-between;align-items:center;font-size:14px;font-weight:600;color:var(--primary);margin-bottom:6px}
.upload-progress .upload-name{font-size:13px;color:var(--muted);margin-bottom:10px;word-break:break-all}
.upload-bar{height:10px;background:#fff;border-radius:6px;overflow:hidden;border:1px solid #c7d2fe}
.upload-fill{height:100%;width:0%;background:linear-gradient(90deg,var(--primary),var(--primary-dark));border-radius:6px;transition:width .2s ease}

.image-card{margin-bottom:22px}
.image-card .img-head{display:flex;align-items:center;justify-content:space-between;margin-bottom:10px}
.image-card .img-head .lbl{font-weight:600;font-size:14px}
.canvas-wrap{position:relative;width:100%;border:1px solid var(--border);border-radius:10px;overflow:hidden;background:#000}
.canvas-wrap canvas{display:block;width:100%;height:auto;cursor:crosshair}
.canvas-wrap .canvas-placeholder{position:absolute;inset:0;display:flex;align-items:center;justify-content:center;background:#111827;color:#9ca3af;font-size:14px;pointer-events:none}
.canvas-wrap .hint{position:absolute;top:8px;left:8px;background:rgba(0,0,0,.55);color:#fff;
  font-size:12px;padding:4px 8px;border-radius:6px;pointer-events:none}

.regions{margin-top:12px;display:flex;flex-direction:column;gap:8px}
.region-row{display:flex;align-items:center;gap:8px;background:#f9fafb;border:1px solid var(--border);
  border-radius:8px;padding:8px 10px}
.region-row.playing{background:#eef2ff;border-color:var(--primary);box-shadow:inset 3px 0 0 var(--primary)}
.region-row .idx{width:22px;height:22px;border-radius:50%;background:var(--primary);color:#fff;
  font-size:12px;display:flex;align-items:center;justify-content:center;flex-shrink:0}
.region-row input{flex:1;border:1px solid var(--border);border-radius:6px;padding:6px 8px;font-size:14px}
.region-row input:focus{outline:none;border-color:var(--primary)}
.region-row .empty-text{color:var(--danger);font-size:13px;flex:1}
.region-row .region-voice,.region-row .region-rate{flex:0 0 auto;padding:6px 8px;border:1px solid var(--border);border-radius:6px;font-size:13px;background:#fff}

/* student viewer */
.lesson-grid{display:grid;grid-template-columns:repeat(auto-fill,minmax(220px,1fr));gap:16px}
.lesson-tile{background:#fff;border:1px solid var(--border);border-radius:12px;overflow:hidden;
  cursor:pointer;transition:.15s;box-shadow:var(--shadow)}
.lesson-tile:hover{transform:translateY(-3px);box-shadow:0 8px 20px rgba(0,0,0,.1)}
.lesson-tile .thumb{height:120px;background:#eef2ff;display:flex;align-items:center;justify-content:center;font-size:40px}
.lesson-tile .meta{padding:12px}
.lesson-tile .meta h3{margin:0 0 4px;font-size:15px}
.lesson-tile .meta span{font-size:12px;color:var(--muted)}
.lesson-tile .thumb{position:relative}
.lesson-tile .unread-badge{position:absolute;top:8px;right:8px;background:var(--danger);color:#fff;font-size:12px;font-weight:600;padding:2px 8px;border-radius:10px;line-height:1.4}
.lesson-tile .tile-class{display:inline-block;margin-top:5px;font-size:12px;color:var(--primary);background:#eef2ff;border-radius:8px;padding:1px 8px}

.viewer-img{position:relative;width:100%;overflow:hidden;background:#000}
.viewer-img img{display:block;width:100%;height:auto}
.hotspot{position:absolute;cursor:pointer}
.hotspot .tag{display:none}

/* student swipe viewer */
.viewer-page{max-width:none;margin:0;padding:0}
.viewer-title{margin:0;padding:12px 12px 8px;font-size:20px;font-weight:600}
.viewer-carousel{display:flex;overflow-x:auto;scroll-snap-type:x mandatory;
  -webkit-overflow-scrolling:touch;scroll-behavior:smooth;scrollbar-width:none}
.viewer-carousel::-webkit-scrollbar{display:none}
.viewer-carousel .viewer-img{flex:0 0 100%;min-width:100%;scroll-snap-align:start}
.page-nav{display:flex;gap:6px;overflow-x:auto;padding:4px 12px 14px;scrollbar-width:thin}
.page-nav::-webkit-scrollbar{height:6px}
.page-btn{flex:0 0 auto;min-width:36px;height:36px;padding:0 10px;border:1px solid var(--border);
  border-radius:8px;background:#fff;color:var(--muted);cursor:pointer;font-size:14px;font-weight:600;transition:.15s}
.page-btn:hover{color:var(--primary);border-color:#c7d2fe}
.page-btn.active{background:var(--primary);color:#fff;border-color:var(--primary)}

.now-playing{position:sticky;bottom:16px;margin:16px auto;max-width:480px;background:#fff;
  border:1px solid var(--border);border-radius:12px;box-shadow:0 6px 20px rgba(0,0,0,.12);
  padding:14px 18px;display:flex;align-items:center;gap:12px;z-index:5}
.now-playing .np-ico{font-size:24px}
.now-playing .np-text{flex:1}
.now-playing .np-text .small{font-size:12px;color:var(--muted)}
.now-playing .np-text .word{font-size:18px;font-weight:600}

/* login */
.login-wrap{min-height:80vh;display:flex;align-items:center;justify-content:center}
.login-box{width:320px;text-align:center}
.login-box input{width:100%;padding:11px 14px;border:1px solid var(--border);border-radius:8px;
  font-size:15px;margin-bottom:12px}
.login-box input:focus{outline:none;border-color:var(--primary)}
.err{color:var(--danger);font-size:13px;margin-bottom:10px;min-height:18px}

.back-link{font-size:13px;margin-bottom:12px;display:inline-block}
.editor-tools{display:flex;align-items:center;gap:8px;flex-wrap:wrap}
.gran-lbl{font-size:13px;color:var(--muted);display:flex;align-items:center;gap:4px}
.gran-lbl select{padding:4px 6px;border:1px solid var(--border);border-radius:6px;font-size:13px;background:#fff}

/* tabs + management */
.tabbar{display:flex;gap:6px;padding:12px 22px 0}
.tab{background:#fff;border:1px solid var(--border);border-radius:8px;padding:8px 16px;font-size:14px;
  font-weight:500;cursor:pointer;color:var(--muted);transition:.15s}
.tab:hover{color:var(--primary)}
.tab.active{background:var(--primary);color:#fff;border-color:var(--primary)}
.tabpane{background:var(--bg);border-top:1px solid var(--border);min-height:60vh}

.mgmt-form{display:flex;gap:8px;flex-wrap:wrap;align-items:center}
.input{padding:9px 12px;border:1px solid var(--border);border-radius:8px;font-size:14px;background:#fff;min-width:120px;flex:1}
.input:focus{outline:none;border-color:var(--primary)}
.mgmt-row{display:flex;align-items:center;gap:10px;padding:12px;border:1px solid var(--border);
  border-radius:10px;margin-bottom:10px;background:#fff}
.mgmt-row .mgmt-main{flex:1;display:flex;align-items:center;gap:10px;flex-wrap:wrap;min-width:0}
.mgmt-row .mgmt-title{font-weight:600;font-size:14px}
.mgmt-row .mgmt-name{border:1px solid var(--border);border-radius:6px;padding:6px 10px;font-size:14px;flex:1;min-width:140px}
.mgmt-row .mgmt-name:focus{outline:none;border-color:var(--primary)}
.mgmt-row .mgmt-sel{padding:6px 8px;border:1px solid var(--border);border-radius:6px;font-size:13px;background:#fff}
.chk-group{display:flex;flex-wrap:wrap;gap:6px 14px;align-items:center}
.chk-item{display:inline-flex;align-items:center;gap:4px;font-size:14px;cursor:pointer;user-select:none}
.chk-item input{margin:0;cursor:pointer}
.mgmt-row .chk-group{flex:1 1 100%;margin-top:4px}
.mgmt-meta{font-size:12px;color:var(--muted)}

.modal-overlay{position:fixed;inset:0;background:rgba(0,0,0,.4);display:flex;align-items:center;
  justify-content:center;z-index:50;padding:20px}
.modal{width:420px;max-width:100%}
.publish-row{display:flex;align-items:center;gap:10px;padding:10px 12px;border:1px solid var(--border);
  border-radius:8px;margin-bottom:8px;cursor:pointer}
.publish-row input{width:18px;height:18px}
.publish-row span{flex:1}
.modal-actions{display:flex;justify-content:flex-end;gap:8px;margin-top:16px}

/* blocking spinner */
.spinner{width:42px;height:42px;margin:0 auto;border:4px solid #e0e7ff;
  border-top-color:var(--primary);border-radius:50%;animation:spin 1s linear infinite}
@keyframes spin{to{transform:rotate(360deg)}}

/* student practice / scoring bar */
.practice-bar{position:sticky;bottom:16px;margin:16px auto 0;max-width:780px;
  background:#fff;border:1px solid var(--border);border-radius:12px;
  box-shadow:0 -4px 18px rgba(0,0,0,.1);padding:12px 16px;
  display:flex;align-items:center;gap:12px;flex-wrap:wrap;z-index:6}
.practice-bar .pb-text{flex:1;min-width:160px;font-weight:600;font-size:15px;word-break:break-word}
.practice-bar .pb-actions{display:flex;gap:8px;align-items:center;flex-wrap:wrap}
.practice-bar .pb-result{flex-basis:100%;display:flex;gap:10px;align-items:center;flex-wrap:wrap;font-size:13px}
.practice-bar .muted{color:var(--muted)}
.practice-bar .err{color:var(--danger)}
.practice-bar .score{font-weight:700;font-size:16px}
.practice-bar .score.good{color:#10b981}
.practice-bar .score.ok{color:#d97706}
.practice-bar .score.bad{color:var(--danger)}
.practice-bar .fb{color:var(--muted)}
.practice-bar .btn.recording{background:var(--danger);color:#fff;border-color:var(--danger);animation:pb-pulse 1s infinite}
@keyframes pb-pulse{50%{opacity:.7}}

/* teacher activity stats */
.act-table{width:100%;border-collapse:collapse;font-size:14px}
.act-table th,.act-table td{padding:8px 10px;border-bottom:1px solid var(--border);text-align:left}
.act-table th{color:var(--muted);font-weight:600;font-size:13px}
.act-table tbody tr:hover{background:#f9fafb}
.act-sec{margin:14px 0 8px;font-size:15px}
.act-list{display:flex;flex-direction:column;gap:8px}
.act-row{display:flex;align-items:center;gap:10px;padding:10px 12px;border:1px solid var(--border);border-radius:8px;background:#fff}
.act-row .act-main{flex:1;min-width:0}
.act-text{font-weight:600;word-break:break-word}
.act-meta{font-size:12px;color:var(--muted);margin-top:2px}
.act-fb{font-size:12px;color:var(--muted);margin-top:4px}
.score.good{color:#10b981}.score.ok{color:#d97706}.score.bad{color:var(--danger)}
/* background recognition lock banner */
.lock-banner{display:flex;align-items:center;gap:10px;margin-bottom:14px;padding:10px 14px;
  background:#eef2ff;border:1px solid #c7d2fe;border-radius:10px;color:#4338ca;font-weight:600;font-size:14px}
.spinner-sm{width:16px;height:16px;border:2px solid #c7d2fe;border-top-color:var(--primary);
  border-radius:50%;animation:spin 1s linear infinite;flex:0 0 auto}
/* while a content is locked for background recognition, disable editing (keep playback) */
#editorBody.locked .dropzone,
#editorBody.locked canvas,
#editorBody.locked .region-row input,
#editorBody.locked .region-row select,
#editorBody.locked [data-act="auto"],
#editorBody.locked [data-act="clear"],
#editorBody.locked [data-act="del-img"],
#editorBody.locked [data-act="regen"],
#editorBody.locked [data-act="del"]{pointer-events:none;opacity:.5}

/* content publish management matrix */
.pub-scroll{overflow:auto;max-height:70vh;border:1px solid var(--border);border-radius:10px}
.pub-table{width:100%;border-collapse:separate;border-spacing:0;font-size:14px;background:#fff}
.pub-table th,.pub-table td{border-bottom:1px solid var(--border);border-right:1px solid var(--border);padding:8px 10px;white-space:nowrap}
.pub-table thead th{position:sticky;top:0;background:#fff;z-index:2}
.pub-table .pub-corner{position:sticky;left:0;top:0;z-index:4;min-width:180px;background:#fff;text-align:left}
.pub-table .pub-row{position:sticky;left:0;z-index:1;min-width:180px;background:#fff;text-align:left}
.pub-table .pub-row-title{font-weight:600;display:block;max-width:240px;overflow:hidden;text-overflow:ellipsis}
.pub-table .pub-col{min-width:96px;text-align:center;font-weight:600}
.pub-table .pub-col-name{font-size:14px}
.pub-table .pub-cell{text-align:center;cursor:pointer;color:var(--primary);font-weight:700;
  user-select:none;min-width:96px;transition:background .12s}
.pub-table .pub-cell:hover{background:#eef2ff}
.pub-table .pub-cell.on{background:#eef2ff}
.pub-table tbody tr:hover .pub-row{background:#f9fafb}
/* folders (teacher content list) */
.folder-group{margin-bottom:2px}
.folder-head{display:flex;align-items:center;gap:6px;padding:8px 10px;border-radius:8px;
  cursor:pointer;border:1px solid transparent;user-select:none}
.folder-head:hover{background:#f3f4f6}
.folder-head.drop-hover{background:#eef2ff;border-color:#c7d2fe}
.folder-caret{display:inline-block;width:12px;text-align:center;color:var(--muted);
  font-size:12px;transition:transform .15s}
.folder-caret.collapsed{transform:rotate(-90deg)}
.folder-ico{font-size:15px}
.folder-name{flex:1;font-size:14px;font-weight:600;overflow:hidden;text-overflow:ellipsis;white-space:nowrap}
.folder-count{font-size:12px;color:var(--muted);background:#f3f4f6;border-radius:10px;padding:1px 8px}
.folder-act{border:none;background:transparent;cursor:pointer;font-size:13px;padding:2px 4px;
  border-radius:6px;opacity:.55}
.folder-act:hover{opacity:1;background:#e5e7eb}
.folder-head.unfiled{cursor:default;font-weight:600;color:var(--muted);margin-top:8px}
.folder-head.unfiled:hover{background:transparent}
.folder-items{margin:2px 0 4px 10px;border-left:2px solid var(--border);padding-left:6px}
.folder-items.drop-hover{border-left-color:var(--primary);background:#f5f7ff;border-radius:0 8px 8px 0}
.folder-empty{color:var(--muted);font-size:12px;padding:6px 10px;font-style:italic}
.content-item .grip{color:#cbd5e1;opacity:0;transition:opacity .15s;cursor:grab;font-size:14px}
.content-item:hover .grip{opacity:1}
.content-item.dragging{opacity:.4}
.content-item.indented{font-size:13px}
/* folders (student lesson list) */
.lesson-folder{margin-bottom:26px}
.lesson-folder-head{display:flex;align-items:center;gap:8px;font-size:16px;font-weight:600;
  margin:0 0 12px}
.lesson-folder-count{font-size:12px;color:var(--muted);background:#f3f4f6;border-radius:10px;
  padding:1px 8px;font-weight:500}
.lesson-folder .lesson-grid{margin-top:0}