/* =========================================================
   在线课堂（/live）
   大厅：明亮卡片风，沿用知识库视觉体系
   教室：深色沉浸，课件为主角，互动在右栏 / 手机端抽屉
   ========================================================= */

/* ---------------- 通用 ---------------- */
.lv-btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 6px;
  padding: 9px 16px;
  border: 1px solid var(--kn-line-2);
  border-radius: 10px;
  background: #fff;
  color: var(--kn-text);
  font-size: 13.5px;
  font-weight: 600;
  cursor: pointer;
  text-decoration: none;
  transition: .18s;
  line-height: 1.2;
}
.lv-btn:hover { border-color: var(--kn-orange); color: var(--kn-orange-deep); transform: translateY(-1px); }
.lv-btn-primary {
  background: var(--kn-grad-main);
  border-color: transparent;
  color: #fff;
  box-shadow: 0 10px 24px -10px rgba(255, 107, 53, .8);
}
.lv-btn-primary:hover { color: #fff; box-shadow: 0 14px 28px -10px rgba(255, 107, 53, .9); }
.lv-btn-sm { padding: 6px 11px; font-size: 12.5px; border-radius: 8px; }

.lv-loading, .lv-empty {
  padding: 44px 12px;
  text-align: center;
  color: var(--kn-muted);
  font-size: 13.5px;
}

/* ---------------- 大厅 ---------------- */
.lv-hero {
  max-width: 1180px;
  margin: 22px auto 0;
  padding: 34px 34px 30px;
  border-radius: 24px;
  background:
    radial-gradient(900px 260px at 88% -30%, rgba(255, 107, 53, .5), transparent 70%),
    radial-gradient(700px 240px at 6% 120%, rgba(131, 56, 236, .45), transparent 70%),
    linear-gradient(135deg, #1a1a2e, #262640);
  color: #fff;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 24px;
  position: relative;
  overflow: hidden;
}
.lv-hero::after {
  content: '';
  position: absolute;
  right: -60px;
  top: -80px;
  width: 300px;
  height: 300px;
  border-radius: 50%;
  background: radial-gradient(circle, rgba(255, 255, 255, .14), transparent 65%);
  pointer-events: none;
}
.lv-hero-badge {
  display: inline-block;
  padding: 4px 11px;
  border-radius: 999px;
  background: rgba(255, 255, 255, .14);
  border: 1px solid rgba(255, 255, 255, .2);
  font-size: 11.5px;
  letter-spacing: .5px;
  margin-bottom: 12px;
}
.lv-hero h1 { font-size: 30px; line-height: 1.25; letter-spacing: -.5px; }
.lv-hero p { margin-top: 10px; color: rgba(255, 255, 255, .78); font-size: 14px; line-height: 1.8; }
.lv-hero-btns { display: flex; gap: 10px; margin-top: 18px; flex-wrap: wrap; }
.lv-hero-btns .lv-btn { background: rgba(255, 255, 255, .12); border-color: rgba(255, 255, 255, .25); color: #fff; }
.lv-hero-btns .lv-btn:hover { background: rgba(255, 255, 255, .2); color: #fff; }
.lv-hero-btns .lv-btn-primary { background: var(--kn-grad-main); border-color: transparent; }

.lv-hero-side { min-width: 210px; display: grid; gap: 10px; position: relative; z-index: 1; }
.lv-hero-stat {
  display: flex;
  align-items: baseline;
  gap: 8px;
  padding: 10px 14px;
  border-radius: 14px;
  background: rgba(255, 255, 255, .08);
  border: 1px solid rgba(255, 255, 255, .12);
}
.lv-hero-stat b { font-size: 22px; line-height: 1; }
.lv-hero-stat span { font-size: 12px; color: rgba(255, 255, 255, .7); }
.lv-hero-stat.hot b { color: #ffd166; }

.lv-wrap { max-width: 1180px; margin: 0 auto; padding: 22px 16px 60px; }

.lv-toolbar {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 12px;
  margin-bottom: 16px;
  flex-wrap: wrap;
}
.lv-scope { display: flex; gap: 8px; flex-wrap: wrap; }
.lv-scope button {
  padding: 7px 15px;
  border-radius: 999px;
  border: 1px solid var(--kn-line-2);
  background: #fff;
  color: var(--kn-text-2);
  font-size: 13px;
  cursor: pointer;
  transition: .16s;
}
.lv-scope button:hover { border-color: #ffb08c; color: var(--kn-orange-deep); }
.lv-scope button.on {
  background: var(--kn-grad-main);
  border-color: transparent;
  color: #fff;
  box-shadow: 0 8px 18px -10px rgba(255, 107, 53, .8);
}

.lv-grid { display: grid; grid-template-columns: repeat(auto-fill, minmax(288px, 1fr)); gap: 16px; }
.lv-grid-sm { grid-template-columns: repeat(auto-fill, minmax(250px, 1fr)); }

.lv-card {
  position: relative;
  display: flex;
  flex-direction: column;
  background: #fff;
  border: 1px solid var(--kn-line);
  border-radius: 18px;
  overflow: hidden;
  transition: .2s;
  cursor: pointer;
}
.lv-card:hover { transform: translateY(-3px); box-shadow: 0 22px 40px -26px rgba(26, 26, 46, .45); border-color: #ffc9ae; }
.lv-card-cover {
  position: relative;
  aspect-ratio: 16 / 9;
  background: linear-gradient(135deg, #2b2b45, #3b2b48);
  display: flex;
  align-items: center;
  justify-content: center;
  color: rgba(255, 255, 255, .5);
  font-size: 26px;
  overflow: hidden;
}
.lv-card-cover img { width: 100%; height: 100%; object-fit: cover; display: block; }
.lv-card-cover .lv-cover-txt { position: absolute; inset: auto 12px 12px 12px; color: #fff; }
.lv-card-cover .lv-cover-txt b { display: block; font-size: 15px; line-height: 1.5; }
.lv-card-badge {
  position: absolute;
  left: 10px;
  top: 10px;
  padding: 3px 9px;
  border-radius: 999px;
  font-size: 11px;
  font-weight: 700;
  color: #fff;
  background: rgba(0, 0, 0, .45);
  backdrop-filter: blur(6px);
}
.lv-card-badge[data-s="1"] { background: #ff2d55; animation: lvPulse 1.8s infinite; }
.lv-card-badge[data-s="1"]::before { content: '●'; margin-right: 4px; font-size: 9px; }
@keyframes lvPulse {
  0% { box-shadow: 0 0 0 0 rgba(255, 45, 85, .55); }
  70% { box-shadow: 0 0 0 10px rgba(255, 45, 85, 0); }
  100% { box-shadow: 0 0 0 0 rgba(255, 45, 85, 0); }
}
.lv-card-need {
  position: absolute;
  right: 10px;
  top: 10px;
  padding: 3px 9px;
  border-radius: 999px;
  font-size: 11px;
  color: #fff;
  background: rgba(255, 255, 255, .18);
  border: 1px solid rgba(255, 255, 255, .28);
  backdrop-filter: blur(6px);
}
.lv-card-body { padding: 13px 15px 15px; display: flex; flex-direction: column; gap: 8px; flex: 1; }
.lv-card-title { font-size: 15px; font-weight: 700; line-height: 1.5; color: var(--kn-text); }
.lv-card-meta { display: flex; gap: 10px; flex-wrap: wrap; font-size: 12px; color: var(--kn-muted); }
.lv-card-meta em { font-style: normal; color: var(--kn-text-2); font-weight: 600; }
.lv-card-ft { display: flex; align-items: center; justify-content: space-between; gap: 8px; margin-top: auto; padding-top: 8px; }
.lv-card-teacher { font-size: 12.5px; color: var(--kn-text-2); display: flex; align-items: center; gap: 6px; }
.lv-card-teacher i {
  width: 22px; height: 22px; border-radius: 50%;
  background: var(--kn-grad-warm); color: #fff; font-style: normal;
  display: inline-flex; align-items: center; justify-content: center; font-size: 11px; font-weight: 700;
}
.lv-card-go {
  padding: 6px 12px;
  border-radius: 999px;
  font-size: 12.5px;
  font-weight: 700;
  color: #fff;
  background: var(--kn-grad-main);
}
.lv-card[data-s="2"] .lv-card-go { background: #eef0f5; color: var(--kn-text-2); }
.lv-card[data-s="0"] .lv-card-go { background: #fff0e8; color: var(--kn-orange-deep); }
.lv-card.lv-card-joined::after {
  content: '已进过';
  position: absolute;
  right: 10px;
  top: 38px;
  font-size: 10.5px;
  color: var(--kn-green-deep);
  background: #e8fbf4;
  padding: 2px 7px;
  border-radius: 999px;
  box-shadow: 0 2px 8px rgba(0, 0, 0, .12);
}

.lv-sec { margin-top: 34px; }
.lv-sec-hd { display: flex; align-items: baseline; gap: 10px; margin-bottom: 14px; }
.lv-sec-hd h2 { font-size: 18px; }
.lv-sec-hd span { font-size: 12.5px; color: var(--kn-muted); }

.lv-how { margin-top: 44px; }
.lv-how h2 { font-size: 19px; margin-bottom: 16px; }
.lv-how-list { display: grid; grid-template-columns: repeat(4, 1fr); gap: 14px; }
.lv-how-item {
  display: flex;
  gap: 12px;
  padding: 16px;
  border-radius: 16px;
  background: #fff;
  border: 1px solid var(--kn-line);
}
.lv-how-item b {
  flex: none;
  width: 26px; height: 26px;
  border-radius: 9px;
  background: var(--kn-orange-soft);
  color: var(--kn-orange-deep);
  font-size: 13px;
  display: inline-flex; align-items: center; justify-content: center;
}
.lv-how-item h3 { font-size: 14px; margin-bottom: 4px; }
.lv-how-item p { font-size: 12.5px; color: var(--kn-muted); line-height: 1.7; }

/* 开课弹窗 */
.lv-modal { position: fixed; inset: 0; z-index: 900; display: flex; align-items: center; justify-content: center; padding: 16px; }
.lv-modal[hidden] { display: none; }
.lv-modal-mask { position: absolute; inset: 0; background: rgba(18, 20, 28, .55); backdrop-filter: blur(3px); }
.lv-modal-card {
  position: relative;
  width: 100%;
  max-width: 620px;
  max-height: 92vh;
  display: flex;
  flex-direction: column;
  background: #fff;
  border-radius: 20px;
  overflow: hidden;
  box-shadow: 0 40px 80px -30px rgba(0, 0, 0, .4);
}
.lv-modal-hd { display: flex; align-items: center; justify-content: space-between; padding: 16px 20px; border-bottom: 1px solid var(--kn-line); }
.lv-modal-hd h3 { font-size: 16px; }
.lv-modal-x { border: 0; background: none; font-size: 22px; line-height: 1; color: var(--kn-muted); cursor: pointer; }
.lv-modal-body { padding: 16px 20px; overflow-y: auto; display: flex; flex-direction: column; gap: 12px; }
.lv-modal-ft { display: flex; justify-content: flex-end; gap: 10px; padding: 14px 20px; border-top: 1px solid var(--kn-line); background: #fdfcfb; }
.lv-field { display: flex; flex-direction: column; gap: 6px; flex: 1; min-width: 0; }
.lv-field > span { font-size: 12.5px; color: var(--kn-text-2); font-weight: 600; }
.lv-field input, .lv-field select, .lv-field textarea {
  width: 100%;
  padding: 9px 12px;
  border: 1px solid var(--kn-line-2);
  border-radius: 10px;
  font-size: 13.5px;
  font-family: inherit;
  color: var(--kn-text);
  background: #fff;
  outline: none;
  transition: .16s;
}
.lv-field input:focus, .lv-field select:focus, .lv-field textarea:focus { border-color: var(--kn-orange); box-shadow: 0 0 0 3px rgba(255, 107, 53, .12); }
.lv-field textarea { min-height: 72px; resize: vertical; }
.lv-field-row { display: flex; gap: 12px; }
.lv-switches { display: flex; gap: 18px; flex-wrap: wrap; font-size: 13px; color: var(--kn-text-2); }
.lv-switches label { display: inline-flex; align-items: center; gap: 6px; cursor: pointer; }

/* =========================================================
   教室（深色）
   ========================================================= */
.lv-body {
  background: #0e1017;
  color: #e8ebf2;
  height: 100vh;
  height: 100dvh;
  overflow: hidden;
  display: flex;
  flex-direction: column;
  font-size: 14px;
}
.lv-body ::-webkit-scrollbar { width: 6px; height: 6px; }
.lv-body ::-webkit-scrollbar-track { background: transparent; }
.lv-body ::-webkit-scrollbar-thumb { background: rgba(255, 255, 255, .16); border: 0; border-radius: 999px; }
.lv-body ::-webkit-scrollbar-thumb:hover { background: rgba(255, 255, 255, .3); }
.lv-body * { scrollbar-width: thin; scrollbar-color: rgba(255, 255, 255, .2) transparent; }

.lv-top {
  flex: none;
  height: 50px;
  padding: 0 14px;
  display: flex;
  align-items: center;
  gap: 12px;
  background: #151824;
  border-bottom: 1px solid rgba(255, 255, 255, .07);
}
.lv-top-back { color: #9aa4ba; font-size: 13px; text-decoration: none; white-space: nowrap; }
.lv-top-back:hover { color: #fff; }
.lv-top-mid { flex: 1; min-width: 0; display: flex; align-items: center; gap: 10px; }
.lv-top-title {
  font-size: 14px;
  font-weight: 600;
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
  max-width: 46vw;
}
.lv-status {
  flex: none;
  font-size: 11px;
  padding: 2px 9px;
  border-radius: 999px;
  background: rgba(255, 255, 255, .1);
  color: #c7cddb;
}
.lv-status[data-s="1"] { background: rgba(255, 45, 85, .18); color: #ff7a95; }
.lv-status[data-s="1"]::before { content: '●'; margin-right: 4px; font-size: 8px; animation: lvBlink 1.4s infinite; }
@keyframes lvBlink { 50% { opacity: .25; } }
.lv-status[data-s="2"] { background: rgba(255, 255, 255, .07); color: #8b93a5; }
.lv-online { flex: none; font-size: 12px; color: #9aa4ba; }
.lv-online b { color: #ffd166; }
.lv-top-right { display: flex; align-items: center; gap: 10px; flex: none; }
.lv-role { font-size: 11.5px; color: #ffb08c; border: 1px solid rgba(255, 176, 140, .35); padding: 2px 8px; border-radius: 999px; }
.lv-role:empty { display: none; }
.lv-top-link { color: #9aa4ba; font-size: 12.5px; text-decoration: none; }
.lv-top-link:hover { color: #fff; }
.lv-exit {
  border: 1px solid rgba(255, 255, 255, .14);
  background: transparent;
  color: #c7cddb;
  font-size: 12.5px;
  padding: 5px 11px;
  border-radius: 8px;
  cursor: pointer;
}
.lv-exit:hover { border-color: #ff6b35; color: #ff9a62; }

.lv-main { flex: 1; min-height: 0; display: grid; grid-template-columns: minmax(0, 1fr) 360px; }
.lv-left { min-width: 0; min-height: 0; display: flex; flex-direction: column; background: #0b0d13; }

.lv-stage {
  position: relative;
  flex: 1;
  min-height: 0;
  display: flex;
  align-items: center;
  justify-content: center;
  background:
    radial-gradient(900px 400px at 50% -10%, rgba(255, 107, 53, .08), transparent 70%),
    #0b0d13;
  overflow: hidden;
  touch-action: none;
}
.lv-slide {
  max-width: 100%;
  max-height: 100%;
  object-fit: contain;
  display: block;
  user-select: none;
  -webkit-user-drag: none;
}
.lv-video { max-width: 100%; max-height: 100%; background: #000; }
.lv-board { position: absolute; inset: 0; width: 100%; height: 100%; pointer-events: none; }
.lv-body.is-teacher .lv-board { pointer-events: auto; cursor: crosshair; }

.lv-blank { text-align: center; color: #6d768c; padding: 20px; }
.lv-blank-ico { font-size: 44px; opacity: .5; margin-bottom: 8px; }
.lv-blank p { font-size: 14px; }
.lv-blank-sub { font-size: 12px; color: #525a6d; margin-top: 6px; }

.lv-gate {
  position: absolute;
  inset: 0;
  background: rgba(9, 11, 17, .88);
  backdrop-filter: blur(6px);
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 20px;
  z-index: 6;
}
.lv-gate-card { max-width: 380px; text-align: center; }
.lv-gate-ico { font-size: 40px; margin-bottom: 10px; }
.lv-gate-card h3 { font-size: 17px; margin-bottom: 8px; }
.lv-gate-card p { font-size: 13px; color: #9aa4ba; line-height: 1.8; }
.lv-gate-form { margin: 14px 0 4px; }
.lv-gate-form input {
  width: 100%;
  padding: 10px 14px;
  border-radius: 10px;
  border: 1px solid rgba(255, 255, 255, .16);
  background: rgba(255, 255, 255, .06);
  color: #fff;
  font-size: 14px;
  text-align: center;
  outline: none;
}
.lv-gate-form input:focus { border-color: #ff6b35; }
.lv-gate-btns { display: flex; gap: 10px; justify-content: center; margin-top: 14px; flex-wrap: wrap; }
.lv-gate-btns .lv-btn { background: rgba(255, 255, 255, .1); border-color: rgba(255, 255, 255, .2); color: #fff; }
.lv-gate-btns .lv-btn-primary { background: var(--kn-grad-main); border-color: transparent; }

.lv-tip {
  position: absolute;
  left: 50%;
  bottom: 22px;
  transform: translate(-50%, 12px);
  padding: 8px 16px;
  border-radius: 999px;
  background: rgba(20, 24, 34, .94);
  border: 1px solid rgba(255, 255, 255, .12);
  color: #e8ebf2;
  font-size: 13px;
  opacity: 0;
  pointer-events: none;
  transition: .22s;
  z-index: 8;
  max-width: 86%;
  text-align: center;
}
.lv-tip.on { opacity: 1; transform: translate(-50%, 0); }

/* 工具栏 */
.lv-bar {
  flex: none;
  display: flex;
  align-items: center;
  gap: 8px;
  padding: 7px 12px;
  background: #151824;
  border-top: 1px solid rgba(255, 255, 255, .06);
}
.lv-bar-btn {
  border: 1px solid rgba(255, 255, 255, .12);
  background: rgba(255, 255, 255, .05);
  color: #c7cddb;
  font-size: 13px;
  padding: 5px 11px;
  border-radius: 8px;
  cursor: pointer;
  line-height: 1.3;
}
.lv-bar-btn:hover { border-color: #ff6b35; color: #ff9a62; }
.lv-bar-btn.on { background: rgba(255, 107, 53, .18); border-color: rgba(255, 107, 53, .5); color: #ffb08c; }
.lv-page { font-size: 12px; color: #9aa4ba; min-width: 56px; text-align: center; font-variant-numeric: tabular-nums; }
.lv-bar-split { width: 1px; height: 16px; background: rgba(255, 255, 255, .1); }
.lv-bar-hint { flex: 1; font-size: 11.5px; color: #6d768c; text-align: right; padding-right: 4px; }

/* 课堂信息 */
.lv-info {
  flex: none;
  padding: 12px 16px 14px;
  background: #12151f;
  border-top: 1px solid rgba(255, 255, 255, .06);
  max-height: 26vh;
  overflow-y: auto;
}
.lv-info-hd { display: flex; align-items: center; justify-content: space-between; gap: 10px; }
.lv-info-hd h1 { font-size: 16px; line-height: 1.45; color: #f2f4f9; }
.lv-info-link { font-size: 12.5px; color: #ff9a62; text-decoration: none; white-space: nowrap; }
.lv-info-meta { display: flex; gap: 12px; flex-wrap: wrap; margin-top: 6px; font-size: 12px; color: #8b93a5; }
.lv-info-tip { margin-top: 8px; font-size: 12px; color: #6d768c; line-height: 1.7; }
.lv-notice {
  margin-top: 10px;
  padding: 8px 12px;
  border-radius: 10px;
  background: rgba(255, 209, 102, .09);
  border: 1px solid rgba(255, 209, 102, .22);
  font-size: 12.5px;
  color: #ffe1a3;
  display: flex;
  gap: 8px;
  line-height: 1.7;
}
.lv-notice b { flex: none; color: #ffd166; }

/* 侧栏 */
.lv-side {
  min-width: 0;
  min-height: 0;
  display: flex;
  flex-direction: column;
  background: #12151f;
  border-left: 1px solid rgba(255, 255, 255, .07);
}
.lv-tabs {
  flex: none;
  display: flex;
  align-items: center;
  gap: 2px;
  padding: 0 8px;
  border-bottom: 1px solid rgba(255, 255, 255, .07);
  position: relative;
}
.lv-tab {
  position: relative;
  border: 0;
  background: none;
  color: #8b93a5;
  font-size: 13px;
  padding: 12px 12px;
  cursor: pointer;
  border-bottom: 2px solid transparent;
}
.lv-tab.on { color: #fff; border-bottom-color: #ff6b35; }
.lv-tab-close {
  margin-left: auto;
  border: 0;
  background: none;
  color: #8b93a5;
  font-size: 20px;
  line-height: 1;
  cursor: pointer;
  display: none;
}
.lv-dot { position: absolute; right: 4px; top: 8px; width: 6px; height: 6px; border-radius: 50%; background: #ff2d55; }
.lv-hand-num {
  position: absolute;
  right: 0;
  top: 6px;
  min-width: 15px;
  height: 15px;
  padding: 0 3px;
  border-radius: 999px;
  background: #ff2d55;
  color: #fff;
  font-size: 10px;
  font-style: normal;
  display: inline-flex;
  align-items: center;
  justify-content: center;
}

.lv-pane { flex: 1; min-height: 0; display: flex; flex-direction: column; overflow: hidden; }
.lv-pane[hidden] { display: none; }

/* 消息 */
.lv-msgs { flex: 1; min-height: 0; overflow-y: auto; padding: 12px 12px 4px; display: flex; flex-direction: column; gap: 10px; }
.lv-msg { display: flex; gap: 8px; align-items: flex-start; }
.lv-msg-av {
  flex: none;
  width: 26px; height: 26px;
  border-radius: 50%;
  background: #2a2f3d;
  color: #b7bfd0;
  font-size: 11px;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  overflow: hidden;
}
.lv-msg-bd { min-width: 0; flex: 1; }
.lv-msg-hd { display: flex; align-items: baseline; gap: 6px; flex-wrap: wrap; }
.lv-msg-name { font-size: 12px; color: #8b93a5; }
.lv-msg-time { font-size: 10.5px; color: #525a6d; }
.lv-msg-tag {
  font-size: 10px;
  padding: 0 5px;
  border-radius: 4px;
  background: rgba(255, 107, 53, .18);
  color: #ff9a62;
}
.lv-msg-tag.ask { background: rgba(76, 201, 240, .16); color: #7adcf5; }
.lv-msg-text {
  margin-top: 2px;
  padding: 7px 11px;
  border-radius: 4px 12px 12px 12px;
  background: #1b2030;
  font-size: 13px;
  line-height: 1.65;
  color: #dde2ec;
  word-break: break-word;
  white-space: pre-wrap;
}
.lv-msg.me .lv-msg-text { background: rgba(255, 107, 53, .16); color: #ffe8dd; }
.lv-msg.teacher .lv-msg-name { color: #ffb08c; font-weight: 700; }
.lv-msg.teacher .lv-msg-text { background: rgba(255, 209, 102, .13); color: #ffeec4; }
.lv-msg-sys {
  text-align: center;
  font-size: 11.5px;
  color: #61708a;
  padding: 2px 10px;
  line-height: 1.6;
}

.lv-quick { flex: none; display: flex; gap: 6px; padding: 6px 12px 0; overflow-x: auto; }
.lv-quick button {
  flex: none;
  border: 1px solid rgba(255, 255, 255, .12);
  background: rgba(255, 255, 255, .04);
  color: #9aa4ba;
  font-size: 11.5px;
  padding: 4px 10px;
  border-radius: 999px;
  cursor: pointer;
}
.lv-quick button:hover { border-color: #ff6b35; color: #ff9a62; }

.lv-send { flex: none; display: flex; gap: 6px; padding: 8px 10px 4px; align-items: center; }
.lv-send input {
  flex: 1;
  min-width: 0;
  padding: 9px 12px;
  border-radius: 10px;
  border: 1px solid rgba(255, 255, 255, .12);
  background: rgba(255, 255, 255, .05);
  color: #eef1f7;
  font-size: 13px;
  outline: none;
}
.lv-send input:focus { border-color: rgba(255, 107, 53, .6); }
.lv-send input::placeholder { color: #5f6879; }
.lv-send-btn, .lv-hand-btn {
  flex: none;
  border: 0;
  border-radius: 10px;
  padding: 9px 14px;
  font-size: 13px;
  cursor: pointer;
  background: var(--kn-grad-main);
  color: #fff;
  font-weight: 600;
}
.lv-hand-btn { background: rgba(255, 255, 255, .08); padding: 9px 11px; }
.lv-hand-btn.on { background: #ffd166; }
.lv-send-tip { flex: none; padding: 0 12px 8px; font-size: 11.5px; color: #6d768c; min-height: 18px; }

/* 测验 */
.lv-quiz { flex: 1; min-height: 0; overflow-y: auto; padding: 14px 14px 20px; }
.lv-quiz-card { border-radius: 14px; background: #171c29; border: 1px solid rgba(255, 255, 255, .08); padding: 14px; }
.lv-quiz-q { font-size: 14px; line-height: 1.7; color: #f0f3f9; font-weight: 600; }
.lv-quiz-sub { margin-top: 4px; font-size: 11.5px; color: #7d8698; }
.lv-quiz-opts { display: flex; flex-direction: column; gap: 8px; margin-top: 12px; }
.lv-opt {
  display: flex;
  align-items: center;
  gap: 10px;
  padding: 10px 12px;
  border-radius: 11px;
  border: 1px solid rgba(255, 255, 255, .1);
  background: rgba(255, 255, 255, .03);
  color: #dde2ec;
  font-size: 13.5px;
  text-align: left;
  cursor: pointer;
  transition: .16s;
  line-height: 1.5;
}
.lv-opt:hover:not(:disabled) { border-color: rgba(255, 107, 53, .55); background: rgba(255, 107, 53, .08); }
.lv-opt b {
  flex: none;
  width: 22px; height: 22px;
  border-radius: 7px;
  background: rgba(255, 255, 255, .08);
  color: #b7bfd0;
  font-size: 12px;
  display: inline-flex; align-items: center; justify-content: center;
}
.lv-opt.picked { border-color: #ff6b35; background: rgba(255, 107, 53, .14); }
.lv-opt.picked b { background: #ff6b35; color: #fff; }
.lv-opt.right { border-color: rgba(6, 214, 160, .6); background: rgba(6, 214, 160, .12); }
.lv-opt.right b { background: #06d6a0; color: #04231a; }
.lv-opt.wrong { border-color: rgba(255, 45, 85, .5); background: rgba(255, 45, 85, .1); }
.lv-opt.wrong b { background: #ff2d55; color: #fff; }
.lv-opt:disabled { cursor: default; }
.lv-quiz-res { margin-top: 12px; font-size: 13px; line-height: 1.8; }
.lv-quiz-res.good { color: #4ce0b3; }
.lv-quiz-res.bad { color: #ff8298; }
.lv-quiz-exp { margin-top: 8px; padding: 10px 12px; border-radius: 10px; background: rgba(255, 255, 255, .05); font-size: 12.5px; color: #b7bfd0; line-height: 1.8; }
.lv-bars { margin-top: 12px; display: flex; flex-direction: column; gap: 7px; }
.lv-bar-row { display: flex; align-items: center; gap: 8px; font-size: 12px; color: #9aa4ba; }
.lv-bar-row > span:first-child { flex: none; width: 18px; color: #dde2ec; font-weight: 700; }
.lv-bar-track { flex: 1; height: 7px; border-radius: 999px; background: rgba(255, 255, 255, .07); overflow: hidden; }
.lv-bar-fill { height: 100%; border-radius: 999px; background: var(--kn-grad-main); transition: width .3s; }
.lv-bar-row.right .lv-bar-fill { background: linear-gradient(90deg, #06d6a0, #4ce0b3); }
.lv-bar-num { flex: none; width: 42px; text-align: right; font-variant-numeric: tabular-nums; }
.lv-quiz-foot { margin-top: 12px; display: flex; justify-content: space-between; align-items: center; font-size: 11.5px; color: #6d768c; }

/* 成员 */
.lv-hands { flex: none; padding: 10px 12px 0; display: flex; flex-wrap: wrap; gap: 6px; }
.lv-hands:empty { display: none; }
.lv-hand-chip {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  padding: 4px 9px;
  border-radius: 999px;
  background: rgba(255, 209, 102, .14);
  border: 1px solid rgba(255, 209, 102, .3);
  color: #ffe1a3;
  font-size: 11.5px;
}
.lv-hand-chip button {
  border: 0;
  background: rgba(0, 0, 0, .25);
  color: #ffe1a3;
  font-size: 10.5px;
  border-radius: 999px;
  padding: 1px 6px;
  cursor: pointer;
}
.lv-members { flex: 1; min-height: 0; overflow-y: auto; padding: 10px 12px 20px; display: flex; flex-direction: column; gap: 6px; }
.lv-member {
  display: flex;
  align-items: center;
  gap: 9px;
  padding: 7px 9px;
  border-radius: 10px;
  background: rgba(255, 255, 255, .03);
}
.lv-member.on { background: rgba(6, 214, 160, .07); }
.lv-member-av {
  flex: none;
  width: 24px; height: 24px;
  border-radius: 50%;
  background: #2a3140;
  color: #b7bfd0;
  font-size: 11px;
  display: inline-flex; align-items: center; justify-content: center;
}
.lv-member-bd { flex: 1; min-width: 0; }
.lv-member-name { font-size: 12.5px; color: #dde2ec; white-space: nowrap; overflow: hidden; text-overflow: ellipsis; }
.lv-member-sub { font-size: 10.5px; color: #6d768c; }
.lv-member-acts { display: flex; gap: 4px; flex: none; }
.lv-member-acts button {
  border: 1px solid rgba(255, 255, 255, .12);
  background: transparent;
  color: #9aa4ba;
  font-size: 10.5px;
  padding: 2px 7px;
  border-radius: 6px;
  cursor: pointer;
}
.lv-member-acts button:hover { border-color: #ff6b35; color: #ff9a62; }

/* 授课台 */
.lv-tools { flex: 1; min-height: 0; overflow-y: auto; padding: 12px 12px 24px; display: flex; flex-direction: column; gap: 14px; }
.lv-tool-group { border-radius: 12px; background: #171c29; border: 1px solid rgba(255, 255, 255, .07); padding: 12px; }
.lv-tool-title { font-size: 12.5px; font-weight: 700; color: #dde2ec; margin-bottom: 9px; }
.lv-tool-row { display: flex; gap: 8px; flex-wrap: wrap; align-items: center; }
.lv-tool-hint { margin-top: 8px; font-size: 11px; color: #61708a; line-height: 1.7; }
.lv-tool-status { margin-top: 8px; font-size: 11.5px; color: #8b93a5; }
.lv-tools .lv-btn { background: rgba(255, 255, 255, .06); border-color: rgba(255, 255, 255, .14); color: #dde2ec; }
.lv-tools .lv-btn:hover { border-color: #ff6b35; color: #ff9a62; }
.lv-tools .lv-btn-primary { background: var(--kn-grad-main); border-color: transparent; color: #fff; }
.lv-input, .lv-textarea {
  width: 100%;
  padding: 8px 11px;
  border-radius: 9px;
  border: 1px solid rgba(255, 255, 255, .12);
  background: rgba(255, 255, 255, .04);
  color: #eef1f7;
  font-size: 12.5px;
  font-family: inherit;
  outline: none;
  margin-bottom: 8px;
}
.lv-input:focus, .lv-textarea:focus { border-color: rgba(255, 107, 53, .6); }
.lv-textarea { min-height: 60px; resize: vertical; }
.lv-slides { display: grid; grid-template-columns: repeat(4, 1fr); gap: 6px; margin: 8px 0 4px; }
.lv-slide-thumb { position: relative; border-radius: 7px; overflow: hidden; border: 1px solid rgba(255, 255, 255, .1); aspect-ratio: 16 / 10; background: #0e1017; }
.lv-slide-thumb img { width: 100%; height: 100%; object-fit: cover; display: block; }
.lv-slide-thumb span { position: absolute; left: 3px; bottom: 2px; font-size: 9px; color: #fff; background: rgba(0, 0, 0, .55); padding: 0 4px; border-radius: 4px; }
.lv-slide-thumb button {
  position: absolute;
  right: 2px;
  top: 2px;
  width: 16px;
  height: 16px;
  border: 0;
  border-radius: 50%;
  background: rgba(0, 0, 0, .6);
  color: #fff;
  font-size: 11px;
  line-height: 1;
  cursor: pointer;
}
.lv-quiz-opts .lv-qopt-row { display: flex; gap: 6px; align-items: center; margin-bottom: 6px; }
.lv-quiz-opts .lv-qopt-row input[type="text"] { margin-bottom: 0; }
.lv-quiz-opts .lv-qopt-row input[type="radio"] { flex: none; accent-color: #ff6b35; }
.lv-quiz-stat { margin-top: 8px; font-size: 11.5px; color: #8b93a5; }
.lv-pen { width: 26px; height: 26px; border-radius: 8px; border: 2px solid transparent; cursor: pointer; }
.lv-pen.on { border-color: #fff; box-shadow: 0 0 0 2px rgba(255, 255, 255, .2); }
.lv-upload { position: relative; overflow: hidden; }

/* 手机浮动工具 */
.lv-fab { display: none; }

/* ---------------- 平板 / 窄屏 ---------------- */
@media (max-width: 1080px) {
  .lv-main { grid-template-columns: minmax(0, 1fr) 320px; }
  .lv-how-list { grid-template-columns: repeat(2, 1fr); }
}

@media (max-width: 860px) {
  .lv-hero { flex-direction: column; align-items: flex-start; padding: 26px 20px; margin: 14px 12px 0; }
  .lv-hero h1 { font-size: 24px; }
  .lv-hero-side { width: 100%; grid-template-columns: repeat(3, 1fr); }
  .lv-hero-stat { flex-direction: column; gap: 2px; padding: 8px 10px; }
  .lv-hero-stat b { font-size: 18px; }
  .lv-pc-only { display: none; }
  .lv-grid, .lv-grid-sm { grid-template-columns: repeat(auto-fill, minmax(240px, 1fr)); }
}

/* ---------------- 手机端教室：单列 + 抽屉 ---------------- */
@media (max-width: 760px) {
  .lv-body { font-size: 13px; }
  .lv-top { height: 46px; padding: 0 10px; gap: 8px; }
  .lv-top-back { font-size: 12px; }
  .lv-top-title { font-size: 13px; max-width: 38vw; }
  .lv-top-link { display: none; }
  .lv-role { display: none; }
  .lv-exit { padding: 4px 9px; font-size: 12px; }
  .lv-online { font-size: 11px; }

  .lv-main { display: block; position: relative; overflow: hidden; }
  .lv-left { height: 100%; }
  .lv-stage { min-height: 0; }
  .lv-blank-ico { font-size: 34px; }
  .lv-blank p { font-size: 13px; }
  .lv-blank-sub { font-size: 11px; }

  .lv-bar { padding: 6px 8px; gap: 6px; }
  .lv-bar-btn { padding: 5px 9px; font-size: 12px; }
  .lv-bar-hint { display: none; }
  .lv-info { max-height: 24vh; padding: 9px 12px 11px; }
  .lv-info-hd h1 { font-size: 14px; }
  .lv-info-meta { gap: 8px; font-size: 11px; }

  /* 侧栏变底部抽屉 */
  .lv-side {
    position: fixed;
    left: 0;
    right: 0;
    bottom: 0;
    height: 68vh;
    z-index: 60;
    border-left: 0;
    border-top: 1px solid rgba(255, 255, 255, .1);
    border-radius: 16px 16px 0 0;
    transform: translateY(calc(100% + 20px));
    transition: transform .26s ease;
    box-shadow: 0 -20px 50px -20px rgba(0, 0, 0, .8);
  }
  .lv-side.open { transform: translateY(0); }
  .lv-tab-close { display: block; }
  .lv-tab { padding: 11px 11px; font-size: 12.5px; }
  .lv-msgs { padding: 10px 10px 4px; }
  .lv-quick { padding: 6px 10px 0; }
  .lv-send { padding: 8px 8px 6px; }
  .lv-send-tip { padding: 0 10px 8px; }

  .lv-fab {
    display: flex;
    position: fixed;
    right: 12px;
    bottom: calc(12px + env(safe-area-inset-bottom));
    gap: 8px;
    z-index: 50;
  }
  .lv-fab button {
    border: 1px solid rgba(255, 255, 255, .16);
    background: rgba(24, 28, 40, .92);
    color: #e8ebf2;
    font-size: 12.5px;
    padding: 9px 13px;
    border-radius: 999px;
    backdrop-filter: blur(8px);
    box-shadow: 0 10px 24px -12px rgba(0, 0, 0, .9);
    cursor: pointer;
  }
  .lv-fab button:active { background: rgba(255, 107, 53, .3); }

  .lv-modal { padding: 0; align-items: flex-end; }
  .lv-modal-card { max-width: none; max-height: 92vh; border-radius: 18px 18px 0 0; }
  .lv-field-row { flex-direction: column; gap: 12px; }
}

/* 无封面时的占位底纹 */
.lv-card-cover-fallback {
  position: absolute;
  inset: 0;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 30px;
  color: rgba(255, 255, 255, .3);
  background:
    radial-gradient(400px 200px at 80% 0%, rgba(255, 107, 53, .32), transparent 70%),
    linear-gradient(135deg, #23233a, #3a2c46);
}
.lv-card-edit {
  position: absolute;
  right: 10px;
  top: 10px;
  z-index: 3;
  border: 1px solid rgba(255, 255, 255, .3);
  background: rgba(0, 0, 0, .35);
  color: #fff;
  font-size: 11px;
  padding: 2px 8px;
  border-radius: 999px;
  cursor: pointer;
  backdrop-filter: blur(4px);
}
.lv-card-edit:hover { background: var(--kn-orange); border-color: transparent; }

@media (max-width: 480px) {
  .lv-hero { margin: 10px 8px 0; padding: 22px 16px; border-radius: 18px; }
  .lv-hero h1 { font-size: 21px; }
  .lv-hero p { font-size: 13px; }
  .lv-hero-btns .lv-btn { flex: 1; }
  .lv-wrap { padding: 16px 10px 48px; }
  .lv-grid, .lv-grid-sm { grid-template-columns: 1fr; gap: 12px; }
  .lv-how-list { grid-template-columns: 1fr; }
  .lv-scope { gap: 6px; }
  .lv-scope button { padding: 6px 12px; font-size: 12px; }
  .lv-toolbar { gap: 8px; }
  .lv-slides { grid-template-columns: repeat(3, 1fr); }
}