:root {
  --bg-deep: #0b0f17;
  --bg-panel: #131a26;
  --bg-card: #1a2333;
  --bg-hover: #222e42;
  --border: #2a3952;
  --text-main: #e7eef8;
  --text-muted: #8fa3bf;
  --radiant: #3dd68c;
  --dire: #ff5c5c;
  --gold: #f5b942;
  --accent: #4f9cff;
  --purple: #a78bfa;
}

* {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

[hidden] {
  display: none !important;
}

button:disabled {
  opacity: 0.55;
  cursor: not-allowed;
}

input:focus-visible, select:focus-visible, button:focus-visible {
  outline: 2px solid var(--accent);
  outline-offset: 3px;
}

.muted {
  color: var(--text-muted);
  font-size: 13px;
}

.small {
  font-size: 12px;
}

.auth-shell {
  max-width: 460px;
  margin: 8vh auto;
  padding: 16px;
}

.auth-card {
  gap: 20px;
  padding: 28px;
}

.lobby-shell {
  max-width: 1100px;
  margin: 40px auto;
  padding: 0 24px;
}

.field {
  display: flex;
  flex-direction: column;
  gap: 7px;
  min-width: 0;
  font-size: 13px;
}

.field input, .field select {
  width: 100%;
  min-width: 0;
}

.section-heading {
  display: flex;
  align-items: center;
  justify-content: space-between;
  flex-wrap: wrap;
  gap: 12px;
}

.section-heading h2 {
  font-size: 20px;
  overflow-wrap: anywhere;
}

.app-notice, .invite-notice {
  padding: 12px 18px;
  background: rgba(79, 156, 255, 0.1);
  border: 1px solid var(--border);
  border-radius: 10px;
  font-size: 13px;
}

.app-notice {
  margin: 16px 24px 0;
}

.invite-notice, .room-card {
  display: flex;
  align-items: center;
  justify-content: space-between;
  flex-wrap: wrap;
  gap: 14px;
}

.room-list, .user-options {
  display: flex;
  flex-direction: column;
  gap: 10px;
}

.room-card {
  padding: 16px;
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: 10px;
  overflow-wrap: anywhere;
}

.settings-summary {
  display: grid;
  grid-template-columns: auto minmax(0, 1fr);
  gap: 8px 12px;
  font-size: 12px;
  overflow-wrap: anywhere;
}

.settings-summary dt {
  color: var(--text-muted);
}

.modal {
  width: min(640px, calc(100% - 32px));
  max-height: 90vh;
  margin: auto;
  padding: 0;
  background: var(--bg-panel);
  color: var(--text-main);
  border: 1px solid var(--border);
  border-radius: 16px;
}

.modal::backdrop {
  background: rgba(0, 0, 0, 0.72);
  backdrop-filter: blur(4px);
}

.modal-content {
  display: flex;
  flex-direction: column;
  gap: 20px;
  padding: 24px;
}

.form-grid {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 16px;
}

.full-width {
  grid-column: 1 / -1;
}

fieldset {
  min-width: 0;
  border: 1px solid var(--border);
  border-radius: 10px;
  padding: 14px;
}

fieldset legend {
  font-size: 13px;
  padding: 0 6px;
}

fieldset .muted {
  margin-top: 10px;
}

.modal-actions {
  display: flex;
  justify-content: flex-end;
  gap: 10px;
}

.form-error {
  color: var(--dire);
  font-size: 13px;
}

@media (max-width: 600px) {
  .form-grid { grid-template-columns: minmax(0, 1fr); }
  .modal-content { padding: 18px; }
}

body {
  font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'PingFang SC',
    'Microsoft YaHei', sans-serif;
  background: radial-gradient(circle at top right, #182235 0%, var(--bg-deep) 55%);
  color: var(--text-main);
  min-height: 100vh;
  line-height: 1.5;
}

.topbar {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  justify-content: space-between;
  gap: 12px;
  padding: 14px 24px;
  background: rgba(19, 26, 38, 0.92);
  border-bottom: 1px solid var(--border);
  backdrop-filter: blur(10px);
  position: sticky;
  top: 0;
  z-index: 20;
}

.brand {
  display: flex;
  align-items: center;
  gap: 12px;
}

.brand-badge {
  background: linear-gradient(135deg, #d946ef, #ef4444, #f59e0b);
  color: #fff;
  font-weight: 800;
  font-size: 13px;
  letter-spacing: 0.06em;
  padding: 6px 10px;
  border-radius: 8px;
}

.brand h1 {
  font-size: 18px;
  font-weight: 700;
}

.brand-sub {
  font-size: 12px;
  color: var(--text-muted);
}

.room-controls {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 8px;
}

input, select, button {
  font: inherit;
  border-radius: 8px;
  border: 1px solid var(--border);
  background: var(--bg-card);
  color: var(--text-main);
  padding: 7px 12px;
  font-size: 13px;
}

button {
  cursor: pointer;
  transition: background 0.15s, border-color 0.15s, transform 0.05s;
}

button:hover {
  background: var(--bg-hover);
  border-color: var(--accent);
}

button:active {
  transform: translateY(1px);
}

.btn-primary {
  background: var(--accent);
  border-color: var(--accent);
  color: #08111f;
  font-weight: 700;
}

.btn-primary:hover {
  background: #6aadff;
}

.btn-radiant {
  background: rgba(61, 214, 140, 0.16);
  border-color: var(--radiant);
  color: var(--radiant);
  font-weight: 600;
}

.btn-dire {
  background: rgba(255, 92, 92, 0.16);
  border-color: var(--dire);
  color: var(--dire);
  font-weight: 600;
}

.layout {
  display: grid;
  grid-template-columns: 340px minmax(0, 1fr);
  gap: 16px;
  padding: 16px 24px 32px;
  max-width: 1680px;
  margin: 0 auto;
}

@media (max-width: 900px) {
  .layout {
    grid-template-columns: 1fr;
  }
}

.panel {
  min-width: 0;
  background: var(--bg-panel);
  border: 1px solid var(--border);
  border-radius: 14px;
  padding: 16px;
  display: flex;
  flex-direction: column;
  gap: 14px;
}

.panel-title {
  font-size: 14px;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  color: var(--text-muted);
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.engine-cards {
  display: flex;
  flex-direction: column;
  gap: 8px;
}

.engine-card {
  border: 1px solid var(--border);
  background: var(--bg-card);
  border-radius: 10px;
  padding: 11px 12px;
  cursor: pointer;
  transition: all 0.15s;
}

.engine-card:hover {
  border-color: #49658e;
}

.engine-card.active {
  border-color: var(--accent);
  background: rgba(79, 156, 255, 0.12);
  box-shadow: 0 0 0 1px rgba(79, 156, 255, 0.35);
}

.engine-card-head {
  display: flex;
  align-items: center;
  justify-content: space-between;
  font-weight: 700;
  font-size: 14px;
  margin-bottom: 4px;
}

.badge {
  font-size: 11px;
  padding: 2px 7px;
  border-radius: 999px;
  font-weight: 600;
  background: rgba(255, 255, 255, 0.08);
  color: var(--text-muted);
}

.badge.green {
  background: rgba(61, 214, 140, 0.16);
  color: var(--radiant);
}

.badge.gold {
  background: rgba(245, 185, 66, 0.18);
  color: var(--gold);
}

.badge.purple {
  background: rgba(167, 139, 250, 0.18);
  color: var(--purple);
}

.engine-card p {
  font-size: 12px;
  color: var(--text-muted);
}

.toggle-row {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 8px;
  font-size: 13px;
  padding: 8px 10px;
  background: var(--bg-card);
  border-radius: 8px;
  border: 1px solid var(--border);
}

.participants-list {
  display: flex;
  flex-direction: column;
  gap: 6px;
}

.participant-item {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 8px 10px;
  border-radius: 8px;
  background: var(--bg-card);
  font-size: 13px;
}

.voice-controls {
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
  align-items: center;
  padding: 12px;
  background: var(--bg-card);
  border-radius: 12px;
  border: 1px solid var(--border);
}

.mic-meter {
  flex: 1;
  min-width: 100px;
  height: 8px;
  background: #0d131d;
  border-radius: 999px;
  overflow: hidden;
}

.mic-meter-fill {
  height: 100%;
  width: 0%;
  background: linear-gradient(90deg, var(--radiant), var(--gold));
  transition: width 0.06s linear;
}

.status-bar {
  font-size: 12px;
  color: var(--text-muted);
  padding: 6px 10px;
  background: rgba(255, 255, 255, 0.03);
  border-radius: 8px;
}

.feed {
  flex: 1;
  min-height: 430px;
  max-height: 62vh;
  overflow-y: auto;
  display: flex;
  flex-direction: column;
  gap: 10px;
  padding-right: 4px;
}

.turn-card {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-left: 4px solid var(--accent);
  border-radius: 10px;
  padding: 10px 14px;
}

.turn-card.coach {
  border-left-color: var(--gold);
}

.turn-card.student {
  border-left-color: var(--radiant);
}

.turn-meta {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  justify-content: space-between;
  gap: 6px;
  font-size: 12px;
  color: var(--text-muted);
  margin-bottom: 6px;
}

.turn-source {
  font-size: 13px;
  color: var(--text-muted);
  margin-bottom: 4px;
}

.turn-target {
  font-size: 16px;
  font-weight: 600;
  color: var(--text-main);
}

.live-Banner {
  padding: 8px 12px;
  border-radius: 8px;
  background: rgba(79, 156, 255, 0.1);
  border: 1px dashed var(--accent);
  font-size: 13px;
  min-height: 38px;
}

.text-input-row {
  display: flex;
  gap: 8px;
}

.text-input-row input {
  flex: 1;
  min-width: 0;
}

.hero-tags {
  display: flex;
  flex-wrap: wrap;
  gap: 5px;
  min-height: 24px;
}

.hero-tag {
  display: inline-flex;
  align-items: center;
  gap: 5px;
  font-size: 11px;
  padding: 3px 8px;
  border-radius: 999px;
  background: rgba(245, 185, 66, 0.16);
  border: 1px solid rgba(245, 185, 66, 0.45);
  color: var(--gold);
}

.hero-tag button {
  border: none;
  background: transparent;
  color: var(--gold);
  padding: 0 2px;
  font-size: 12px;
  line-height: 1;
}