:root[data-theme="dark"] {
  color-scheme: dark;
  --bg: #131d19;
  --surface: #1d2a24;
  --text: #e4eee8;
  --muted: #aabbb1;
  --accent: #9bd4b7;
  --accent-hover: #c1ead5;
  --danger: #ff929c;
  --success: #88d8a5;
  --warning: #edcb84;
  --border: #3b4f43;
  --input-bg: #17231d;
  --button-blue: #85bfff;
  --button-pressed: #245f9b;
}
.theme-toggle {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-height: 44px;
  padding: .6rem .85rem;
  border-radius: 8px;
  font: inherit;
  font-size: .9rem;
  font-weight: 600;
  cursor: pointer;
  flex-shrink: 0;
}
:root[data-theme="dark"] :is(.chat-msg, .chat-rating-box, .chat-appointment) {
  background: var(--surface);
}
:root[data-theme="dark"] :is(.study-card, .floating-note, .step-card) {
  background: var(--surface);
  border-color: var(--border);
}
:root[data-theme="dark"] :is(.benefit-strip, .study-card-bottom, .scene-orbit, .auth-page .card, .welcome-page .site-footer) {
  border-color: var(--border);
}
:root[data-theme="dark"] .learning-scene::before,
:root[data-theme="dark"] .welcome-cta {
  background: #28392c;
}
:root[data-theme="dark"] .auth-page .stack-form input {
  background: var(--input-bg);
  border-color: var(--border);
}
:root[data-theme="dark"] :is(.study-kicker, .study-subtitle, .avatar-stack small, .sample-message strong span, .example-label, .study-card-bottom, .note-bottom div > span, .scene-caption, .step-number, .step-detail) {
  color: var(--muted);
}
:root[data-theme="dark"] .hero-copy h1 > span { color: #accb91; }

:root[data-theme="dark"] .sample-message { background: var(--bg); }
:root[data-theme="dark"] .reply { background: #28392c; }
:root[data-theme="dark"] .message-avatar { color: #203b34; }

.theme-settings { margin-bottom: 1.5rem; padding-bottom: 1.5rem; border-bottom: 1px solid var(--border); }