:root {
  --bg: #f5f7fa;
  --surface: #ffffff;
  --surface-2: #f0f3f7;
  --ink: #0f172a;
  --ink-soft: #475569;
  --ink-faint: #64748b;
  --border: #e2e8f0;
  --accent: #0e7c66;
  --accent-strong: #0a5e4d;
  --accent-soft: #e6f4f0;
  --warn: #b45309;
  --warn-soft: #fef3c7;
  --danger: #b91c1c;
  --danger-soft: #fee2e2;
  --shadow-sm: 0 1px 2px rgba(15, 23, 42, 0.06);
  --shadow-md: 0 8px 24px rgba(15, 23, 42, 0.08);
  --shadow-lg: 0 24px 60px rgba(15, 23, 42, 0.18);
  --radius: 14px;
  --radius-sm: 10px;
  --maxw: 820px;
  --header-h: 64px;
  --footer-h: 28px;
}

* {
  box-sizing: border-box;
}

html,
body {
  height: 100%;
  margin: 0;
}

body {
  font-family: ui-sans-serif, system-ui, -apple-system, "Segoe UI", Roboto,
    "Helvetica Neue", Arial, "Noto Sans", sans-serif;
  font-size: 16px;
  line-height: 1.55;
  color: var(--ink);
  background: linear-gradient(180deg, #f5f7fa 0%, #eef2f7 100%);
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

code {
  font-family: ui-monospace, SFMono-Regular, "SF Mono", Menlo, Consolas,
    "Liberation Mono", monospace;
  font-size: 0.92em;
  background: var(--surface-2);
  border: 1px solid var(--border);
  border-radius: 6px;
  padding: 0.05em 0.35em;
}

button {
  font: inherit;
  color: inherit;
  cursor: pointer;
}

/* ------- Pre-chat scope gate ------- */

.gate {
  position: fixed;
  inset: 0;
  display: grid;
  place-items: center;
  padding: 24px;
  background: radial-gradient(
      1200px 600px at 70% -10%,
      rgba(14, 124, 102, 0.18),
      transparent 60%
    ),
    radial-gradient(900px 500px at 0% 100%, rgba(15, 23, 42, 0.08), transparent 70%),
    #f5f7fa;
  z-index: 100;
  overflow-y: auto;
}

.gate__card {
  width: 100%;
  max-width: 640px;
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 18px;
  box-shadow: var(--shadow-lg);
  padding: 36px 36px 32px;
}

.gate__eyebrow {
  font-size: 12px;
  font-weight: 600;
  letter-spacing: 0.14em;
  text-transform: uppercase;
  color: var(--accent);
}

.gate__title {
  margin: 6px 0 8px;
  font-size: 30px;
  line-height: 1.15;
  letter-spacing: -0.01em;
}

.gate__lede {
  margin: 0 0 18px;
  color: var(--ink-soft);
}

.gate__section {
  background: var(--surface-2);
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  padding: 14px 16px;
  margin: 12px 0;
}

.gate__section h2 {
  margin: 0 0 6px;
  font-size: 14px;
  letter-spacing: 0.02em;
  color: var(--ink);
}

.gate__section ul {
  margin: 0;
  padding-left: 1.15em;
  color: var(--ink-soft);
}

.gate__section li + li {
  margin-top: 4px;
}

.gate__section--warn {
  background: var(--warn-soft);
  border-color: #fde68a;
}

.gate__section--warn h2 {
  color: #92400e;
}

.gate__section--warn em {
  font-style: normal;
  text-decoration: underline;
}

.gate__fineprint {
  margin: 16px 0 18px;
  font-size: 13px;
  color: var(--ink-faint);
}

.gate__cta {
  width: 100%;
  background: var(--accent);
  color: #fff;
  border: 1px solid var(--accent-strong);
  border-radius: 12px;
  padding: 14px 18px;
  font-size: 16px;
  font-weight: 600;
  letter-spacing: 0.01em;
  box-shadow: var(--shadow-sm);
  transition: transform 0.05s ease, background 0.15s ease;
}

.gate__cta:hover {
  background: var(--accent-strong);
}

.gate__cta:active {
  transform: translateY(1px);
}

/* ------- App shell ------- */

.app {
  display: grid;
  grid-template-rows: var(--header-h) 1fr auto var(--footer-h);
  height: 100vh;
  max-width: var(--maxw);
  margin: 0 auto;
}

.app__header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 0 18px;
  border-bottom: 1px solid var(--border);
  background: rgba(255, 255, 255, 0.85);
  backdrop-filter: saturate(180%) blur(8px);
}

.app__brand {
  display: flex;
  align-items: center;
  gap: 12px;
  min-width: 0;
}

.app__brand-mark {
  width: 36px;
  height: 36px;
  border-radius: 10px;
  background: linear-gradient(135deg, var(--accent), #14b8a6);
  color: #fff;
  display: grid;
  place-items: center;
  font-weight: 700;
  letter-spacing: 0.02em;
  box-shadow: var(--shadow-sm);
}

.app__brand-name {
  font-weight: 600;
  font-size: 15px;
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
}

.app__brand-sub {
  font-size: 12px;
  color: var(--ink-faint);
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
}

.app__icon-btn {
  background: transparent;
  border: 1px solid transparent;
  color: var(--ink-soft);
  border-radius: 10px;
  width: 36px;
  height: 36px;
  display: grid;
  place-items: center;
  transition: background 0.15s ease, color 0.15s ease;
}

.app__icon-btn:hover {
  background: var(--surface-2);
  color: var(--ink);
  border-color: var(--border);
}

/* ------- Chat thread ------- */

.thread {
  overflow-y: auto;
  padding: 22px 18px 8px;
  display: flex;
  flex-direction: column;
  gap: 16px;
}

.thread__welcome {
  margin: 24px auto 8px;
  max-width: 560px;
  text-align: center;
  color: var(--ink-soft);
}

.thread__welcome h2 {
  margin: 0 0 6px;
  font-size: 22px;
  color: var(--ink);
  letter-spacing: -0.01em;
}

.thread__welcome p {
  margin: 0 0 14px;
  font-size: 14px;
}

.thread__suggestions {
  display: grid;
  gap: 8px;
}

.suggestion {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 12px;
  padding: 10px 14px;
  text-align: left;
  font-size: 14px;
  color: var(--ink);
  box-shadow: var(--shadow-sm);
  transition: border-color 0.15s ease, transform 0.05s ease;
}

.suggestion:hover {
  border-color: var(--accent);
}

.suggestion:active {
  transform: translateY(1px);
}

.msg {
  display: flex;
  gap: 10px;
  align-items: flex-start;
  max-width: 100%;
}

.msg__avatar {
  flex: 0 0 auto;
  width: 28px;
  height: 28px;
  border-radius: 8px;
  display: grid;
  place-items: center;
  font-size: 12px;
  font-weight: 600;
  letter-spacing: 0.02em;
}

.msg--user {
  flex-direction: row-reverse;
}

.msg--user .msg__avatar {
  background: var(--surface-2);
  color: var(--ink-soft);
  border: 1px solid var(--border);
}

.msg--bot .msg__avatar {
  background: linear-gradient(135deg, var(--accent), #14b8a6);
  color: #fff;
}

.msg__bubble {
  max-width: min(680px, calc(100% - 50px));
  padding: 12px 14px;
  border-radius: 14px;
  border: 1px solid var(--border);
  background: var(--surface);
  box-shadow: var(--shadow-sm);
  white-space: pre-wrap;
  overflow-wrap: anywhere;
}

.msg--user .msg__bubble {
  background: var(--accent);
  color: #fff;
  border-color: var(--accent-strong);
  border-top-right-radius: 4px;
}

.msg--bot .msg__bubble {
  border-top-left-radius: 4px;
}

.msg--error .msg__bubble {
  background: var(--danger-soft);
  border-color: #fecaca;
  color: var(--danger);
}

.msg__cite {
  background: var(--accent-soft);
  border: 1px solid #c7e8df;
  color: var(--accent-strong);
  border-radius: 6px;
  padding: 0.05em 0.4em;
  font-size: 0.9em;
  font-family: ui-monospace, SFMono-Regular, Menlo, Consolas, monospace;
  white-space: nowrap;
}

.msg__meta {
  margin-top: 8px;
  display: flex;
  flex-wrap: wrap;
  gap: 6px;
  font-size: 12px;
  color: var(--ink-faint);
}

.tag {
  display: inline-flex;
  align-items: center;
  gap: 4px;
  background: var(--surface-2);
  border: 1px solid var(--border);
  border-radius: 999px;
  padding: 2px 8px;
  font-size: 11px;
  color: var(--ink-soft);
}

.tag--source {
  background: var(--accent-soft);
  border-color: #c7e8df;
  color: var(--accent-strong);
}

.typing {
  display: inline-flex;
  align-items: center;
  gap: 4px;
  height: 1em;
}

.typing span {
  width: 6px;
  height: 6px;
  border-radius: 50%;
  background: var(--ink-faint);
  animation: typing-bounce 1.2s infinite ease-in-out;
}

.typing span:nth-child(2) {
  animation-delay: 0.15s;
}

.typing span:nth-child(3) {
  animation-delay: 0.3s;
}

@keyframes typing-bounce {
  0%,
  60%,
  100% {
    transform: translateY(0);
    opacity: 0.6;
  }
  30% {
    transform: translateY(-4px);
    opacity: 1;
  }
}

/* ------- Composer ------- */

.composer {
  display: grid;
  grid-template-columns: 1fr auto;
  gap: 8px;
  padding: 10px 12px 12px;
  background: var(--surface);
  border-top: 1px solid var(--border);
}

.composer__input {
  resize: none;
  width: 100%;
  max-height: 180px;
  min-height: 44px;
  padding: 11px 12px;
  font: inherit;
  color: var(--ink);
  background: var(--surface-2);
  border: 1px solid var(--border);
  border-radius: 12px;
  outline: none;
  transition: border-color 0.15s ease, background 0.15s ease,
    box-shadow 0.15s ease;
}

.composer__input:focus {
  border-color: var(--accent);
  background: var(--surface);
  box-shadow: 0 0 0 3px rgba(14, 124, 102, 0.12);
}

.composer__send {
  width: 44px;
  height: 44px;
  align-self: end;
  border-radius: 12px;
  background: var(--accent);
  color: #fff;
  border: 1px solid var(--accent-strong);
  display: grid;
  place-items: center;
  transition: background 0.15s ease, transform 0.05s ease;
}

.composer__send:hover:not(:disabled) {
  background: var(--accent-strong);
}

.composer__send:active:not(:disabled) {
  transform: translateY(1px);
}

.composer__send:disabled {
  opacity: 0.45;
  cursor: not-allowed;
}

.footer-note {
  font-size: 11px;
  color: var(--ink-faint);
  text-align: center;
  padding: 6px 12px;
  border-top: 1px solid var(--border);
  background: var(--surface);
}

/* ------- Responsive ------- */

@media (max-width: 600px) {
  .gate__card {
    padding: 24px 20px 22px;
  }

  .gate__title {
    font-size: 24px;
  }

  .app__brand-sub {
    display: none;
  }

  .thread {
    padding: 16px 12px 6px;
  }

  .footer-note {
    display: none;
  }
}

/* Hide content visually but keep it accessible. */
[hidden] {
  display: none !important;
}