:root {
  --bg: #f4efe5;
  --bg-soft: #fbf8f2;
  --card: rgba(255, 255, 255, 0.9);
  --card-strong: #fffdfa;
  --line: rgba(72, 52, 34, 0.12);
  --line-strong: rgba(72, 52, 34, 0.18);
  --text: #1e1712;
  --muted: #726456;
  --accent: #9f4025;
  --accent-strong: #7c2f18;
  --accent-soft: rgba(159, 64, 37, 0.1);
  --success: #3f7a60;
  --warn: #87621c;
  --danger: #9f4035;
  --shadow: 0 18px 42px rgba(82, 58, 33, 0.08);
  --shadow-soft: 0 10px 26px rgba(82, 58, 33, 0.06);
  --shell-side-padding: 18px;
  --composer-desktop-offset: 18px;
  --composer-desktop-space: 156px;
  --composer-desktop-width: 1004px;
}

* {
  box-sizing: border-box;
}

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

body {
  overflow: hidden;
  color: var(--text);
  font-family: "Source Han Sans SC", "PingFang SC", "Microsoft YaHei UI", sans-serif;
  background:
    radial-gradient(circle at top left, rgba(199, 133, 81, 0.18), transparent 26%),
    radial-gradient(circle at right 18%, rgba(120, 86, 45, 0.08), transparent 20%),
    linear-gradient(180deg, #f9f5ef 0%, #f2ebde 100%);
}

body::before {
  content: "";
  position: fixed;
  inset: 0;
  pointer-events: none;
  opacity: 0.28;
  background-image:
    linear-gradient(rgba(112, 87, 58, 0.03) 1px, transparent 1px),
    linear-gradient(90deg, rgba(112, 87, 58, 0.03) 1px, transparent 1px);
  background-size: 28px 28px;
}

.app-shell {
  position: relative;
  z-index: 1;
  max-width: 1040px;
  height: 100vh;
  margin: 0 auto;
  padding: 18px var(--shell-side-padding) calc(16px + env(safe-area-inset-bottom));
  display: grid;
  grid-template-rows: auto minmax(0, 1fr) auto;
  gap: 12px;
}

.topbar {
  display: flex;
  align-items: flex-start;
  justify-content: space-between;
  gap: 18px;
}

.brand {
  min-width: 0;
}

.brand-mark {
  display: inline-block;
  color: var(--accent);
  font-size: 0.76rem;
  letter-spacing: 0.18em;
  text-transform: uppercase;
  font-weight: 700;
}

.brand h1 {
  margin: 8px 0 6px;
  font-family: "Source Han Serif SC", "Songti SC", "Noto Serif SC", serif;
  font-size: 1.7rem;
  line-height: 1.15;
  font-weight: 700;
}

.brand p {
  margin: 0;
  max-width: 640px;
  color: var(--muted);
  line-height: 1.7;
  font-size: 0.95rem;
}

.topbar-actions {
  display: flex;
  gap: 8px;
  flex-shrink: 0;
  min-width: 0;
}

.topbar-btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-height: 42px;
  padding: 10px 14px;
  border: 0;
  border-radius: 999px;
  background: rgba(255, 255, 255, 0.8);
  box-shadow: var(--shadow-soft);
  color: var(--text);
  font: inherit;
  font-weight: 600;
  text-decoration: none;
  cursor: pointer;
}

.topbar-btn.danger {
  color: var(--danger);
}

.chat-stage {
  min-height: 0;
  min-width: 0;
  display: flex;
  flex-direction: column;
  gap: 10px;
}

.chat-feed {
  min-height: 0;
  flex: 1;
  overflow-y: auto;
  overflow-x: hidden;
  display: flex;
  flex-direction: column;
  gap: 14px;
  padding: 8px 4px 12px;
  scrollbar-width: none;
}

.chat-feed::-webkit-scrollbar,
.reasoning-inner pre::-webkit-scrollbar {
  display: none;
}

.empty-state {
  flex: 1;
  display: grid;
  place-items: center;
}

.empty-card {
  width: min(100%, 620px);
  padding: 30px 26px;
  border-radius: 30px;
  border: 1px solid var(--line);
  background:
    linear-gradient(180deg, rgba(255, 255, 255, 0.88), rgba(249, 244, 236, 0.98)),
    linear-gradient(135deg, rgba(159, 64, 37, 0.05), transparent 55%);
  box-shadow: var(--shadow);
}

.empty-mark {
  margin: 0 0 8px;
  color: var(--accent);
  font-size: 0.78rem;
  letter-spacing: 0.16em;
  text-transform: uppercase;
  font-weight: 700;
}

.empty-card h2 {
  margin: 0;
  font-family: "Source Han Serif SC", "Songti SC", "Noto Serif SC", serif;
  font-size: 1.45rem;
  line-height: 1.35;
}

.empty-card p {
  margin: 12px 0 0;
  color: var(--muted);
  line-height: 1.78;
}

.message {
  display: flex;
  flex-direction: column;
  gap: 6px;
  max-width: 88%;
  animation: rise 180ms ease-out;
}

.message.user {
  align-self: flex-end;
}

.message.assistant {
  align-self: flex-start;
}

.message-role {
  color: var(--muted);
  font-size: 0.76rem;
  letter-spacing: 0.08em;
}

.message-bubble {
  padding: 16px 18px;
  border-radius: 24px;
  box-shadow: var(--shadow-soft);
  line-height: 1.78;
  white-space: pre-wrap;
  word-break: break-word;
}

.message.user .message-bubble {
  background: linear-gradient(135deg, var(--accent), var(--accent-strong));
  color: #fff8f2;
  border-top-right-radius: 10px;
}

.message.assistant .message-bubble {
  background: var(--card-strong);
  border: 1px solid rgba(84, 62, 39, 0.08);
  border-top-left-radius: 10px;
}

.message.error .message-bubble {
  color: var(--danger);
  background: rgba(159, 64, 53, 0.08);
  border: 1px solid rgba(159, 64, 53, 0.18);
}

.message-meta {
  color: var(--muted);
  font-size: 0.82rem;
}

.reasoning-inline {
  flex-shrink: 0;
}

.reasoning-inner {
  padding: 12px 14px;
  border-radius: 18px;
  background: rgba(36, 27, 20, 0.96);
  color: #f8ead8;
  box-shadow: var(--shadow-soft);
}

.reasoning-inner p {
  margin: 0 0 8px;
  font-size: 0.82rem;
  letter-spacing: 0.08em;
}

.reasoning-inner pre {
  margin: 0;
  max-height: 180px;
  overflow-y: auto;
  white-space: pre-wrap;
  font: 0.88rem/1.7 "Cascadia Code", "Consolas", monospace;
  scrollbar-width: none;
}

.composer {
  position: relative;
  z-index: 2;
  min-width: 0;
  display: flex;
  flex-direction: column;
  gap: 8px;
}

.tool-row {
  display: flex;
  gap: 8px;
  overflow-x: auto;
  min-width: 0;
  padding: 0 2px;
  scrollbar-width: none;
}

.tool-row::-webkit-scrollbar {
  display: none;
}

.tool-chip {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  min-height: 38px;
  padding: 8px 12px;
  white-space: nowrap;
  border-radius: 999px;
  background: rgba(255, 255, 255, 0.8);
  border: 1px solid rgba(90, 68, 43, 0.08);
  box-shadow: var(--shadow-soft);
  color: var(--muted);
  font-size: 0.88rem;
}

.tool-chip input[type="checkbox"] {
  margin: 0;
}

.tool-chip.compact input[type="number"] {
  width: 48px;
  border: 0;
  outline: 0;
  background: transparent;
  color: var(--text);
  font: inherit;
  text-align: center;
}

.composer-shell {
  display: flex;
  align-items: flex-end;
  gap: 10px;
  min-width: 0;
  padding: 10px 12px;
  border-radius: 28px;
  border: 1px solid rgba(90, 68, 43, 0.08);
  background: rgba(255, 255, 255, 0.92);
  box-shadow: 0 12px 28px rgba(83, 58, 31, 0.08);
}

.composer textarea {
  flex: 1;
  min-width: 0;
  min-height: 26px;
  max-height: 120px;
  padding: 8px 4px;
  border: 0;
  outline: 0;
  resize: none;
  background: transparent;
  color: var(--text);
  font: inherit;
  line-height: 1.6;
  scrollbar-width: none;
}

.composer textarea::-webkit-scrollbar {
  display: none;
}

.composer textarea::placeholder {
  color: #9c9082;
}

.send-btn {
  flex-shrink: 0;
  min-width: 88px;
  border: 0;
  border-radius: 999px;
  padding: 12px 18px;
  background: linear-gradient(135deg, var(--accent), var(--accent-strong));
  color: #fff8f1;
  font: inherit;
  font-weight: 700;
  cursor: pointer;
}

.composer-note {
  margin: 0;
  padding: 0 6px;
  color: var(--muted);
  font-size: 0.84rem;
  line-height: 1.6;
}

@media (min-width: 761px) {
  .app-shell {
    padding-bottom: calc(var(--composer-desktop-space) + env(safe-area-inset-bottom));
  }

  .chat-feed {
    padding-bottom: calc(var(--composer-desktop-space) - 36px);
  }

  .composer {
    position: fixed;
    z-index: 4;
    left: 50%;
    bottom: calc(var(--composer-desktop-offset) + env(safe-area-inset-bottom));
    transform: translateX(-50%);
    width: min(calc(100vw - 36px), var(--composer-desktop-width));
  }
}

.send-btn:disabled,
.topbar-btn:disabled {
  opacity: 0.5;
  cursor: not-allowed;
}

.sr-only {
  position: absolute;
  width: 1px;
  height: 1px;
  padding: 0;
  margin: -1px;
  overflow: hidden;
  clip: rect(0, 0, 0, 0);
  white-space: nowrap;
  border: 0;
}

@keyframes rise {
  from {
    opacity: 0;
    transform: translateY(8px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

@media (max-width: 760px) {
  .app-shell {
    max-width: 100%;
    padding: 10px 10px calc(12px + env(safe-area-inset-bottom));
    gap: 10px;
  }

  .topbar {
    flex-direction: column;
    gap: 12px;
  }

  .topbar-actions {
    width: 100%;
    flex-wrap: wrap;
  }

  .topbar-btn {
    flex: 1;
    min-width: 0;
  }

  .brand h1 {
    font-size: 1.32rem;
  }

  .brand p {
    font-size: 0.84rem;
  }

  .chat-feed {
    padding: 6px 2px 8px;
  }

  .tool-row {
    flex-wrap: wrap;
    overflow-x: visible;
  }

  .tool-chip {
    max-width: 100%;
    white-space: normal;
  }

  .message {
    max-width: 100%;
  }

  .message-bubble {
    padding: 14px 15px;
    border-radius: 20px;
  }

  .empty-card {
    border-radius: 24px;
    padding: 24px 18px;
  }

  .empty-card h2 {
    font-size: 1.16rem;
  }

  .composer-shell {
    flex-direction: column;
    align-items: stretch;
    padding: 10px;
    border-radius: 24px;
  }

  .send-btn {
    width: 100%;
    min-width: 0;
    padding: 11px 14px;
  }
}