:root {
  --bg: #ffffff;
  --surface: #f3f4f6;
  --text: #111827;
  --muted: #6b7280;
  --accent: #4f46e5;
  --accent-text: #ffffff;
  --border: #e5e7eb;
}
@media (prefers-color-scheme: dark) {
  :root {
    --bg: #0f1115;
    --surface: #1a1d24;
    --text: #e5e7eb;
    --muted: #9ca3af;
    --accent: #6366f1;
    --border: #2a2e37;
  }
}
* { box-sizing: border-box; }
html, body { height: 100%; }
body {
  margin: 0;
  background: var(--bg);
  color: var(--text);
  font-family: "Sarabun", "Leelawadee UI", Tahoma, sans-serif;
  font-size: 16px;
  line-height: 1.7;
}
main {
  max-width: 720px;
  height: 100%;
  margin: 0 auto;
  padding: 0 16px;
  display: flex;
  flex-direction: column;
}
header { padding: 24px 0 12px; text-align: center; }
h1 { margin: 0; font-size: 1.5rem; font-weight: 600; }
#subtitle { margin: 4px 0 0; color: var(--muted); font-size: 0.95rem; }

#log { flex: 1; overflow-y: auto; padding: 8px 0 16px; display: flex; flex-direction: column; gap: 10px; }
.msg { max-width: 88%; padding: 10px 14px; border-radius: 16px; background: var(--surface); word-wrap: break-word; }
.msg p { margin: 0; }
.msg p + p, .msg p + ul, .msg ul + p { margin-top: 8px; }
.msg ul { margin: 8px 0 0; padding-left: 20px; }
.msg li + li { margin-top: 4px; }
.user { align-self: flex-end; background: var(--accent); color: var(--accent-text); }
.bot { align-self: flex-start; }
.typing { color: var(--muted); }

.chips { display: flex; flex-wrap: wrap; gap: 8px; align-self: flex-start; }
.chip {
  font: inherit; font-size: 0.9rem; color: var(--text); background: transparent;
  border: 1px solid var(--border); border-radius: 999px; padding: 6px 12px; cursor: pointer;
}
.chip:hover, .chip:focus-visible { border-color: var(--accent); color: var(--accent); outline: none; }

form { display: flex; gap: 8px; padding: 12px 0 max(16px, env(safe-area-inset-bottom)); border-top: 1px solid var(--border); background: var(--bg); }
input {
  flex: 1; min-width: 0; font: inherit; color: var(--text); background: var(--surface);
  border: 1px solid transparent; border-radius: 12px; padding: 10px 14px;
}
input:focus { outline: none; border-color: var(--accent); }
button[type="submit"] {
  font: inherit; font-weight: 600; color: var(--accent-text); background: var(--accent);
  border: 0; border-radius: 12px; padding: 0 20px; cursor: pointer;
}
button[type="submit"]:disabled { opacity: 0.5; cursor: default; }