:root {
  --bg: #f4f6fa;
  --surface: #ffffff;
  --border: #d9dee8;
  --text: #1c2333;
  --muted: #5b6579;
  --accent: #1f5fd1;
  --accent-strong: #174aa6;
  --accent-soft: #e8f0fd;
  --danger: #b42318;
  --danger-soft: #fdecea;
  --radius: 10px;
  --shadow: 0 1px 2px rgba(20, 30, 60, 0.06);
  font-family: system-ui, -apple-system, 'Segoe UI', 'Thonburi', 'Sukhumvit Set', 'Noto Sans Thai', sans-serif;
  color: var(--text);
  line-height: 1.6;
}

* {
  box-sizing: border-box;
}

[hidden] {
  display: none !important;
}

html,
body {
  height: 100%;
  margin: 0;
  background: var(--bg);
}

body {
  display: flex;
  flex-direction: column;
  height: 100dvh;
  font-size: 15px;
}

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

.skip-link {
  position: absolute;
  left: 8px;
  top: -48px;
  z-index: 10;
  padding: 8px 12px;
  background: var(--accent);
  color: #fff;
  border-radius: 6px;
}
.skip-link:focus {
  top: 8px;
}

:focus-visible {
  outline: 3px solid #f5a623;
  outline-offset: 2px;
}

/* ---------- แถบบน ---------- */
.topbar {
  display: flex;
  align-items: center;
  gap: 16px;
  padding: 10px 20px;
  background: var(--surface);
  border-bottom: 1px solid var(--border);
}
.brand h1 {
  margin: 0;
  font-size: 18px;
  line-height: 1.3;
}
.subtitle {
  margin: 0;
  font-size: 13px;
  color: var(--muted);
}
.status {
  display: flex;
  flex-wrap: wrap;
  gap: 6px;
  margin-left: auto;
}
.badge {
  padding: 2px 10px;
  font-size: 12.5px;
  border: 1px solid var(--border);
  border-radius: 999px;
  background: #f0f3f8;
  color: var(--muted);
}
.badge.ok {
  background: #e7f6ec;
  border-color: #b6e0c3;
  color: #1b6b35;
}
.badge.warn {
  background: #fff4e0;
  border-color: #f2d49b;
  color: #8a5300;
}
.badge.error {
  background: var(--danger-soft);
  border-color: #f3b9b3;
  color: var(--danger);
}

/* ---------- ปุ่ม ---------- */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 6px;
  min-height: 38px;
  padding: 6px 14px;
  font: inherit;
  color: var(--text);
  text-decoration: none;
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 8px;
  cursor: pointer;
}
.btn:hover:not(:disabled) {
  background: #f0f3f8;
}
.btn:disabled {
  opacity: 0.5;
  cursor: not-allowed;
}
.btn.primary {
  color: #fff;
  background: var(--accent);
  border-color: var(--accent);
}
.btn.primary:hover:not(:disabled) {
  background: var(--accent-strong);
}
.btn.danger {
  color: #fff;
  background: var(--danger);
  border-color: var(--danger);
}
.btn.danger-outline {
  color: var(--danger);
  border-color: #f0b3ad;
}
.btn.small {
  min-height: 34px;
  padding: 4px 10px;
  font-size: 14px;
}
.link-btn {
  padding: 0;
  font: inherit;
  font-size: 13px;
  color: var(--accent);
  background: none;
  border: 0;
  text-decoration: underline;
  cursor: pointer;
}

/* ---------- เลย์เอาต์ ---------- */
.tabs {
  display: none;
}
.layout {
  flex: 1;
  display: grid;
  grid-template-columns: minmax(360px, 1fr) minmax(360px, 1fr);
  gap: 14px;
  min-height: 0;
  padding: 14px 20px 18px;
}
.panel {
  display: flex;
  flex-direction: column;
  min-width: 0;
  min-height: 0;
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  box-shadow: var(--shadow);
  overflow: hidden;
}

/* ---------- แชต ---------- */
.messages {
  flex: 1;
  min-height: 0;
  padding: 16px;
  overflow-y: auto;
  display: flex;
  flex-direction: column;
  gap: 14px;
}
.empty {
  margin: auto;
  max-width: 520px;
  text-align: center;
  color: var(--muted);
}
.empty h2 {
  margin: 0 0 6px;
  font-size: 18px;
  color: var(--text);
}
.suggestions {
  display: flex;
  flex-direction: column;
  gap: 8px;
  margin-top: 14px;
}
.suggestions button {
  padding: 10px 14px;
  font: inherit;
  text-align: left;
  color: var(--text);
  background: var(--accent-soft);
  border: 1px solid #c9dbf8;
  border-radius: 8px;
  cursor: pointer;
}
.suggestions button:hover {
  background: #dce8fb;
}

.msg {
  max-width: 92%;
  padding: 10px 14px;
  border-radius: 12px;
  overflow-wrap: anywhere;
}
.msg.user {
  align-self: flex-end;
  color: #fff;
  background: var(--accent);
  white-space: pre-wrap;
}
.msg.assistant {
  align-self: flex-start;
  background: #f1f4f9;
  border: 1px solid var(--border);
}
.msg.assistant.error {
  background: var(--danger-soft);
  border-color: #f3b9b3;
}
.msg p {
  margin: 0 0 8px;
}
.msg p:last-child,
.msg ul:last-child,
.msg ol:last-child {
  margin-bottom: 0;
}
.msg ul,
.msg ol {
  margin: 0 0 8px;
  padding-left: 22px;
}
.msg code {
  padding: 1px 5px;
  font-size: 0.92em;
  background: rgba(20, 30, 60, 0.08);
  border-radius: 4px;
}
.typing {
  color: var(--muted);
}

.cite {
  display: inline-block;
  min-width: 22px;
  height: 22px;
  margin: 0 2px;
  padding: 0 6px;
  font: inherit;
  font-size: 12.5px;
  font-weight: 600;
  line-height: 20px;
  color: var(--accent-strong);
  background: var(--accent-soft);
  border: 1px solid #b8cff5;
  border-radius: 999px;
  vertical-align: baseline;
  cursor: pointer;
}
.cite:hover {
  background: #d3e2fa;
}

.sources {
  margin-top: 10px;
  padding-top: 8px;
  border-top: 1px dashed var(--border);
  font-size: 13.5px;
}
.sources-title {
  margin: 0 0 6px;
  color: var(--muted);
}
.source-chips {
  display: flex;
  flex-wrap: wrap;
  gap: 6px;
}
.source-chip {
  padding: 3px 10px;
  font: inherit;
  font-size: 13px;
  color: var(--text);
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 8px;
  cursor: pointer;
}
.source-chip:hover {
  background: var(--accent-soft);
  border-color: #b8cff5;
}
.passages {
  margin-top: 8px;
}
.passages summary {
  color: var(--muted);
  cursor: pointer;
}
.passage {
  margin: 8px 0 0;
  padding: 8px 10px;
  font-size: 12.5px;
  color: var(--muted);
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 8px;
}
.passage strong {
  color: var(--text);
}
.passage-note {
  margin: 6px 0 0;
  font-size: 12.5px;
  color: var(--muted);
}

.composer {
  display: flex;
  align-items: flex-end;
  gap: 8px;
  padding: 12px 16px 6px;
  border-top: 1px solid var(--border);
}
.composer textarea {
  flex: 1;
  min-height: 42px;
  max-height: 160px;
  padding: 9px 12px;
  font: inherit;
  color: var(--text);
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 8px;
  resize: none;
}
.composer .btn {
  min-height: 42px;
}
.composer-foot {
  display: flex;
  flex-wrap: wrap;
  gap: 4px 12px;
  padding: 0 16px 12px;
  font-size: 12.5px;
  color: var(--muted);
}

/* ---------- ตัวอย่างไฟล์ ---------- */
.toolbar {
  display: flex;
  flex-direction: column;
  gap: 8px;
  padding: 10px 12px;
  border-bottom: 1px solid var(--border);
  background: #fafbfd;
}
.toolbar-row {
  display: flex;
  align-items: center;
  gap: 8px;
  flex-wrap: wrap;
}
.toolbar select {
  flex: 1;
  min-width: 160px;
  max-width: 100%;
  min-height: 34px;
  padding: 4px 8px;
  font: inherit;
  color: var(--text);
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 8px;
}
.toolbar input[type='number'] {
  width: 64px;
  min-height: 34px;
  padding: 4px 8px;
  font: inherit;
  text-align: center;
  border: 1px solid var(--border);
  border-radius: 8px;
}
.spacer {
  flex: 1;
}
.muted {
  color: var(--muted);
  font-size: 14px;
}
.viewer-note {
  min-height: 0;
  padding: 0 12px;
  font-size: 13.5px;
  color: var(--accent-strong);
  background: var(--accent-soft);
  overflow: hidden;
  max-height: 0;
  transition: max-height 0.2s ease;
}
.viewer-note.show {
  max-height: 48px;
  padding: 6px 12px;
}
.viewer {
  position: relative;
  flex: 1;
  min-height: 0;
  padding: 18px 22px 28px;
  overflow: auto;
  background: var(--surface);
}
.page-text {
  --page-font: 16px;
  max-width: 760px;
  margin: 0 auto;
  font-size: var(--page-font);
  line-height: 1.85;
  overflow-wrap: anywhere;
}
.page-text p {
  margin: 0 0 0.8em;
  padding: 2px 10px;
  border-left: 4px solid transparent;
  border-radius: 4px;
}
.page-text p.bullet {
  padding-left: 22px;
}
.page-text p.hit {
  background: #fff4d6;
  border-left-color: #f5a623;
}
.page-text p.flash {
  background: #ffe6a8;
}
.page-empty {
  color: var(--muted);
  font-style: italic;
}
.viewer-msg {
  margin: 24px 0 0;
  text-align: center;
  color: var(--muted);
}
.viewer-msg:empty {
  display: none;
}

/* ---------- จอแคบ ---------- */
@media (max-width: 900px) {
  .topbar {
    flex-wrap: wrap;
    gap: 8px 12px;
    padding: 10px 14px;
  }
  .status {
    order: 3;
    width: 100%;
    margin-left: 0;
  }
  .actions {
    margin-left: auto;
  }
  .tabs {
    display: flex;
    gap: 6px;
    padding: 8px 14px 0;
  }
  .tabs button {
    flex: 1;
    min-height: 40px;
    font: inherit;
    color: var(--muted);
    background: var(--surface);
    border: 1px solid var(--border);
    border-radius: 8px 8px 0 0;
    cursor: pointer;
  }
  .tabs button[aria-selected='true'] {
    color: var(--accent-strong);
    font-weight: 600;
    background: var(--accent-soft);
    border-color: #b8cff5;
  }
  .layout {
    grid-template-columns: 1fr;
    padding: 0 14px 14px;
  }
  .layout[data-view='chat'] #preview-panel,
  .layout[data-view='preview'] #chat-panel {
    display: none;
  }
}

@media (prefers-reduced-motion: reduce) {
  * {
    transition: none !important;
    scroll-behavior: auto !important;
  }
}