:root {
  --color-bg: #ffffff;
  --color-surface: #f7f7f8;
  --color-border: #e5e5e8;
  --color-text: #1a1a1e;
  --color-text-muted: #6b6b73;
  --color-primary: #2b5fd9;
  --color-primary-text: #ffffff;
  --color-assistant-bubble: #f0f1f4;
  --radius: 12px;
}

@media (prefers-color-scheme: dark) {
  :root:not([data-theme="light"]) {
    --color-bg: #16161a;
    --color-surface: #1e1e24;
    --color-border: #2c2c34;
    --color-text: #f2f2f4;
    --color-text-muted: #9a9aa2;
    --color-assistant-bubble: #26262e;
  }
}

:root[data-theme="dark"] {
  --color-bg: #16161a;
  --color-surface: #1e1e24;
  --color-border: #2c2c34;
  --color-text: #f2f2f4;
  --color-text-muted: #9a9aa2;
  --color-assistant-bubble: #26262e;
}

* {
  box-sizing: border-box;
}

body {
  margin: 0;
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
  background: var(--color-bg);
  color: var(--color-text);
}

.chat-container {
  max-width: 640px;
  margin: 0 auto;
  padding: 16px;
  display: flex;
  flex-direction: column;
  min-height: 100vh;
}

.chat-header h1 {
  font-size: 1.4rem;
  margin: 8px 0 4px;
}

.chat-header p {
  color: var(--color-text-muted);
  font-size: 0.9rem;
  margin: 0 0 16px;
}

.messages {
  flex: 1;
  overflow-y: auto;
  display: flex;
  flex-direction: column;
  gap: 12px;
  padding: 8px 0;
  min-height: 200px;
}

.message {
  max-width: 85%;
  padding: 10px 14px;
  border-radius: var(--radius);
  line-height: 1.45;
  font-size: 0.95rem;
  white-space: pre-wrap;
  word-wrap: break-word;
}

.message-user {
  align-self: flex-end;
  background: var(--color-primary);
  color: var(--color-primary-text);
  border-bottom-right-radius: 4px;
}

.message-assistant {
  align-self: flex-start;
  background: var(--color-assistant-bubble);
  border-bottom-left-radius: 4px;
}

.message-loading {
  color: var(--color-text-muted);
  font-style: italic;
}

.citations {
  margin-top: 8px;
  font-size: 0.8rem;
  color: var(--color-text-muted);
}

.citations summary {
  cursor: pointer;
  font-weight: 600;
}

.citations ul {
  margin: 6px 0 0;
  padding-left: 18px;
}

.chat-form {
  display: flex;
  gap: 8px;
  padding-top: 12px;
  border-top: 1px solid var(--color-border);
}

#question-input {
  flex: 1;
  padding: 10px 14px;
  border-radius: 999px;
  border: 1px solid var(--color-border);
  background: var(--color-surface);
  color: var(--color-text);
  font-size: 0.95rem;
  min-width: 0;
}

#question-input:focus {
  outline: 2px solid var(--color-primary);
  outline-offset: 1px;
}

#send-button {
  padding: 10px 20px;
  border-radius: 999px;
  border: none;
  background: var(--color-primary);
  color: var(--color-primary-text);
  font-weight: 600;
  cursor: pointer;
  flex-shrink: 0;
}

#send-button:disabled {
  opacity: 0.6;
  cursor: not-allowed;
}

.suggestions {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  margin-bottom: 4px;
}

.suggestion-chip {
  padding: 6px 12px;
  border-radius: 999px;
  border: 1px solid var(--color-border);
  background: var(--color-surface);
  color: var(--color-text);
  font-size: 0.8rem;
  cursor: pointer;
}

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

@media (max-width: 480px) {
  .chat-container {
    padding: 12px;
  }

  .message {
    max-width: 92%;
  }
}

/* Technical architecture panel (collapsed by default so the chat stays primary) */
.arch {
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  background: var(--color-surface);
  margin: 0 0 16px;
  font-size: 0.85rem;
  line-height: 1.5;
}

.arch > summary {
  cursor: pointer;
  padding: 10px 14px;
  font-weight: 600;
  font-size: 0.9rem;
  list-style: none;
  display: flex;
  align-items: center;
  gap: 8px;
}

.arch > summary::-webkit-details-marker {
  display: none;
}

.arch > summary::before {
  content: "\25B8";
  color: var(--color-text-muted);
  transition: transform 0.15s ease;
}

.arch[open] > summary::before {
  transform: rotate(90deg);
}

.arch > summary:focus-visible {
  outline: 2px solid var(--color-primary);
  outline-offset: -2px;
  border-radius: var(--radius);
}

.arch-body {
  padding: 0 14px 14px;
  border-top: 1px solid var(--color-border);
  /* Long content scrolls inside the panel so opening it never pushes the chat off-screen. */
  max-height: 60vh;
  overflow-y: auto;
}

.arch-lede {
  margin: 12px 0 4px;
  color: var(--color-text-muted);
}

.arch h3 {
  margin: 16px 0 6px;
  font-size: 0.72rem;
  text-transform: uppercase;
  letter-spacing: 0.06em;
  color: var(--color-text-muted);
}

.arch ol,
.arch ul {
  margin: 0;
  padding-left: 20px;
}

.arch li {
  margin: 0 0 8px;
}

.arch p {
  margin: 0;
}

.arch code {
  font-family: ui-monospace, SFMono-Regular, Menlo, Consolas, monospace;
  font-size: 0.8rem;
  padding: 1px 5px;
  border-radius: 4px;
  background: var(--color-assistant-bubble);
  word-break: break-word;
}

.arch-tags {
  display: flex;
  flex-wrap: wrap;
  gap: 6px;
}

.arch .tag {
  padding: 2px 9px;
  border-radius: 999px;
  border: 1px solid var(--color-border);
  background: var(--color-bg);
  font-family: ui-monospace, SFMono-Regular, Menlo, Consolas, monospace;
  font-size: 0.72rem;
}