*,
*::before,
*::after {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

:root {
  --bg: #0f1117;
  --surface: #1a1d27;
  --border: #2a2f3e;
  --text: #e8eaed;
  --text-muted: #8b92a5;
  --accent: #6c8cff;
  --accent-hover: #5a7af5;
  --user-bg: #2a3a6e;
  --assistant-bg: #1e2230;
  --error: #ff6b6b;
  --radius: 12px;
}

html, body {
  height: 100%;
}

body {
  font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
  background: var(--bg);
  color: var(--text);
  line-height: 1.5;
}

.app {
  display: flex;
  flex-direction: column;
  max-width: 720px;
  height: 100dvh;
  margin: 0 auto;
  padding: 0 16px;
}

.header {
  padding: 24px 0 16px;
  text-align: center;
  border-bottom: 1px solid var(--border);
}

.header h1 {
  font-size: 1.25rem;
  font-weight: 600;
}

.subtitle {
  font-size: 0.85rem;
  color: var(--text-muted);
  margin-top: 4px;
}

.chat {
  flex: 1;
  overflow-y: auto;
  padding: 20px 0;
  display: flex;
  flex-direction: column;
  gap: 16px;
}

.message {
  max-width: 85%;
  padding: 12px 16px;
  border-radius: var(--radius);
  font-size: 0.95rem;
  white-space: pre-wrap;
  word-break: break-word;
  animation: fadeIn 0.2s ease;
}

@keyframes fadeIn {
  from { opacity: 0; transform: translateY(6px); }
  to { opacity: 1; transform: translateY(0); }
}

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

.message.assistant {
  align-self: flex-start;
  background: var(--assistant-bg);
  border: 1px solid var(--border);
  border-bottom-left-radius: 4px;
  white-space: normal;
}

.message.assistant > * + * {
  margin-top: 0.7rem;
}

.message.assistant p,
.message.assistant ul,
.message.assistant ol,
.message.assistant pre,
.message.assistant h1,
.message.assistant h2,
.message.assistant h3,
.message.assistant h4,
.message.assistant h5,
.message.assistant h6 {
  margin-bottom: 0;
}

.message.assistant h1,
.message.assistant h2,
.message.assistant h3,
.message.assistant h4,
.message.assistant h5,
.message.assistant h6 {
  font-size: 1rem;
  line-height: 1.35;
}

.message.assistant ul,
.message.assistant ol {
  padding-left: 1.25rem;
}

.message.assistant li + li {
  margin-top: 0.35rem;
}

.message.assistant code {
  padding: 0.1rem 0.3rem;
  border-radius: 4px;
  background: rgba(255, 255, 255, 0.08);
  font-family: 'SFMono-Regular', Consolas, 'Liberation Mono', monospace;
  font-size: 0.9em;
}

.message.assistant pre {
  overflow-x: auto;
  padding: 10px 12px;
  border-radius: 8px;
  background: rgba(0, 0, 0, 0.25);
  white-space: pre;
}

.message.assistant pre code {
  display: block;
  padding: 0;
  background: transparent;
}

.message.assistant a {
  color: var(--accent);
}

.message.error {
  align-self: center;
  background: transparent;
  color: var(--error);
  border: 1px solid var(--error);
  font-size: 0.85rem;
}

.message.loading {
  align-self: flex-start;
  background: var(--assistant-bg);
  border: 1px solid var(--border);
  color: var(--text-muted);
}

.typing-dots span {
  animation: blink 1.4s infinite;
}

.typing-dots span:nth-child(2) { animation-delay: 0.2s; }
.typing-dots span:nth-child(3) { animation-delay: 0.4s; }

@keyframes blink {
  0%, 80%, 100% { opacity: 0.2; }
  40% { opacity: 1; }
}

.empty-state {
  flex: 1;
  display: flex;
  align-items: center;
  justify-content: center;
  color: var(--text-muted);
  font-size: 0.9rem;
}

.input-area {
  display: flex;
  gap: 10px;
  padding: 16px 0 24px;
  border-top: 1px solid var(--border);
}

#input {
  flex: 1;
  resize: none;
  padding: 12px 16px;
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  color: var(--text);
  font: inherit;
  outline: none;
  max-height: 120px;
  transition: border-color 0.15s;
}

#input:focus {
  border-color: var(--accent);
}

#input::placeholder {
  color: var(--text-muted);
}

#send-btn {
  flex-shrink: 0;
  width: 44px;
  height: 44px;
  display: flex;
  align-items: center;
  justify-content: center;
  background: var(--accent);
  border: none;
  border-radius: var(--radius);
  color: #fff;
  cursor: pointer;
  transition: background 0.15s;
}

#send-btn:hover:not(:disabled) {
  background: var(--accent-hover);
}

#send-btn:disabled {
  opacity: 0.4;
  cursor: not-allowed;
}