:root {
  --bg: #1e1f22;
  --bg-alt: #2a2b2f;
  --border: #3a3b40;
  --text: #e8e8ea;
  --text-dim: #9a9ba0;
  --accent: #5b8def;
  --user-bubble: #3a3f4b;
  --assistant-bubble: #2a2b2f;
}

* { box-sizing: border-box; }

html, body {
  height: 100%;
  margin: 0;
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
  background: var(--bg);
  color: var(--text);
}

.app {
  display: flex;
  height: 100vh;
}

.sidebar {
  width: 260px;
  flex-shrink: 0;
  background: var(--bg-alt);
  border-right: 1px solid var(--border);
  display: flex;
  flex-direction: column;
  padding: 12px;
  overflow-y: auto;
}

.new-chat-btn {
  background: var(--accent);
  color: white;
  border: none;
  border-radius: 8px;
  padding: 10px;
  font-size: 14px;
  cursor: pointer;
  margin-bottom: 12px;
}

.new-chat-btn:hover { opacity: 0.9; }

.conversation-list {
  display: flex;
  flex-direction: column;
  gap: 4px;
  overflow-y: auto;
}

.conversation-item {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 6px;
  padding: 8px 10px;
  border-radius: 6px;
  cursor: pointer;
  font-size: 13px;
  color: var(--text-dim);
}

.conversation-item:hover { background: rgba(255,255,255,0.05); }
.conversation-item.active { background: rgba(91,141,239,0.15); color: var(--text); }

.conversation-item .title {
  overflow: hidden;
  text-overflow: ellipsis;
  white-space: nowrap;
  flex: 1;
}

.conversation-item .delete-btn {
  background: none;
  border: none;
  color: var(--text-dim);
  cursor: pointer;
  font-size: 14px;
  padding: 0 4px;
  visibility: hidden;
}

.conversation-item:hover .delete-btn { visibility: visible; }
.conversation-item .delete-btn:hover { color: #e5484d; }

.main {
  flex: 1;
  display: flex;
  flex-direction: column;
  min-width: 0;
}

.chat-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 12px 20px;
  border-bottom: 1px solid var(--border);
}

.chat-title {
  font-size: 14px;
  color: var(--text-dim);
  overflow: hidden;
  text-overflow: ellipsis;
  white-space: nowrap;
}

.model-select {
  background: var(--bg-alt);
  color: var(--text);
  border: 1px solid var(--border);
  border-radius: 6px;
  padding: 6px 8px;
  font-size: 12px;
}

.messages {
  flex: 1;
  overflow-y: auto;
  padding: 20px;
  display: flex;
  flex-direction: column;
  gap: 14px;
}

.message {
  max-width: 70%;
  padding: 10px 14px;
  border-radius: 12px;
  white-space: pre-wrap;
  word-wrap: break-word;
  line-height: 1.45;
  font-size: 14px;
}

.message.user {
  align-self: flex-end;
  background: var(--user-bubble);
}

.message.assistant {
  align-self: flex-start;
  background: var(--assistant-bubble);
  border: 1px solid var(--border);
}

.message.pending::after {
  content: "▍";
  animation: blink 1s step-start infinite;
}

@keyframes blink { 50% { opacity: 0; } }

.composer {
  display: flex;
  gap: 10px;
  padding: 16px 20px;
  border-top: 1px solid var(--border);
}

.composer textarea {
  flex: 1;
  resize: none;
  background: var(--bg-alt);
  color: var(--text);
  border: 1px solid var(--border);
  border-radius: 8px;
  padding: 10px 12px;
  font-size: 14px;
  font-family: inherit;
  max-height: 160px;
}

.composer button {
  background: var(--accent);
  color: white;
  border: none;
  border-radius: 8px;
  padding: 0 18px;
  cursor: pointer;
  font-size: 14px;
}

.composer button:disabled {
  opacity: 0.5;
  cursor: not-allowed;
}

.empty-state {
  color: var(--text-dim);
  text-align: center;
  margin-top: 40px;
  font-size: 14px;
}