:root {
  --primary-bg: #0f172a;
  --secondary-bg: #1e293b;
  --accent: #38bdf8;
  --text-primary: #f8fafc;
  --text-secondary: #94a3b8;
  --border: #334155;
  --danger: #ef4444;
  --success: #22c55e;
  --gradient: linear-gradient(135deg, #0f172a 0%, #1e293b 100%);
}

body {
  margin: 0;
  font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', 'Roboto', 'Oxygen',
    'Ubuntu', 'Cantarell', 'Fira Sans', 'Droid Sans', 'Helvetica Neue',
    sans-serif;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  background: var(--gradient);
  color: var(--text-primary);
  height: 100vh;
  overflow: hidden;
}

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

/* Sidebar / Session List */
.sidebar {
  width: 300px;
  background-color: rgba(15, 23, 42, 0.8);
  border-right: 1px solid var(--border);
  display: flex;
  flex-direction: column;
}

.sidebar-header {
  padding: 1.5rem;
  border-bottom: 1px solid var(--border);
}

.sidebar-header h1 {
  margin: 0;
  font-size: 1.25rem;
  color: var(--accent);
  margin-bottom: 1rem;
}

.search-input {
  width: 100%;
  padding: 0.5rem;
  background-color: var(--secondary-bg);
  border: 1px solid var(--border);
  border-radius: 0.375rem;
  color: var(--text-primary);
  font-size: 0.875rem;
  box-sizing: border-box;
}

.search-input:focus {
  outline: none;
  border-color: var(--accent);
}

.session-list {
  flex: 1;
  overflow-y: auto;
  padding: 0;
  margin: 0;
  list-style: none;
}

.session-item {
  padding: 1rem 1.5rem;
  border-bottom: 1px solid var(--border);
  cursor: pointer;
  transition: background-color 0.2s;
}

.session-item:hover {
  background-color: rgba(56, 189, 248, 0.1);
}

.session-item.active {
  background-color: rgba(56, 189, 248, 0.2);
  border-left: 4px solid var(--accent);
}

.session-item .key {
  font-weight: bold;
  font-size: 0.9rem;
  display: block;
  margin-bottom: 0.25rem;
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
}

.session-item .summary {
  font-size: 0.8rem;
  color: var(--text-secondary);
  display: block;
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
}

.session-item .date {
  font-size: 0.7rem;
  color: var(--text-secondary);
  margin-top: 0.5rem;
  display: block;
}

/* Main Content / Session Detail */
.main-content {
  flex: 1;
  display: flex;
  flex-direction: column;
  background-color: rgba(30, 41, 59, 0.5);
}

.session-header {
  padding: 1.5rem;
  border-bottom: 1px solid var(--border);
  display: flex;
  justify-content: space-between;
  align-items: center;
}

.session-info h2 {
  margin: 0;
  font-size: 1.5rem;
}

.session-info p {
  margin: 0.5rem 0 0;
  color: var(--text-secondary);
}

.message-list {
  flex: 1;
  overflow-y: auto;
  padding: 2rem;
}

.message-item {
  margin-bottom: 2rem;
  padding: 1.5rem;
  background-color: var(--secondary-bg);
  border-radius: 0.75rem;
  border: 1px solid var(--border);
  position: relative;
}

.message-item:hover .message-actions {
  display: flex;
}

.message-item.user {
  border-left: 4px solid var(--accent);
}

.message-item.assistant {
  border-left: 4px solid var(--success);
}

.message-role {
  font-weight: bold;
  font-size: 0.75rem;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  margin-bottom: 0.5rem;
  display: block;
}

.message-role.user { color: var(--accent); }
.message-role.assistant { color: var(--success); }

.message-content {
  line-height: 1.6;
  white-space: pre-wrap;
  word-break: break-word;
}

.message-actions {
  position: absolute;
  top: 1rem;
  right: 1rem;
  display: none;
  gap: 0.5rem;
}

button {
  background-color: var(--accent);
  color: var(--primary-bg);
  border: none;
  padding: 0.5rem 1rem;
  border-radius: 0.375rem;
  cursor: pointer;
  font-weight: bold;
  transition: opacity 0.2s;
}

button:hover {
  opacity: 0.9;
}

button.danger {
  background-color: var(--danger);
  color: white;
}

button.secondary {
  background-color: var(--border);
  color: var(--text-primary);
}

textarea {
  width: 100%;
  background-color: var(--primary-bg);
  color: var(--text-primary);
  border: 1px solid var(--border);
  border-radius: 0.375rem;
  padding: 0.75rem;
  font-family: inherit;
  font-size: 1rem;
  resize: vertical;
}

.empty-state {
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  height: 100%;
  color: var(--text-secondary);
}