:root {
  --bg: #0e1624;
  --card: rgba(255, 255, 255, 0.06);
  --muted: #94a3b8;
  --accent-gradient: linear-gradient(135deg, #7c3aed, #06b6d4);
  --text-light: #f8fafc;
  --radius: 14px;
  --shadow: 0 8px 20px rgba(0, 0, 0, 0.3);
}

* { box-sizing: border-box; }

body {
  margin: 0;
  font-family: 'Inter', ui-sans-serif, system-ui, Roboto;
  background: radial-gradient(1200px 500px at 10% 10%, rgba(99, 102, 241, 0.08), transparent), var(--bg);
  color: var(--text-light);
  overflow: hidden;
}

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

/* Sidebar */
.sidebar {
  width: 280px;
  padding: 20px;
  background: var(--card);
  backdrop-filter: blur(12px);
  border-right: 1px solid rgba(255, 255, 255, 0.05);
  display: flex;
  flex-direction: column;
  box-shadow: var(--shadow);
  position: relative;
  transition: left 0.3s ease;
}

.sidebar-close {
  display: none;
  position: absolute;
  top: 12px;
  right: 12px;
  font-size: 20px;
  background: none;
  border: none;
  color: var(--text-light);
  cursor: pointer;
}

.brand {
  font-weight: 800;
  font-size: 20px;
  margin-bottom: 20px;
  background: var(--accent-gradient);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
}

.sidebar-section h4 { color: var(--muted); font-size: 13px; margin-bottom: 8px; }

.prompt {
  width: 100%;
  padding: 10px;
  margin: 6px 0;
  border-radius: var(--radius);
  border: none;
  background: rgba(255,255,255,0.03);
  color: var(--text-light);
  text-align: left;
  cursor: pointer;
  transition: all 0.2s ease;
}
.prompt:hover { background: rgba(255,255,255,0.06); transform: translateY(-2px); box-shadow: var(--shadow); }

.option input {
  padding: 8px;
  border-radius: var(--radius);
  border: 1px solid rgba(255,255,255,0.08);
  background: transparent;
  color: inherit;
  outline: none;
  transition: border 0.2s;
}
.option input:focus { border-color: #7c3aed; }

#clearHistory {
  margin-top: 8px;
  padding: 8px;
  border-radius: var(--radius);
  background: rgba(255,255,255,0.05);
  cursor: pointer;
  transition: all 0.2s ease;
}
#clearHistory:hover { background: rgba(255,255,255,0.1); }

.sidebar-foot { margin-top: auto; font-size: 12px; color: var(--muted); }

/* Chat Area */
.chat-area { flex: 1; display: flex; flex-direction: column; background: rgba(255,255,255,0.02); }

.chat-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 12px 18px;
  border-bottom: 1px solid rgba(255,255,255,0.05);
  flex-wrap: wrap;
}

.chat-header .title { flex: 1 1 auto; text-align: center; font-weight: 600; font-size: 18px; margin: 8px 0; }

.controls { display: flex; gap: 8px; flex-shrink: 0; align-items: center; }
.controls select { padding: 8px; border-radius: var(--radius); border: none; background: rgba(10,0,0,0.527); color: inherit; }

.messages {
  flex: 1;
  list-style: none;
  padding: 28px;
  overflow-y: auto;
  display: flex;
  flex-direction: column;
  gap: 12px;
  scroll-behavior: smooth;
}

.message {
  max-width: 85%;
  padding: 14px;
  border-radius: var(--radius);
  line-height: 1.45;
  animation: fadeInUp 0.3s ease;
}

.message.user { align-self: flex-end; background: var(--accent-gradient); color: #022c2b; }
.message.assistant { align-self: flex-start; background: rgba(255,255,255,0.05); color: var(--text-light); }

.typing span { background: var(--text-light); }

/* Composer */
.composer { display: flex; gap: 12px; padding: 16px; border-top: 1px solid rgba(255,255,255,0.05); flex-wrap: wrap; }
.composer textarea {
  flex: 1 1 200px;
  resize: none;
  padding: 12px;
  border-radius: var(--radius);
  border: none;
  background: rgba(255,255,255,0.03);
  color: inherit;
  min-height: 50px;
}
.composer-actions { display: flex; gap: 8px; flex-wrap: wrap; flex: 1 1 auto; }
.composer-actions button {
  flex: 1 1 48%;
  padding: 10px;
  border: none;
  border-radius: var(--radius);
  background: var(--accent-gradient);
  color: white;
  cursor: pointer;
  transition: all 0.2s ease;
}
.composer-actions button:hover { transform: scale(1.05); box-shadow: var(--shadow); }

/* Dark / Light toggle */
#themeToggle { padding: 8px 10px; border-radius: var(--radius); border: none; cursor: pointer; }
#themeToggle:hover { background: rgba(255,255,255,0.15); }

/* Animations */
@keyframes fadeInUp { from { opacity:0; transform:translateY(6px); } to { opacity:1; transform:translateY(0); } }

/* Light Mode */
:root.light-mode { --bg:#f8fafc; --card:rgba(0,0,0,0.04); --muted:#475569; --accent-gradient:linear-gradient(135deg,#6366f1,#0ea5e9); --text-light:#1e293b; --shadow:0 8px 20px rgba(0,0,0,0.08); }

/* Mobile */
@media (max-width: 900px) {
  .sidebar { position: fixed; z-index:10; height:100%; left:-100%; width:280px; }
  .sidebar.open { left:0; }
  .sidebar-close { display:block; }
  .chat-header { flex-direction: column; align-items:center; }
  .controls { width:100%; justify-content:center; }
  .composer { flex-direction: column; }
  .composer-actions button { width: 100%; }
  .messages { padding: 16px; }
}

/* Extra mobile toggle */
.sidebar-toggle { display:block; position: absolute; top:55px; left:35px; z-index:15; }
@media(min-width:901px){ .sidebar-toggle { display:none; } }