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

body {
  font-family: 'Segoe UI', sans-serif;
  background: #0f172a;
  color: #e2e8f0;
  height: 100vh;
  display: flex;
  align-items: center;
  justify-content: center;
}

.container {
  width: 100%;
  max-width: 800px;
  height: 90vh;
  display: flex;
  flex-direction: column;
  background: #1e293b;
  border-radius: 16px;
  overflow: hidden;
  box-shadow: 0 25px 50px rgba(0,0,0,0.5);
}

.header {
  background: #f97316;
  padding: 20px;
  text-align: center;
}

.header h1 { font-size: 1.5rem; }
.header p { font-size: 0.85rem; opacity: 0.9; margin-top: 4px; }

.chat-box {
  flex: 1;
  overflow-y: auto;
  padding: 20px;
  display: flex;
  flex-direction: column;
  gap: 12px;
}

.message {
  padding: 12px 16px;
  border-radius: 12px;
  max-width: 80%;
  line-height: 1.6;
  font-size: 0.95rem;
  white-space: pre-wrap;
}

.message.user {
  background: #f97316;
  color: white;
  align-self: flex-end;
  border-bottom-right-radius: 4px;
}

.message.assistant {
  background: #334155;
  color: #e2e8f0;
  align-self: flex-start;
  border-bottom-left-radius: 4px;
}

.message.thinking {
  background: #1e3a5f;
  color: #94a3b8;
  font-style: italic;
  align-self: flex-start;
}

.input-area {
  padding: 16px;
  border-top: 1px solid #334155;
  display: flex;
  flex-direction: column;
  gap: 10px;
}

textarea {
  width: 100%;
  background: #0f172a;
  border: 1px solid #475569;
  border-radius: 8px;
  color: #e2e8f0;
  padding: 10px;
  font-size: 0.95rem;
  resize: none;
  outline: none;
}

textarea:focus { border-color: #f97316; }

.buttons { display: flex; gap: 10px; }

button {
  padding: 10px 20px;
  border: none;
  border-radius: 8px;
  cursor: pointer;
  font-size: 0.95rem;
  font-weight: 600;
  transition: opacity 0.2s;
}

button:disabled { opacity: 0.4; cursor: not-allowed; }

#startBtn { background: #22c55e; color: white; }
#sendBtn { background: #f97316; color: white; flex: 1; }