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

:root {
    --primary-color: #2563eb;
    --secondary-color: #1e40af;
    --bg-color: #f8fafc;
    --surface-color: #ffffff;
    --text-primary: #1e293b;
    --text-secondary: #64748b;
    --border-color: #e2e8f0;
    --user-msg-bg: #2563eb;
    --ai-msg-bg: #f1f5f9;
    --shadow: 0 1px 3px 0 rgba(0, 0, 0, 0.1);
    --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.1);
}

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', 'Roboto', 'Oxygen',
        'Ubuntu', 'Cantarell', 'Fira Sans', 'Droid Sans', 'Helvetica Neue', sans-serif;
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    min-height: 100vh;
    display: flex;
    align-items: center;
    justify-content: center;
    padding: 20px;
}

.container {
    width: 100%;
    max-width: 900px;
    height: 90vh;
    background: var(--surface-color);
    border-radius: 16px;
    box-shadow: var(--shadow-lg);
    display: flex;
    flex-direction: column;
    overflow: hidden;
}

.header {
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    color: white;
    padding: 20px 24px;
    border-bottom: 1px solid rgba(255, 255, 255, 0.1);
}

.header h1 {
    font-size: 24px;
    font-weight: 600;
    margin-bottom: 8px;
}

.status-bar {
    display: flex;
    align-items: center;
    gap: 12px;
    font-size: 14px;
}

.status-indicator {
    opacity: 0.9;
}

.chat-container {
    flex: 1;
    overflow-y: auto;
    padding: 24px;
    background: var(--bg-color);
    scroll-behavior: smooth;
}

.welcome-message {
    text-align: center;
    padding: 60px 20px;
    color: var(--text-secondary);
}

.welcome-message h2 {
    font-size: 28px;
    margin-bottom: 12px;
    color: var(--text-primary);
}

.welcome-message p {
    font-size: 16px;
}

.message {
    margin-bottom: 20px;
    display: flex;
    gap: 12px;
    animation: fadeIn 0.3s ease-in;
}

@keyframes fadeIn {
    from {
        opacity: 0;
        transform: translateY(10px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

.message.user {
    flex-direction: row-reverse;
}

.message-avatar {
    width: 36px;
    height: 36px;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 18px;
    flex-shrink: 0;
}

.message.user .message-avatar {
    background: var(--primary-color);
    color: white;
}

.message.ai .message-avatar {
    background: var(--ai-msg-bg);
    color: var(--text-primary);
}

.message-content {
    max-width: 70%;
    padding: 12px 16px;
    border-radius: 12px;
    line-height: 1.6;
    word-wrap: break-word;
}

.message.user .message-content {
    background: var(--user-msg-bg);
    color: white;
    border-bottom-right-radius: 4px;
}

.message.ai .message-content {
    background: var(--surface-color);
    color: var(--text-primary);
    border-bottom-left-radius: 4px;
    box-shadow: var(--shadow);
}

.message-content p {
    margin-bottom: 8px;
}

.message-content p:last-child {
    margin-bottom: 0;
}

.message-content code {
    background: rgba(0, 0, 0, 0.05);
    padding: 2px 6px;
    border-radius: 4px;
    font-family: 'Courier New', monospace;
    font-size: 14px;
}

.message.user .message-content code {
    background: rgba(255, 255, 255, 0.2);
}

.message-content pre {
    background: #1e293b;
    color: #e2e8f0;
    padding: 12px;
    border-radius: 8px;
    overflow-x: auto;
    margin: 8px 0;
}

.message-content pre code {
    background: transparent;
    padding: 0;
    color: inherit;
}

.typing-indicator {
    display: flex;
    gap: 4px;
    padding: 12px 16px;
}

.typing-indicator span {
    width: 8px;
    height: 8px;
    border-radius: 50%;
    background: var(--text-secondary);
    animation: typing 1.4s infinite;
}

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

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

@keyframes typing {
    0%, 60%, 100% {
        transform: translateY(0);
        opacity: 0.4;
    }
    30% {
        transform: translateY(-10px);
        opacity: 1;
    }
}

.input-container {
    display: flex;
    gap: 12px;
    padding: 20px 24px;
    background: var(--surface-color);
    border-top: 1px solid var(--border-color);
}

#userInput {
    flex: 1;
    border: 2px solid var(--border-color);
    border-radius: 12px;
    padding: 12px 16px;
    font-size: 15px;
    font-family: inherit;
    resize: none;
    max-height: 120px;
    transition: border-color 0.2s;
}

#userInput:focus {
    outline: none;
    border-color: var(--primary-color);
}

.send-btn {
    width: 48px;
    height: 48px;
    border: none;
    border-radius: 12px;
    background: var(--primary-color);
    color: white;
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
    transition: all 0.2s;
    flex-shrink: 0;
}

.send-btn:hover:not(:disabled) {
    background: var(--secondary-color);
    transform: translateY(-2px);
    box-shadow: var(--shadow);
}

.send-btn:disabled {
    opacity: 0.5;
    cursor: not-allowed;
}

.footer {
    padding: 12px 24px;
    text-align: center;
    color: var(--text-secondary);
    background: var(--surface-color);
    border-top: 1px solid var(--border-color);
}

/* 滚动条样式 */
.chat-container::-webkit-scrollbar {
    width: 8px;
}

.chat-container::-webkit-scrollbar-track {
    background: transparent;
}

.chat-container::-webkit-scrollbar-thumb {
    background: var(--border-color);
    border-radius: 4px;
}

.chat-container::-webkit-scrollbar-thumb:hover {
    background: var(--text-secondary);
}

/* 响应式设计 */
@media (max-width: 768px) {
    body {
        padding: 0;
    }

    .container {
        height: 100vh;
        border-radius: 0;
        max-width: 100%;
    }

    .header h1 {
        font-size: 20px;
    }

    .message-content {
        max-width: 85%;
    }

    .welcome-message {
        padding: 40px 20px;
    }
}