/* ===== CSS 变量 ===== */
:root {
    --bg-primary: #0f0f0f;
    --bg-secondary: #1a1a1a;
    --bg-tertiary: #252525;
    --bg-hover: #2a2a2a;
    --bg-active: #333333;
    
    --text-primary: #ffffff;
    --text-secondary: #a0a0a0;
    --text-tertiary: #666666;
    
    --accent-primary: #6366f1;
    --accent-secondary: #818cf8;
    --accent-gradient: linear-gradient(135deg, #6366f1 0%, #8b5cf6 50%, #a855f7 100%);
    
    --success: #22c55e;
    --warning: #f59e0b;
    --error: #ef4444;
    
    --border-color: #2a2a2a;
    --border-radius: 12px;
    --border-radius-sm: 8px;
    --border-radius-lg: 16px;
    
    --shadow-sm: 0 2px 8px rgba(0, 0, 0, 0.3);
    --shadow-md: 0 4px 16px rgba(0, 0, 0, 0.4);
    --shadow-lg: 0 8px 32px rgba(0, 0, 0, 0.5);
    
    --transition-fast: 0.15s ease;
    --transition-normal: 0.25s ease;
    
    --sidebar-width: 280px;
}

/* ===== 重置样式 ===== */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

html, body {
    height: 100%;
    font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
    background: var(--bg-primary);
    color: var(--text-primary);
    line-height: 1.6;
    overflow: hidden;
}

/* ===== 滚动条样式 ===== */
::-webkit-scrollbar {
    width: 6px;
    height: 6px;
}

::-webkit-scrollbar-track {
    background: transparent;
}

::-webkit-scrollbar-thumb {
    background: var(--bg-tertiary);
    border-radius: 3px;
}

::-webkit-scrollbar-thumb:hover {
    background: var(--text-tertiary);
}

/* ===== 应用容器 ===== */
.app-container {
    display: flex;
    height: 100vh;
    width: 100vw;
}

/* ===== 侧边栏 ===== */
.sidebar {
    width: var(--sidebar-width);
    background: var(--bg-secondary);
    border-right: 1px solid var(--border-color);
    display: flex;
    flex-direction: column;
    flex-shrink: 0;
    transition: transform var(--transition-normal);
}

.sidebar-header {
    padding: 20px;
    border-bottom: 1px solid var(--border-color);
}

.logo {
    display: flex;
    align-items: center;
    gap: 12px;
    font-size: 1.25rem;
    font-weight: 700;
    color: var(--text-primary);
    margin-bottom: 16px;
}

.logo svg {
    color: var(--accent-primary);
}

.new-chat-btn {
    width: 100%;
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 8px;
    padding: 12px 16px;
    background: var(--accent-gradient);
    border: none;
    border-radius: var(--border-radius);
    color: white;
    font-size: 0.9rem;
    font-weight: 600;
    cursor: pointer;
    transition: all var(--transition-fast);
    box-shadow: var(--shadow-sm);
}

.new-chat-btn:hover {
    transform: translateY(-1px);
    box-shadow: var(--shadow-md);
}

.new-chat-btn:active {
    transform: translateY(0);
}

/* 历史对话列表 */
.chat-history {
    flex: 1;
    overflow-y: auto;
    padding: 12px;
}

.chat-history-item {
    display: flex;
    align-items: center;
    gap: 10px;
    padding: 12px;
    border-radius: var(--border-radius-sm);
    cursor: pointer;
    transition: background var(--transition-fast);
    margin-bottom: 4px;
}

.chat-history-item:hover {
    background: var(--bg-hover);
}

.chat-history-item.active {
    background: var(--bg-active);
}

.chat-history-item svg {
    flex-shrink: 0;
    color: var(--text-secondary);
}

.chat-history-item span {
    flex: 1;
    white-space: nowrap;
    overflow: hidden;
    text-overflow: ellipsis;
    font-size: 0.9rem;
    color: var(--text-secondary);
}

/* 侧边栏底部设置 */
.sidebar-footer {
    padding: 16px;
    border-top: 1px solid var(--border-color);
    background: var(--bg-primary);
}

.settings-group {
    margin-bottom: 12px;
}

.settings-group:last-child {
    margin-bottom: 0;
}

.settings-group label {
    display: block;
    font-size: 0.75rem;
    font-weight: 600;
    color: var(--text-tertiary);
    text-transform: uppercase;
    letter-spacing: 0.5px;
    margin-bottom: 6px;
}

.settings-group select,
.settings-group input {
    width: 100%;
    padding: 10px 12px;
    background: var(--bg-tertiary);
    border: 1px solid var(--border-color);
    border-radius: var(--border-radius-sm);
    color: var(--text-primary);
    font-size: 0.875rem;
    font-family: inherit;
    transition: all var(--transition-fast);
}

.settings-group select:focus,
.settings-group input:focus {
    outline: none;
    border-color: var(--accent-primary);
    box-shadow: 0 0 0 3px rgba(99, 102, 241, 0.2);
}

.settings-group select option {
    background: var(--bg-secondary);
    color: var(--text-primary);
}

/* ===== 主聊天区域 ===== */
.chat-main {
    flex: 1;
    display: flex;
    flex-direction: column;
    min-width: 0;
}

.chat-header {
    display: flex;
    align-items: center;
    padding: 16px 24px;
    border-bottom: 1px solid var(--border-color);
    background: var(--bg-secondary);
}

.mobile-menu-btn {
    display: none;
    padding: 8px;
    background: transparent;
    border: none;
    color: var(--text-secondary);
    cursor: pointer;
    border-radius: var(--border-radius-sm);
    margin-right: 12px;
}

.mobile-menu-btn:hover {
    background: var(--bg-hover);
}

.current-model {
    display: flex;
    align-items: center;
    gap: 8px;
    padding: 8px 16px;
    background: var(--bg-tertiary);
    border-radius: var(--border-radius);
    font-size: 0.9rem;
    font-weight: 500;
}

.model-icon {
    font-size: 1.1rem;
}

/* ===== 消息区域 ===== */
.chat-messages {
    flex: 1;
    overflow-y: auto;
    padding: 24px;
    display: flex;
    flex-direction: column;
    gap: 24px;
}

/* 欢迎消息 */
.welcome-message {
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    text-align: center;
    padding: 60px 20px;
    animation: fadeIn 0.5s ease;
}

@keyframes fadeIn {
    from { opacity: 0; transform: translateY(20px); }
    to { opacity: 1; transform: translateY(0); }
}

.welcome-icon {
    width: 80px;
    height: 80px;
    display: flex;
    align-items: center;
    justify-content: center;
    background: var(--accent-gradient);
    border-radius: 50%;
    margin-bottom: 24px;
    box-shadow: var(--shadow-lg);
}

.welcome-icon svg {
    color: white;
}

.welcome-message h1 {
    font-size: 1.75rem;
    font-weight: 700;
    margin-bottom: 8px;
    background: var(--accent-gradient);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.welcome-message p {
    color: var(--text-secondary);
    margin-bottom: 32px;
}

.quick-actions {
    display: flex;
    flex-wrap: wrap;
    gap: 12px;
    justify-content: center;
}

.quick-action {
    display: flex;
    align-items: center;
    gap: 8px;
    padding: 12px 20px;
    background: var(--bg-secondary);
    border: 1px solid var(--border-color);
    border-radius: var(--border-radius);
    color: var(--text-primary);
    font-size: 0.9rem;
    cursor: pointer;
    transition: all var(--transition-fast);
}

.quick-action:hover {
    background: var(--bg-tertiary);
    border-color: var(--accent-primary);
    transform: translateY(-2px);
}

/* 消息气泡 */
.message {
    display: flex;
    gap: 16px;
    max-width: 800px;
    animation: messageIn 0.3s ease;
}

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

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

.message-avatar {
    width: 36px;
    height: 36px;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    flex-shrink: 0;
    font-size: 1rem;
}

.message.user .message-avatar {
    background: var(--accent-gradient);
}

.message.assistant .message-avatar {
    background: var(--bg-tertiary);
    border: 1px solid var(--border-color);
}

.message-content {
    padding: 16px 20px;
    border-radius: var(--border-radius-lg);
    line-height: 1.7;
}

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

.message.assistant .message-content {
    background: var(--bg-secondary);
    border: 1px solid var(--border-color);
    border-bottom-left-radius: 4px;
}

/* 代码块样式 */
.message-content pre {
    background: var(--bg-primary);
    border-radius: var(--border-radius-sm);
    padding: 16px;
    margin: 12px 0;
    overflow-x: auto;
    font-family: 'Fira Code', 'Consolas', monospace;
    font-size: 0.875rem;
}

.message-content code {
    font-family: 'Fira Code', 'Consolas', monospace;
    background: var(--bg-tertiary);
    padding: 2px 6px;
    border-radius: 4px;
    font-size: 0.875rem;
}

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

/* 加载动画 */
.typing-indicator {
    display: flex;
    gap: 4px;
    padding: 8px 0;
}

.typing-indicator span {
    width: 8px;
    height: 8px;
    background: var(--text-secondary);
    border-radius: 50%;
    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(-8px); opacity: 1; }
}

/* ===== 输入区域 ===== */
.chat-input-container {
    padding: 16px 24px 24px;
    background: var(--bg-primary);
    border-top: 1px solid var(--border-color);
}

.chat-input-wrapper {
    display: flex;
    align-items: flex-end;
    gap: 12px;
    background: var(--bg-secondary);
    border: 1px solid var(--border-color);
    border-radius: var(--border-radius-lg);
    padding: 12px 16px;
    transition: all var(--transition-fast);
}

.chat-input-wrapper:focus-within {
    border-color: var(--accent-primary);
    box-shadow: 0 0 0 3px rgba(99, 102, 241, 0.2);
}

.chat-input-wrapper textarea {
    flex: 1;
    background: transparent;
    border: none;
    color: var(--text-primary);
    font-size: 1rem;
    font-family: inherit;
    resize: none;
    max-height: 200px;
    line-height: 1.5;
}

.chat-input-wrapper textarea::placeholder {
    color: var(--text-tertiary);
}

.chat-input-wrapper textarea:focus {
    outline: none;
}

.send-btn {
    width: 40px;
    height: 40px;
    display: flex;
    align-items: center;
    justify-content: center;
    background: var(--accent-gradient);
    border: none;
    border-radius: 50%;
    color: white;
    cursor: pointer;
    flex-shrink: 0;
    transition: all var(--transition-fast);
    box-shadow: var(--shadow-sm);
}

.send-btn:hover {
    transform: scale(1.05);
    box-shadow: var(--shadow-md);
}

.send-btn:active {
    transform: scale(0.95);
}

.send-btn:disabled {
    opacity: 0.5;
    cursor: not-allowed;
    transform: none;
}

.input-hint {
    display: flex;
    align-items: center;
    gap: 8px;
    margin-top: 8px;
    padding: 0 4px;
    font-size: 0.75rem;
    color: var(--text-tertiary);
}

.input-hint .divider {
    color: var(--border-color);
}

/* ===== 响应式设计 ===== */
@media (max-width: 768px) {
    .sidebar {
        position: fixed;
        left: 0;
        top: 0;
        height: 100%;
        z-index: 1000;
        transform: translateX(-100%);
    }
    
    .sidebar.open {
        transform: translateX(0);
    }
    
    .mobile-menu-btn {
        display: flex;
    }
    
    .chat-messages {
        padding: 16px;
    }
    
    .chat-input-container {
        padding: 12px 16px 16px;
    }
    
    .welcome-message h1 {
        font-size: 1.5rem;
    }
    
    .quick-actions {
        flex-direction: column;
    }
    
    .quick-action {
        width: 100%;
        justify-content: center;
    }
}

/* 侧边栏遮罩 */
.sidebar-overlay {
    display: none;
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: rgba(0, 0, 0, 0.5);
    z-index: 999;
}

.sidebar-overlay.show {
    display: block;
}

/* ===== 错误提示 ===== */
.error-message {
    background: rgba(239, 68, 68, 0.1);
    border: 1px solid var(--error);
    color: var(--error);
    padding: 12px 16px;
    border-radius: var(--border-radius);
    margin: 12px 0;
}

/* ===== 复制按钮 ===== */
.copy-btn {
    position: absolute;
    top: 8px;
    right: 8px;
    padding: 6px 10px;
    background: var(--bg-tertiary);
    border: 1px solid var(--border-color);
    border-radius: var(--border-radius-sm);
    color: var(--text-secondary);
    font-size: 0.75rem;
    cursor: pointer;
    opacity: 0;
    transition: all var(--transition-fast);
}

.message-content:hover .copy-btn {
    opacity: 1;
}

.copy-btn:hover {
    background: var(--bg-hover);
    color: var(--text-primary);
}