/* 色彩系统 */
:root {
    /* 主色调 */
    --primary: #2563EB;
    --primary-foreground: #FFFFFF;
    
    /* 背景和文本 */
    --background: #FFFFFF;
    --foreground: #1E293B;
    
    /* 次要颜色 */
    --secondary: #F1F5F9;
    --secondary-foreground: #475569;
    
    /* 中性色 */
    --muted: #E2E8F0;
    --muted-foreground: #64748B;
    
    /* 强调色 */
    --accent: #2563EB;
    --accent-foreground: #FFFFFF;
    
    /* 边界和输入 */
    --border: #E2E8F0;
    --input: #E2E8F0;
    
    /* 间距系统 */
    --radius: 0.5rem;
    --spacing-xs: 0.25rem;
    --spacing-sm: 0.5rem;
    --spacing-md: 1rem;
    --spacing-lg: 1.5rem;
    --spacing-xl: 2rem;
    --spacing-2xl: 3rem;
}

/* ===== 基础样式 ===== */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

html {
    font-family: 'Geist', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
    scroll-behavior: smooth;
}

body {
    background-color: var(--background);
    background-image: url('../picture/guestbook.jpg');
    background-size: cover;
    background-position: center;
    background-attachment: fixed;
    color: var(--foreground);
    line-height: 1.6;
    font-size: 16px;
}

/* 添加半透明白色遮罩 */
body::before {
    content: '';
    position: fixed;
    inset: 0;
    background-color: rgba(255, 255, 255, 0.85);
    pointer-events: none;
    z-index: -1;
}
/* ===== 容器 ===== */
.container {
    width: 100%;
    margin: 0 auto;
    padding: 0 var(--spacing-md);
    max-width: 800px;
}

@media (min-width: 768px) {
    .container {
        padding: 0 var(--spacing-lg);
    }
}

/* ===== 导航栏 ===== */
.navbar {
    border-bottom: 1px solid var(--border);
    background-color: var(--background);
    position: sticky;
    top: 0;
    z-index: 50;
    box-shadow: 0 1px 2px rgba(0, 0, 0, 0.05);
}

.navbar .container {
    padding: var(--spacing-md);
}

.navbar-content {
    display: flex;
    align-items: center;
    justify-content: space-between;
}

.navbar-brand {
    display: flex;
    align-items: center;
    gap: var(--spacing-md);
}
.floating-back-btn {
    position: fixed;
    top: 2rem;
    left: 2rem;
    background-color: var(--primary);
    color: var(--primary-foreground);
    padding: 0.75rem 1.5rem;
    border-radius: var(--radius);
    text-decoration: none;
    font-weight: 600;
    box-shadow: 0 4px 6px rgba(0, 0, 0, 0.1);
    transition: all 200ms ease-out;
    z-index: 40;
}

.floating-back-btn:hover {
    transform: translateY(-2px);
    box-shadow: 0 6px 12px rgba(0, 0, 0, 0.15);
}

@media (max-width: 640px) {
    .floating-back-btn {
        top: 1rem;
        left: 1rem;
        padding: 0.5rem 1rem;
        font-size: 0.875rem;
    }
}
.brand-icon {
    font-size: 1.5rem;
    width: 2rem;
    height: 2rem;
    background-color: var(--primary);
    border-radius: var(--radius);
    display: flex;
    align-items: center;
    justify-content: center;
}

.navbar-brand h1 {
    font-size: 1.125rem;
    font-weight: 600;
    color: var(--foreground);
}

.navbar-subtitle {
    font-size: 0.875rem;
    color: var(--muted-foreground);
}

@media (max-width: 640px) {
    .navbar-subtitle {
        display: none;
    }
}

/* ===== 主容器 ===== */
main {
    padding: var(--spacing-2xl) 0;
}

/* ===== Hero 部分 ===== */
.hero-section {
    position: relative;
    margin-bottom: var(--spacing-2xl);
    overflow: hidden;
    border-radius: var(--radius);
    background: linear-gradient(135deg, var(--secondary) 0%, var(--background) 100%);
    border: 1px solid var(--border);
    padding: var(--spacing-xl) var(--spacing-lg);
}

.hero-background {
    position: absolute;
    inset: 0;
    opacity: 0.05;
    overflow: hidden;
}

.hero-pattern {
    width: 100%;
    height: 100%;
    color: var(--foreground);
}

.hero-content {
    position: relative;
    z-index: 10;
    text-align: center;
}

.hero-icon {
    font-size: 4rem;
    margin-bottom: var(--spacing-md);
    display: inline-block;
    animation: slideInUp 300ms cubic-bezier(0.4, 0, 0.2, 1);
}

.hero-content h2 {
    font-size: 2rem;
    font-weight: 700;
    color: var(--foreground);
    margin-bottom: var(--spacing-md);
    animation: slideInUp 300ms cubic-bezier(0.4, 0, 0.2, 1) 100ms backwards;
}

.hero-content p {
    font-size: 1.125rem;
    color: var(--muted-foreground);
    max-width: 28rem;
    margin: 0 auto;
    animation: slideInUp 300ms cubic-bezier(0.4, 0, 0.2, 1) 200ms backwards;
}

@media (max-width: 640px) {
    .hero-section {
        padding: var(--spacing-lg) var(--spacing-md);
    }
    
    .hero-content h2 {
        font-size: 1.5rem;
    }
    
    .hero-content p {
        font-size: 1rem;
    }
}

/* ===== 特性卡片 ===== */
.features-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: var(--spacing-lg);
    margin-bottom: var(--spacing-2xl);
}

.feature-card {
    padding: var(--spacing-lg);
    background-color: #FFFFFF;
    border: 1px solid var(--border);
    border-radius: var(--radius);
    transition: all 200ms cubic-bezier(0.4, 0, 0.2, 1);
    cursor: default;
}

.feature-card:hover {
    box-shadow: 0 4px 6px rgba(0, 0, 0, 0.1);
    border-color: var(--primary);
}

.feature-icon {
    font-size: 2rem;
    margin-bottom: var(--spacing-md);
    display: block;
}

.feature-card h3 {
    font-size: 1rem;
    font-weight: 600;
    color: var(--foreground);
    margin-bottom: var(--spacing-sm);
}

.feature-card p {
    font-size: 0.875rem;
    color: var(--muted-foreground);
    line-height: 1.5;
}

/* ===== 分隔线 ===== */
.divider {
    height: 1px;
    background-color: var(--border);
    margin: var(--spacing-2xl) 0;
}

/* ===== 留言部分 ===== */
.comments-header {
    margin-bottom: var(--spacing-xl);
}

.comments-header h3 {
    font-size: 1.5rem;
    font-weight: 700;
    color: var(--foreground);
    margin-bottom: var(--spacing-sm);
}

.comments-header p {
    font-size: 0.875rem;
    color: var(--muted-foreground);
}

/* ===== 留言表单 ===== */
.comment-form-container {
    margin-bottom: var(--spacing-2xl);
}

.comment-form {
    background-color: #FFFFFF;
    border: 1px solid var(--border);
    border-radius: var(--radius);
    padding: var(--spacing-xl);
}

.form-group {
    margin-bottom: var(--spacing-lg);
}

.form-group:last-of-type {
    margin-bottom: var(--spacing-xl);
}

.form-input,
.form-textarea {
    width: 100%;
    padding: var(--spacing-md);
    border: 1px solid var(--border);
    border-radius: var(--radius);
    font-family: 'Geist', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
    font-size: 1rem;
    color: var(--foreground);
    background-color: #FFFFFF;
    transition: all 200ms ease-out;
}

.form-input::placeholder,
.form-textarea::placeholder {
    color: var(--muted-foreground);
}

.form-input:focus,
.form-textarea:focus {
    outline: none;
    border-color: var(--primary);
    box-shadow: 0 0 0 3px rgba(37, 99, 235, 0.1);
}

.form-textarea {
    resize: vertical;
    min-height: 6rem;
}

.form-actions {
    display: flex;
    align-items: center;
    gap: var(--spacing-lg);
}

.form-hint {
    font-size: 0.75rem;
    color: var(--muted-foreground);
/* ===== 按钮 ===== */
.btn {
    padding: 0.75rem 1.5rem;
    border: none;
    border-radius: var(--radius);
    font-weight: 600;
    font-size: 1rem;
    cursor: pointer;
    transition: all 200ms ease-out;
    font-family: 'Geist', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
}

.btn-primary {
    background-color: var(--primary);
    color: var(--primary-foreground);
}

.btn-primary:hover {
    background-color: #1D4ED8;
    transform: translateY(-1px);
    box-shadow: 0 4px 6px rgba(37, 99, 235, 0.3);
}

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

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

/* ===== 留言列表 ===== */
.comments-list {
    margin-bottom: var(--spacing-2xl);
}

.comment-item {
    background-color: #FFFFFF;
    border: 1px solid var(--border);
    border-radius: var(--radius);
    padding: var(--spacing-lg);
    margin-bottom: var(--spacing-lg);
    animation: slideInUp 300ms cubic-bezier(0.4, 0, 0.2, 1);
    box-shadow: 0 1px 2px rgba(0, 0, 0, 0.05);
    transition: all 200ms cubic-bezier(0.4, 0, 0.2, 1);
}

.comment-item:hover {
    box-shadow: 0 4px 6px rgba(0, 0, 0, 0.1);
}

.comment-header {
    display: flex;
    align-items: center;
    gap: var(--spacing-md);
    margin-bottom: var(--spacing-md);
}

.comment-avatar {
    width: 2.5rem;
    height: 2.5rem;
    border-radius: 50%;
    background-color: var(--secondary);
    display: flex;
    align-items: center;
    justify-content: center;
    font-weight: 700;
    color: var(--primary);
    flex-shrink: 0;
    font-size: 1rem;
}

.comment-meta {
    flex: 1;
}

.comment-author {
    font-weight: 600;
    color: var(--foreground);
    font-size: 0.95rem;
}

.comment-time {
    font-size: 0.75rem;
    color: var(--muted-foreground);
    margin-top: 0.25rem;
}

.comment-content {
    color: var(--foreground);
    line-height: 1.6;
    margin-bottom: var(--spacing-md);
    word-break: break-word;
}

.comment-content p {
    margin-bottom: var(--spacing-sm);
}

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

.comment-content code {
    background-color: var(--secondary);
    padding: 0.2rem 0.4rem;
    border-radius: 0.25rem;
    font-family: 'Geist Mono', monospace;
    font-size: 0.9em;
    color: var(--primary);
}

.comment-content pre {
    background-color: var(--secondary);
    padding: var(--spacing-md);
    border-radius: var(--radius);
    overflow-x: auto;
    margin: var(--spacing-md) 0;
}

.comment-content pre code {
    background-color: transparent;
    padding: 0;
    color: var(--foreground);
}

.comment-actions {
    display: flex;
    gap: var(--spacing-lg);
    font-size: 0.875rem;
}

.comment-action {
    background: none;
    border: none;
    color: var(--muted-foreground);
    cursor: pointer;
    transition: color 200ms ease-out;
    padding: 0;
    font-size: inherit;
}

.comment-action:hover {
    color: var(--primary);
}

.comment-website {
    color: var(--primary);
    text-decoration: none;
    transition: color 200ms ease-out;
}

.comment-website:hover {
    text-decoration: underline;
}

/* ===== 空状态 ===== */
.empty-state {
    text-align: center;
    padding: var(--spacing-2xl) var(--spacing-lg);
    color: var(--muted-foreground);
}

.empty-state.hidden {
    display: none;
}

.empty-icon {
    font-size: 3rem;
    margin-bottom: var(--spacing-md);
    display: block;
}

.empty-state p {
    font-size: 1rem;
}

/* ===== 页脚 ===== */
.footer {
    border-top: 1px solid var(--border);
    background-color: var(--background);
    margin-top: var(--spacing-2xl);
    padding: var(--spacing-xl) 0;
}

.footer .container {
    text-align: center;
    position: relative;
    z-index: 1;
}

.footer p {
    font-size: 0.875rem;
    color: var(--muted-foreground);
}

/* ===== 通知消息 ===== */
.notification {
    position: fixed;
    bottom: var(--spacing-lg);
    right: var(--spacing-lg);
    padding: var(--spacing-md) var(--spacing-lg);
    background-color: var(--primary);
    color: var(--primary-foreground);
    border-radius: var(--radius);
    box-shadow: 0 4px 6px rgba(0, 0, 0, 0.1);
    opacity: 0;
    transform: translateY(20px);
    pointer-events: none;
    transition: all 200ms ease-out;
    max-width: 300px;
    z-index: 1000;
}

.notification.show {
    opacity: 1;
    transform: translateY(0);
    pointer-events: auto;
}

.notification.error {
    background-color: #DC2626;
}

.notification.success {
    background-color: #16A34A;
}

/* ===== 动画 ===== */
@keyframes slideInUp {
    from {
        opacity: 0;
        transform: translateY(20px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

@keyframes fadeIn {
    from {
        opacity: 0;
    }
    to {
        opacity: 1;
    }
}

/* ===== 响应式设计 ===== */
@media (max-width: 640px) {
    .features-grid {
        grid-template-columns: 1fr;
    }
    
    .comment-form {
        padding: var(--spacing-lg);
    }
    
    .form-actions {
        flex-direction: column;
        align-items: flex-start;
    }
    
    .btn {
        width: 100%;
    }
    
    .notification {
        left: var(--spacing-lg);
        right: var(--spacing-lg);
        max-width: none;
    }
}