/* ========================================
   小张的学习笔记 - 主样式表
   ======================================== */

/* --- 基础重置与变量 --- */
*, *::before, *::after {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
}

:root {
    --color-primary: #2c3e50;
    --color-accent: #3498db;
    --color-accent-hover: #2980b9;
    --color-bg: #f8f9fa;
    --color-white: #ffffff;
    --color-text: #333333;
    --color-text-light: #666666;
    --color-text-lighter: #999999;
    --color-border: #e0e0e0;
    --color-tag-bg: #eef5fb;
    --color-tag-text: #3498db;
    --color-category-bg: #f0f0f0;
    --color-footer-bg: #2c3e50;
    --color-footer-text: #cccccc;
    --shadow-sm: 0 1px 3px rgba(0,0,0,0.08);
    --shadow-md: 0 2px 8px rgba(0,0,0,0.1);
    --radius: 8px;
    --max-width: 1100px;
}

html {
    font-size: 16px;
    scroll-behavior: smooth;
}

body {
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", "Helvetica Neue", Arial, sans-serif;
    color: var(--color-text);
    background-color: var(--color-bg);
    line-height: 1.7;
    min-height: 100vh;
    display: flex;
    flex-direction: column;
}

.container {
    max-width: var(--max-width);
    margin: 0 auto;
    padding: 0 20px;
}

a {
    color: var(--color-accent);
    text-decoration: none;
    transition: color 0.2s;
}

a:hover {
    color: var(--color-accent-hover);
}

/* --- 头部导航 --- */
.site-header {
    background: var(--color-white);
    border-bottom: 1px solid var(--color-border);
    box-shadow: var(--shadow-sm);
    position: sticky;
    top: 0;
    z-index: 100;
}

.header-inner {
    display: flex;
    justify-content: space-between;
    align-items: center;
    height: 60px;
    flex-wrap: wrap;
}

.site-logo {
    font-size: 1.25rem;
    font-weight: 700;
    color: var(--color-primary);
    white-space: nowrap;
}

.site-logo:hover {
    color: var(--color-accent);
}

.site-nav {
    display: flex;
    gap: 4px;
}

.nav-link {
    padding: 8px 16px;
    border-radius: 6px;
    color: var(--color-text);
    font-size: 0.95rem;
    font-weight: 500;
    transition: background 0.2s, color 0.2s;
}

.nav-link:hover,
.nav-link.active {
    background: var(--color-accent);
    color: var(--color-white);
}

/* --- Hero 横幅 --- */
.hero {
    background: linear-gradient(135deg, #2c3e50 0%, #3498db 100%);
    color: var(--color-white);
    padding: 60px 0;
    text-align: center;
}

.hero h1 {
    font-size: 2.2rem;
    font-weight: 700;
    margin-bottom: 12px;
    letter-spacing: 2px;
}

.hero-subtitle {
    font-size: 1.15rem;
    opacity: 0.9;
    margin-bottom: 10px;
}

.hero-desc {
    font-size: 0.95rem;
    opacity: 0.75;
    max-width: 600px;
    margin: 0 auto;
}

/* --- 主要内容区 --- */
main.container {
    display: grid;
    grid-template-columns: 1fr 300px;
    gap: 30px;
    padding-top: 30px;
    padding-bottom: 40px;
    flex: 1;
}

.section-title {
    font-size: 1.4rem;
    margin-bottom: 20px;
    padding-bottom: 10px;
    border-bottom: 2px solid var(--color-accent);
    display: inline-block;
}

/* --- 文章卡片 --- */
.post-card {
    background: var(--color-white);
    padding: 24px;
    margin-bottom: 20px;
    border-radius: var(--radius);
    box-shadow: var(--shadow-md);
    transition: transform 0.2s, box-shadow 0.2s;
}

.post-card:hover {
    transform: translateY(-2px);
    box-shadow: 0 4px 16px rgba(0,0,0,0.12);
}

.post-meta {
    display: flex;
    gap: 12px;
    align-items: center;
    margin-bottom: 10px;
    font-size: 0.85rem;
}

.post-date {
    color: var(--color-text-lighter);
}

.post-category {
    background: var(--color-category-bg);
    padding: 2px 10px;
    border-radius: 12px;
    font-size: 0.8rem;
    color: var(--color-text-light);
}

.post-title {
    font-size: 1.2rem;
    margin-bottom: 10px;
}

.post-title a {
    color: var(--color-primary);
}

.post-title a:hover {
    color: var(--color-accent);
}

.post-excerpt {
    color: var(--color-text-light);
    font-size: 0.95rem;
    margin-bottom: 12px;
    line-height: 1.8;
}

.post-tags {
    display: flex;
    gap: 8px;
    flex-wrap: wrap;
}

.tag {
    background: var(--color-tag-bg);
    color: var(--color-tag-text);
    padding: 3px 10px;
    border-radius: 4px;
    font-size: 0.8rem;
}

/* --- 侧边栏 --- */
.sidebar {
    padding-top: 6px;
}

.sidebar-widget {
    background: var(--color-white);
    padding: 20px;
    margin-bottom: 20px;
    border-radius: var(--radius);
    box-shadow: var(--shadow-md);
}

.sidebar-widget h3 {
    font-size: 1.05rem;
    margin-bottom: 12px;
    padding-bottom: 8px;
    border-bottom: 1px solid var(--color-border);
    color: var(--color-primary);
}

.sidebar-widget p {
    font-size: 0.9rem;
    color: var(--color-text-light);
    line-height: 1.8;
}

.category-list,
.friend-links {
    list-style: none;
}

.category-list li,
.friend-links li {
    padding: 6px 0;
    border-bottom: 1px dashed var(--color-border);
}

.category-list li:last-child,
.friend-links li:last-child {
    border-bottom: none;
}

.category-list a,
.friend-links a {
    font-size: 0.9rem;
    color: var(--color-text-light);
    display: block;
    transition: color 0.2s, padding-left 0.2s;
}

.category-list a:hover,
.friend-links a:hover {
    color: var(--color-accent);
    padding-left: 4px;
}

/* --- 页面内容区（笔记列表页、关于页、留言板） --- */
.page-content {
    grid-column: 1 / -1;
    max-width: 800px;
}

.page-title {
    font-size: 1.8rem;
    margin-bottom: 10px;
    color: var(--color-primary);
}

.page-desc {
    color: var(--color-text-light);
    margin-bottom: 30px;
    font-size: 0.95rem;
}

/* --- 分类标题 --- */
.category-heading {
    font-size: 1.2rem;
    color: var(--color-primary);
    margin: 30px 0 15px;
    padding-bottom: 8px;
    border-bottom: 1px solid var(--color-border);
}

/* --- 笔记网格 --- */
.notes-grid {
    margin-bottom: 20px;
}

.note-item {
    display: flex;
    align-items: center;
    gap: 16px;
    padding: 14px 16px;
    background: var(--color-white);
    border-radius: 6px;
    margin-bottom: 8px;
    box-shadow: var(--shadow-sm);
    transition: background 0.2s;
    flex-wrap: wrap;
}

.note-item:hover {
    background: #f0f7ff;
}

.note-date {
    color: var(--color-text-lighter);
    font-size: 0.85rem;
    white-space: nowrap;
    min-width: 90px;
}

.note-title {
    flex: 1;
    font-weight: 500;
    color: var(--color-primary);
    min-width: 200px;
}

.note-tags {
    color: var(--color-text-lighter);
    font-size: 0.8rem;
    white-space: nowrap;
}

/* --- 关于页 --- */
.about-section {
    margin-bottom: 30px;
}

.about-section h2 {
    font-size: 1.2rem;
    color: var(--color-primary);
    margin-bottom: 12px;
}

.about-section p {
    color: var(--color-text-light);
    line-height: 1.9;
    margin-bottom: 8px;
}

.about-list {
    list-style: none;
    padding-left: 0;
    margin-bottom: 10px;
}

.about-list li {
    padding: 6px 0;
    color: var(--color-text-light);
    line-height: 1.8;
}

.about-list li::before {
    content: "• ";
    color: var(--color-accent);
    font-weight: bold;
}

/* --- 留言板 --- */
.guestbook-form {
    background: var(--color-white);
    padding: 24px;
    border-radius: var(--radius);
    box-shadow: var(--shadow-md);
    margin-bottom: 30px;
}

.guestbook-form h3 {
    margin-bottom: 16px;
    color: var(--color-primary);
}

.form-group {
    margin-bottom: 14px;
}

.form-group label {
    display: block;
    font-weight: 500;
    margin-bottom: 6px;
    color: var(--color-primary);
    font-size: 0.9rem;
}

.form-group input,
.form-group textarea {
    width: 100%;
    padding: 10px 14px;
    border: 1px solid var(--color-border);
    border-radius: 6px;
    font-size: 0.95rem;
    font-family: inherit;
    transition: border-color 0.2s;
    background: var(--color-bg);
}

.form-group input:focus,
.form-group textarea:focus {
    outline: none;
    border-color: var(--color-accent);
    background: var(--color-white);
}

.btn-submit {
    background: var(--color-accent);
    color: var(--color-white);
    border: none;
    padding: 10px 28px;
    border-radius: 6px;
    font-size: 0.95rem;
    cursor: pointer;
    transition: background 0.2s;
    letter-spacing: 2px;
}

.btn-submit:hover {
    background: var(--color-accent-hover);
}

/* --- 留言列表 --- */
.guestbook-entries h3 {
    margin-bottom: 16px;
    color: var(--color-primary);
}

.guestbook-entry {
    background: var(--color-white);
    padding: 20px;
    border-radius: var(--radius);
    box-shadow: var(--shadow-sm);
    margin-bottom: 14px;
}

.entry-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 10px;
}

.entry-author {
    font-weight: 600;
    color: var(--color-primary);
}

.entry-date {
    font-size: 0.85rem;
    color: var(--color-text-lighter);
}

.entry-content {
    color: var(--color-text-light);
    line-height: 1.8;
    font-size: 0.95rem;
}

/* --- 页脚 --- */
.site-footer {
    background: var(--color-footer-bg);
    color: var(--color-footer-text);
    padding: 24px 0;
    margin-top: auto;
}

.footer-inner {
    display: flex;
    justify-content: space-between;
    align-items: center;
    flex-wrap: wrap;
    gap: 16px;
}

.footer-info p {
    font-size: 0.85rem;
    line-height: 1.8;
}

.icp-info {
    margin-top: 4px;
}

.icp-info a {
    color: var(--color-footer-text);
    font-size: 0.85rem;
}

.icp-info a:hover {
    color: var(--color-white);
    text-decoration: underline;
}

.footer-statement p {
    font-size: 0.8rem;
    opacity: 0.7;
    text-align: right;
}

/* --- 响应式 --- */
@media (max-width: 768px) {
    main.container {
        grid-template-columns: 1fr;
    }

    .sidebar {
        order: 2;
    }

    .hero {
        padding: 40px 0;
    }

    .hero h1 {
        font-size: 1.6rem;
    }

    .header-inner {
        height: auto;
        padding: 12px 0;
        gap: 10px;
    }

    .site-nav {
        width: 100%;
        justify-content: center;
        flex-wrap: wrap;
    }

    .nav-link {
        padding: 6px 12px;
        font-size: 0.85rem;
    }

    .footer-inner {
        flex-direction: column;
        text-align: center;
    }

    .footer-statement p {
        text-align: center;
    }

    .note-item {
        flex-direction: column;
        align-items: flex-start;
        gap: 6px;
    }

    .post-meta {
        flex-wrap: wrap;
    }
}