/*
 Theme Name: PetNN — 南宁宠物网资讯主题
 Theme URI: https://petnn.com
 Version: 1.0
 Author: PetNN Team
 Description: 为南宁宠物网量身定制的 Typecho 博客主题，与主站风格一脉相承。
*/

/* ========================================
   CSS Custom Properties (Design Tokens)
   ======================================== */
:root {
  --color-primary: #FF4500;
  --color-primary-dark: #E03E00;
  --color-primary-light: #FFF5F0;
  --color-accent: #006FFD;
  --color-accent-hover: #0056CC;
  --color-text: #333333;
  --color-text-secondary: #555555;
  --color-text-muted: #999999;
  --color-bg: #FFFFFF;
  --color-bg-alt: #F5F5F5;
  --color-bg-warm: #FFFAF8;
  --color-border: #DDDDDD;
  --color-border-light: #EEEEEE;
  --color-success: #52C41A;
  --color-warning: #FAAD14;
  --color-error: #FF4D4F;

  --font-family: "Microsoft YaHei", "PingFang SC", "Hiragino Sans GB", "WenQuanYi Micro Hei", sans-serif;
  --font-family-heading: "Microsoft YaHei", "PingFang SC", "Hiragino Sans GB", sans-serif;

  --container-width: 1000px;
  --container-wide: 1200px;
  --content-width: 680px;
  --sidebar-width: 290px;

  --space-xs: 4px;
  --space-sm: 8px;
  --space-md: 12px;
  --space-lg: 16px;
  --space-xl: 24px;
  --space-2xl: 32px;
  --space-3xl: 48px;

  --radius-sm: 4px;
  --radius-md: 8px;
  --radius-lg: 12px;

  --shadow-sm: 0 1px 2px rgba(0, 0, 0, 0.04);
  --shadow-md: 0 2px 8px rgba(0, 0, 0, 0.08);
  --shadow-lg: 0 4px 16px rgba(0, 0, 0, 0.12);

  --transition-fast: 150ms ease;
  --transition-normal: 250ms ease;
  --transition-slow: 400ms ease;
}

/* ========================================
   Reset & Base
   ======================================== */
*, *::before, *::after {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

html {
  font-size: 16px;
  -webkit-text-size-adjust: 100%;
  scroll-behavior: smooth;
}

body {
  font-family: var(--font-family);
  font-size: 14px;
  line-height: 1.8;
  color: var(--color-text-secondary);
  background-color: var(--color-bg);
  text-align: left;
  min-height: 100vh;
  display: flex;
  flex-direction: column;
}

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

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

img {
  max-width: 100%;
  height: auto;
  vertical-align: middle;
}

ul, ol {
  list-style: none;
}

h1, h2, h3, h4, h5, h6 {
  font-family: var(--font-family-heading);
  color: var(--color-text);
  line-height: 1.4;
  font-weight: 700;
}

h1 { font-size: 1.75rem; }
h2 { font-size: 1.375rem; }
h3 { font-size: 1.125rem; }
h4 { font-size: 1rem; }

/* ========================================
   Top Bar
   ======================================== */
.top-bar {
  background-color: var(--color-bg-alt);
  height: 36px;
  line-height: 36px;
  font-size: 12px;
  color: #585858;
  border-bottom: 1px solid var(--color-border-light);
}

.top-bar-inner {
  max-width: var(--container-wide);
  margin: 0 auto;
  padding: 0 var(--space-lg);
  display: flex;
  justify-content: space-between;
  align-items: center;
}

.top-bar-left {
  display: flex;
  align-items: center;
  gap: var(--space-lg);
}

.top-bar-left .welcome {
  color: #585858;
}

.top-bar-left .divider {
  width: 1px;
  height: 12px;
  background: #d4d4d4;
}

.top-bar-right a {
  color: #585858;
  font-size: 12px;
}

.top-bar-right a:hover {
  color: var(--color-primary);
}

/* ========================================
   Header / Logo Area
   ======================================== */
.site-header {
  background: var(--color-bg);
  border-bottom: 1px solid var(--color-border-light);
  position: sticky;
  top: 0;
  z-index: 100;
  backdrop-filter: blur(8px);
  background: rgba(255, 255, 255, 0.95);
}

.header-inner {
  max-width: var(--container-wide);
  margin: 0 auto;
  padding: var(--space-md) var(--space-lg);
  display: flex;
  justify-content: space-between;
  align-items: center;
}

.site-branding {
  display: flex;
  align-items: center;
  gap: var(--space-md);
}

.site-logo-img {
  height: 48px;
  width: auto;
}

.site-title {
  font-size: 1.5rem;
  font-weight: 700;
  color: var(--color-text);
}

.site-title a {
  color: var(--color-text);
}

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

.site-description {
  font-size: 12px;
  color: var(--color-text-muted);
  margin-top: 2px;
}

/* Back to main site button */
.btn-back-main {
  display: inline-flex;
  align-items: center;
  gap: var(--space-xs);
  padding: var(--space-sm) var(--space-lg);
  background: var(--color-primary);
  color: #fff;
  font-size: 14px;
  border-radius: var(--radius-sm);
  font-weight: 500;
  transition: background var(--transition-fast);
}

.btn-back-main:hover {
  background: var(--color-primary-dark);
  color: #fff;
}

/* ========================================
   Navigation
   ======================================== */
.site-nav {
  border-top: 1px solid var(--color-border-light);
  background: var(--color-bg);
}

.nav-inner {
  max-width: var(--container-wide);
  margin: 0 auto;
  padding: 0 var(--space-lg);
  display: flex;
  align-items: center;
}

.nav-menu {
  display: flex;
  align-items: center;
  gap: 0;
}

.nav-menu a {
  display: block;
  padding: var(--space-md) var(--space-xl);
  font-size: 14px;
  color: var(--color-text);
  position: relative;
  font-weight: 500;
  transition: all var(--transition-fast);
}

.nav-menu a::after {
  content: '';
  position: absolute;
  bottom: 0;
  left: 50%;
  transform: translateX(-50%);
  width: 0;
  height: 2px;
  background: var(--color-primary);
  transition: width var(--transition-normal);
}

.nav-menu a:hover,
.nav-menu a.current {
  color: var(--color-primary);
}

.nav-menu a:hover::after,
.nav-menu a.current::after {
  width: 60%;
}

.nav-search {
  margin-left: auto;
  position: relative;
}

.nav-search input {
  padding: var(--space-xs) var(--space-md);
  padding-right: 36px;
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  font-size: 13px;
  width: 180px;
  transition: all var(--transition-fast);
  font-family: var(--font-family);
}

.nav-search input:focus {
  outline: none;
  border-color: var(--color-primary);
  box-shadow: 0 0 0 2px rgba(255, 69, 0, 0.1);
  width: 220px;
}

.nav-search button {
  position: absolute;
  right: 4px;
  top: 50%;
  transform: translateY(-50%);
  background: none;
  border: none;
  cursor: pointer;
  color: var(--color-text-muted);
  padding: var(--space-xs);
  display: flex;
  align-items: center;
}

.nav-search button:hover {
  color: var(--color-primary);
}

/* ========================================
   Slogan Bar
   ======================================== */
.slogan-bar {
  background: linear-gradient(135deg, var(--color-primary-light), #FFF0E6);
  text-align: center;
  padding: var(--space-xl) var(--space-lg);
  border-bottom: 1px solid var(--color-border-light);
}

.slogan-bar h2 {
  font-size: 1.25rem;
  color: var(--color-primary-dark);
  font-weight: 600;
  margin: 0;
}

.slogan-bar p {
  font-size: 14px;
  color: var(--color-text-secondary);
  margin-top: var(--space-xs);
}

/* ========================================
   Main Layout
   ======================================== */
.main-container {
  max-width: var(--container-wide);
  margin: 0 auto;
  padding: var(--space-2xl) var(--space-lg);
  display: flex;
  gap: var(--space-2xl);
  flex: 1;
}

.content-area {
  flex: 1;
  min-width: 0;
}

.sidebar {
  width: var(--sidebar-width);
  flex-shrink: 0;
}

/* ========================================
   Breadcrumb
   ======================================== */
.breadcrumb {
  display: flex;
  align-items: center;
  gap: var(--space-sm);
  font-size: 13px;
  color: var(--color-text-muted);
  margin-bottom: var(--space-xl);
  padding-bottom: var(--space-lg);
  border-bottom: 1px solid var(--color-border-light);
}

.breadcrumb a {
  color: var(--color-text-secondary);
}

.breadcrumb a:hover {
  color: var(--color-primary);
}

.breadcrumb .sep {
  color: var(--color-border);
}

.breadcrumb .current {
  color: var(--color-text);
}

/* ========================================
   Article List
   ======================================== */
.post-item {
  margin-bottom: var(--space-xl);
  padding-bottom: var(--space-xl);
  border-bottom: 1px solid var(--color-border-light);
  transition: transform var(--transition-fast);
}

.post-item:last-child {
  border-bottom: none;
}

.post-item:hover {
  transform: translateX(4px);
}

.post-item .post-title {
  font-size: 1.25rem;
  margin-bottom: var(--space-sm);
}

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

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

.post-meta {
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-lg);
  margin-bottom: var(--space-md);
  font-size: 13px;
  color: var(--color-text-muted);
}

.post-meta-item {
  display: inline-flex;
  align-items: center;
  gap: 4px;
}

.meta-icon {
  flex-shrink: 0;
}

.post-excerpt {
  color: var(--color-text-secondary);
  line-height: 1.8;
  margin-bottom: var(--space-md);
}

.post-item .read-more {
  display: inline-flex;
  align-items: center;
  gap: 4px;
  font-size: 13px;
  color: var(--color-primary);
  font-weight: 500;
}

.post-item .read-more:hover {
  color: var(--color-primary-dark);
  gap: 8px;
}

/* Post with thumbnail layout */
.post-item.has-thumb {
  display: flex;
  gap: var(--space-xl);
}

.post-thumb {
  flex-shrink: 0;
  width: 200px;
  height: 140px;
  border-radius: var(--radius-md);
  overflow: hidden;
  background: var(--color-bg-alt);
}

.post-thumb img {
  width: 100%;
  height: 100%;
  object-fit: cover;
  transition: transform var(--transition-slow);
}

.post-item:hover .post-thumb img {
  transform: scale(1.05);
}

.post-item.has-thumb .post-body {
  flex: 1;
  min-width: 0;
}

/* ========================================
   Archive Title
   ======================================== */
.archive-title {
  font-size: 1.125rem;
  color: var(--color-primary);
  margin-bottom: var(--space-xl);
  padding-bottom: var(--space-md);
  border-bottom: 2px solid var(--color-primary);
  display: inline-block;
}

/* ========================================
   Pagination
   ======================================== */
.page-navigator {
  display: flex;
  justify-content: center;
  gap: var(--space-sm);
  margin-top: var(--space-2xl);
  padding-top: var(--space-xl);
  border-top: 1px solid var(--color-border-light);
}

.page-navigator li {
  display: inline-block;
}

.page-navigator a,
.page-navigator span {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-width: 36px;
  height: 36px;
  padding: 0 var(--space-md);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-sm);
  font-size: 14px;
  color: var(--color-text-secondary);
  transition: all var(--transition-fast);
}

.page-navigator a:hover {
  border-color: var(--color-primary);
  color: var(--color-primary);
  background: var(--color-primary-light);
}

.page-navigator .current a,
.page-navigator .current span {
  background: var(--color-primary);
  border-color: var(--color-primary);
  color: #fff;
}

/* ========================================
   Single Post
   ======================================== */
.single-post .post-header {
  margin-bottom: var(--space-xl);
}

.single-post .post-title {
  font-size: 1.75rem;
  line-height: 1.4;
  margin-bottom: var(--space-lg);
  color: var(--color-text);
}

.single-post .post-meta {
  padding-bottom: var(--space-lg);
  border-bottom: 1px solid var(--color-border-light);
}

/* Post content typography */
.post-content {
  font-size: 15px;
  line-height: 1.9;
  color: var(--color-text);
}

.post-content h2 {
  font-size: 1.375rem;
  margin: var(--space-2xl) 0 var(--space-lg);
  padding-left: var(--space-md);
  border-left: 4px solid var(--color-primary);
}

.post-content h3 {
  font-size: 1.125rem;
  margin: var(--space-xl) 0 var(--space-md);
}

.post-content h4 {
  font-size: 1rem;
  margin: var(--space-lg) 0 var(--space-sm);
}

.post-content p {
  margin-bottom: var(--space-lg);
}

.post-content ul, .post-content ol {
  margin: var(--space-lg) 0;
  padding-left: var(--space-2xl);
}

.post-content ul li {
  list-style: disc;
  margin-bottom: var(--space-sm);
}

.post-content ol li {
  list-style: decimal;
  margin-bottom: var(--space-sm);
}

.post-content blockquote {
  margin: var(--space-xl) 0;
  padding: var(--space-lg) var(--space-xl);
  background: var(--color-bg-warm);
  border-left: 4px solid var(--color-primary);
  border-radius: 0 var(--radius-sm) var(--radius-sm) 0;
  color: var(--color-text-secondary);
}

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

.post-content img {
  display: block;
  max-width: 100%;
  height: auto;
  margin: var(--space-xl) auto;
  border-radius: var(--radius-md);
}

.post-content table {
  width: 100%;
  border-collapse: collapse;
  margin: var(--space-xl) 0;
  font-size: 14px;
}

.post-content table th,
.post-content table td {
  padding: var(--space-md) var(--space-lg);
  border: 1px solid var(--color-border);
  text-align: left;
}

.post-content table th {
  background: var(--color-bg-alt);
  font-weight: 600;
}

.post-content table tr:nth-child(even) {
  background: #FAFAFA;
}

.post-content code {
  background: var(--color-bg-alt);
  padding: 2px 6px;
  border-radius: 3px;
  font-size: 0.9em;
  color: #D14;
  font-family: "Consolas", "Monaco", "Courier New", monospace;
}

.post-content pre {
  background: #282C34;
  color: #ABB2BF;
  padding: var(--space-lg);
  border-radius: var(--radius-md);
  overflow-x: auto;
  margin: var(--space-xl) 0;
  font-size: 13px;
  line-height: 1.6;
}

.post-content pre code {
  background: none;
  color: inherit;
  padding: 0;
}

.post-content strong {
  color: var(--color-text);
}

.post-content a {
  color: var(--color-accent);
  text-decoration: underline;
  text-underline-offset: 2px;
}

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

/* Post tags */
.post-tags {
  margin-top: var(--space-2xl);
  padding-top: var(--space-xl);
  border-top: 1px solid var(--color-border-light);
  display: flex;
  align-items: center;
  gap: var(--space-sm);
  flex-wrap: wrap;
}

.post-tags-label {
  font-size: 13px;
  color: var(--color-text-muted);
  margin-right: var(--space-sm);
}

.post-tags a {
  display: inline-block;
  padding: 2px var(--space-md);
  background: var(--color-bg-alt);
  border: 1px solid var(--color-border-light);
  border-radius: var(--radius-lg);
  font-size: 12px;
  color: var(--color-text-secondary);
  transition: all var(--transition-fast);
}

.post-tags a:hover {
  background: var(--color-primary-light);
  border-color: var(--color-primary);
  color: var(--color-primary);
}

/* Post navigation (prev/next) */
.post-near {
  display: flex;
  justify-content: space-between;
  gap: var(--space-lg);
  margin-top: var(--space-2xl);
  padding-top: var(--space-xl);
  border-top: 1px solid var(--color-border-light);
}

.post-near li {
  flex: 1;
}

.post-near a {
  display: block;
  padding: var(--space-lg);
  background: var(--color-bg-alt);
  border-radius: var(--radius-md);
  font-size: 13px;
  color: var(--color-text-secondary);
  transition: all var(--transition-fast);
}

.post-near a:hover {
  background: var(--color-primary-light);
  color: var(--color-primary);
}

.post-near .prev {
  text-align: left;
}

.post-near .next {
  text-align: right;
}

/* Related posts */
.related-posts {
  margin-top: var(--space-2xl);
  padding-top: var(--space-xl);
  border-top: 1px solid var(--color-border-light);
}

.related-posts h3 {
  font-size: 1.125rem;
  margin-bottom: var(--space-lg);
  color: var(--color-text);
}

.related-posts ul {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: var(--space-md);
}

.related-posts li a {
  display: block;
  padding: var(--space-md);
  background: var(--color-bg-alt);
  border-radius: var(--radius-sm);
  font-size: 14px;
  color: var(--color-text);
  transition: all var(--transition-fast);
}

.related-posts li a:hover {
  background: var(--color-primary-light);
  color: var(--color-primary);
  transform: translateX(4px);
}

/* ========================================
   Sidebar
   ======================================== */
.sidebar .widget {
  margin-bottom: var(--space-xl);
  background: var(--color-bg);
  border: 1px solid var(--color-border-light);
  border-radius: var(--radius-md);
  overflow: hidden;
}

.widget-title {
  font-size: 15px;
  font-weight: 600;
  color: var(--color-text);
  padding: var(--space-lg) var(--space-lg);
  background: var(--color-bg-alt);
  border-bottom: 1px solid var(--color-border-light);
  display: flex;
  align-items: center;
  gap: var(--space-sm);
}

.widget-title::before {
  content: '';
  width: 4px;
  height: 16px;
  background: var(--color-primary);
  border-radius: 2px;
}

.widget-body {
  padding: var(--space-lg);
}

.widget-list li {
  padding: var(--space-sm) 0;
  border-bottom: 1px dashed var(--color-border-light);
}

.widget-list li:last-child {
  border-bottom: none;
}

.widget-list a {
  font-size: 14px;
  color: var(--color-text-secondary);
  transition: color var(--transition-fast);
}

.widget-list a:hover {
  color: var(--color-primary);
  padding-left: 4px;
}

/* Tag cloud —— 纯文字云：去掉方框/背景，依赖内联 font-size + 随机 rotate/margin-top 形成错落 */
.tag-cloud {
  display: flex;
  flex-wrap: wrap;
  gap: 10px 14px;
  line-height: 2;
  align-items: center;
}

.tag-cloud a {
  display: inline-block;
  text-decoration: none;
  color: var(--color-text-secondary);
  transition: color var(--transition-fast), filter var(--transition-fast);
  line-height: 1;
}

.tag-cloud a:hover {
  filter: brightness(1.18);
  text-decoration: underline;
}

/* 标签云热度分档配色：高频深/暖 → 低频浅灰（仅覆盖 color，去除边框/背景，呈纯文字云） */
.tag-cloud a.tc-tier-1 { color: #dc2626; }   /* 深红 */
.tag-cloud a.tc-tier-2 { color: #ea580c; }   /* 橙 */
.tag-cloud a.tc-tier-3 { color: #d97706; }   /* 琥珀 */
.tag-cloud a.tc-tier-4 { color: #ca8a04; }   /* 浅金 */
.tag-cloud a.tc-tier-5 { color: #94a3b8; }   /* 浅灰蓝 */

/* 侧边栏"查看完整标签云"链接 */
.widget-more { margin-top: var(--space-md); font-size: 13px; text-align: right; }
.widget-more a { color: var(--color-primary); text-decoration: none; }
.widget-more a:hover { text-decoration: underline; }

/* 独立标签云页：加大间距，更明显的错落 */
.tag-cloud--page { gap: 16px 22px; line-height: 2.4; }

/* Archive list */
.archive-list {
  max-height: 300px;
  overflow-y: auto;
}

.archive-list .archive-year {
  font-weight: 600;
  color: var(--color-text);
  padding: var(--space-sm) 0;
}

/* ========================================
   Comments
   ======================================== */
#comments {
  margin-top: var(--space-3xl);
  padding-top: var(--space-2xl);
  border-top: 1px solid var(--color-border-light);
}

#comments h3 {
  font-size: 1.125rem;
  margin-bottom: var(--space-xl);
  color: var(--color-text);
}

.comment-list {
  margin-bottom: var(--space-2xl);
}

.comment-list li {
  margin-bottom: var(--space-lg);
}

.comment-body {
  display: flex;
  gap: var(--space-lg);
  padding: var(--space-lg);
  background: var(--color-bg-alt);
  border-radius: var(--radius-md);
}

.comment-avatar {
  flex-shrink: 0;
}

.comment-avatar .avatar {
  width: 40px;
  height: 40px;
  border-radius: 50%;
}

.comment-content-wrapper {
  flex: 1;
  min-width: 0;
}

.comment-author {
  font-weight: 600;
  color: var(--color-text);
  margin-bottom: var(--space-xs);
}

.comment-author a {
  color: var(--color-text);
}

.comment-meta {
  font-size: 12px;
  color: var(--color-text-muted);
  margin-bottom: var(--space-sm);
}

.comment-content {
  font-size: 14px;
  line-height: 1.7;
  color: var(--color-text-secondary);
}

.comment-reply {
  margin-top: var(--space-sm);
  text-align: right;
}

.comment-reply a {
  font-size: 12px;
  color: var(--color-accent);
}

/* Comment form */
#comment-form {
  background: var(--color-bg-alt);
  padding: var(--space-xl);
  border-radius: var(--radius-md);
}

#comment-form label {
  display: block;
  font-size: 14px;
  font-weight: 500;
  color: var(--color-text);
  margin-bottom: var(--space-xs);
}

#comment-form .required:after {
  content: " *";
  color: var(--color-primary);
}

#comment-form input[type="text"],
#comment-form input[type="email"],
#comment-form input[type="url"],
#comment-form textarea {
  width: 100%;
  padding: var(--space-md);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-sm);
  font-size: 14px;
  font-family: var(--font-family);
  transition: border-color var(--transition-fast);
  margin-bottom: var(--space-lg);
}

#comment-form input:focus,
#comment-form textarea:focus {
  outline: none;
  border-color: var(--color-primary);
  box-shadow: 0 0 0 2px rgba(255, 69, 0, 0.1);
}

#comment-form textarea {
  resize: vertical;
  min-height: 120px;
}

#comment-form .submit {
  display: inline-flex;
  align-items: center;
  padding: var(--space-md) var(--space-2xl);
  background: var(--color-primary);
  color: #fff;
  border: none;
  border-radius: var(--radius-sm);
  font-size: 14px;
  font-weight: 500;
  cursor: pointer;
  transition: background var(--transition-fast);
  font-family: var(--font-family);
}

#comment-form .submit:hover {
  background: var(--color-primary-dark);
}

.cancel-comment-reply {
  margin-left: var(--space-md);
  font-size: 13px;
}

/* ========================================
   Footer
   ======================================== */
.site-footer {
  background: #2C2C2C;
  color: #B0B0B0;
  margin-top: var(--space-3xl);
}

.footer-inner {
  max-width: var(--container-wide);
  margin: 0 auto;
  padding: var(--space-3xl) var(--space-lg);
  display: grid;
  grid-template-columns: 2fr 1fr 1fr 1fr;
  gap: var(--space-2xl);
}

.footer-col h4 {
  font-size: 16px;
  color: #E0E0E0;
  margin-bottom: var(--space-lg);
  padding-bottom: var(--space-sm);
  border-bottom: 2px solid var(--color-primary);
  display: inline-block;
}

.footer-col ul li {
  margin-bottom: var(--space-sm);
}

.footer-col ul li a {
  color: #B0B0B0;
  font-size: 13px;
  transition: color var(--transition-fast);
}

.footer-col ul li a:hover {
  color: var(--color-primary);
}

.footer-brand p {
  font-size: 13px;
  line-height: 1.8;
  margin-bottom: var(--space-lg);
}

.footer-bottom {
  border-top: 1px solid #3A3A3A;
  padding: var(--space-lg) var(--space-lg);
  text-align: center;
  font-size: 12px;
  color: #808080;
}

.footer-bottom a {
  color: #B0B0B0;
}

.footer-bottom a:hover {
  color: var(--color-primary);
}

/* ========================================
   Back to Top
   ======================================== */
.back-to-top {
  position: fixed;
  bottom: 60px;
  right: 30px;
  width: 40px;
  height: 40px;
  background: var(--color-primary);
  color: #fff;
  border: none;
  border-radius: 50%;
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 18px;
  opacity: 0;
  visibility: hidden;
  transition: all var(--transition-normal);
  box-shadow: var(--shadow-md);
  z-index: 99;
}

.back-to-top.visible {
  opacity: 1;
  visibility: visible;
}

.back-to-top:hover {
  background: var(--color-primary-dark);
  transform: translateY(-2px);
}

/* ========================================
   404 Page
   ======================================== */
.error-page {
  text-align: center;
  padding: var(--space-3xl) 0;
}

.error-page h2 {
  font-size: 6rem;
  color: var(--color-primary);
  margin-bottom: var(--space-xl);
  line-height: 1;
}

.error-page p {
  font-size: 16px;
  color: var(--color-text-secondary);
  margin-bottom: var(--space-2xl);
}

.error-page .btn-back {
  display: inline-flex;
  align-items: center;
  padding: var(--space-md) var(--space-2xl);
  background: var(--color-primary);
  color: #fff;
  border-radius: var(--radius-sm);
  font-size: 14px;
  font-weight: 500;
  transition: background var(--transition-fast);
}

.error-page .btn-back:hover {
  background: var(--color-primary-dark);
  color: #fff;
}

/* ========================================
   Utility
   ======================================== */
.clearfix::after {
  content: "";
  display: table;
  clear: both;
}

.hidden {
  display: none !important;
}

.sr-only {
  position: absolute;
  width: 1px;
  height: 1px;
  padding: 0;
  margin: -1px;
  overflow: hidden;
  clip: rect(0, 0, 0, 0);
  border: 0;
}

/* ========================================
   Responsive Design
   ======================================== */
@media (max-width: 1024px) {
  .main-container {
    flex-direction: column;
  }

  .sidebar {
    width: 100%;
  }

  .footer-inner {
    grid-template-columns: repeat(2, 1fr);
  }

  .nav-search input {
    width: 140px;
  }

  .nav-search input:focus {
    width: 180px;
  }
}

@media (max-width: 768px) {
  .top-bar {
    display: none;
  }

  .header-inner {
    flex-direction: column;
    gap: var(--space-md);
    text-align: center;
  }

  .site-branding {
    flex-direction: column;
    align-items: center;
  }

  .nav-menu {
    flex-wrap: wrap;
    justify-content: center;
  }

  .nav-menu a {
    padding: var(--space-sm) var(--space-md);
    font-size: 13px;
  }

  .nav-search {
    margin: var(--space-sm) auto 0;
    width: 100%;
  }

  .nav-search input {
    width: 100%;
  }

  .post-item.has-thumb {
    flex-direction: column;
  }

  .post-thumb {
    width: 100%;
    height: 200px;
  }

  .post-meta {
    gap: var(--space-md);
  }

  .post-near {
    flex-direction: column;
  }

  .related-posts ul {
    grid-template-columns: 1fr;
  }

  .footer-inner {
    grid-template-columns: 1fr;
  }

  .main-container {
    padding: var(--space-lg) var(--space-md);
  }

  .single-post .post-title {
    font-size: 1.375rem;
  }

  .post-content {
    font-size: 14px;
  }

  .back-to-top {
    right: 16px;
    bottom: 40px;
  }
}

@media (max-width: 480px) {
  .nav-menu a {
    padding: var(--space-sm) var(--space-xs);
    font-size: 12px;
  }

  .post-content h2 {
    font-size: 1.125rem;
  }

  .error-page h2 {
    font-size: 4rem;
  }
}

/* Print styles */
@media print {
  .top-bar,
  .site-nav,
  .sidebar,
  .back-to-top,
  #comments,
  .site-footer {
    display: none;
  }

  .main-container {
    display: block;
    padding: 0;
  }

  .post-content {
    font-size: 12pt;
    line-height: 1.6;
  }
}