/* ========================================
   AI科技前沿 — 全局变量与主题
   ======================================== */
:root {
  /* 暗色主题（默认） */
  --bg-primary: #0a0e1a;
  --bg-secondary: #111827;
  --bg-tertiary: #1a2332;
  --bg-card: #151c2c;
  --bg-card-hover: #1c2640;
  --border-color: rgba(255, 255, 255, 0.08);
  --border-hover: rgba(0, 212, 255, 0.3);

  --text-primary: #f0f4ff;
  --text-secondary: #a0aec0;
  --text-tertiary: #6b7280;

  --accent-cyan: #00d4ff;
  --accent-purple: #7c4dff;
  --accent-pink: #ff4081;
  --accent-green: #00e676;
  --accent-orange: #ff9100;

  --gradient-primary: linear-gradient(135deg, #00d4ff 0%, #7c4dff 100%);
  --gradient-secondary: linear-gradient(135deg, #7c4dff 0%, #ff4081 100%);
  --gradient-bg: linear-gradient(180deg, #0a0e1a 0%, #111827 100%);

  --shadow-sm: 0 2px 8px rgba(0, 0, 0, 0.3);
  --shadow-md: 0 4px 20px rgba(0, 0, 0, 0.4);
  --shadow-lg: 0 8px 40px rgba(0, 0, 0, 0.5);
  --shadow-glow: 0 0 30px rgba(0, 212, 255, 0.15);

  --radius-sm: 8px;
  --radius-md: 12px;
  --radius-lg: 20px;
  --radius-full: 9999px;

  --transition-fast: 0.2s ease;
  --transition-normal: 0.3s ease;
  --transition-slow: 0.5s ease;

  --header-height: 70px;
  --container-max: 1280px;
  --container-pad: 24px;
}

[data-theme="light"] {
  --bg-primary: #f7f9fc;
  --bg-secondary: #ffffff;
  --bg-tertiary: #f0f4f8;
  --bg-card: #ffffff;
  --bg-card-hover: #f5f8ff;
  --border-color: rgba(0, 0, 0, 0.08);
  --border-hover: rgba(0, 150, 255, 0.3);

  --text-primary: #1a202c;
  --text-secondary: #4a5568;
  --text-tertiary: #718096;

  --gradient-bg: linear-gradient(180deg, #f7f9fc 0%, #eef2f8 100%);
  --shadow-sm: 0 2px 8px rgba(0, 0, 0, 0.06);
  --shadow-md: 0 4px 20px rgba(0, 0, 0, 0.08);
  --shadow-lg: 0 8px 40px rgba(0, 0, 0, 0.12);
  --shadow-glow: 0 0 30px rgba(0, 150, 255, 0.08);
}

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

html {
  scroll-behavior: smooth;
  scroll-padding-top: var(--header-height);
  -webkit-text-size-adjust: 100%;
  overflow-x: hidden;
}

body {
  font-family: "Noto Sans SC", -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
  background: var(--bg-primary);
  color: var(--text-primary);
  line-height: 1.6;
  overflow-x: hidden;
  transition: background var(--transition-normal), color var(--transition-normal);
}

a {
  color: inherit;
  text-decoration: none;
}

ul { list-style: none; }

img, video, canvas, svg {
  max-width: 100%;
}

img, video {
  display: block;
}

button {
  font-family: inherit;
  cursor: pointer;
  border: none;
  background: none;
  color: inherit;
}

input {
  font-family: inherit;
  font-size: inherit;
}

::selection {
  background: var(--accent-cyan);
  color: var(--bg-primary);
}

/* 滚动条 */
::-webkit-scrollbar { width: 8px; height: 8px; }
::-webkit-scrollbar-track { background: var(--bg-secondary); }
::-webkit-scrollbar-thumb {
  background: var(--bg-tertiary);
  border-radius: 4px;
}
::-webkit-scrollbar-thumb:hover { background: var(--accent-purple); }

/* ========================================
   布局工具
   ======================================== */
.container {
  width: 100%;
  max-width: var(--container-max);
  margin: 0 auto;
  padding: 0 var(--container-pad);
}

.gradient-text {
  background: var(--gradient-primary);
  -webkit-background-clip: text;
  background-clip: text;
  -webkit-text-fill-color: transparent;
}

.section {
  padding: 80px 0;
  position: relative;
}

.section--alt {
  background: var(--bg-secondary);
}

.section__header {
  text-align: center;
  margin-bottom: 56px;
}

.section__tag {
  display: inline-block;
  font-family: "JetBrains Mono", monospace;
  font-size: 0.75rem;
  letter-spacing: 2px;
  color: var(--accent-cyan);
  padding: 4px 16px;
  border: 1px solid var(--border-color);
  border-radius: var(--radius-full);
  margin-bottom: 16px;
}

.section__title {
  font-size: clamp(1.75rem, 4vw, 2.5rem);
  font-weight: 700;
  margin-bottom: 12px;
  letter-spacing: -0.02em;
}

.section__subtitle {
  color: var(--text-secondary);
  font-size: 1.05rem;
  max-width: 600px;
  margin: 0 auto;
}

.section__more {
  text-align: center;
  margin-top: 40px;
}

/* ========================================
   按钮
   ======================================== */
.btn {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 12px 28px;
  border-radius: var(--radius-full);
  font-size: 0.95rem;
  font-weight: 500;
  transition: all var(--transition-normal);
  white-space: nowrap;
}

.btn--primary {
  background: var(--gradient-primary);
  color: #fff;
  box-shadow: 0 4px 20px rgba(0, 212, 255, 0.3);
}

.btn--primary:hover {
  transform: translateY(-2px);
  box-shadow: 0 6px 30px rgba(0, 212, 255, 0.45);
}

.btn--outline {
  border: 1px solid var(--border-color);
  color: var(--text-primary);
  background: transparent;
}

.btn--outline:hover {
  border-color: var(--accent-cyan);
  color: var(--accent-cyan);
  background: rgba(0, 212, 255, 0.05);
}

.btn--ghost {
  padding: 8px;
  border-radius: var(--radius-sm);
}

.btn--block {
  width: 100%;
  justify-content: center;
}

/* ========================================
   Header 导航
   ======================================== */
.header {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  height: var(--header-height);
  z-index: 1000;
  background: rgba(10, 14, 26, 0.8);
  backdrop-filter: blur(20px);
  -webkit-backdrop-filter: blur(20px);
  border-bottom: 1px solid var(--border-color);
  transition: all var(--transition-normal);
}

[data-theme="light"] .header {
  background: rgba(255, 255, 255, 0.85);
}

.header--scrolled {
  box-shadow: var(--shadow-md);
}

.header__inner {
  height: 100%;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 24px;
}

.logo {
  display: flex;
  align-items: center;
  gap: 10px;
  flex-shrink: 0;
}

.logo__icon {
  display: flex;
  align-items: center;
}

.logo__text {
  font-size: 1.25rem;
  font-weight: 700;
  letter-spacing: -0.02em;
}

.logo__accent {
  color: var(--accent-cyan);
}

.nav {
  display: flex;
  gap: 32px;
}

.nav__link {
  font-size: 0.95rem;
  color: var(--text-secondary);
  position: relative;
  padding: 4px 0;
  transition: color var(--transition-fast);
}

.nav__link::after {
  content: "";
  position: absolute;
  bottom: 0;
  left: 0;
  width: 0;
  height: 2px;
  background: var(--gradient-primary);
  border-radius: 2px;
  transition: width var(--transition-normal);
}

.nav__link:hover,
.nav__link--active {
  color: var(--text-primary);
}

.nav__link:hover::after,
.nav__link--active::after {
  width: 100%;
}

.header__actions {
  display: flex;
  align-items: center;
  gap: 12px;
}

.theme-toggle {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 40px;
  height: 40px;
  border-radius: var(--radius-sm);
  border: 1px solid var(--border-color);
  transition: all var(--transition-fast);
}

.theme-toggle:hover {
  border-color: var(--accent-cyan);
  color: var(--accent-cyan);
}

.theme-toggle .icon-sun { display: none; }
.theme-toggle .icon-moon { display: block; }

[data-theme="light"] .theme-toggle .icon-sun { display: block; }
[data-theme="light"] .theme-toggle .icon-moon { display: none; }

.header__menu-btn {
  display: none;
}

/* ========================================
   Hero 区
   ======================================== */
.hero {
  position: relative;
  min-height: 100vh;
  display: flex;
  align-items: center;
  justify-content: center;
  text-align: center;
  padding: var(--header-height) 0 60px;
  overflow: hidden;
}

.hero__bg {
  position: absolute;
  inset: 0;
  z-index: 0;
  overflow: hidden;
}

.hero__orb {
  position: absolute;
  border-radius: 50%;
  filter: blur(80px);
  opacity: 0.4;
  animation: orbFloat 20s ease-in-out infinite;
}

.hero__orb--1 {
  width: 500px;
  height: 500px;
  background: radial-gradient(circle, #00d4ff, transparent);
  top: -10%;
  left: -5%;
}

.hero__orb--2 {
  width: 400px;
  height: 400px;
  background: radial-gradient(circle, #7c4dff, transparent);
  bottom: -10%;
  right: -5%;
  animation-delay: -7s;
}

.hero__orb--3 {
  width: 350px;
  height: 350px;
  background: radial-gradient(circle, #ff4081, transparent);
  top: 40%;
  left: 50%;
  transform: translateX(-50%);
  opacity: 0.2;
  animation-delay: -14s;
}

@keyframes orbFloat {
  0%, 100% { transform: translate(0, 0) scale(1); }
  33% { transform: translate(30px, -40px) scale(1.1); }
  66% { transform: translate(-20px, 30px) scale(0.95); }
}

.hero__grid {
  position: absolute;
  inset: 0;
  background-image:
    linear-gradient(var(--border-color) 1px, transparent 1px),
    linear-gradient(90deg, var(--border-color) 1px, transparent 1px);
  background-size: 60px 60px;
  mask-image: radial-gradient(ellipse at center, black 30%, transparent 70%);
  -webkit-mask-image: radial-gradient(ellipse at center, black 30%, transparent 70%);
  opacity: 0.5;
}

.hero__content {
  position: relative;
  z-index: 1;
}

.hero__badge {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 6px 16px;
  border-radius: var(--radius-full);
  background: rgba(0, 212, 255, 0.1);
  border: 1px solid rgba(0, 212, 255, 0.2);
  font-size: 0.85rem;
  color: var(--accent-cyan);
  margin-bottom: 24px;
}

.pulse-dot {
  width: 8px;
  height: 8px;
  border-radius: 50%;
  background: var(--accent-green);
  animation: pulse 2s ease-in-out infinite;
}

@keyframes pulse {
  0%, 100% { box-shadow: 0 0 0 0 rgba(0, 230, 118, 0.4); }
  50% { box-shadow: 0 0 0 8px rgba(0, 230, 118, 0); }
}

.hero__title {
  font-size: clamp(2.5rem, 7vw, 4.5rem);
  font-weight: 900;
  line-height: 1.15;
  letter-spacing: -0.03em;
  margin-bottom: 24px;
}

.hero__title-sub {
  font-size: clamp(1.1rem, 3vw, 1.8rem);
  font-weight: 400;
  color: var(--text-secondary);
}

.hero__desc {
  font-size: 1.1rem;
  color: var(--text-secondary);
  max-width: 560px;
  margin: 0 auto 36px;
  line-height: 1.8;
}

.hero__actions {
  display: flex;
  gap: 16px;
  justify-content: center;
  margin-bottom: 64px;
  flex-wrap: wrap;
}

.hero__stats {
  display: flex;
  gap: 48px;
  justify-content: center;
  flex-wrap: wrap;
}

.stat {
  text-align: center;
}

.stat__num {
  display: block;
  font-size: 2rem;
  font-weight: 700;
  font-family: "JetBrains Mono", monospace;
  background: var(--gradient-primary);
  -webkit-background-clip: text;
  background-clip: text;
  -webkit-text-fill-color: transparent;
}

.stat__label {
  font-size: 0.85rem;
  color: var(--text-tertiary);
  margin-top: 4px;
  display: block;
}

.hero__scroll {
  position: absolute;
  bottom: 30px;
  left: 50%;
  transform: translateX(-50%);
  z-index: 1;
  color: var(--text-tertiary);
  animation: scrollBounce 2s ease-in-out infinite;
}

@keyframes scrollBounce {
  0%, 100% { transform: translateX(-50%) translateY(0); }
  50% { transform: translateX(-50%) translateY(10px); }
}

/* ========================================
   AI 要闻
   ======================================== */
.news__filter {
  display: flex;
  gap: 12px;
  justify-content: center;
  margin-bottom: 40px;
  flex-wrap: wrap;
}

.filter-btn {
  padding: 8px 20px;
  border-radius: var(--radius-full);
  font-size: 0.9rem;
  color: var(--text-secondary);
  border: 1px solid var(--border-color);
  transition: all var(--transition-fast);
}

.filter-btn:hover {
  border-color: var(--accent-cyan);
  color: var(--accent-cyan);
}

.filter-btn--active {
  background: var(--gradient-primary);
  color: #fff;
  border-color: transparent;
}

.news__grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 24px;
}

.news-card {
  background: var(--bg-card);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-md);
  overflow: hidden;
  transition: all var(--transition-normal);
  display: flex;
  flex-direction: column;
}

.news-card:hover {
  transform: translateY(-4px);
  border-color: var(--border-hover);
  box-shadow: var(--shadow-lg);
}

.news-card--featured {
  grid-column: span 2;
  grid-row: span 1;
  flex-direction: column;
}

.news-card--featured .news-card__img {
  width: 100%;
  padding-top: 50%;
  min-height: 0;
}

.news-card--featured .news-card__body {
  width: 100%;
}

.news-card__img {
  position: relative;
  width: 100%;
  padding-top: 60%;
  background-color: rgba(124, 77, 255, 0.08);
  background-size: cover;
  background-position: center;
  overflow: hidden;
}

/* 懒加载占位骨架 */
.news-card__img.lazy-img {
  background-image: linear-gradient(
    110deg,
    rgba(255, 255, 255, 0) 40%,
    rgba(255, 255, 255, 0.08) 50%,
    rgba(255, 255, 255, 0) 60%
  );
  background-size: 200% 100%;
  animation: skeleton-shimmer 1.6s infinite linear;
}

.news-card__img.is-loaded {
  background-image: var(--img-url);
  background-size: cover;
  background-position: center;
  background-repeat: no-repeat;
  animation: none;
}

@keyframes skeleton-shimmer {
  0% { background-position: 200% 0; }
  100% { background-position: -200% 0; }
}

.news-card__img::after {
  content: "";
  position: absolute;
  inset: 0;
  background: linear-gradient(180deg, transparent 50%, rgba(0, 0, 0, 0.4) 100%);
}

.news-card__badge {
  position: absolute;
  top: 12px;
  left: 12px;
  z-index: 1;
  padding: 4px 10px;
  border-radius: var(--radius-sm);
  font-size: 0.75rem;
  font-weight: 500;
  background: rgba(0, 0, 0, 0.6);
  color: #fff;
  backdrop-filter: blur(8px);
}

.news-card__badge--hot {
  background: var(--accent-pink);
}

.news-card__badge--new {
  background: var(--accent-green);
  color: #000;
}

.news-card__body {
  padding: 20px;
  display: flex;
  flex-direction: column;
  flex: 1;
}

.news-card__cat {
  font-size: 0.75rem;
  color: var(--accent-cyan);
  font-weight: 500;
  margin-bottom: 8px;
}

.news-card__title {
  font-size: 1.05rem;
  font-weight: 600;
  line-height: 1.4;
  margin-bottom: 8px;
}

.news-card--featured .news-card__title {
  font-size: 1.25rem;
}

.news-card__excerpt {
  font-size: 0.9rem;
  color: var(--text-secondary);
  margin-bottom: 16px;
  flex: 1;
  display: -webkit-box;
  -webkit-line-clamp: 2;
  -webkit-box-orient: vertical;
  overflow: hidden;
}

.news-card__meta {
  display: flex;
  gap: 16px;
  font-size: 0.8rem;
  color: var(--text-tertiary);
}

.news-card__readmore {
  display: inline-block;
  margin-top: 12px;
  font-size: 0.85rem;
  font-weight: 500;
  color: var(--accent-cyan);
  transition: gap 0.2s;
}

.news-card:hover .news-card__readmore {
  letter-spacing: 0.5px;
}

/* ========================================
   技能知识分享
   ======================================== */
.skills__layout {
  display: grid;
  grid-template-columns: 260px 1fr;
  gap: 32px;
  align-items: start;
}

.skills__sidebar {
  position: sticky;
  top: calc(var(--header-height) + 24px);
}

.skills__sidebar-title {
  font-size: 1rem;
  font-weight: 600;
  margin-bottom: 16px;
  padding-bottom: 12px;
  border-bottom: 1px solid var(--border-color);
}

.skills__paths {
  display: flex;
  flex-direction: column;
  gap: 4px;
}

.path-item {
  display: flex;
  align-items: center;
  gap: 12px;
  padding: 10px 14px;
  border-radius: var(--radius-sm);
  cursor: pointer;
  transition: all var(--transition-fast);
  font-size: 0.9rem;
  color: var(--text-secondary);
}

.path-item:hover {
  background: var(--bg-tertiary);
  color: var(--text-primary);
}

.path-item--active {
  background: rgba(0, 212, 255, 0.1);
  color: var(--accent-cyan);
}

.path-item__icon {
  font-size: 1.2rem;
}

.path-item__text {
  flex: 1;
}

.path-item__count {
  font-size: 0.75rem;
  color: var(--text-tertiary);
  background: var(--bg-tertiary);
  padding: 2px 8px;
  border-radius: var(--radius-full);
}

.skills__tip {
  margin-top: 24px;
  padding: 16px;
  border-radius: var(--radius-sm);
  background: var(--bg-tertiary);
  border: 1px solid var(--border-color);
}

.skills__tip h4 {
  font-size: 0.9rem;
  margin-bottom: 8px;
}

.skills__tip p {
  font-size: 0.82rem;
  color: var(--text-secondary);
  line-height: 1.6;
}

.skills__content {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 20px;
}

.skill-card {
  background: var(--bg-card);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-md);
  padding: 24px;
  transition: all var(--transition-normal);
}

.skill-card:hover {
  transform: translateY(-4px);
  border-color: var(--border-hover);
  box-shadow: var(--shadow-lg);
}

/* 可点击的技能卡片（进入教程详情页） */
.skill-card--clickable {
  cursor: pointer;
}

.skill-card__top {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-bottom: 16px;
}

.skill-card__icon {
  font-size: 2rem;
  display: block;
}

.skill-card__level {
  font-size: 0.72rem;
  padding: 3px 10px;
  border-radius: var(--radius-full);
  background: rgba(124, 77, 255, 0.15);
  color: var(--accent-purple);
  font-weight: 500;
}

.skill-card__title {
  font-size: 1.1rem;
  font-weight: 600;
  margin-bottom: 8px;
}

.skill-card__desc {
  font-size: 0.88rem;
  color: var(--text-secondary);
  margin-bottom: 16px;
  line-height: 1.6;
}

.skill-card__tags {
  display: flex;
  gap: 8px;
  flex-wrap: wrap;
  margin-bottom: 16px;
}

.tag {
  font-size: 0.75rem;
  padding: 3px 10px;
  border-radius: var(--radius-sm);
  background: var(--bg-tertiary);
  color: var(--text-secondary);
}

.skill-card__footer {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding-top: 16px;
  border-top: 1px solid var(--border-color);
}

.skill-card__duration {
  font-size: 0.8rem;
  color: var(--text-tertiary);
}

.skill-card__link {
  font-size: 0.85rem;
  color: var(--accent-cyan);
  font-weight: 500;
  transition: color var(--transition-fast);
}

.skill-card__link:hover {
  color: var(--accent-purple);
}

/* ========================================
   视频专区
   ======================================== */
.videos__grid {
  display: grid;
  grid-template-columns: 1fr 380px;
  gap: 24px;
}

.video-main {
  background: var(--bg-card);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-md);
  overflow: hidden;
}

.video-main__player {
  position: relative;
}

.video-main__player video {
  width: 100%;
  display: block;
  aspect-ratio: 16 / 9;
  background: #000;
}

/* 嵌入视频（B站等）iframe，与 video 同比例 */
.video-main__embed {
  width: 100%;
  display: block;
  aspect-ratio: 16 / 9;
  border: 0;
  background: #000;
}

.video-main__overlay {
  padding: 20px 24px;
}

.video-main__overlay h3 {
  font-size: 1.15rem;
  font-weight: 600;
  margin-bottom: 8px;
}

.video-main__meta {
  display: flex;
  gap: 20px;
  font-size: 0.85rem;
  color: var(--text-tertiary);
}

.video-list {
  display: flex;
  flex-direction: column;
  gap: 12px;
}

.video-item {
  display: flex;
  gap: 12px;
  padding: 12px;
  border-radius: var(--radius-sm);
  background: var(--bg-card);
  border: 1px solid var(--border-color);
  cursor: pointer;
  transition: all var(--transition-fast);
}

.video-item:hover {
  border-color: var(--border-hover);
  background: var(--bg-card-hover);
}

.video-item__thumb {
  position: relative;
  width: 140px;
  height: 80px;
  border-radius: var(--radius-sm);
  background-image: var(--img-url);
  background-size: cover;
  background-position: center;
  flex-shrink: 0;
  overflow: hidden;
}

.video-item__duration {
  position: absolute;
  bottom: 4px;
  right: 4px;
  font-size: 0.7rem;
  padding: 1px 6px;
  border-radius: 4px;
  background: rgba(0, 0, 0, 0.7);
  color: #fff;
}

.video-item__play {
  position: absolute;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%);
  font-size: 1.2rem;
  color: #fff;
  opacity: 0;
  transition: opacity var(--transition-fast);
}

.video-item:hover .video-item__play {
  opacity: 1;
}

.video-item__info {
  display: flex;
  flex-direction: column;
  justify-content: center;
  gap: 4px;
  flex: 1;
  min-width: 0;
}

.video-item__info h4 {
  font-size: 0.85rem;
  font-weight: 500;
  line-height: 1.3;
  overflow: hidden;
  text-overflow: ellipsis;
  display: -webkit-box;
  -webkit-line-clamp: 2;
  -webkit-box-orient: vertical;
}

.video-item__info span {
  font-size: 0.75rem;
  color: var(--text-tertiary);
}

/* ===== 更多视频（第 7 个起折叠分页） ===== */
.video-more {
  margin-top: 28px;
}

.video-more__head {
  display: flex;
  align-items: baseline;
  gap: 12px;
  margin-bottom: 16px;
  padding-bottom: 12px;
  border-bottom: 1px solid var(--border-color);
}

.video-more__title {
  font-size: 1.05rem;
  font-weight: 600;
}

.video-more__count {
  font-size: 0.8rem;
  color: var(--text-tertiary);
}

/* 两列网格：第 7-8 个一行，第 9-10 个一行，依此类推 */
.video-more__grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 16px;
}

/* 网格卡片：竖排布局（缩略图在上，信息在下） */
.video-item--grid {
  flex-direction: column;
  gap: 0;
  padding: 0;
  overflow: hidden;
}

.video-item--grid .video-item__thumb {
  width: 100%;
  height: 0;
  padding-bottom: 56.25%; /* 16:9 */
  border-radius: var(--radius-sm) var(--radius-sm) 0 0;
}

.video-item--grid .video-item__info {
  padding: 12px 14px;
  gap: 6px;
}

.video-item--grid .video-item__info h4 {
  font-size: 0.92rem;
  -webkit-line-clamp: 2;
}

/* 分页按钮 */
.video-more__pager {
  display: flex;
  justify-content: center;
  align-items: center;
  gap: 16px;
  margin-top: 20px;
}

.video-pager__btn {
  padding: 8px 18px;
  font-size: 0.85rem;
  font-family: inherit;
  border: 1px solid var(--border-color);
  border-radius: var(--radius-sm);
  background: var(--bg-card);
  color: var(--text-primary);
  cursor: pointer;
  transition: all var(--transition-fast);
}

.video-pager__btn:hover:not(:disabled) {
  border-color: var(--border-hover);
  background: var(--bg-card-hover);
}

.video-pager__btn:disabled {
  opacity: 0.4;
  cursor: not-allowed;
}

.video-pager__info {
  font-size: 0.85rem;
  color: var(--text-tertiary);
}

/* ========================================
   数据可视化
   ======================================== */
.charts__grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 24px;
}

.chart-card {
  background: var(--bg-card);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-md);
  padding: 24px;
  transition: border-color var(--transition-normal);
}

.chart-card:hover {
  border-color: var(--border-hover);
}

.chart-card--wide {
  grid-column: span 2;
}

.chart-card__head {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-bottom: 20px;
}

.chart-card__head h3 {
  font-size: 1rem;
  font-weight: 600;
}

.chart-card__badge {
  font-size: 0.72rem;
  padding: 3px 10px;
  border-radius: var(--radius-full);
  background: rgba(0, 212, 255, 0.1);
  color: var(--accent-cyan);
}

.chart-card__body {
  position: relative;
  height: 280px;
}

.chart-card--wide .chart-card__body {
  height: 320px;
}

/* ========================================
   学习交流社区
   ======================================== */
.community__layout {
  display: grid;
  grid-template-columns: 1fr 340px;
  gap: 32px;
  align-items: start;
}

.community__sub-title {
  font-size: 1.1rem;
  font-weight: 600;
  margin-bottom: 20px;
}

.discussion {
  display: flex;
  gap: 16px;
  padding: 20px;
  background: var(--bg-card);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-md);
  margin-bottom: 16px;
  transition: all var(--transition-fast);
}

.discussion:hover {
  border-color: var(--border-hover);
}

.discussion__avatar {
  width: 44px;
  height: 44px;
  border-radius: 50%;
  background: var(--gradient-primary);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1.1rem;
  font-weight: 600;
  color: #fff;
  flex-shrink: 0;
}

.discussion__avatar--alt {
  background: var(--gradient-secondary);
}

.discussion__content {
  flex: 1;
  min-width: 0;
}

.discussion__head {
  display: flex;
  align-items: center;
  gap: 12px;
  margin-bottom: 8px;
}

.discussion__author {
  font-weight: 500;
  font-size: 0.9rem;
}

.discussion__time {
  font-size: 0.8rem;
  color: var(--text-tertiary);
}

.discussion__title {
  font-size: 1rem;
  font-weight: 600;
  margin-bottom: 6px;
}

.discussion__text {
  font-size: 0.88rem;
  color: var(--text-secondary);
  margin-bottom: 10px;
  line-height: 1.6;
}

.discussion__tags {
  display: flex;
  gap: 8px;
  flex-wrap: wrap;
  margin-bottom: 10px;
}

.discussion__stats {
  display: flex;
  gap: 20px;
  font-size: 0.8rem;
  color: var(--text-tertiary);
}

.community__more {
  margin-top: 8px;
}

/* --- 讨论区互动：点赞 / 评论 --- */
.like-btn {
  display: inline-flex;
  align-items: center;
  gap: 4px;
  padding: 2px 10px;
  border: 1px solid var(--border-color);
  border-radius: 999px;
  background: var(--bg-tertiary);
  color: var(--text-secondary);
  font-size: 0.8rem;
  cursor: pointer;
  transition: all 0.2s ease;
  line-height: 1.6;
  font-family: inherit;
}
.like-btn:hover {
  border-color: var(--accent-cyan);
  color: var(--accent-cyan);
}
.like-btn.is-liked {
  border-color: var(--accent-cyan);
  background: rgba(0, 212, 255, 0.1);
  color: var(--accent-cyan);
}
.like-btn__count {
  font-weight: 700;
}

/* 已审核评论列表 */
.discussion-comments {
  margin-top: 12px;
  padding-left: 8px;
  border-left: 2px solid var(--border-color);
  display: flex;
  flex-direction: column;
  gap: 10px;
}
.discussion-comment {
  padding: 10px 14px;
  background: var(--bg-tertiary);
  border-radius: var(--radius-sm);
}
.discussion-comment__head {
  display: flex;
  align-items: center;
  gap: 10px;
  margin-bottom: 4px;
}
.discussion-comment__author {
  font-size: 0.8rem;
  font-weight: 700;
  color: var(--accent-cyan);
}
.discussion-comment__time {
  font-size: 0.72rem;
  color: var(--text-tertiary);
}
.discussion-comment__text {
  font-size: 0.85rem;
  color: var(--text-secondary);
  line-height: 1.55;
  margin: 0;
}

/* 留言折叠：主页只显示最新 1 条 */
.discussion-comments__latest {
  position: relative;
}

.discussion-comments__badge {
  display: inline-block;
  font-size: 0.7rem;
  font-weight: 600;
  color: var(--accent-cyan);
  margin-bottom: 6px;
  padding: 1px 8px;
  border: 1px solid currentColor;
  border-radius: 10px;
  opacity: 0.9;
}

/* "查看全部 N 条留言" 按钮 */
.comments-toggle {
  display: inline-block;
  margin-top: 8px;
  padding: 6px 14px;
  font-size: 0.78rem;
  font-family: inherit;
  color: var(--text-secondary);
  background: none;
  border: 1px dashed var(--border-color);
  border-radius: var(--radius-sm);
  cursor: pointer;
  transition: all var(--transition-fast);
}

.comments-toggle:hover {
  color: var(--accent-cyan);
  border-color: var(--accent-cyan);
}

/* 展开的全部留言（分页） */
.discussion-comments__all {
  margin-top: 10px;
  padding-top: 10px;
  border-top: 1px dashed var(--border-color);
}

.discussion-comments__list {
  display: flex;
  flex-direction: column;
  gap: 10px;
}

.comments-pager {
  display: flex;
  justify-content: center;
  align-items: center;
  gap: 14px;
  margin-top: 12px;
}

/* 我也说两句 */
.discussion-reply {
  margin-top: 12px;
}
.discussion-reply__toggle {
  background: none;
  border: 1px dashed var(--border-color);
  color: var(--text-secondary);
  font-size: 0.8rem;
  padding: 6px 14px;
  border-radius: 999px;
  cursor: pointer;
  transition: all 0.2s ease;
  font-family: inherit;
}
.discussion-reply__toggle:hover {
  color: var(--accent-cyan);
  border-color: var(--accent-cyan);
}
.reply-form {
  margin-top: 10px;
  display: flex;
  flex-direction: column;
  gap: 8px;
}
.reply-form__row {
  display: flex;
  gap: 8px;
}
.reply-form__name {
  flex: 1;
  min-width: 0;
  padding: 8px 12px;
  border-radius: var(--radius-sm);
  background: var(--bg-tertiary);
  border: 1px solid var(--border-color);
  color: var(--text-primary);
  font-size: 0.85rem;
  outline: none;
  font-family: inherit;
}
.reply-form__content {
  width: 100%;
  min-height: 64px;
  padding: 10px 12px;
  border-radius: var(--radius-sm);
  background: var(--bg-tertiary);
  border: 1px solid var(--border-color);
  color: var(--text-primary);
  font-size: 0.85rem;
  outline: none;
  resize: vertical;
  font-family: inherit;
  box-sizing: border-box;
}
.reply-form__name:focus,
.reply-form__content:focus {
  border-color: var(--accent-cyan);
}

.community__sidebar {
  position: sticky;
  top: calc(var(--header-height) + 24px);
  display: flex;
  flex-direction: column;
  gap: 20px;
}

.join-card {
  background: var(--bg-card);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-md);
  padding: 28px 24px;
  text-align: center;
}

.join-card h3 {
  font-size: 1.2rem;
  font-weight: 700;
  margin-bottom: 8px;
}

.join-card > p {
  font-size: 0.88rem;
  color: var(--text-secondary);
  margin-bottom: 20px;
}

.join-form {
  display: flex;
  flex-direction: column;
  gap: 12px;
}

.join-form input {
  padding: 12px 16px;
  border-radius: var(--radius-sm);
  background: var(--bg-tertiary);
  border: 1px solid var(--border-color);
  color: var(--text-primary);
  outline: none;
  transition: border-color var(--transition-fast);
}

.join-form input:focus {
  border-color: var(--accent-cyan);
}

.join-form input::placeholder {
  color: var(--text-tertiary);
}

.join-card__note {
  margin-top: 16px;
  font-size: 0.85rem;
  color: var(--text-tertiary);
}

.join-card__note a {
  color: var(--accent-cyan);
}

.contributor-card {
  background: var(--bg-card);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-md);
  padding: 24px;
}

.contributor-card h3 {
  font-size: 1rem;
  font-weight: 600;
  margin-bottom: 16px;
}

.contributor-list {
  display: flex;
  flex-direction: column;
  gap: 12px;
}

.contributor-list li {
  display: flex;
  align-items: center;
  gap: 12px;
  padding: 8px 0;
}

.contributor-list__rank {
  width: 24px;
  height: 24px;
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 0.75rem;
  font-weight: 600;
  background: var(--bg-tertiary);
  color: var(--text-tertiary);
  flex-shrink: 0;
}

.contributor-list li:nth-child(1) .contributor-list__rank {
  background: var(--accent-orange);
  color: #000;
}

.contributor-list li:nth-child(2) .contributor-list__rank {
  background: var(--text-tertiary);
  color: #fff;
}

.contributor-list li:nth-child(3) .contributor-list__rank {
  background: #cd7f32;
  color: #fff;
}

.contributor-list__avatar {
  width: 32px;
  height: 32px;
  border-radius: 50%;
  background: var(--gradient-primary);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 0.85rem;
  color: #fff;
  font-weight: 500;
}

.contributor-list__name {
  flex: 1;
  font-size: 0.88rem;
}

.contributor-list__score {
  font-size: 0.82rem;
  font-family: "JetBrains Mono", monospace;
  color: var(--accent-cyan);
  font-weight: 500;
}

/* ========================================
   Footer
   ======================================== */
.footer {
  background: var(--bg-secondary);
  border-top: 1px solid var(--border-color);
  padding: 64px 0 32px;
}

.footer__grid {
  display: grid;
  grid-template-columns: 2fr 1fr 1fr 1fr;
  gap: 40px;
  margin-bottom: 40px;
}

.footer__col--brand {
  max-width: 360px;
}

.logo--footer {
  margin-bottom: 16px;
}

.footer__desc {
  font-size: 0.88rem;
  color: var(--text-secondary);
  line-height: 1.7;
  margin-bottom: 20px;
}

.footer__social {
  display: flex;
  gap: 12px;
}

.footer__social-link {
  width: 40px;
  height: 40px;
  border-radius: var(--radius-sm);
  display: flex;
  align-items: center;
  justify-content: center;
  border: 1px solid var(--border-color);
  color: var(--text-secondary);
  transition: all var(--transition-fast);
}

.footer__social-link:hover {
  border-color: var(--accent-cyan);
  color: var(--accent-cyan);
  transform: translateY(-2px);
}

.footer__title {
  font-size: 0.95rem;
  font-weight: 600;
  margin-bottom: 16px;
}

.footer__links li {
  margin-bottom: 10px;
}

.footer__links a {
  font-size: 0.88rem;
  color: var(--text-secondary);
  transition: color var(--transition-fast);
}

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

.footer__bottom {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding-top: 24px;
  border-top: 1px solid var(--border-color);
  font-size: 0.82rem;
  color: var(--text-tertiary);
}

.footer__built {
  font-family: "JetBrains Mono", monospace;
}

/* ========================================
   返回顶部
   ======================================== */
.back-to-top {
  position: fixed;
  bottom: 30px;
  right: 30px;
  width: 44px;
  height: 44px;
  border-radius: 50%;
  background: var(--gradient-primary);
  color: #fff;
  display: flex;
  align-items: center;
  justify-content: center;
  box-shadow: var(--shadow-md);
  z-index: 900;
  opacity: 0;
  visibility: hidden;
  transform: translateY(20px);
  transition: all var(--transition-normal);
}

.back-to-top--visible {
  opacity: 1;
  visibility: visible;
  transform: translateY(0);
}

.back-to-top:hover {
  transform: translateY(-4px);
  box-shadow: var(--shadow-lg);
}

/* ========================================
   滚动揭示动画
   ======================================== */
.reveal {
  opacity: 0;
  transform: translateY(30px);
  transition: opacity 0.6s ease, transform 0.6s ease;
}

.reveal--visible {
  opacity: 1;
  transform: translateY(0);
}

/* ========================================
   响应式 — 平板
   ======================================== */
@media (max-width: 1024px) {
  .news__grid {
    grid-template-columns: repeat(2, 1fr);
  }

  .news-card--featured {
    grid-column: span 2;
    flex-direction: column;
  }

  .news-card--featured .news-card__img {
    width: 100%;
    min-height: 200px;
    padding-top: 50%;
  }

  .news-card--featured .news-card__body {
    width: 100%;
  }

  .skills__layout {
    grid-template-columns: 220px 1fr;
  }

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

  .videos__grid {
    grid-template-columns: 1fr;
  }

  /* 平板及手机：视频列表纵向排列，不横向 */
  .video-list {
    flex-direction: column;
    flex-wrap: nowrap;
  }

  .video-item {
    flex: none;
    min-width: 0;
  }

  .charts__grid {
    grid-template-columns: 1fr;
  }

  .chart-card--wide {
    grid-column: span 1;
  }

  .community__layout {
    grid-template-columns: 1fr;
  }

  .community__sidebar {
    position: static;
    flex-direction: row;
    flex-wrap: wrap;
  }

  .join-card,
  .contributor-card {
    flex: 1 1 300px;
  }

  .footer__grid {
    grid-template-columns: 1fr 1fr;
  }

  .footer__col--brand {
    grid-column: span 2;
  }
}

/* ========================================
   响应式 — 手机
   ======================================== */
@media (max-width: 768px) {
  :root {
    --container-pad: 16px;
    --header-height: 60px;
  }

  .section {
    padding: 56px 0;
  }

  .section__header {
    margin-bottom: 40px;
  }

  /* 导航 */
  .nav {
    position: fixed;
    top: var(--header-height);
    left: 0;
    right: 0;
    background: var(--bg-secondary);
    border-bottom: 1px solid var(--border-color);
    flex-direction: column;
    padding: 16px;
    gap: 0;
    transform: translateY(-200%);
    transition: transform var(--transition-normal);
    z-index: 999;
  }

  .nav--open {
    transform: translateY(0);
  }

  .nav__link {
    padding: 14px 16px;
    border-radius: var(--radius-sm);
  }

  .nav__link:hover,
  .nav__link--active {
    background: var(--bg-tertiary);
  }

  .nav__link::after {
    display: none;
  }

  .header__menu-btn {
    display: flex;
  }

  /* Hero */
  .hero {
    min-height: auto;
    padding: calc(var(--header-height) + 40px) 0 48px;
  }

  .hero__stats {
    gap: 24px;
  }

  .stat__num {
    font-size: 1.5rem;
  }

  .hero__actions {
    flex-direction: column;
    align-items: stretch;
    max-width: 280px;
    margin-left: auto;
    margin-right: auto;
  }

  .hero__scroll {
    display: none;
  }

  /* 要闻 */
  .news__grid {
    grid-template-columns: 1fr;
  }

  .news-card--featured {
    grid-column: span 1;
  }

  /* 技能 */
  .skills__layout {
    grid-template-columns: 1fr;
  }

  .skills__sidebar {
    position: static;
  }

  .skills__paths {
    flex-direction: row;
    flex-wrap: wrap;
    gap: 8px;
  }

  .path-item {
    padding: 8px 14px;
  }

  .path-item__count {
    display: none;
  }

  .skills__tip {
    display: none;
  }

  .skills__content {
    grid-template-columns: 1fr;
  }

  /* 视频 */
  .video-list {
    flex-direction: column;
    flex-wrap: nowrap;
    gap: 10px;
  }

  /* 手机端：更多视频单列向下排列，从第 7 个起分页折叠 */
  .video-more {
    margin-top: 20px;
  }

  .video-more__grid {
    grid-template-columns: 1fr;
    gap: 12px;
  }

  .video-more__pager {
    gap: 10px;
    margin-top: 16px;
  }

  .video-pager__btn {
    padding: 7px 14px;
    font-size: 0.8rem;
  }

  .video-item {
    flex: none;
    min-width: 0;
    padding: 10px;
    gap: 10px;
  }

  .video-item__thumb {
    width: 104px;
    height: 60px;
    flex-shrink: 0;
  }

  .video-item__info h4 {
    font-size: 0.82rem;
    -webkit-line-clamp: 2;
  }

  .video-item__info span {
    font-size: 0.72rem;
  }

  .video-item__duration {
    font-size: 0.65rem;
    padding: 1px 4px;
  }

  /* 社区 */
  .community__sidebar {
    flex-direction: column;
  }

  /* Footer */
  .footer__grid {
    grid-template-columns: repeat(2, 1fr);
    gap: 28px 20px;
  }

  .footer__col--brand {
    grid-column: span 2;
    max-width: none;
    text-align: center;
  }

  .footer__col--brand .footer__social {
    justify-content: center;
  }

  .footer__col:last-child {
    grid-column: span 2;
  }

  .footer__col:last-child .footer__links {
    display: flex;
    flex-wrap: wrap;
    justify-content: center;
    gap: 8px 24px;
  }

  .footer__col:last-child .footer__links li {
    margin-bottom: 0;
  }

  .footer__bottom {
    flex-direction: column;
    gap: 8px;
    text-align: center;
  }

  /* 返回顶部 */
  .back-to-top {
    bottom: 20px;
    right: 20px;
    width: 40px;
    height: 40px;
  }
}

/* ========================================
   响应式 — 小手机
   ======================================== */
@media (max-width: 420px) {
  .hero__title {
    font-size: 2rem;
  }

  .hero__stats {
    gap: 16px;
  }

  .stat__num {
    font-size: 1.25rem;
  }

  .news__filter {
    gap: 8px;
  }

  .filter-btn {
    padding: 6px 14px;
    font-size: 0.82rem;
  }
}

/* ========================================
   减弱动画 (无障碍)
   ======================================== */
@media (prefers-reduced-motion: reduce) {
  *,
  *::before,
  *::after {
    animation-duration: 0.01ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.01ms !important;
    scroll-behavior: auto !important;
  }

  .reveal {
    opacity: 1;
    transform: none;
  }
}

/* ========================================
   站内搜索
   ======================================== */
.search-toggle {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 7px;
  height: 40px;
  padding: 0 14px;
  border-radius: var(--radius-sm);
  border: 1px solid var(--border-color);
  background: transparent;
  color: var(--text-secondary);
  font-size: 0.85rem;
  cursor: pointer;
  transition: all var(--transition-fast);
}

.search-toggle__label-short {
  display: none;
}

.search-toggle:hover {
  border-color: var(--accent-cyan);
  color: var(--accent-cyan);
}

@media (max-width: 480px) {
  .search-toggle {
    padding: 0 10px;
    font-size: 0.8rem;
  }
  .search-toggle__label-full {
    display: none;
  }
  .search-toggle__label-short {
    display: inline;
  }
}

.search-overlay {
  position: fixed;
  inset: 0;
  z-index: 1000;
  display: flex;
  align-items: flex-start;
  justify-content: center;
  padding: 120px 20px 20px;
  background: rgba(0, 0, 0, 0.55);
  opacity: 0;
  visibility: hidden;
  transition: opacity var(--transition-normal), visibility var(--transition-normal);
}

.search-overlay--open {
  opacity: 1;
  visibility: visible;
}

.search-modal {
  width: 100%;
  max-width: 640px;
  background: var(--bg-card);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow-xl);
  overflow: hidden;
  transform: translateY(-12px);
  transition: transform var(--transition-normal);
}

.search-overlay--open .search-modal {
  transform: translateY(0);
}

.search-input-wrap {
  display: flex;
  align-items: center;
  gap: 12px;
  padding: 14px 18px;
  border-bottom: 1px solid var(--border-color);
}

.search-input__icon {
  flex-shrink: 0;
  color: var(--text-tertiary);
}

.search-input {
  flex: 1;
  border: none;
  background: transparent;
  color: var(--text-primary);
  font-size: 1rem;
  outline: none;
}

.search-input::placeholder {
  color: var(--text-tertiary);
}

.search-kbd {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-width: 52px;
  padding: 4px 8px;
  border: 1px solid var(--border-color);
  border-radius: var(--radius-sm);
  background: var(--bg-body);
  color: var(--text-tertiary);
  font-family: var(--font-mono);
  font-size: 0.75rem;
}

.search-results {
  max-height: 320px;
  overflow-y: auto;
  padding: 8px;
}

.search-empty,
.search-no-results {
  padding: 32px 16px;
  text-align: center;
  color: var(--text-tertiary);
  font-size: 0.9rem;
}

.search-result-item {
  display: block;
  padding: 12px 14px;
  border-radius: var(--radius-sm);
  text-decoration: none;
  color: inherit;
  cursor: pointer;
  transition: background var(--transition-fast);
}

.search-result-item:hover,
.search-result-item--active {
  background: var(--bg-body);
}

.search-result__meta {
  display: flex;
  align-items: center;
  gap: 10px;
  margin-bottom: 6px;
}

.search-result__badge {
  flex-shrink: 0;
  padding: 2px 8px;
  border-radius: 999px;
  font-size: 0.7rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.02em;
}

.search-result__badge--article { background: rgba(0, 212, 255, 0.12); color: var(--accent-cyan); }
.search-result__badge--skill { background: rgba(124, 77, 255, 0.15); color: #a88aff; }
.search-result__badge--video { background: rgba(255, 107, 107, 0.12); color: #ff6b6b; }

.search-result__title {
  font-size: 0.95rem;
  font-weight: 600;
  color: var(--text-primary);
  overflow: hidden;
  text-overflow: ellipsis;
  white-space: nowrap;
}

.search-result__desc {
  font-size: 0.82rem;
  color: var(--text-secondary);
  line-height: 1.5;
  display: -webkit-box;
  -webkit-line-clamp: 2;
  -webkit-box-orient: vertical;
  overflow: hidden;
}

.search-footer {
  display: flex;
  gap: 16px;
  align-items: center;
  justify-content: flex-end;
  padding: 10px 18px;
  border-top: 1px solid var(--border-color);
  font-size: 0.75rem;
  color: var(--text-tertiary);
}

.search-footer kbd {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-width: 24px;
  padding: 2px 5px;
  margin: 0 2px;
  border: 1px solid var(--border-color);
  border-radius: 4px;
  background: var(--bg-body);
  font-family: var(--font-mono);
  font-size: 0.7rem;
}

@media (max-width: 640px) {
  .search-overlay {
    padding: 80px 12px 12px;
  }

  .search-kbd {
    display: none;
  }

  .search-footer {
    display: none;
  }
}

/* ========================================
   移动端溢出防护（长文本/长链接不撑破布局）
   ======================================== */
.discussion__text,
.discussion-comment__text,
.news-card__excerpt,
.search-result__excerpt,
.article-content,
.footer__desc,
.hero__desc {
  overflow-wrap: break-word;
  word-break: break-word;
}

/* 容器与网格子项防溢出 */
.container,
.hero__content,
.community__main,
.community__sidebar,
.skills__content,
.skills__layout {
  min-width: 0;
}