/* ============================================================
   ydckcode 原点创客 首页 —— 核桃编程风格忠实复刻 (hta.css)
   视觉规范以 hetao101.com 实测值为准：
   - 导航 fixed 80px 半透明白 rgba(255,255,255,.4) 阴影 0 5px 25px rgba(0,0,0,.05)
   - 首屏 banner rgb(228,235,255) 浅蓝 100vh
   - 浩瀚宇宙 rgb(29,29,29) 深黑 + 星尘 canvas
   - 科技区块 rgb(11,11,11)
   - 页脚 rgb(255,80,0) 橙
   ============================================================ */
* { margin: 0; padding: 0; box-sizing: border-box; }
html { scroll-behavior: smooth; }
body {
  font-family: "PingFang SC", "Helvetica Neue", Helvetica, "Hiragino Sans GB", "Microsoft YaHei", Arial, sans-serif;
  font-size: 14px; color: #323232; background: #fff; line-height: 1.6; overflow-x: hidden;
}
a { text-decoration: none; color: inherit; }
ul, ol { list-style: none; }
img { max-width: 100%; display: block; }

.wrap_box { max-width: 1280px; margin: 0 auto; padding: 50px 20px; position: relative; }

/* ============ 导航（复刻核桃 fixed 半透明） ============ */
.nav {
  position: fixed; top: 0; left: 0; right: 0; height: 80px; padding: 0 40px;
  background: rgba(255,255,255,0.4);
  -webkit-backdrop-filter: blur(12px); backdrop-filter: blur(12px);
  box-shadow: 0 5px 25px rgba(0,0,0,0.05);
  display: flex; align-items: center; justify-content: space-between;
  z-index: 1000; transition: background .3s;
}
.nav.scrolled { background: rgba(255,255,255,0.92); }
.nav .logo {
  display: flex; align-items: center; gap: 6px; flex: 0 0 auto;
  font-size: 26px; font-weight: 800; color: #1D2129; letter-spacing: 1px; white-space: nowrap;
}
.nav .logo .dot { width: 10px; height: 10px; border-radius: 50%; background: #167BFF; display: inline-block; }
.nav_link { display: flex; align-items: center; flex: 1 1 auto; justify-content: center; }
.nav_link a {
  font-size: 18px; color: rgb(50,50,50); padding: 8px 20px; line-height: 28px;
  white-space: nowrap; transition: color .2s;
}
.nav_link a:hover { color: #167BFF; }
.nav_link a.current { color: #167BFF; font-weight: 700; }
.nav_link .dd { position: relative; }
.nav_link .dd-menu {
  display: none; position: absolute; top: 100%; left: 50%; transform: translateX(-50%);
  min-width: 220px; background: rgba(255,255,255,.97); border-radius: 10px;
  box-shadow: 0 12px 32px rgba(0,0,0,.12); padding: 8px; z-index: 1001;
}
.nav_link .dd:hover .dd-menu { display: block; }
.nav_link .dd-menu a { display: block; font-size: 15px; padding: 10px 14px; color: #4E5969; border-radius: 8px; white-space: nowrap; }
.nav_link .dd-menu a:hover { background: #eef4ff; color: #167BFF; }

.nav_right { display: flex; align-items: center; gap: 10px; flex: 0 0 auto; }
.nav_right .user-pa-btn {
  font-size: 15px; color: #323232; padding: 7px 18px; border-radius: 20px;
  border: 1px solid rgba(0,0,0,.15); background: rgba(255,255,255,.6); transition: all .2s; white-space: nowrap;
}
.nav_right .user-pa-btn:hover { border-color: #167BFF; color: #167BFF; }
.nav_right .user-pa-btn.primary { background: #FF8819; border-color: #FF8819; color: #fff; }
.nav_right .user-pa-btn.primary:hover { background: #e9750a; color: #fff; }
.nav_right .bell { position: relative; font-size: 22px; color: #323232; padding: 6px; cursor: pointer; }
.nav_right .bell .badge { position: absolute; top: 0; right: 0; min-width: 16px; height: 16px; background: #fc486f; color: #fff; font-size: 11px; border-radius: 8px; text-align: center; line-height: 16px; padding: 0 4px; }
.akc-hamburger { display: none; flex-direction: column; justify-content: center; gap: 5px; width: 42px; height: 42px; border: none; border-radius: 10px; cursor: pointer; background: rgba(255,255,255,.6); padding: 11px 10px; }
.akc-hamburger span { display: block; height: 2.5px; border-radius: 2px; background: #3A4150; }

/* ============ 首屏 Banner（浅蓝 全屏图） ============ */
.banner_wrap {
  position: relative; width: 100%; height: 100vh; min-height: 700px;
  background: rgb(228,235,255); overflow: hidden;
}
.banner_wrap .banner_bg {
  position: absolute; inset: 0; z-index: 1;
  background-color:#E4EBFF;
  background-image:linear-gradient(135deg,#E4EBFF 0%,#F4F8FF 55%,#EAF1FF 100%);
  background-repeat:no-repeat;
  background-position:center center;
  background-size:cover;
}
.banner_wrap .banner_bg::after {
  content: ""; position: absolute; inset: 0;
  background: linear-gradient(90deg, rgba(228,235,255,.94) 0%, rgba(228,235,255,.72) 34%, rgba(228,235,255,.25) 62%, rgba(228,235,255,.05) 100%);
}
.banner_wrap .banner_title { position: absolute; z-index: 3; left: 7%; top: 50%; transform: translateY(-50%); width: 620px; max-width: 88%; }
.banner_wrap .banner_title h1 { font-size: 72px; font-weight: 800; color: #1D2129; line-height: 1.15; letter-spacing: 2px; }
.banner_wrap .banner_title h1 .accent { color: #FF8819; }
.banner_wrap .banner_title .sub { margin-top: 18px; font-size: 26px; font-weight: 600; color: #323232; }
.banner_wrap .banner_title .desc { margin-top: 14px; font-size: 16px; color: #4E5969; line-height: 1.8; max-width: 520px; }
.banner_wrap .banner_title .btns { margin-top: 34px; display: flex; gap: 16px; flex-wrap: wrap; }
.banner_wrap .banner_title .btn {
  display: inline-block; padding: 14px 34px; border-radius: 999px; font-size: 17px; font-weight: 700;
  transition: all .25s; cursor: pointer; border: none;
}
.banner_wrap .banner_title .btn.primary { background: #FF8819; color: #fff; box-shadow: 0 8px 22px rgba(255,136,25,.4); }
.banner_wrap .banner_title .btn.primary:hover { transform: translateY(-2px); box-shadow: 0 12px 28px rgba(255,136,25,.5); }
.banner_wrap .banner_title .btn.ghost { background: #fff; color: #167BFF; border: 1px solid rgba(22,123,255,.35); }
.banner_wrap .banner_title .btn.ghost:hover { background: #eef4ff; transform: translateY(-2px); }

/* ============ 浩瀚宇宙 Starry Sky ============ */
.starry_sky { position: relative; background: rgb(29,29,29); overflow: hidden; min-height: 560px; }
.starry_sky #starrySky { position: absolute; top: 0; left: 0; width: 100%; height: 100%; z-index: 0; }
.starry_sky .wrap_box { z-index: 1; padding-top: 120px; }
.starry_sky .title { font-size: 38px; font-weight: 600; color: #fff; line-height: 56px; text-align: center; }
.starry_sky .subtitle { font-size: 20px; color: #fff; line-height: 36px; text-align: center; margin-top: 6px; }
.course_grid { display: grid; grid-template-columns: repeat(4, 1fr); gap: 22px; margin-top: 42px; }
.course_card {
  position: relative; border-radius: 12px; overflow: hidden; background: rgba(255,255,255,.06);
  border: 1px solid rgba(255,255,255,.12); cursor: pointer; transition: transform .3s, border-color .3s, box-shadow .3s;
}
.course_card:hover { transform: translateY(-6px); border-color: rgba(255,255,255,.35); box-shadow: 0 18px 40px rgba(0,0,0,.45); }
.course_card .img { width: 100%; aspect-ratio: 16 / 10; object-fit: cover; display: block; }
.course_card .name {
  padding: 14px 16px; font-size: 18px; font-weight: 600; color: #fff; text-align: center;
  background: linear-gradient(180deg, rgba(255,255,255,0) 0%, rgba(0,0,0,.35) 100%);
}

/* ============ 科技区块 Programming（深色 科技感） ============ */
.programming { position: relative; background: rgb(11,11,11); overflow: hidden; }
.programming::before {
  content: ""; position: absolute; inset: 0; opacity: .5;
  background:
    radial-gradient(700px 400px at 85% 15%, rgba(22,123,255,.22), transparent 60%),
    radial-gradient(600px 380px at 10% 85%, rgba(255,136,25,.16), transparent 60%),
    linear-gradient(rgba(255,255,255,.035) 1px, transparent 1px),
    linear-gradient(90deg, rgba(255,255,255,.035) 1px, transparent 1px);
  background-size: auto, auto, 48px 48px, 48px 48px;
}
.programming .wrap_box { z-index: 1; }
.programming .title { font-size: 38px; font-weight: 600; color: #fff; text-align: center; line-height: 56px; }
.programming .subtitle { font-size: 20px; color: rgba(255,255,255,.85); text-align: center; margin-top: 6px; }
.tech_grid { display: grid; grid-template-columns: repeat(2, 1fr); gap: 26px; margin-top: 42px; }
.tech_card {
  display: flex; gap: 20px; align-items: center; background: rgba(255,255,255,.05);
  border: 1px solid rgba(255,255,255,.14); border-radius: 16px; padding: 22px; transition: all .3s;
}
.tech_card:hover { background: rgba(255,255,255,.09); border-color: rgba(255,255,255,.3); transform: translateY(-4px); }
.tech_card .icon { width: 96px; height: 96px; border-radius: 14px; overflow: hidden; flex: 0 0 auto; }
.tech_card .icon img { width: 100%; height: 100%; object-fit: cover; }
.tech_card .info .t { font-size: 22px; font-weight: 700; color: #fff; }
.tech_card .info .d { font-size: 14px; color: rgba(255,255,255,.7); margin-top: 8px; line-height: 1.7; }

/* ============ 荣耀见证 / 证书 ============ */
.carousel-container { background: #fff; overflow: hidden; }
.carousel_title { text-align: center; }
.carousel_title .title { font-size: 38px; font-weight: 600; color: #323232; line-height: 56px; }
.carousel_title .subtitle { font-size: 18px; color: #86909C; margin-top: 4px; }
.cert_marquee { position: relative; overflow: hidden; padding: 30px 0 50px; }
.cert_track { display: flex; gap: 26px; width: max-content; animation: certScroll 36s linear infinite; }
.cert_track:hover { animation-play-state: paused; }
@keyframes certScroll { 0% { transform: translateX(0); } 100% { transform: translateX(-50%); } }
.cert_item { width: 260px; flex: 0 0 auto; border-radius: 12px; overflow: hidden; box-shadow: 0 8px 24px rgba(0,0,0,.1); background: #F7FAFF; }
.cert_item img { width: 100%; height: 360px; object-fit: cover; }

/* ============ 学生作品 ============ */
.works_section { background: #F7FAFF; }
.works_section .title { font-size: 38px; font-weight: 600; color: #323232; text-align: center; line-height: 56px; }
.works_section .subtitle { font-size: 18px; color: #86909C; text-align: center; margin-top: 4px; }
.works_grid { display: grid; grid-template-columns: repeat(4, 1fr); gap: 22px; margin-top: 40px; }
.work_card { background: #fff; border-radius: 14px; overflow: hidden; box-shadow: 0 6px 18px rgba(0,0,0,.06); transition: all .3s; cursor: pointer; }
.work_card:hover { transform: translateY(-6px); box-shadow: 0 16px 34px rgba(0,0,0,.14); }
.work_card .img { width: 100%; aspect-ratio: 4/3; object-fit: cover; }
.work_card .meta { padding: 14px 16px; }
.work_card .meta .t { font-size: 16px; font-weight: 700; color: #1D2129; }
.work_card .meta .a { font-size: 13px; color: #86909C; margin-top: 4px; }

/* ============ CTA ============ */
.cta_section { position: relative; background: rgb(11,11,11); text-align: center; padding: 90px 20px; overflow: hidden; }
.cta_section::before { content: ""; position: absolute; inset: 0; background: radial-gradient(600px 300px at 50% 0%, rgba(22,123,255,.28), transparent 65%); }
.cta_section .t { position: relative; font-size: 40px; font-weight: 800; color: #fff; }
.cta_section .d { position: relative; font-size: 18px; color: rgba(255,255,255,.8); margin-top: 14px; }
.cta_section .btn { position: relative; display: inline-block; margin-top: 34px; padding: 15px 46px; border-radius: 999px; background: #FF8819; color: #fff; font-size: 18px; font-weight: 700; box-shadow: 0 10px 28px rgba(255,136,25,.45); transition: all .25s; }
.cta_section .btn:hover { transform: translateY(-2px); box-shadow: 0 14px 34px rgba(255,136,25,.55); }

/* ============ 页脚（核桃橙） ============ */
.component_footer { background: rgb(255,80,0); color: #fff; }
.component_footer .main { max-width: 1280px; margin: 0 auto; padding: 46px 20px 0; display: flex; flex-wrap: wrap; gap: 40px; }
.component_footer .logo { font-size: 30px; font-weight: 800; color: #fff; display: flex; align-items: center; gap: 8px; flex: 0 0 100%; margin-bottom: 8px; }
.component_footer .logo .dot { width: 12px; height: 12px; border-radius: 50%; background: #fff; }
.component_footer .left { flex: 1 1 380px; }
.component_footer .left h3, .component_footer .right h3 { font-size: 20px; color: #fff; margin-bottom: 14px; }
.component_footer .left p { font-size: 14px; color: rgba(255,255,255,.92); line-height: 30px; }
.component_footer .right { flex: 1 1 300px; }
.component_footer .right a { display: inline-block; font-size: 14px; color: rgba(255,255,255,.92); margin: 0 18px 12px 0; }
.component_footer .right a:hover { color: #fff; text-decoration: underline; }
.component_footer .tips { max-width: 1280px; margin: 0 auto; padding: 20px; font-size: 12px; color: #fff; border-top: 1px solid rgb(215,69,2); margin-top: 30px; line-height: 1.8; }

/* ============ 移动端 ============ */
@media (max-width: 1024px) {
  .course_grid, .works_grid { grid-template-columns: repeat(2, 1fr); }
  .tech_grid { grid-template-columns: 1fr; }
  .banner_wrap .banner_title h1 { font-size: 52px; }
  .nav_link a { font-size: 16px; padding: 8px 12px; }
}
@media (max-width: 768px) {
  .nav { height: 64px; padding: 0 16px; }
  .nav_link { display: none; position: absolute; top: 64px; left: 0; right: 0; flex-direction: column; background: rgba(255,255,255,.97); padding: 12px 16px 20px; box-shadow: 0 12px 30px rgba(0,0,0,.12); align-items: flex-start; }
  .nav.open .nav_link { display: flex; }
  .nav_link a { width: 100%; padding: 12px 14px; font-size: 16px; }
  .nav_link .dd-menu { position: static; transform: none; box-shadow: none; background: transparent; padding: 0 0 0 16px; }
  .nav_link .dd:hover .dd-menu { display: none; }
  .nav_link .dd.open .dd-menu { display: block; }
  .akc-hamburger { display: flex; }
  .nav_right .user-pa-btn { padding: 6px 14px; font-size: 14px; }
  .banner_wrap .banner_title { left: 6%; width: 92%; }
  .banner_wrap .banner_title h1 { font-size: 40px; }
  .banner_wrap .banner_title .sub { font-size: 20px; }
  .starry_sky .title, .programming .title, .carousel_title .title, .works_section .title { font-size: 28px; line-height: 40px; }
  .course_grid, .works_grid { grid-template-columns: 1fr; }
  .cert_item { width: 200px; }
  .cert_item img { height: 280px; }
  .cta_section .t { font-size: 28px; }
}

/* ============================================================
   以下为「课程体系 / 课堂瞬间 / 学员作品 / 深色页脚」区块样式
   （移植自旧版 style.css，保证原有视觉与交互）
   ============================================================ */
:root {
  --brand-primary: #167BFF;
  --brand-accent: #FF8819;
  --text-title: #1D2129;
  --text-body: #4E5969;
  --text-secondary: #86909C;
  --bg-page: #F7FAFF;
  --bg-white: #FFFFFF;
  --border-light: rgba(0,0,0,0.06);
  --shadow-card: 0 4px 20px rgba(0,0,0,0.06);
  --shadow-hover: 0 8px 30px rgba(0,0,0,0.12);
  --radius-sm: 8px;
  --radius-md: 12px;
  --radius-lg: 16px;
}
.container { max-width: 1280px; margin: 0 auto; padding: 0 24px; }
.img-placeholder {
  background: #E5E6EB; display: flex; align-items: center; justify-content: center;
  color: var(--text-secondary); font-size: 14px; width: 100%; height: 100%;
}
.fade-in-up { opacity: 1; transform: none; }

/* ---- 星空过渡区 ---- */
.starry_scroll {
  margin: 0 auto; padding: 0; text-align: center;
  color: rgba(255,255,255,.95); font-size: 15px; font-weight: 500; letter-spacing: 2px;
}
.starry_scroll .arrow {
  display: block; font-style: normal; font-size: 18px; line-height: 1; margin-top: 6px;
  color: rgba(255,255,255,.85); animation: bounceDown 1.6s ease-in-out infinite;
}
@keyframes bounceDown { 0%,100%{ transform: translateY(0); } 50%{ transform: translateY(6px); } }
/* 挂在大图底部边缘的滚动提示（绝对定位覆盖在大图底部） */
.banner_wrap .banner-scroll {
  position: absolute; left: 0; right: 0; bottom: 22px; z-index: 5;
  color: rgba(29,33,41,.75); text-align: center; pointer-events: none;
}
.banner_wrap .banner-scroll .arrow { color: rgba(29,33,41,.65); }
@keyframes bounceDown { 0%,100%{ transform: translateY(0); } 50%{ transform: translateY(8px); } }

/* ===== 课程体系 Core Features ===== */
.features-section { padding: 60px 0; background: var(--bg-page); }
.section-header { text-align: center; margin-bottom: 48px; }
.section-title { font-size: 32px; font-weight: 800; color: var(--text-title); line-height: 1.4; margin-bottom: 8px; }
.section-subtitle { font-size: 16px; color: var(--text-secondary); }
.features-layout { display: grid; grid-template-columns: 300px 1fr; gap: 24px; align-items: start; }
.features-list { display: flex; flex-direction: column; gap: 4px; }
.feature-item {
  display: flex; align-items: center; gap: 12px; padding: 16px 20px; border-radius: var(--radius-sm);
  font-size: 17px; font-weight: 500; color: var(--text-body); cursor: pointer; transition: all 0.3s;
  position: relative; overflow: hidden;
}
.feature-item::before { content: ''; position: absolute; left: 0; top: 0; bottom: 0; width: 4px; background: var(--brand-primary); transform: scaleY(0); transition: transform 0.3s; }
.feature-item:hover { background: rgba(22,123,255,0.04); color: var(--brand-primary); }
.feature-item.active { background: linear-gradient(90deg, rgba(22,123,255,0.12) 0%, rgba(22,123,255,0.04) 100%); color: var(--brand-primary); font-weight: 600; }
.feature-item.active::before { transform: scaleY(1); }
.feature-icon { width: 28px; height: 28px; display: flex; align-items: center; justify-content: center; flex-shrink: 0; }
.features-display { position: relative; }
.feature-preview-main {
  position: relative; width: 100%; aspect-ratio: 16/9; border-radius: var(--radius-lg); overflow: hidden;
  background: linear-gradient(135deg, #1a1a2e 0%, #16213e 100%); box-shadow: 0 10px 40px rgba(0,0,0,0.15); margin-bottom: 20px;
}
.feature-preview-main img { width: 100%; height: 100%; object-fit: cover; transition: opacity 0.4s; }
.feature-enter-btn {
  position: absolute; bottom: 20px; right: 20px; padding: 10px 24px; background: var(--brand-primary); color: #fff;
  border-radius: 8px; font-size: 14px; font-weight: 600; box-shadow: 0 4px 14px rgba(22,123,255,0.4); transition: all 0.3s; z-index: 2;
}
.feature-enter-btn:hover { background: #0E6BE0; transform: translateY(-2px); box-shadow: 0 6px 20px rgba(22,123,255,0.5); }
.feature-bottom { display: grid; grid-template-columns: 1fr 1fr; gap: 20px; align-items: start; }
.feature-desc { font-size: 14px; color: var(--text-body); line-height: 1.8; }
.feature-desc p { margin-bottom: 8px; padding-left: 18px; position: relative; }
.feature-desc p::before { content: '✓'; position: absolute; left: 0; color: var(--brand-primary); font-weight: 700; }
.feature-thumbs { display: grid; grid-template-columns: 1fr 1fr; gap: 12px; }
.feature-thumb { aspect-ratio: 4/3; border-radius: var(--radius-sm); overflow: hidden; border: 2px solid var(--border-light); transition: all 0.3s; cursor: pointer; }
.feature-thumb:hover { border-color: var(--brand-primary); transform: translateY(-2px); }
.feature-thumb img { width: 100%; height: 100%; object-fit: cover; }

/* ===== 精彩课堂瞬间 ===== */
.video-section { padding: 60px 0; background: var(--bg-page); }
.video-display { aspect-ratio: 16/7; border-radius: 16px; overflow: hidden; box-shadow: 0 10px 40px rgba(0,0,0,0.1); }
.video-display img { width: 100%; height: 100%; object-fit: cover; }

/* ===== 学员优秀作品 Showcase ===== */
.showcase-section { padding: 60px 0; background: #fff; }
.showcase-tabs { display: flex; justify-content: center; gap: 8px; margin-bottom: 36px; flex-wrap: wrap; }
.showcase-tab { padding: 8px 24px; border-radius: 18px; font-size: 14px; font-weight: 500; color: var(--text-body); cursor: pointer; transition: all 0.3s; }
.showcase-tab:hover { color: var(--brand-primary); }
.showcase-tab.active { background: var(--text-title); color: #fff; }
.showcase-grid { display: grid; grid-template-columns: repeat(4, 1fr); gap: 20px; }
.showcase-card { background: #fff; border-radius: var(--radius-md); overflow: hidden; box-shadow: var(--shadow-card); transition: all 0.3s; cursor: pointer; border: 1px solid var(--border-light); }
.showcase-card:hover { transform: translateY(-6px); box-shadow: var(--shadow-hover); }
.showcase-thumb { aspect-ratio: 4/3; overflow: hidden; position: relative; }
.showcase-thumb img { width: 100%; height: 100%; object-fit: cover; transition: transform 0.4s; }
.showcase-card:hover .showcase-thumb img { transform: scale(1.05); }
.showcase-info { padding: 14px 16px; }
.showcase-title { font-size: 15px; font-weight: 600; color: var(--text-title); margin-bottom: 6px; overflow: hidden; text-overflow: ellipsis; white-space: nowrap; }
.showcase-meta { display: flex; align-items: center; justify-content: space-between; font-size: 12px; color: var(--text-secondary); }

/* ===== 深色页脚（替换橙色） ===== */
.footer { background: #1D2129; color: rgba(255,255,255,0.7); padding: 50px 0 24px; }
.footer-top { display: grid; grid-template-columns: 2fr 1fr 1fr 1fr 1fr; gap: 40px; margin-bottom: 40px; }
.footer-brand .footer-logo { display: flex; align-items: center; gap: 6px; font-size: 22px; font-weight: 700; color: #fff; margin-bottom: 16px; }
.footer-brand .footer-logo .dot { width: 8px; height: 8px; border-radius: 50%; background: var(--brand-primary); }
.footer-brand p { font-size: 13px; line-height: 1.8; margin-bottom: 16px; max-width: 280px; }
.footer-col h4 { font-size: 15px; font-weight: 600; color: #fff; margin-bottom: 18px; }
.footer-col ul { display: flex; flex-direction: column; gap: 10px; list-style: none; }
.footer-col a { font-size: 13px; color: rgba(255,255,255,0.6); transition: color 0.2s; text-decoration: none; }
.footer-col a:hover { color: #fff; }
.footer-bottom { border-top: 1px solid rgba(255,255,255,0.1); padding-top: 24px; display: flex; align-items: center; justify-content: space-between; font-size: 12px; color: rgba(255,255,255,0.4); }
.footer-bottom-links { display: flex; gap: 20px; }
.footer-bottom-links a { color: rgba(255,255,255,0.4); transition: color 0.2s; text-decoration: none; }
.footer-bottom-links a:hover { color: rgba(255,255,255,0.7); }

/* ===== 响应式（旧板块） ===== */
@media (max-width: 1100px) {
  .features-layout { grid-template-columns: 1fr; }
  .features-list { flex-direction: row; overflow-x: auto; gap: 8px; padding-bottom: 8px; }
  .feature-item { flex-shrink: 0; padding: 10px 16px; font-size: 14px; }
  .feature-item::before { display: none; }
  .showcase-grid { grid-template-columns: repeat(3, 1fr); }
  .footer-top { grid-template-columns: 1fr 1fr 1fr; }
  .footer-brand { grid-column: 1 / -1; }
}
@media (max-width: 768px) {
  .section-title { font-size: 24px; }
  .feature-bottom { grid-template-columns: 1fr; }
  .feature-thumbs { grid-template-columns: 1fr 1fr; }
  .showcase-grid { grid-template-columns: repeat(2, 1fr); }
  .showcase-tabs { flex-wrap: wrap; }
  .footer-top { grid-template-columns: 1fr 1fr; }
  .footer-bottom { flex-direction: column; gap: 12px; text-align: center; }
}
@media (max-width: 480px) {
  .showcase-grid { grid-template-columns: 1fr; }
  .footer-top { grid-template-columns: 1fr; }
}
html, body { overflow-x: hidden; }

/* ============================================================
   星空区：头条公告 + 白名单赛事/等级考试 发光按钮
   ============================================================ */
.starry_notice { margin-top: 30px; }
.starry_notice_inner {
  max-width: 860px; margin: 0 auto; display: flex; align-items: center; gap: 14px;
  background: rgba(255,255,255,0.08); border: 1px solid rgba(255,255,255,0.16);
  border-radius: 999px; padding: 12px 22px;
  -webkit-backdrop-filter: blur(8px); backdrop-filter: blur(8px);
}
.starry_notice_tag {
  flex-shrink: 0; font-size: 14px; font-weight: 700; color: #FFD166;
  background: rgba(255,209,102,0.14); padding: 4px 12px; border-radius: 999px;
  white-space: nowrap;
}
.starry_notice_text { flex: 1; min-width: 0; font-size: 15px; color: rgba(255,255,255,0.92); overflow: hidden; text-overflow: ellipsis; white-space: nowrap; }
.starry_notice_more { flex-shrink: 0; font-size: 14px; color: #7FB3FF; white-space: nowrap; text-decoration: none; }
.starry_notice_more:hover { color: #fff; }

/* 发光按钮组 */
.starry_ctas { margin-top: 26px; display: flex; justify-content: center; gap: 22px; flex-wrap: wrap; }
.starry_contest_btn {
  display: flex; align-items: center; gap: 14px; min-width: 300px;
  padding: 14px 20px; border-radius: 16px; text-decoration: none; position: relative; overflow: hidden;
  background: rgba(255,255,255,0.07); border: 1px solid rgba(255,255,255,0.18);
  transition: transform .25s ease, box-shadow .25s ease, border-color .25s ease;
}
.starry_contest_btn .sc_icon {
  width: 52px; height: 52px; border-radius: 12px; overflow: hidden; flex-shrink: 0;
  background: rgba(255,255,255,0.1); display: flex; align-items: center; justify-content: center;
}
.starry_contest_btn .sc_icon img { width: 100%; height: 100%; object-fit: cover; }
.starry_contest_btn .sc_info { display: flex; flex-direction: column; gap: 3px; flex: 1; min-width: 0; }
.starry_contest_btn .sc_badge { font-size: 12px; font-weight: 700; }
.starry_contest_btn .sc_title { font-size: 16px; font-weight: 700; color: #fff; line-height: 1.35; }
.starry_contest_btn .sc_arrow { font-size: 26px; color: rgba(255,255,255,0.75); flex-shrink: 0; transition: transform .25s ease; }
.starry_contest_btn:hover { transform: translateY(-4px); }
.starry_contest_btn:hover .sc_arrow { transform: translateX(4px); }

/* 蓝色光效（白名单赛事） */
.starry_contest_btn.blue {
  border-color: rgba(22,123,255,0.55);
  box-shadow: 0 0 18px rgba(22,123,255,0.35), inset 0 0 12px rgba(22,123,255,0.12);
}
.starry_contest_btn.blue:hover {
  border-color: rgba(82,160,255,0.9);
  box-shadow: 0 0 34px rgba(22,123,255,0.6), 0 8px 26px rgba(0,0,0,0.35), inset 0 0 18px rgba(22,123,255,0.2);
}
.starry_contest_btn.blue .sc_badge { color: #7FB3FF; }
@keyframes pulseBlue {
  0%, 100% { box-shadow: 0 0 16px rgba(22,123,255,0.32), inset 0 0 10px rgba(22,123,255,0.1); }
  50% { box-shadow: 0 0 30px rgba(22,123,255,0.55), inset 0 0 16px rgba(22,123,255,0.18); }
}
.starry_contest_btn.blue { animation: pulseBlue 3s ease-in-out infinite; }

/* 橙色光效（等级考试） */
.starry_contest_btn.orange {
  border-color: rgba(255,136,25,0.55);
  box-shadow: 0 0 18px rgba(255,136,25,0.35), inset 0 0 12px rgba(255,136,25,0.12);
}
.starry_contest_btn.orange:hover {
  border-color: rgba(255,160,70,0.9);
  box-shadow: 0 0 34px rgba(255,136,25,0.6), 0 8px 26px rgba(0,0,0,0.35), inset 0 0 18px rgba(255,136,25,0.2);
}
.starry_contest_btn.orange .sc_badge { color: #FFB25E; }
@keyframes pulseOrange {
  0%, 100% { box-shadow: 0 0 16px rgba(255,136,25,0.32), inset 0 0 10px rgba(255,136,25,0.1); }
  50% { box-shadow: 0 0 30px rgba(255,136,25,0.55), inset 0 0 16px rgba(255,136,25,0.18); }
}
.starry_contest_btn.orange { animation: pulseOrange 3s ease-in-out infinite; }

@media (max-width: 768px) {
  .starry_notice_inner { flex-wrap: wrap; border-radius: 16px; padding: 14px 16px; }
  .starry_notice_text { white-space: normal; }
  .starry_contest_btn { min-width: 100%; }
}

/* ============================================================
   V4 玻璃拟态科技风（参考 home-v4-balanced，纯 CSS 实现，不依赖 CDN）
   ============================================================ */
:root {
  --v4-primary: #1E6FFF;
  --v4-primary-hover: #0e5cd6;
  --v4-accent: #FF6B4A;
  --v4-accent-hover: #e55737;
  --v4-text: #1a1f36;
  --v4-muted: #4f566b;
  --v4-border: #e3e8ee;
  --v4-purple: #7C3AED;
  --v4-cyan: #06B6D4;
}
.v4-wrap { max-width: 1280px; margin: 0 auto; padding: 0 24px; position: relative; }
.v4-section { padding: 88px 0; position: relative; }

/* ---- 玻璃拟态 ---- */
.v4-glass {
  background: rgba(255,255,255,0.7);
  -webkit-backdrop-filter: blur(16px); backdrop-filter: blur(16px);
  border: 1px solid rgba(255,255,255,0.4);
}
.v4-glass-card {
  background: rgba(255,255,255,0.8);
  -webkit-backdrop-filter: blur(12px); backdrop-filter: blur(12px);
  border: 1px solid rgba(255,255,255,0.5);
  position: relative; overflow: hidden;
}
.v4-glass-card::before {
  content: ""; position: absolute; inset: 0; border-radius: inherit; padding: 1px;
  background: linear-gradient(135deg, rgba(30,111,255,0.3) 0%, transparent 50%, rgba(124,58,237,0.3) 100%);
  -webkit-mask: linear-gradient(#fff 0 0) content-box, linear-gradient(#fff 0 0);
  -webkit-mask-composite: xor; mask-composite: exclude; pointer-events: none;
}
.v4-glass-card::after {
  content: ""; position: absolute; bottom: 0; left: 10%; right: 10%; height: 2px;
  background: radial-gradient(circle, rgba(30,111,255,0.4) 0%, transparent 100%);
  filter: blur(2px);
}

/* ---- 渐变文字 / 科技图标 ---- */
.v4-grad-text {
  background: linear-gradient(135deg, var(--v4-primary) 0%, var(--v4-cyan) 100%);
  -webkit-background-clip: text; background-clip: text; color: transparent;
  text-shadow: 0 0 20px rgba(30,111,255,0.3);
}
.v4-tech-icon { font-family: monospace; font-weight: 700; color: var(--v4-primary); opacity: 0.8; }

/* ---- 区块标题 ---- */
.v4-sec-head { text-align: center; margin-bottom: 56px; max-width: 760px; margin-left: auto; margin-right: auto; }
.v4-sec-title { font-size: 34px; font-weight: 700; color: var(--v4-text); line-height: 1.3; letter-spacing: -0.5px; display: flex; align-items: center; justify-content: center; gap: 12px; flex-wrap: wrap; }
.v4-sec-sub { font-size: 17px; color: var(--v4-muted); margin-top: 12px; line-height: 1.7; }

/* ---- 渐变按钮（带扫光） ---- */
.v4-btn {
  display: inline-flex; align-items: center; gap: 8px; justify-content: center;
  background: linear-gradient(135deg, var(--v4-primary) 0%, var(--v4-cyan) 100%);
  color: #fff; border: none; border-radius: 12px; padding: 12px 28px;
  font-size: 15px; font-weight: 500; cursor: pointer; position: relative; overflow: hidden;
  box-shadow: 0 8px 32px rgba(30,111,255,0.15); transition: all .25s; text-decoration: none;
}
.v4-btn::before {
  content: ""; position: absolute; top: 0; left: -100%; width: 50%; height: 100%;
  background: linear-gradient(to right, transparent, rgba(255,255,255,0.3), transparent);
  transform: skewX(-20deg); transition: 0.5s;
}
.v4-btn:hover::before { left: 150%; }
.v4-btn:hover { transform: translateY(-2px); box-shadow: 0 12px 40px rgba(30,111,255,0.25); }

/* ============================================================
   星空区：头条 + 赛事卡片（v4 玻璃样式，放在深空上）—— 放大整齐版
   ============================================================ */
.v4-announce {
  margin: 18px auto 0; max-width: 1180px; display: flex; align-items: center; justify-content: space-between; gap: 20px;
  background: rgba(255,255,255,0.10); border: 1px solid rgba(255,255,255,0.18); border-radius: 16px;
  padding: 18px 28px; -webkit-backdrop-filter: blur(10px); backdrop-filter: blur(10px);
}
.v4-announce .tag {
  flex-shrink: 0; font-size: 16px; font-weight: 600; color: var(--v4-primary);
  background: rgba(30,111,255,0.15); border: 1px solid rgba(30,111,255,0.3); padding: 6px 16px; border-radius: 10px;
}
.v4-announce .text { flex: 1; min-width: 0; font-size: 17px; line-height: 1.6; color: rgba(255,255,255,0.92); overflow: hidden; text-overflow: ellipsis; white-space: nowrap; }
.v4-announce .more { flex-shrink: 0; font-size: 16px; font-weight: 500; color: #9EC5FF; text-decoration: none; display: flex; align-items: center; gap: 6px; white-space: nowrap; }
.v4-announce .more:hover { color: #fff; }

.v4-contest-grid {
  display: grid; grid-template-columns: 1fr 1fr; gap: 34px; margin: 44px auto 0;
  max-width: 1220px; align-items: stretch;
}
.v4-contest-card {
  display: flex; align-items: center; gap: 26px; padding: 30px 32px;
  background: rgba(255,255,255,0.10); border: 1px solid rgba(255,255,255,0.20); border-radius: 20px;
  -webkit-backdrop-filter: blur(10px); backdrop-filter: blur(10px);
  transition: all .3s; position: relative; overflow: hidden; text-decoration: none;
  min-height: 200px; height: 100%; box-sizing: border-box;
}
.v4-contest-card:hover { transform: translateY(-4px); border-color: rgba(30,111,255,0.65); box-shadow: 0 0 24px rgba(30,111,255,0.28); background: rgba(255,255,255,0.14); }
.v4-contest-card .badge {
  position: absolute; top: 14px; right: 14px; font-size: 12px; font-family: monospace; font-weight: 700;
  border: 1px solid; border-radius: 4px; padding: 2px 8px; opacity: 0.55; transition: opacity .3s;
}
.v4-contest-card:hover .badge { opacity: 1; }
.v4-contest-card .badge.blue { color: #9EC5FF; border-color: rgba(30,111,255,0.5); }
.v4-contest-card .badge.orange { color: #FFB08A; border-color: rgba(255,107,74,0.5); }
.v4-contest-card .thumb {
  width: 148px; height: 148px; border-radius: 16px; overflow: hidden; flex-shrink: 0;
  border: 1px solid rgba(255,255,255,0.25); background: rgba(255,255,255,0.08); padding: 4px; box-sizing: border-box;
}
.v4-contest-card .thumb > div { width: 100%; height: 100%; border-radius: 12px; overflow: hidden; }
.v4-contest-card .thumb img { width: 100%; height: 100%; object-fit: cover; }
.v4-contest-card .info { flex: 1; min-width: 0; display: flex; flex-direction: column; align-items: flex-start; }
.v4-contest-card .info .c-badge { display: inline-block; font-size: 14px; font-weight: 600; margin-bottom: 12px; padding: 5px 14px; border-radius: 8px; }
.v4-contest-card .info .c-badge.blue { color: #9EC5FF; background: rgba(30,111,255,0.15); border: 1px solid rgba(30,111,255,0.3); }
.v4-contest-card .info .c-badge.orange { color: #FFB08A; background: rgba(255,107,74,0.15); border: 1px solid rgba(255,107,74,0.3); }
.v4-contest-card .info .c-org { font-size: 14px; line-height: 1.6; color: rgba(255,255,255,0.65); margin-bottom: 14px; }
.v4-contest-card .info .c-title { font-size: 23px; font-weight: 700; color: #fff; line-height: 1.5; margin-bottom: 20px; }
.v4-contest-card .info .c-link { display: inline-flex; align-items: center; gap: 6px; font-size: 15px; font-weight: 500; color: #9EC5FF; text-decoration: none; }
.v4-contest-card .info .c-link:hover { color: #fff; }

/* ============================================================
   课程体系（v4：左侧菜单 + 右侧玻璃预览，交互切换）
   ============================================================ */
.v4-features { background: linear-gradient(180deg, #FFFFFF 0%, #F0F7FF 100%); }
.v4-features-layout { display: grid; grid-template-columns: 360px 1fr; gap: 40px; align-items: start; }
.v4-feature-menu { display: flex; flex-direction: column; gap: 10px; }
.v4-feature-item {
  display: flex; align-items: center; gap: 14px; padding: 15px 18px; border-radius: 12px;
  background: rgba(255,255,255,0.7); border: 1px solid rgba(255,255,255,0.4); cursor: pointer;
  font-size: 16px; font-weight: 500; color: var(--v4-muted); transition: all .25s; text-align: left;
}
.v4-feature-item:hover { background: rgba(255,255,255,0.9); color: var(--v4-text); border-color: #fff; }
.v4-feature-item.active {
  background: linear-gradient(90deg, rgba(30,111,255,0.12) 0%, rgba(255,255,255,0.5) 100%);
  color: var(--v4-primary); font-weight: 600; border: 1px solid rgba(30,111,255,0.25);
  box-shadow: inset 3px 0 0 var(--v4-primary);
}
.v4-feature-item .fi-icon { font-size: 22px; width: 28px; text-align: center; flex-shrink: 0; opacity: 0.85; }
.v4-feature-panel { position: sticky; top: 100px; }
.v4-feature-card { border-radius: 18px; padding: 24px; box-shadow: 0 10px 40px rgba(0,0,0,0.06); }
.v4-feature-main { position: relative; aspect-ratio: 16/9; border-radius: 14px; overflow: hidden; background: #f0f2f5; margin-bottom: 22px; border: 1px solid rgba(255,255,255,0.5); }
.v4-feature-main img { width: 100%; height: 100%; object-fit: cover; transition: transform .6s; }
.v4-feature-main:hover img { transform: scale(1.04); }
.v4-feature-main .hover-layer {
  position: absolute; inset: 0; display: flex; align-items: center; justify-content: center;
  background: linear-gradient(to top, rgba(30,111,255,0.45) 0%, transparent 100%);
  opacity: 0; transition: opacity .3s; -webkit-backdrop-filter: blur(2px); backdrop-filter: blur(2px);
}
.v4-feature-main:hover .hover-layer { opacity: 1; }
.v4-feature-body { display: grid; grid-template-columns: 1.4fr 1fr; gap: 24px; align-items: start; }
.v4-feature-body h3 { font-size: 20px; font-weight: 600; color: var(--v4-text); margin-bottom: 14px; display: flex; align-items: center; gap: 8px; }
.v4-feature-body h3 .dot { width: 8px; height: 8px; border-radius: 50%; background: var(--v4-cyan); box-shadow: 0 0 8px rgba(6,182,212,0.8); flex-shrink: 0; }
.v4-feature-body ul { display: flex; flex-direction: column; gap: 10px; }
.v4-feature-body li { display: flex; align-items: flex-start; gap: 8px; font-size: 14px; color: var(--v4-muted); line-height: 1.6; }
.v4-feature-body li svg { flex-shrink: 0; margin-top: 2px; color: var(--v4-primary); }
.v4-feature-thumbs { display: grid; grid-template-columns: 1fr 1fr; gap: 12px; }
.v4-feature-thumb { aspect-ratio: 1/1; border-radius: 10px; overflow: hidden; background: #f0f2f5; border: 1px solid rgba(255,255,255,0.6); padding: 3px; }
.v4-feature-thumb > div { width: 100%; height: 100%; border-radius: 8px; overflow: hidden; }
.v4-feature-thumb img { width: 100%; height: 100%; object-fit: cover; }

/* ============================================================
   开放创客教育生态（v4：tab 切换 + 内容）
   ============================================================ */
.v4-matrix { background: linear-gradient(180deg, #FFFFFF 0%, rgba(30,111,255,0.04) 50%, #FFFFFF 100%); border-top: 1px solid rgba(30,111,255,0.06); border-bottom: 1px solid rgba(30,111,255,0.06); }
.v4-matrix-tabs { display: flex; justify-content: center; gap: 10px; margin-bottom: 48px; flex-wrap: wrap; }
.v4-matrix-tab {
  padding: 11px 26px; border-radius: 999px; background: rgba(255,255,255,0.7); border: 1px solid rgba(255,255,255,0.4);
  color: var(--v4-muted); font-size: 14px; font-weight: 500; cursor: pointer; transition: all .25s; white-space: nowrap;
}
.v4-matrix-tab:hover { color: var(--v4-primary); background: rgba(255,255,255,0.9); }
.v4-matrix-tab.active { background: linear-gradient(135deg, #1a1f36 0%, #333a50 100%); color: #fff; border-color: #333a50; box-shadow: 0 6px 18px rgba(0,0,0,0.18); }
.v4-matrix-body { display: grid; grid-template-columns: 1fr 1fr; gap: 48px; align-items: center; }
.v4-matrix-info h3 { font-size: 30px; font-weight: 600; color: var(--v4-text); margin-bottom: 16px; }
.v4-matrix-info p { font-size: 16px; color: var(--v4-muted); line-height: 1.8; margin-bottom: 26px; }
.v4-matrix-feats { display: grid; grid-template-columns: 1fr 1fr; gap: 16px 20px; margin-bottom: 26px; }
.v4-matrix-feat { display: flex; align-items: center; gap: 10px; font-size: 14px; font-weight: 500; color: var(--v4-text); }
.v4-matrix-feat .chk {
  width: 28px; height: 28px; border-radius: 50%; background: rgba(30,111,255,0.1); color: var(--v4-primary);
  display: flex; align-items: center; justify-content: center; font-size: 14px; flex-shrink: 0; transition: all .25s;
}
.v4-matrix-feat:hover .chk { background: rgba(30,111,255,0.2); box-shadow: 0 0 10px rgba(30,111,255,0.2); }
.v4-matrix-visual { position: relative; }
.v4-matrix-shot { position: relative; aspect-ratio: 16/10; border-radius: 18px; overflow: hidden; padding: 6px; box-shadow: 0 18px 50px rgba(0,0,0,0.14); z-index: 10; }
.v4-matrix-shot > div { width: 100%; height: 100%; border-radius: 14px; overflow: hidden; background: #fff; }
.v4-matrix-shot img { width: 100%; height: 100%; object-fit: cover; }
.v4-float-card {
  position: absolute; display: flex; align-items: center; gap: 10px; padding: 12px 16px; border-radius: 14px;
  background: rgba(255,255,255,0.85); -webkit-backdrop-filter: blur(12px); backdrop-filter: blur(12px);
  border: 1px solid rgba(255,255,255,0.6); box-shadow: 0 12px 30px rgba(0,0,0,0.12); z-index: 20;
}
.v4-float-card .bar { width: 8px; height: 32px; border-radius: 999px; flex-shrink: 0; }
.v4-float-card .bar.blue { background: linear-gradient(180deg, var(--v4-primary), var(--v4-cyan)); box-shadow: 0 0 8px rgba(30,111,255,0.5); }
.v4-float-card .bar.orange { background: linear-gradient(180deg, var(--v4-accent), #fb923c); box-shadow: 0 0 8px rgba(255,107,74,0.5); }
.v4-float-card .fl-tag { font-size: 11px; color: var(--v4-muted); font-family: monospace; }
.v4-float-card .fl-title { font-size: 14px; font-weight: 600; color: var(--v4-text); }

/* ============================================================
   课堂精彩瞬间（v4：大图 + hover 遮罩）
   ============================================================ */
.v4-classroom { background: #fff; }
.v4-classroom-shot { position: relative; aspect-ratio: 21/9; border-radius: 22px; overflow: hidden; padding: 8px; box-shadow: 0 20px 60px rgba(0,0,0,0.14); }
.v4-classroom-shot > div { position: relative; width: 100%; height: 100%; border-radius: 16px; overflow: hidden; }
.v4-classroom-shot img { width: 100%; height: 100%; object-fit: cover; transition: transform .7s; }
.v4-classroom-shot:hover img { transform: scale(1.05); }
.v4-classroom-overlay {
  position: absolute; inset: 0; display: flex; align-items: flex-end;
  background: linear-gradient(to top, rgba(17,24,39,0.8) 0%, rgba(17,24,39,0.2) 55%, transparent 100%);
  opacity: 1; transition: opacity .3s;
}
.v4-classroom-shot:hover .v4-classroom-overlay { opacity: 1; }
.v4-classroom-overlay .inner { padding: 28px 36px; color: #fff; width: 100%; border-top: 1px solid rgba(255,255,255,0.2); -webkit-backdrop-filter: blur(4px); backdrop-filter: blur(4px); background: rgba(0,0,0,0.1); }
.v4-classroom-overlay h3 { font-size: 24px; font-weight: 700; margin-bottom: 8px; display: flex; align-items: center; gap: 10px; }
.v4-classroom-overlay h3 .dot { width: 10px; height: 10px; border-radius: 50%; background: var(--v4-cyan); box-shadow: 0 0 10px rgba(6,182,212,1); }
.v4-classroom-overlay p { color: rgba(255,255,255,0.8); font-size: 15px; max-width: 640px; }

/* ============================================================
   学员优秀作品（v4：玻璃卡网格 + 分类）
   ============================================================ */
.v4-works { background: linear-gradient(180deg, #F0F7FF 0%, #FFFFFF 100%); }
.v4-works-head { display: flex; align-items: flex-end; justify-content: space-between; gap: 20px; margin-bottom: 36px; flex-wrap: wrap; }
.v4-works-head .v4-sec-title { justify-content: flex-start; }
.v4-works-tabs { display: flex; justify-content: center; gap: 8px; margin-bottom: 34px; flex-wrap: wrap; }
.v4-work-tab { padding: 8px 22px; border-radius: 999px; font-size: 14px; font-weight: 500; color: var(--v4-muted); background: rgba(255,255,255,0.7); border: 1px solid rgba(255,255,255,0.4); cursor: pointer; transition: all .25s; }
.v4-work-tab:hover { color: var(--v4-primary); }
.v4-work-tab.active { background: #1a1f36; color: #fff; border-color: #1a1f36; }
.v4-works-grid { display: grid; grid-template-columns: repeat(4, 1fr); gap: 22px; }
.v4-work-card { border-radius: 14px; overflow: hidden; cursor: pointer; transition: all .3s; background: rgba(255,255,255,0.85); box-shadow: 0 4px 20px rgba(0,0,0,0.05); }
.v4-work-card:hover { transform: translateY(-6px); box-shadow: 0 0 15px rgba(30,111,255,0.15), 0 12px 30px rgba(0,0,0,0.1); }
.v4-work-card .ver { position: absolute; top: 8px; right: 8px; z-index: 10; background: rgba(0,0,0,0.4); -webkit-backdrop-filter: blur(6px); backdrop-filter: blur(6px); color: #fff; font-size: 10px; font-family: monospace; padding: 2px 8px; border-radius: 6px; border: 1px solid rgba(255,255,255,0.2); }
.v4-work-card .shot { position: relative; aspect-ratio: 4/3; overflow: hidden; background: #f0f2f5; padding: 4px; }
.v4-work-card .shot > div { width: 100%; height: 100%; border-radius: 10px; overflow: hidden; }
.v4-work-card .shot img { width: 100%; height: 100%; object-fit: cover; transition: transform .5s; }
.v4-work-card:hover .shot img { transform: scale(1.05); }
.v4-work-card .meta { padding: 14px 16px; background: rgba(255,255,255,0.6); -webkit-backdrop-filter: blur(8px); backdrop-filter: blur(8px); border-top: 1px solid rgba(255,255,255,0.4); }
.v4-work-card .meta h4 { font-size: 15px; font-weight: 600; color: var(--v4-text); margin-bottom: 8px; white-space: nowrap; overflow: hidden; text-overflow: ellipsis; }
.v4-work-card:hover .meta h4 { color: var(--v4-primary); }
.v4-work-card .meta .row { display: flex; align-items: center; justify-content: space-between; font-size: 13px; color: var(--v4-muted); }
.v4-work-card .meta .row .author { display: flex; align-items: center; gap: 6px; }
.v4-work-card .meta .row .avatar { width: 18px; height: 18px; border-radius: 50%; background: #e5e7eb; border: 1px solid #fff; }
.v4-work-card .meta .row .likes { display: flex; align-items: center; gap: 4px; color: #9ca3af; }

/* 滚动渐入动画 */
.rx { opacity: 0; transform: translateY(26px); transition: opacity .7s cubic-bezier(.2,.7,.3,1), transform .7s cubic-bezier(.2,.7,.3,1); will-change: opacity, transform; }
.rx.in-view { opacity: 1; transform: none; }

/* ============================================================
   V4 响应式
   ============================================================ */
@media (max-width: 1024px) {
  .v4-features-layout { grid-template-columns: 1fr; }
  .v4-feature-panel { position: static; }
  .v4-feature-menu { flex-direction: row; overflow-x: auto; padding-bottom: 8px; }
  .v4-feature-item { flex-shrink: 0; }
  .v4-matrix-body { grid-template-columns: 1fr; gap: 36px; }
  .v4-works-grid { grid-template-columns: repeat(3, 1fr); }
}
@media (max-width: 768px) {
  .v4-section { padding: 60px 0; }
  .v4-sec-title { font-size: 26px; }
  .v4-contest-grid { grid-template-columns: 1fr; }
  .v4-feature-body { grid-template-columns: 1fr; }
  .v4-matrix-feats { grid-template-columns: 1fr 1fr; }
  .v4-works-grid { grid-template-columns: repeat(2, 1fr); }
  .v4-announce { flex-wrap: wrap; }
  .v4-announce .text { white-space: normal; }
  .v4-classroom-overlay .inner { padding: 18px 20px; }
  .v4-classroom-overlay h3 { font-size: 18px; }
}
@media (max-width: 480px) {
  .v4-works-grid { grid-template-columns: 1fr; }
  .v4-matrix-feats { grid-template-columns: 1fr; }
}