/* ===================================================================
   银河云 YinHeYun - 天体物理黑洞视觉样式表 (Pure Native CSS)
   视觉风格：黑洞奇点 + 引力坍缩 + 天体物理
   配色方案：主背景 #000000 纯黑 | 主色 #FCD34D 吸积黄 | 次色 #FF6B35 喷流橙
   特性：无外部框架依赖、硬件加速物理动效、全端单栏自适应
   =================================================================== */

:root {
  /* 配色系统 (天体物理：黑洞与吸积盘) */
  --bg-main: #000000;
  --bg-card: #08080a;
  --bg-card-hover: #121216;
  --bg-card-alt: #050507;
  
  --primary: #FCD34D;        /* 吸积黄 */
  --primary-hover: #F59E0B;
  --primary-light: #FDE68A;
  --primary-glow: rgba(252, 211, 77, 0.55);
  
  --secondary: #FF6B35;      /* 喷流橙 */
  --secondary-hover: #EA580C;
  --secondary-glow: rgba(255, 107, 53, 0.45);
  
  --border-color: rgba(252, 211, 77, 0.16);
  --border-focus: rgba(252, 211, 77, 0.65);
  
  --text-main: #FFFFFF;
  --text-muted: #D1D5DB;
  --text-dim: #9CA3AF;
  
  --radius-sm: 6px;
  --radius-md: 8px;          /* 按钮与卡片圆角 8px 规范 */
  --radius-lg: 14px;
  --radius-full: 9999px;
  
  --shadow-card: 0 10px 30px -10px rgba(0, 0, 0, 0.85);
  --shadow-glow-amber: 0 0 30px rgba(252, 211, 77, 0.5);
  --container-width: 1200px;
  --font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", sans-serif;
}

*, *::before, *::after {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

/* ================= ACCESSIBILITY: SKIP LINK & FOCUS ================= */
.skip-link {
  position: absolute;
  top: -100px;
  left: 20px;
  background: var(--primary);
  color: #000000;
  padding: 10px 18px;
  font-weight: 700;
  font-size: 14px;
  border-radius: var(--radius-sm);
  z-index: 999999;
  text-decoration: none;
  box-shadow: 0 0 20px rgba(252, 211, 77, 0.7);
  transition: top 0.2s cubic-bezier(0.4, 0, 0.2, 1);
}

.skip-link:focus,
.skip-link:focus-visible {
  top: 20px;
  outline: 3px solid #FFFFFF;
}

:focus-visible {
  outline: 2px solid var(--primary);
  outline-offset: 3px;
}

a:focus-visible,
button:focus-visible,
summary:focus-visible {
  outline: 2px solid var(--primary);
  outline-offset: 2px;
}

/* 锚点滚动吸顶留白 */
section[id],
article[id],
.seo-article-card {
  scroll-margin-top: 90px;
}

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

body {
  font-family: var(--font-family);
  background-color: #000000;
  color: var(--text-main);
  line-height: 1.6;
  overflow-x: hidden;
  position: relative;
}

a {
  color: inherit;
  text-decoration: none;
  transition: all 0.2s ease;
}

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

ul {
  list-style: none;
}

.container {
  width: 100%;
  max-width: var(--container-width);
  margin: 0 auto;
  padding: 0 24px;
  position: relative;
  z-index: 2;
}

/* ================= 背景宇宙画布 (80 颗星点 + 2 个螺旋尘埃粒子) ================= */
.cosmos-bg-canvas {
  position: fixed;
  inset: 0;
  pointer-events: none;
  z-index: 1;
  overflow: hidden;
  background: #000000;
}

/* 80 颗闪烁星点 */
.twinkle-star {
  position: absolute;
  background: #FFFFFF;
  border-radius: 50%;
  animation: starTwinkle ease-in-out infinite;
  pointer-events: none;
}

@keyframes starTwinkle {
  0%, 100% {
    opacity: 0.15;
    transform: scale(0.7);
  }
  50% {
    opacity: 1;
    transform: scale(1.3);
    box-shadow: 0 0 5px rgba(252, 211, 77, 0.9);
  }
}

/* 2 个黄/橙宇宙尘埃粒子按螺旋轨道向中心坠落 (720° 旋转) */
.dust-spiral-system {
  position: absolute;
  top: 45%;
  left: 65%;
  width: 0;
  height: 0;
  pointer-events: none;
}

.cosmic-dust {
  position: absolute;
  border-radius: 50%;
  pointer-events: none;
}

.dust-particle-yellow {
  width: 7px;
  height: 7px;
  background: #FCD34D;
  box-shadow: 0 0 16px 4px #FCD34D, 0 0 30px rgba(252, 211, 77, 0.8);
  animation: spiralCollapseYellow 9s cubic-bezier(0.35, 0, 0.25, 1) infinite;
}

.dust-particle-orange {
  width: 6px;
  height: 6px;
  background: #FF6B35;
  box-shadow: 0 0 16px 4px #FF6B35, 0 0 30px rgba(255, 107, 53, 0.8);
  animation: spiralCollapseOrange 11s cubic-bezier(0.35, 0, 0.25, 1) infinite 2.5s;
}

@keyframes spiralCollapseYellow {
  0% {
    transform: rotate(0deg) translateX(460px) rotate(0deg) scale(1.3);
    opacity: 0;
  }
  15% {
    opacity: 1;
    box-shadow: 0 0 22px 6px #FCD34D;
  }
  80% {
    opacity: 0.9;
  }
  100% {
    transform: rotate(720deg) translateX(12px) rotate(-720deg) scale(0.12);
    opacity: 0;
  }
}

@keyframes spiralCollapseOrange {
  0% {
    transform: rotate(180deg) translateX(410px) rotate(-180deg) scale(1.2);
    opacity: 0;
  }
  15% {
    opacity: 1;
    box-shadow: 0 0 20px 6px #FF6B35;
  }
  80% {
    opacity: 0.9;
  }
  100% {
    transform: rotate(900deg) translateX(12px) rotate(-900deg) scale(0.12);
    opacity: 0;
  }
}

/* ================= HEADER & NAV ================= */
.header {
  position: sticky;
  top: 0;
  z-index: 100;
  backdrop-filter: blur(18px);
  -webkit-backdrop-filter: blur(18px);
  background: rgba(0, 0, 0, 0.88);
  border-bottom: 1px solid var(--border-color);
}

.nav {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 72px;
}

.brand {
  display: flex;
  align-items: center;
  gap: 12px;
  font-size: 20px;
  font-weight: 700;
  letter-spacing: -0.5px;
}

.brand-icon {
  width: 36px;
  height: 36px;
  background: linear-gradient(135deg, var(--primary), var(--secondary));
  border-radius: 8px;
  display: flex;
  align-items: center;
  justify-content: center;
  box-shadow: 0 0 20px rgba(252, 211, 77, 0.5);
}

.brand-icon svg {
  width: 20px;
  height: 20px;
  fill: #000;
}

.brand-text {
  background: linear-gradient(to right, #FFFFFF, #FCD34D);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
}

.brand-en {
  font-size: 13px;
  font-weight: 600;
  color: var(--secondary);
  margin-left: 4px;
  opacity: 0.95;
  letter-spacing: 0.5px;
}

.nav-links {
  display: flex;
  align-items: center;
  gap: 28px;
}

.nav-link {
  font-size: 15px;
  font-weight: 500;
  color: var(--text-muted);
  display: inline-flex;
  align-items: center;
}

.nav-link:hover {
  color: var(--primary);
  text-shadow: 0 0 10px rgba(252, 211, 77, 0.5);
}

.nav-badge-hot {
  font-size: 10px;
  font-weight: 800;
  background: linear-gradient(135deg, var(--secondary), #EA580C);
  color: #FFFFFF;
  padding: 1px 6px;
  border-radius: var(--radius-full);
  margin-left: 6px;
  line-height: 1.4;
  letter-spacing: 0.5px;
  box-shadow: 0 0 8px rgba(255, 107, 53, 0.6);
}

.nav-actions {
  display: flex;
  align-items: center;
  gap: 16px;
}

/* ================= CTA BUTTONS (规范：黄到橙渐变、文字黑、圆角8px、30px黄色辉光) ================= */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  font-weight: 700;
  font-size: 15px;
  padding: 11px 24px;
  border-radius: 8px !important;
  transition: all 0.25s cubic-bezier(0.4, 0, 0.2, 1);
  white-space: nowrap;
  user-select: none;
}

.btn-primary,
.plan-cta.btn-primary,
.btn.btn-primary {
  background: linear-gradient(135deg, #FCD34D 0%, #FF6B35 100%) !important;
  color: #000000 !important;
  font-weight: 750 !important;
  border-radius: 8px !important;
  border: 1px solid rgba(255, 255, 255, 0.25) !important;
  box-shadow: 0 0 30px rgba(252, 211, 77, 0.5) !important;
}

.btn-primary:hover,
.plan-cta.btn-primary:hover,
.btn.btn-primary:hover {
  transform: translateY(-2px);
  box-shadow: 0 0 45px rgba(252, 211, 77, 0.85), 0 0 20px rgba(255, 107, 53, 0.7) !important;
  background: linear-gradient(135deg, #FFE066 0%, #FF7A45 100%) !important;
  color: #000000 !important;
}

.btn-secondary {
  background: rgba(252, 211, 77, 0.06) !important;
  color: #FCD34D !important;
  border: 1px solid rgba(252, 211, 77, 0.35) !important;
  border-radius: 8px !important;
}

.btn-secondary:hover {
  background: rgba(252, 211, 77, 0.15) !important;
  border-color: #FCD34D !important;
  color: #FFFFFF !important;
  box-shadow: 0 0 20px rgba(252, 211, 77, 0.35) !important;
  transform: translateY(-1px);
}

.btn-lg {
  padding: 14px 34px;
  font-size: 16px;
  border-radius: 8px !important;
}

.btn-sm {
  padding: 7px 18px;
  font-size: 13px;
  border-radius: 8px !important;
}

/* ================= HERO SECTION (标题与黑洞动画整体靠左排版) ================= */
.hero {
  padding: 80px 0 60px;
  text-align: left;
  position: relative;
  overflow: visible;
}

.hero-main-row {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 40px;
  margin-bottom: 50px;
  text-align: left;
}

.hero-text-col {
  flex: 1;
  max-width: 680px;
  text-align: left;
}

.hero-visual-col {
  flex: 0 0 440px;
  display: flex;
  align-items: center;
  justify-content: center;
  position: relative;
  min-height: 440px;
}

/* ================= TOKAMAK 式黑洞物理动画 (置于容器内，无裁切) =================
   要素：
   1. 外层 conic-gradient 吸积盘（黄/橙循环，rotateX 75° 倾斜，8 秒旋转）
   2. 内层反向旋转
   3. 140px 黑色事件视界
   4. 150px 黄色光子环（脉冲呼吸）
   5. 上下 2 条相对论性喷流（脉冲缩放）
==================================================================== */
.tokamak-blackhole-stage {
  position: relative;
  width: 440px;
  height: 440px;
  pointer-events: none;
  z-index: 2;
  perspective: 1000px;
  display: flex;
  align-items: center;
  justify-content: center;
}

.tokamak-blackhole {
  position: relative;
  width: 100%;
  height: 100%;
  transform-style: preserve-3d;
}

/* 上下 2 条相对论性喷流 (脉冲缩放) */
.rel-jet {
  position: absolute;
  left: 50%;
  width: 12px;
  margin-left: -6px;
  border-radius: var(--radius-full);
  pointer-events: none;
  z-index: 4;
}

.jet-top {
  bottom: 50%;
  height: 210px;
  transform-origin: bottom center;
  background: linear-gradient(
    to top,
    rgba(252, 211, 77, 1) 0%,
    rgba(255, 107, 53, 0.85) 30%,
    rgba(255, 107, 53, 0.35) 70%,
    transparent 100%
  );
  box-shadow: 0 0 25px #FCD34D, 0 0 50px #FF6B35;
  animation: jetTopPulse 2.6s ease-in-out infinite;
}

.jet-bottom {
  top: 50%;
  height: 210px;
  transform-origin: top center;
  background: linear-gradient(
    to bottom,
    rgba(252, 211, 77, 1) 0%,
    rgba(255, 107, 53, 0.85) 30%,
    rgba(255, 107, 53, 0.35) 70%,
    transparent 100%
  );
  box-shadow: 0 0 25px #FCD34D, 0 0 50px #FF6B35;
  animation: jetBottomPulse 2.6s ease-in-out infinite 0.25s;
}

@keyframes jetTopPulse {
  0%, 100% {
    transform: scaleY(0.85) scaleX(0.9);
    opacity: 0.85;
  }
  50% {
    transform: scaleY(1.22) scaleX(1.15);
    opacity: 1;
  }
}

@keyframes jetBottomPulse {
  0%, 100% {
    transform: scaleY(0.85) scaleX(0.9);
    opacity: 0.85;
  }
  50% {
    transform: scaleY(1.22) scaleX(1.15);
    opacity: 1;
  }
}

/* 外层 conic-gradient 吸积盘 (黄/橙循环, rotateX 75° 倾斜, 8 秒旋转) */
.accretion-disk-outer {
  position: absolute;
  top: 50%;
  left: 50%;
  width: 360px;
  height: 360px;
  margin-left: -180px;
  margin-top: -180px;
  border-radius: 50%;
  background: conic-gradient(
    from 0deg,
    #FCD34D 0deg,
    #FF6B35 60deg,
    #F59E0B 120deg,
    #FF6B35 180deg,
    #FCD34D 240deg,
    #FF6B35 300deg,
    #FCD34D 360deg
  );
  transform: rotateX(75deg);
  animation: outerAccretionRotate 8s linear infinite;
  filter: drop-shadow(0 0 35px rgba(255, 107, 53, 0.85)) blur(1px);
  opacity: 0.92;
  z-index: 2;
}

@keyframes outerAccretionRotate {
  0% {
    transform: rotateX(75deg) rotateZ(0deg);
  }
  100% {
    transform: rotateX(75deg) rotateZ(360deg);
  }
}

/* 内层反向旋转吸积盘 */
.accretion-disk-inner {
  position: absolute;
  top: 50%;
  left: 50%;
  width: 250px;
  height: 250px;
  margin-left: -125px;
  margin-top: -125px;
  border-radius: 50%;
  background: conic-gradient(
    from 180deg,
    #FF6B35 0deg,
    #FCD34D 90deg,
    #FF6B35 180deg,
    #FCD34D 270deg,
    #FF6B35 360deg
  );
  transform: rotateX(75deg);
  animation: innerAccretionReverse 5s linear infinite;
  filter: drop-shadow(0 0 25px rgba(252, 211, 77, 0.9)) blur(0.5px);
  opacity: 0.88;
  z-index: 3;
}

@keyframes innerAccretionReverse {
  0% {
    transform: rotateX(75deg) rotateZ(360deg);
  }
  100% {
    transform: rotateX(75deg) rotateZ(0deg);
  }
}

/* 150px 黄色光子环 (脉冲呼吸) */
.photon-ring-150 {
  position: absolute;
  top: 50%;
  left: 50%;
  width: 150px;
  height: 150px;
  margin-left: -75px;
  margin-top: -75px;
  border-radius: 50%;
  border: 3px solid #FCD34D;
  box-shadow:
    0 0 30px #FCD34D,
    0 0 50px rgba(252, 211, 77, 0.6),
    inset 0 0 20px #FCD34D;
  animation: photonRingBreathing 2.4s ease-in-out infinite;
  z-index: 5;
}

@keyframes photonRingBreathing {
  0%, 100% {
    transform: scale(0.96);
    box-shadow:
      0 0 25px #FCD34D,
      0 0 45px rgba(252, 211, 77, 0.5),
      inset 0 0 15px #FCD34D;
  }
  50% {
    transform: scale(1.05);
    box-shadow:
      0 0 40px #FCD34D,
      0 0 70px rgba(255, 107, 53, 0.8),
      inset 0 0 25px #FCD34D;
  }
}

/* 140px 黑色事件视界 */
.event-horizon-140 {
  position: absolute;
  top: 50%;
  left: 50%;
  width: 140px;
  height: 140px;
  margin-left: -70px;
  margin-top: -70px;
  border-radius: 50%;
  background: #000000;
  box-shadow:
    inset 0 0 30px #000000,
    0 0 30px rgba(0, 0, 0, 0.98);
  z-index: 6;
}

/* ================= HERO TEXT & METRICS (靠左对齐规范) ================= */
.hero-badge {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  background: rgba(252, 211, 77, 0.08);
  border: 1px solid rgba(252, 211, 77, 0.3);
  padding: 6px 18px;
  border-radius: var(--radius-full);
  font-size: 13px;
  font-weight: 600;
  color: var(--primary);
  margin-bottom: 20px;
}

.hero-badge .pulse {
  width: 8px;
  height: 8px;
  background-color: var(--secondary);
  border-radius: 50%;
  box-shadow: 0 0 0 rgba(255, 107, 53, 0.7);
  animation: pulse-ring 1.8s infinite;
}

@keyframes pulse-ring {
  0% { transform: scale(0.95); box-shadow: 0 0 0 0 rgba(255, 107, 53, 0.7); }
  70% { transform: scale(1); box-shadow: 0 0 0 8px rgba(255, 107, 53, 0); }
  100% { transform: scale(0.95); box-shadow: 0 0 0 0 rgba(255, 107, 53, 0); }
}

.hero-title {
  font-size: clamp(32px, 5vw, 56px);
  font-weight: 850;
  line-height: 1.18;
  letter-spacing: -1.2px;
  margin-bottom: 22px;
  color: #FFFFFF;
  text-align: left;
}

.hero-title .gradient-text {
  background: linear-gradient(135deg, #FFFFFF 0%, #FCD34D 45%, #FF6B35 100%);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  filter: drop-shadow(0 0 20px rgba(252, 211, 77, 0.3));
}

.hero-intro-card {
  max-width: 660px;
  margin: 0 0 28px 0;
  padding: 22px 26px;
  background: rgba(8, 8, 10, 0.85);
  border: 1px solid var(--border-color);
  border-radius: 8px;
  backdrop-filter: blur(12px);
  box-shadow: 0 10px 30px -10px rgba(0, 0, 0, 0.9);
  text-align: left;
}

.hero-desc {
  max-width: 100%;
  margin: 0;
  font-size: clamp(15px, 1.6vw, 16.5px);
  color: #D1D5DB;
  line-height: 1.8;
  text-align: left;
}

.hero-cta-group {
  display: flex;
  align-items: center;
  justify-content: flex-start;
  gap: 16px;
  margin-bottom: 30px;
}

.hero-metrics {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 18px;
  max-width: 960px;
  margin: 0 auto;
  padding: 24px;
  background: rgba(8, 8, 10, 0.75);
  border: 1px solid var(--border-color);
  border-radius: 8px;
  backdrop-filter: blur(8px);
}

.metric-item {
  text-align: center;
  position: relative;
}

.metric-item:not(:last-child)::after {
  content: "";
  position: absolute;
  right: 0;
  top: 15%;
  height: 70%;
  width: 1px;
  background: var(--border-color);
}

.metric-value {
  font-size: 28px;
  font-weight: 850;
  color: #FFFFFF;
  letter-spacing: -0.5px;
  background: linear-gradient(to bottom right, #FFFFFF, #FCD34D);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
}

.metric-label {
  font-size: 13px;
  color: var(--text-dim);
  margin-top: 4px;
}

/* ================= SECTION COMMON ================= */
.section {
  padding: 90px 0;
  position: relative;
}

.section-head {
  text-align: center;
  max-width: 680px;
  margin: 0 auto 56px;
}

.section-tag {
  display: inline-block;
  font-size: 12px;
  font-weight: 750;
  letter-spacing: 1.5px;
  text-transform: uppercase;
  color: var(--primary);
  margin-bottom: 12px;
}

.section-title {
  font-size: clamp(26px, 3.5vw, 38px);
  font-weight: 800;
  letter-spacing: -0.8px;
  margin-bottom: 14px;
  color: #FFFFFF;
}

.section-subtitle {
  font-size: 16px;
  color: var(--text-muted);
}

/* ================= 3 CORE ADVANTAGES ================= */
.features-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 24px;
}

.feature-card {
  background: var(--bg-card);
  border: 1px solid var(--border-color);
  border-radius: 8px;
  padding: 36px 30px;
  transition: all 0.3s ease;
  position: relative;
  overflow: hidden;
}

.feature-card::before {
  content: "";
  position: absolute;
  inset: 0;
  background: radial-gradient(circle at 80% 20%, rgba(252, 211, 77, 0.08), transparent 70%);
  pointer-events: none;
}

.feature-card:hover {
  transform: translateY(-5px);
  border-color: var(--border-focus);
  box-shadow: 0 16px 36px -10px rgba(0, 0, 0, 0.8), 0 0 25px rgba(252, 211, 77, 0.15);
}

.feature-icon-wrapper {
  width: 58px;
  height: 58px;
  border-radius: 8px;
  display: flex;
  align-items: center;
  justify-content: center;
  margin-bottom: 24px;
  border: 1px solid rgba(252, 211, 77, 0.25);
}

.feature-icon-wrapper svg {
  width: 28px;
  height: 28px;
}

.icon-blue { background: rgba(252, 211, 77, 0.12); color: #FCD34D; }
.icon-cyan { background: rgba(255, 107, 53, 0.12); color: #FF6B35; }
.icon-purple { background: rgba(245, 158, 11, 0.12); color: #F59E0B; }

.feature-title {
  font-size: 20px;
  font-weight: 700;
  margin-bottom: 12px;
  color: #FFFFFF;
}

.feature-desc {
  font-size: 14.5px;
  color: var(--text-muted);
  line-height: 1.65;
  margin-bottom: 20px;
}

.feature-points {
  display: flex;
  flex-direction: column;
  gap: 10px;
  border-top: 1px solid var(--border-color);
  padding-top: 18px;
}

.feature-point {
  display: flex;
  align-items: center;
  gap: 8px;
  font-size: 13.5px;
  color: #E5E7EB;
}

.feature-point svg {
  width: 16px;
  height: 16px;
  fill: var(--primary);
  flex-shrink: 0;
}

/* ================= STREAMING & AI SUPPORT ================= */
.media-ai-grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 28px;
}

.media-ai-card {
  background: var(--bg-card);
  border: 1px solid var(--border-color);
  border-radius: 8px;
  padding: 38px 32px;
  position: relative;
  overflow: hidden;
  transition: all 0.3s ease;
}

.media-ai-card:hover {
  border-color: var(--border-focus);
  box-shadow: 0 16px 40px -12px rgba(252, 211, 77, 0.2);
}

.badge-tag {
  display: inline-block;
  padding: 4px 12px;
  font-size: 12px;
  font-weight: 700;
  border-radius: var(--radius-full);
  margin-bottom: 16px;
}

.tag-stream {
  background: rgba(255, 107, 53, 0.18);
  color: #FF6B35;
  border: 1px solid rgba(255, 107, 53, 0.35);
}

.tag-ai {
  background: rgba(252, 211, 77, 0.18);
  color: #FCD34D;
  border: 1px solid rgba(252, 211, 77, 0.35);
}

.media-card-title {
  font-size: 24px;
  font-weight: 750;
  margin-bottom: 12px;
  color: #FFFFFF;
}

.media-card-desc {
  font-size: 15px;
  color: var(--text-muted);
  line-height: 1.6;
  margin-bottom: 26px;
}

.supported-logos {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
  margin-bottom: 26px;
}

.logo-badge {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  background: rgba(255, 255, 255, 0.04);
  border: 1px solid var(--border-color);
  padding: 8px 14px;
  border-radius: 8px;
  font-size: 13.5px;
  font-weight: 600;
  color: #F3F4F6;
  transition: all 0.2s ease;
}

.logo-badge:hover {
  background: rgba(252, 211, 77, 0.08);
  border-color: var(--primary);
  transform: translateY(-2px);
}

.logo-badge svg {
  width: 18px;
  height: 18px;
}

.card-highlights {
  list-style: none;
  background: var(--bg-card-alt);
  padding: 16px 20px;
  border-radius: 8px;
  border: 1px solid var(--border-color);
  display: flex;
  flex-direction: column;
  gap: 8px;
  font-size: 13.5px;
  color: #E5E7EB;
}

.card-highlights li {
  display: flex;
  align-items: center;
  gap: 8px;
}

.card-highlights li::before {
  content: "✦";
  color: var(--primary);
  font-size: 12px;
}

/* ================= PRICING SECTION ================= */
.pricing-grid {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 20px;
  align-items: stretch;
}

.pricing-card {
  background: var(--bg-card);
  border: 1px solid var(--border-color);
  border-radius: 8px;
  padding: 34px 24px;
  display: flex;
  flex-direction: column;
  position: relative;
  transition: all 0.3s ease;
}

.pricing-card:hover {
  transform: translateY(-6px);
  border-color: var(--border-focus);
  box-shadow: 0 18px 40px -10px rgba(0, 0, 0, 0.8), 0 0 25px rgba(252, 211, 77, 0.2);
}

.pricing-card.featured {
  background: linear-gradient(180deg, rgba(26, 20, 10, 0.9) 0%, rgba(8, 8, 10, 0.98) 100%);
  border: 2px solid var(--primary);
  box-shadow: 0 10px 35px -5px rgba(252, 211, 77, 0.4);
  transform: scale(1.03);
}

.pricing-card.featured:hover {
  transform: scale(1.03) translateY(-6px);
}

.popular-ribbon {
  position: absolute;
  top: -12px;
  left: 50%;
  transform: translateX(-50%);
  background: linear-gradient(135deg, #FCD34D, #FF6B35);
  color: #000000;
  font-size: 11px;
  font-weight: 800;
  letter-spacing: 0.5px;
  padding: 4px 14px;
  border-radius: var(--radius-full);
  text-transform: uppercase;
  box-shadow: 0 4px 12px rgba(255, 107, 53, 0.5);
}

.plan-header {
  margin-bottom: 22px;
  text-align: center;
}

.plan-name {
  font-size: 19px;
  font-weight: 750;
  color: #FFFFFF;
  margin-bottom: 6px;
}

.plan-desc {
  font-size: 13px;
  color: var(--text-dim);
}

.plan-price-box {
  text-align: center;
  margin-bottom: 24px;
  padding: 16px 0;
  border-top: 1px dashed var(--border-color);
  border-bottom: 1px dashed var(--border-color);
}

.currency {
  font-size: 20px;
  font-weight: 600;
  color: var(--text-muted);
  vertical-align: top;
  margin-right: 2px;
}

.price-number {
  font-size: 42px;
  font-weight: 850;
  color: #FFFFFF;
  line-height: 1;
}

.billing-cycle {
  font-size: 13px;
  color: var(--text-muted);
  margin-left: 4px;
}

.plan-features {
  list-style: none;
  display: flex;
  flex-direction: column;
  gap: 12px;
  margin-bottom: 30px;
  flex-grow: 1;
}

.plan-feature-item {
  display: flex;
  align-items: center;
  gap: 10px;
  font-size: 13.5px;
  color: #E5E7EB;
}

.plan-feature-item svg {
  width: 16px;
  height: 16px;
  fill: var(--primary);
  flex-shrink: 0;
}

.plan-cta {
  width: 100%;
}

/* ================= TESTIMONIALS (USER REVIEWS) ================= */
.reviews-grid {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 20px;
}

.review-card {
  background: var(--bg-card);
  border: 1px solid var(--border-color);
  border-radius: 8px;
  padding: 26px 22px;
  display: flex;
  flex-direction: column;
  justify-content: space-between;
  transition: all 0.25s ease;
}

.review-card:hover {
  transform: translateY(-4px);
  border-color: var(--border-focus);
}

.review-stars {
  color: var(--primary);
  margin-bottom: 14px;
  display: flex;
  gap: 3px;
}

.review-stars svg {
  width: 15px;
  height: 15px;
  fill: currentColor;
}

.review-text {
  font-size: 14px;
  color: #D1D5DB;
  line-height: 1.6;
  margin-bottom: 20px;
}

.review-author {
  display: flex;
  align-items: center;
  gap: 12px;
  border-top: 1px solid var(--border-color);
  padding-top: 14px;
}

.author-avatar {
  width: 40px;
  height: 40px;
  border-radius: 50%;
  background: linear-gradient(135deg, var(--primary), var(--secondary));
  display: flex;
  align-items: center;
  justify-content: center;
  font-weight: 800;
  font-size: 15px;
  color: #000000;
  flex-shrink: 0;
}

.author-info h4 {
  font-size: 14px;
  font-weight: 600;
  color: #FFFFFF;
}

.author-info p {
  font-size: 12px;
  color: var(--text-dim);
}

/* ================= FAQ SECTION ================= */
.faq-wrap {
  max-width: 860px;
  margin: 0 auto;
  display: flex;
  flex-direction: column;
  gap: 14px;
}

.faq-item,
details.faq-item {
  background: var(--bg-card);
  border: 1px solid var(--border-color);
  border-radius: 8px;
  overflow: hidden;
  transition: border-color 0.2s ease;
}

.faq-item:hover,
details.faq-item:hover {
  border-color: var(--border-focus);
}

.faq-question,
summary.faq-question {
  width: 100%;
  padding: 20px 24px;
  text-align: left;
  font-size: 16px;
  font-weight: 600;
  color: #FFFFFF;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
  cursor: pointer;
  background: transparent;
  list-style: none;
  user-select: none;
}

summary.faq-question::-webkit-details-marker {
  display: none;
}

.faq-icon {
  width: 20px;
  height: 20px;
  flex-shrink: 0;
  transition: transform 0.3s cubic-bezier(0.4, 0, 0.2, 1);
  fill: var(--text-muted);
}

details.faq-item[open] .faq-icon,
.faq-item.active .faq-icon {
  transform: rotate(180deg);
  fill: var(--primary);
}

.faq-answer {
  font-size: 14.5px;
  color: var(--text-muted);
  line-height: 1.7;
  padding: 0 24px 22px;
  display: block;
}

details.faq-item:not([open]) .faq-answer {
  display: none;
}

.faq-item:not(.active):not([open]) .faq-answer {
  display: none;
}

.faq-answer a {
  color: var(--primary);
  text-decoration: underline;
  text-underline-offset: 3px;
  font-weight: 500;
  transition: color 0.2s ease;
}

.faq-answer a:hover {
  color: var(--secondary);
}

/* 知识科普专栏单篇文章内部 FAQ 样式 */
.article-faq-section {
  margin-top: 24px;
  padding-top: 18px;
  border-top: 1px dashed var(--border-color);
}

.article-faq-title {
  font-size: 15.5px;
  font-weight: 700;
  color: var(--primary);
  margin-bottom: 12px;
  display: flex;
  align-items: center;
  gap: 8px;
}

.article-faq-section .faq-wrap {
  gap: 10px;
}

.article-faq-section .faq-item,
.article-faq-section details.faq-item {
  background: rgba(255, 255, 255, 0.02);
  border: 1px solid rgba(252, 211, 77, 0.15);
}

.article-faq-section .faq-item:hover,
.article-faq-section details.faq-item:hover {
  border-color: var(--border-focus);
}

.article-faq-section .faq-question,
.article-faq-section summary.faq-question {
  padding: 12px 16px;
  font-size: 14px;
}

.article-faq-section .faq-answer {
  font-size: 13.5px;
  padding: 0 16px 16px;
  line-height: 1.65;
}

/* ================= BOTTOM CTA BANNER ================= */
.bottom-cta-banner {
  margin: 80px 0 30px;
  padding: 60px 40px;
  background: linear-gradient(135deg, rgba(20, 15, 8, 0.95) 0%, rgba(5, 5, 7, 0.98) 100%);
  border: 1px solid var(--border-focus);
  border-radius: 8px;
  text-align: center;
  position: relative;
  overflow: hidden;
  box-shadow: 0 0 40px rgba(252, 211, 77, 0.2);
}

.bottom-cta-banner::before {
  content: "";
  position: absolute;
  top: -50%;
  left: 50%;
  transform: translateX(-50%);
  width: 500px;
  height: 300px;
  background: radial-gradient(circle, rgba(252, 211, 77, 0.25), transparent 70%);
  pointer-events: none;
}

.cta-banner-title {
  font-size: clamp(24px, 3.5vw, 36px);
  font-weight: 850;
  color: #FFFFFF;
  margin-bottom: 14px;
}

.cta-banner-desc {
  font-size: 16px;
  color: #D1D5DB;
  max-width: 600px;
  margin: 0 auto 30px;
}

/* ================= FOOTER ================= */
.footer {
  background: #000000;
  border-top: 1px solid var(--border-color);
  padding: 48px 0 36px;
  margin-top: 60px;
  position: relative;
  z-index: 2;
}

.footer-nav {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 48px;
  margin-bottom: 28px;
}

.footer-nav-link {
  font-size: 15px;
  font-weight: 600;
  color: #D1D5DB;
  position: relative;
  padding: 6px 0;
  transition: color 0.2s ease;
}

.footer-nav-link:hover {
  color: var(--primary);
  text-shadow: 0 0 10px rgba(252, 211, 77, 0.6);
}

.footer-bottom {
  text-align: center;
  font-size: 13px;
  color: var(--text-dim);
  border-top: 1px solid rgba(252, 211, 77, 0.1);
  padding-top: 24px;
}

/* ================= SUB-PAGE COMMON STYLES ================= */
.subpage-hero {
  padding: 60px 0 40px;
  border-bottom: 1px solid var(--border-color);
  background: rgba(8, 8, 10, 0.6);
  position: relative;
  z-index: 2;
}

.subpage-title {
  font-size: 34px;
  font-weight: 850;
  color: #FFFFFF;
  margin-bottom: 10px;
}

.subpage-desc {
  color: var(--text-muted);
  font-size: 16px;
}

.content-block {
  max-width: 880px;
  margin: 40px auto 80px;
  background: var(--bg-card);
  border: 1px solid var(--border-color);
  border-radius: 8px;
  padding: 48px;
  position: relative;
  z-index: 2;
}

.content-block h2 {
  font-size: 22px;
  color: #FFFFFF;
  margin: 32px 0 14px;
  display: flex;
  align-items: center;
  gap: 10px;
}

.content-block h2:first-of-type {
  margin-top: 0;
}

.content-block h2::before {
  content: "";
  display: inline-block;
  width: 4px;
  height: 20px;
  background: var(--primary);
  border-radius: 2px;
}

.content-block p {
  color: #D1D5DB;
  font-size: 15px;
  line-height: 1.8;
  margin-bottom: 16px;
}

.content-block ul {
  margin: 12px 0 20px 20px;
  list-style: disc;
  color: #9CA3AF;
}

.content-block li {
  margin-bottom: 8px;
  line-height: 1.7;
}

.alert-box {
  background: rgba(252, 211, 77, 0.08);
  border-left: 4px solid var(--primary);
  padding: 16px 20px;
  border-radius: 6px;
  margin: 24px 0;
  font-size: 14.5px;
  color: #E5E7EB;
}

.alert-box.warning {
  background: rgba(255, 107, 53, 0.1);
  border-left-color: var(--secondary);
}

.sitemap-grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 24px;
  margin-top: 20px;
}

.sitemap-card {
  background: var(--bg-card-alt);
  border: 1px solid var(--border-color);
  border-radius: 8px;
  padding: 24px;
}

.sitemap-card h3 {
  font-size: 17px;
  color: #FFFFFF;
  margin-bottom: 12px;
  padding-bottom: 8px;
  border-bottom: 1px solid var(--border-color);
}

.sitemap-links {
  display: flex;
  flex-direction: column;
  gap: 10px;
}

.sitemap-links a {
  color: var(--primary);
  font-size: 14.5px;
  display: flex;
  align-items: center;
  gap: 6px;
}

.sitemap-links a:hover {
  text-decoration: underline;
  color: #FFFFFF;
}

/* ================= SEO 知识科普专栏样式 ================= */
.article-hub-intro {
  margin-bottom: 36px;
  background: rgba(8, 8, 10, 0.85);
  border: 1px solid var(--border-color);
  border-radius: 8px;
  padding: 24px 28px;
  backdrop-filter: blur(8px);
}

.article-toc-box {
  background: var(--bg-card);
  border: 1px solid var(--border-color);
  border-radius: 8px;
  padding: 28px;
  margin-bottom: 48px;
}

.toc-title {
  font-size: 19px;
  font-weight: 700;
  color: #FFFFFF;
  margin-bottom: 18px;
  display: flex;
  align-items: center;
  gap: 8px;
}

.toc-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 14px;
}

.toc-item {
  display: flex;
  align-items: flex-start;
  gap: 10px;
  padding: 12px 14px;
  background: var(--bg-card-alt);
  border: 1px solid var(--border-color);
  border-radius: 8px;
  font-size: 13.5px;
  line-height: 1.45;
  color: #D1D5DB;
  transition: all 0.2s ease;
}

.toc-item:hover {
  border-color: var(--primary);
  color: #FFFFFF;
  transform: translateY(-2px);
  background: rgba(252, 211, 77, 0.08);
  box-shadow: 0 0 15px rgba(252, 211, 77, 0.2);
}

.toc-number {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 20px;
  height: 20px;
  background: rgba(252, 211, 77, 0.2);
  color: var(--primary);
  border-radius: 50%;
  font-size: 11px;
  font-weight: 750;
  flex-shrink: 0;
}

.articles-stack {
  display: flex;
  flex-direction: column;
  gap: 40px;
}

.seo-article-card {
  background: var(--bg-card);
  border: 1px solid var(--border-color);
  border-radius: 8px;
  padding: 42px 36px;
  scroll-margin-top: 100px;
  position: relative;
  transition: border-color 0.25s ease;
}

.seo-article-card:hover {
  border-color: var(--border-focus);
  box-shadow: 0 10px 30px rgba(252, 211, 77, 0.1);
}

.article-header {
  margin-bottom: 24px;
  padding-bottom: 20px;
  border-bottom: 1px solid var(--border-color);
}

.article-meta-tags {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 10px;
  margin-bottom: 14px;
}

.article-tag {
  font-size: 11.5px;
  font-weight: 700;
  padding: 3px 10px;
  border-radius: var(--radius-full);
  background: rgba(252, 211, 77, 0.12);
  color: var(--primary);
  border: 1px solid rgba(252, 211, 77, 0.3);
}

.article-word-count {
  font-size: 12px;
  color: var(--text-dim);
}

.article-headline {
  font-size: clamp(20px, 2.8vw, 26px);
  font-weight: 800;
  color: #FFFFFF;
  line-height: 1.35;
  letter-spacing: -0.5px;
}

.article-body {
  color: #D1D5DB;
  font-size: 15px;
  line-height: 1.85;
}

.article-body h3 {
  font-size: 18px;
  font-weight: 700;
  color: #FFFFFF;
  margin: 26px 0 12px;
  display: flex;
  align-items: center;
  gap: 8px;
}

.article-body h3::before {
  content: "✦";
  color: var(--primary);
  font-size: 14px;
}

.article-body p {
  margin-bottom: 16px;
}

.article-body ul {
  margin: 12px 0 20px 22px;
  list-style: disc;
  color: #9CA3AF;
}

.article-body li {
  margin-bottom: 8px;
  line-height: 1.7;
}

.article-internal-link {
  color: var(--primary);
  font-weight: 700;
  text-decoration: underline;
  text-underline-offset: 4px;
  transition: color 0.2s ease;
}

.article-internal-link:hover {
  color: #FFFFFF;
  text-shadow: 0 0 10px rgba(252, 211, 77, 0.8);
}

.article-footer-cta {
  margin-top: 28px;
  padding-top: 20px;
  border-top: 1px dashed var(--border-color);
  display: flex;
  align-items: center;
  justify-content: space-between;
  flex-wrap: wrap;
  gap: 16px;
}

.back-to-toc {
  font-size: 13.5px;
  color: var(--text-muted);
  display: inline-flex;
  align-items: center;
  gap: 6px;
}

.back-to-toc:hover {
  color: var(--primary);
}

/* ================= RESPONSIVE DESIGN (MEDIA QUERIES) ================= */
@media (max-width: 1280px) {
  .hero-main-row {
    gap: 30px;
  }
  .hero-text-col {
    max-width: 600px;
  }
  .hero-visual-col {
    flex: 0 0 380px;
  }
  .tokamak-blackhole-stage {
    transform: scale(0.88);
  }
}

@media (max-width: 1024px) {
  .hero-main-row {
    flex-direction: column;
    align-items: flex-start;
    gap: 30px;
  }
  .hero-text-col {
    max-width: 100%;
    width: 100%;
  }
  .hero-visual-col {
    width: 100%;
    flex: none;
    min-height: 380px;
    margin: 10px 0 20px;
  }
  .tokamak-blackhole-stage {
    transform: scale(0.8);
  }
  .features-grid {
    grid-template-columns: repeat(2, 1fr);
  }
  .pricing-grid {
    grid-template-columns: repeat(2, 1fr);
  }
  .pricing-card.featured {
    transform: none;
  }
  .pricing-card.featured:hover {
    transform: translateY(-6px);
  }
  .reviews-grid {
    grid-template-columns: repeat(2, 1fr);
  }
  .toc-grid {
    grid-template-columns: repeat(2, 1fr);
  }
}

@media (max-width: 768px) {
  .nav-links {
    display: none;
  }
  .hero {
    padding: 60px 0 40px;
  }
  .hero-cta-group {
    flex-direction: column;
    width: 100%;
    max-width: 340px;
    margin-left: 0;
    margin-right: auto;
  }
  .hero-cta-group .btn {
    width: 100%;
    padding: 14px 20px;
  }
  .hero-visual-col {
    min-height: 300px;
  }
  .tokamak-blackhole-stage {
    transform: scale(0.68);
  }
  .hero-metrics {
    grid-template-columns: repeat(2, 1fr);
    gap: 16px;
    padding: 18px;
  }
  .metric-item:nth-child(2)::after {
    display: none;
  }
  .features-grid {
    grid-template-columns: 1fr;
  }
  .media-ai-grid {
    grid-template-columns: 1fr;
  }
  .pricing-grid {
    grid-template-columns: 1fr;
    max-width: 440px;
    margin: 0 auto;
  }
  .reviews-grid {
    grid-template-columns: 1fr;
    max-width: 440px;
    margin: 0 auto;
  }
  .footer-nav {
    flex-wrap: wrap;
    gap: 20px 32px;
  }
  .content-block {
    padding: 28px 20px;
  }
  .sitemap-grid {
    grid-template-columns: 1fr;
  }
  .toc-grid {
    grid-template-columns: 1fr;
  }
  .seo-article-card {
    padding: 28px 20px;
  }
  .article-footer-cta {
    flex-direction: column;
    align-items: stretch;
  }
}

@media (max-width: 480px) {
  .container {
    padding: 0 16px;
  }
  .brand {
    font-size: 18px;
  }
  .hero-metrics {
    grid-template-columns: 1fr;
  }
  .metric-item::after {
    display: none !important;
  }
  .footer-nav {
    flex-direction: column;
    gap: 16px;
  }
}

/* ================= 移动端 44×44px 人体工学触控热区规范 ================= */
@media (max-width: 768px) {
  .btn-sm {
    min-height: 44px;
    padding: 10px 18px;
    display: inline-flex;
    align-items: center;
    justify-content: center;
  }
  .nav-link,
  .footer-nav-link {
    min-height: 44px;
    display: inline-flex;
    align-items: center;
  }
  .faq-question,
  summary.faq-question {
    min-height: 48px;
  }
}

/* ================= BREADCRUMB & ARTICLE STANDALONE ================= */
.breadcrumb-nav {
  display: flex;
  align-items: center;
  flex-wrap: wrap;
  gap: 8px;
  font-size: 14px;
  color: var(--text-muted);
  margin-bottom: 20px;
}
.breadcrumb-nav a {
  color: var(--text-secondary);
  text-decoration: none;
  transition: color 0.2s ease;
}
.breadcrumb-nav a:hover {
  color: var(--primary);
}
.breadcrumb-separator {
  color: var(--text-muted);
  opacity: 0.6;
}
.breadcrumb-current {
  color: var(--primary-light);
  font-weight: 500;
  max-width: 320px;
  overflow: hidden;
  text-overflow: ellipsis;
  white-space: nowrap;
}
.article-standalone-container {
  max-width: 900px;
  margin: 0 auto;
  padding: 40px 20px 80px;
}
.article-standalone-card {
  background: var(--bg-card);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-lg);
  padding: 36px 32px;
  box-shadow: 0 10px 30px rgba(0, 0, 0, 0.4);
}
.article-standalone-header {
  margin-bottom: 28px;
  padding-bottom: 20px;
  border-bottom: 1px solid var(--border-color);
}
.article-standalone-header h1 {
  font-size: clamp(22px, 3.5vw, 32px);
  line-height: 1.4;
  color: var(--text-primary);
  margin-top: 14px;
  margin-bottom: 12px;
}
.article-nav-pager {
  display: flex;
  justify-content: space-between;
  align-items: center;
  flex-wrap: wrap;
  gap: 16px;
  margin-top: 36px;
  padding-top: 24px;
  border-top: 1px solid var(--border-color);
}
.article-nav-pager a {
  color: var(--primary-light);
  text-decoration: none;
  font-size: 14.5px;
  display: inline-flex;
  align-items: center;
  gap: 6px;
  transition: color 0.2s ease;
}
.article-nav-pager a:hover {
  color: var(--secondary);
  text-decoration: underline;
}

/* ================= ACCESSIBILITY: PREFERS-REDUCED-MOTION ================= */
@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;
  }
  .twinkle-star,
  .cosmic-dust,
  .accretion-disk,
  .accretion-inner,
  .photon-ring,
  .relativistic-jet,
  .pulse {
    animation: none !important;
  }
}