/* ============================================
   第六届未来视听创新大赛 - 公共样式
   深融致远 视听无界
   ============================================ */

/* --- CSS Variables --- */
:root {
  /* 主色调 - 政府蓝体系 */
  --deep-blue: #1A3A8A;
  --electric-indigo: #3B5FC0;
  --neon-cyan: #2196F3;
  --energy-orange: #FF7B42;
  --deep-purple: #5C6BC0;
  
  /* 背景色 - 活力蓝底系（适度加深，避免过白） */
  --bg-deep: #E2EBF8;
  --bg-dark: #CFDBF2;
  --bg-card: #F4F7FD;
  --bg-card-hover: #E8EFFA;
  --bg-overlay: rgba(26, 58, 138, 0.08);
  
  /* 文字色 */
  --text-white: #FFFFFF;
  --text-primary: #1E293B;
  --text-secondary: #475569;
  --text-muted: #64748B;
  
  /* 边框 */
  --border-light: rgba(26, 58, 138, 0.12);
  --border-medium: rgba(26, 58, 138, 0.22);
  --border-glow: rgba(33, 150, 243, 0.35);
  
  /* 渐变 */
  --gradient-primary: linear-gradient(135deg, #1A3A8A 0%, #3B5FC0 50%, #5C6BC0 100%);
  --gradient-cta: linear-gradient(90deg, #2196F3 0%, #1A3A8A 100%);
  --gradient-hero: linear-gradient(135deg, #C9D8F5 0%, #AEC3EF 50%, #8DAEE8 100%);
  --gradient-card: linear-gradient(180deg, rgba(26, 58, 138, 0.06) 0%, rgba(33, 150, 243, 0.04) 100%);
  --gradient-text: linear-gradient(90deg, #1A3A8A, #2196F3);
  
  /* 阴影 */
  --shadow-sm: 0 2px 8px rgba(26, 58, 138, 0.09);
  --shadow-md: 0 4px 20px rgba(26, 58, 138, 0.12);
  --shadow-lg: 0 8px 40px rgba(26, 58, 138, 0.16);
  --shadow-glow: 0 0 20px rgba(33, 150, 243, 0.15);
  --shadow-glow-strong: 0 0 40px rgba(33, 150, 243, 0.22);
  
  /* 圆角 */
  --radius-sm: 6px;
  --radius-md: 12px;
  --radius-lg: 20px;
  --radius-xl: 28px;
  --radius-full: 9999px;
  
  /* 字体 */
  --font-sans: -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", "Helvetica Neue", Helvetica, Arial, sans-serif;
  --font-mono: "SF Mono", "Fira Code", "Fira Mono", "Roboto Mono", monospace;
  
  /* 间距 */
  --section-gap: 100px;
  --content-max: 1200px;
  --nav-height: 72px;
  
  /* 过渡 */
  --ease-out: cubic-bezier(0.16, 1, 0.3, 1);
  --ease-in-out: cubic-bezier(0.65, 0, 0.35, 1);
  --duration-fast: 0.2s;
  --duration-normal: 0.35s;
  --duration-slow: 0.6s;
}

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

html {
  scroll-behavior: smooth;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  font-size: 16px;
}

body {
  font-family: var(--font-sans);
  background-color: var(--bg-deep);
  color: var(--text-primary);
  line-height: 1.7;
  overflow-x: hidden;
  min-height: 100vh;
}

a {
  color: inherit;
  text-decoration: none;
  transition: color var(--duration-fast) var(--ease-out);
}

img {
  max-width: 100%;
  height: auto;
  display: block;
}

ul, ol {
  list-style: none;
}

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

input, textarea, select {
  font-family: inherit;
  font-size: inherit;
}

/* --- Typography --- */
h1, h2, h3, h4, h5, h6 {
  font-weight: 700;
  line-height: 1.3;
}

.section-title {
  font-size: clamp(1.75rem, 3vw, 2.75rem);
  font-weight: 800;
  color: var(--deep-blue);
  text-align: center;
  margin-bottom: 1rem;
  letter-spacing: -0.02em;
}

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

/* Tbg.png 标题装饰背景 */
.section-title-decorated {
  display: inline-block;
  padding: 0.3rem 1.8rem;
  border-radius: 60px;
  background-image: url('../img/Tbg.png');
  background-size: cover;
  background-position: center;
  background-repeat: no-repeat;
  text-shadow: 0 2px 12px rgba(0, 0, 0, 0.4);
  letter-spacing: 0.06em;
  color: var(--text-white);
}

.section-subtitle {
  font-size: 1.05rem;
  color: var(--text-secondary);
  text-align: center;
  max-width: 600px;
  margin: 0 auto 3.5rem;
  line-height: 1.8;
}

/* --- Navigation --- */
.navbar {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  z-index: 1000;
  height: var(--nav-height);
  transition: background var(--duration-normal) var(--ease-out),
              box-shadow var(--duration-normal) var(--ease-out),
              height var(--duration-normal) var(--ease-out),
              backdrop-filter var(--duration-normal) var(--ease-out);
  /* 蓝色半透明背景 */
  background: rgba(26, 58, 138, 0.2);
  backdrop-filter: blur(8px);
  -webkit-backdrop-filter: blur(8px);
}

/* 首页 Hero：更透的蓝色 */
.navbar.hero-dark {
  background: rgba(26, 58, 138, 0.2);
  backdrop-filter: blur(8px);
  -webkit-backdrop-filter: blur(8px);
}

/* 滚动后：更深的蓝色 */
.navbar.scrolled {
  background: rgba(26, 58, 138, 0.85);
  backdrop-filter: blur(20px);
  -webkit-backdrop-filter: blur(20px);
  box-shadow: 0 1px 0 rgba(255, 255, 255, 0.1);
}

.nav-inner {
  max-width: var(--content-max);
  margin: 0 auto;
  padding: 0 2rem;
  height: 100%;
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.nav-logo {
  display: flex;
  align-items: center;
  gap: 0.75rem;
  z-index: 1001;
}

.nav-logo img {
  height: 40px;
  width: auto;
}

.nav-logo-text {
  font-size: 0.85rem;
  font-weight: 700;
  color: var(--text-white);
  line-height: 1.3;
  letter-spacing: 0.02em;
}

.nav-links {
  display: flex;
  align-items: center;
  gap: 0.25rem;
}

.nav-links a {
  position: relative;
  padding: 0.5rem 1rem;
  font-size: 0.9rem;
  font-weight: 500;
  color: rgba(255, 255, 255, 0.85);
  border-radius: var(--radius-full);
  transition: color var(--duration-fast), background var(--duration-fast);
  white-space: nowrap;
}

.nav-links a:hover,
.nav-links a.active {
  color: #fff;
}

.nav-links a.active {
  background: rgba(255, 255, 255, 0.12);
  color: #fff;
}

.nav-links a::after {
  content: '';
  position: absolute;
  bottom: -2px;
  left: 50%;
  transform: translateX(-50%) scaleX(0);
  width: 20px;
  height: 2px;
  background: rgba(255, 255, 255, 0.7);
  border-radius: 1px;
  transition: transform var(--duration-fast) var(--ease-out);
}

.nav-links a:hover::after,
.nav-links a.active::after {
  transform: translateX(-50%) scaleX(1);
}

/* 首页 Hero 深色背景：导航文字切换为白色 */
.navbar.hero-dark .nav-links a {
  color: rgba(255, 255, 255, 0.85);
}

.navbar.hero-dark .nav-links a:hover,
.navbar.hero-dark .nav-links a.active {
  color: #fff;
}

.navbar.hero-dark .nav-links a.active {
  background: rgba(255, 255, 255, 0.12);
}

.navbar.hero-dark .nav-links a::after {
  background: rgba(255, 255, 255, 0.7);
}

/* 滚动后保持白色文字 */
.navbar.scrolled .nav-links a {
  color: rgba(255, 255, 255, 0.85);
}

.navbar.scrolled .nav-links a:hover,
.navbar.scrolled .nav-links a.active {
  color: #fff;
}

.navbar.scrolled .nav-links a.active {
  background: rgba(255, 255, 255, 0.12);
}

.navbar.scrolled .nav-links a::after {
  background: rgba(255, 255, 255, 0.7);
}

/* CTA 报名按钮突出 */
.nav-links a.nav-cta {
  background: var(--gradient-cta);
  color: var(--text-white);
  font-weight: 700;
  padding: 0.5rem 1.25rem;
  border-radius: var(--radius-full);
  box-shadow: 0 2px 12px rgba(26, 58, 138, 0.2);
  margin-left: 0.5rem;
}

.nav-links a.nav-cta:hover {
  box-shadow: 0 4px 20px rgba(26, 58, 138, 0.35);
  transform: translateY(-1px);
  background: var(--gradient-cta);
}

.nav-links a.nav-cta::after {
  display: none;
}

/* 暂时隐藏 交流会 */
.nav-links a[href="event.html"] {
  display: none;
}

.footer a[href="event.html"],
.footer a[href="about.html#tracks"] {
  display: none;
}

.footer-col a[href="#"] {
  display: none;
}

/* Hamburger */
.nav-toggle {
  display: none;
  flex-direction: column;
  gap: 5px;
  padding: 0.5rem;
  z-index: 1001;
}

.nav-toggle span {
  display: block;
  width: 24px;
  height: 2px;
  background: var(--deep-blue);
  border-radius: 1px;
  transition: transform var(--duration-normal) var(--ease-out),
              opacity var(--duration-fast);
}

.navbar.hero-dark .nav-toggle span {
  background: rgba(255, 255, 255, 0.9);
}

.navbar.scrolled .nav-toggle span {
  background: var(--deep-blue);
}

.nav-toggle.active span:nth-child(1) {
  transform: translateY(7px) rotate(45deg);
}

.nav-toggle.active span:nth-child(2) {
  opacity: 0;
}

.nav-toggle.active span:nth-child(3) {
  transform: translateY(-7px) rotate(-45deg);
}

/* --- Page Hero Banner (通用) --- */
.page-hero {
  position: relative;
  min-height: clamp(280px, 32vw, 600px);
  padding-top: var(--nav-height);
  overflow: hidden;
  background: var(--gradient-hero);
}

.page-hero::before {
  content: '';
  position: absolute;
  inset: 0;
  background-image: url('../img/topBanner2j.jpg');
  background-size: cover;
  background-position: center;
  background-repeat: no-repeat;
  z-index: 0;
}

/* --- Hero Text Below Banner --- */
.hero-text-section {
  padding: 3rem 2rem;
  text-align: center;
  background: var(--bg-deep);
  display: flex;
  flex-direction: column;
  align-items: center;
}

.page-hero-content {
  width: 100%;
  max-width: var(--content-max);
}

.page-hero-tag {
  display: inline-block;
  padding: 0.3rem 1.2rem;
  font-size: 0.8rem;
  font-weight: 600;
  color: var(--deep-blue);
  border: 1px solid rgba(26, 58, 138, 0.2);
  border-radius: var(--radius-full);
  background: rgba(26, 58, 138, 0.05);
  letter-spacing: 0.08em;
  text-transform: uppercase;
  margin-top: 0.75rem;
  margin-bottom: 1.25rem;
}

.hero-text-section h1 {
  font-size: clamp(2rem, 4vw, 3.5rem);
  font-weight: 800;
  color: var(--deep-blue);
  margin-bottom: 0;
  letter-spacing: -0.02em;
}

.hero-text-section p {
  font-size: 1.1rem;
  color: var(--text-secondary);
  line-height: 1.8;
  max-width: 720px;
  margin: 0 auto;
}

/* --- Buttons --- */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 0.5rem;
  padding: 0.75rem 2rem;
  font-size: 0.95rem;
  font-weight: 600;
  border-radius: var(--radius-full);
  transition: all var(--duration-fast) var(--ease-out);
  white-space: nowrap;
  letter-spacing: 0.01em;
}

.btn-primary {
  background: var(--gradient-cta);
  color: var(--text-white);
  box-shadow: 0 4px 15px rgba(26, 58, 138, 0.25);
}

.btn-primary:hover {
  transform: translateY(-2px);
  box-shadow: 0 8px 25px rgba(26, 58, 138, 0.4);
}

.btn-outline {
  border: 1.5px solid rgba(26, 58, 138, 0.2);
  color: var(--deep-blue);
  background: transparent;
}

.btn-outline:hover {
  border-color: var(--deep-blue);
  color: var(--deep-blue);
  background: rgba(26, 58, 138, 0.04);
}

.btn-outline-light {
  border: 1.5px solid rgba(255, 255, 255, 0.45);
  color: rgba(255, 255, 255, 0.9);
  background: transparent;
}

.btn-outline-light:hover {
  border-color: rgba(255, 255, 255, 0.85);
  color: var(--text-white);
  background: rgba(255, 255, 255, 0.1);
}

.btn-ghost {
  color: var(--text-secondary);
  padding: 0.5rem 1rem;
}

.btn-ghost:hover {
  color: var(--deep-blue);
}

.btn-lg {
  padding: 1rem 2.5rem;
  font-size: 1.05rem;
}

.btn-sm {
  padding: 0.5rem 1.25rem;
  font-size: 0.85rem;
}

/* --- Cards --- */
.card {
  background: var(--bg-card);
  border: 1px solid var(--border-light);
  border-radius: var(--radius-lg);
  padding: 2rem;
  transition: all var(--duration-normal) var(--ease-out);
}

.card:hover {
  background: var(--bg-card-hover);
  border-color: var(--border-medium);
  transform: translateY(-4px);
  box-shadow: var(--shadow-glow);
}

.card-icon {
  width: 48px;
  height: 48px;
  display: flex;
  align-items: center;
  justify-content: center;
  border-radius: var(--radius-md);
  font-size: 1.4rem;
  margin-bottom: 1.25rem;
  background: var(--gradient-card);
  color: var(--deep-blue);
}

.card h3 {
  font-size: 1.15rem;
  color: var(--text-primary);
  margin-bottom: 0.6rem;
}

.card p {
  font-size: 0.9rem;
  color: var(--text-secondary);
  line-height: 1.7;
}

/* --- Section --- */
.section {
  padding: var(--section-gap) 2rem;
  position: relative;
}

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

.section-inner {
  max-width: var(--content-max);
  margin: 0 auto;
}

/* --- Content Layout (通用) --- */
.content-section {
  padding: var(--section-gap) 2rem;
}

.content-section-alt {
  padding: var(--section-gap) 2rem;
  background: var(--bg-dark);
}

.content-inner {
  max-width: var(--content-max);
  margin: 0 auto;
}

.content-inner-narrow {
  max-width: 860px;
  margin: 0 auto;
}

/* --- CTA Section --- */
.cta-section {
  padding: 6rem 2rem;
  text-align: center;
  position: relative;
  overflow: hidden;
  background: var(--gradient-primary);
}

.cta-section::before {
  content: '';
  position: absolute;
  inset: 0;
  background: 
    radial-gradient(circle at 20% 50%, rgba(33, 150, 243, 0.08) 0%, transparent 40%),
    radial-gradient(circle at 80% 50%, rgba(92, 107, 192, 0.08) 0%, transparent 40%);
  pointer-events: none;
}

.cta-content {
  position: relative;
  z-index: 1;
  max-width: 600px;
  margin: 0 auto;
}

.cta-content h2 {
  font-size: clamp(1.75rem, 3vw, 2.5rem);
  font-weight: 800;
  color: var(--text-white);
  margin-bottom: 1rem;
}

.cta-content p {
  font-size: 1.05rem;
  color: rgba(255, 255, 255, 0.8);
  line-height: 1.8;
  margin-bottom: 2rem;
}

/* CTA 区域内 outline 按钮用白色文字 */
.cta-content .btn-outline {
  color: rgba(255, 255, 255, 0.9);
  border-color: rgba(255, 255, 255, 0.4);
}

.cta-content .btn-outline:hover {
  color: var(--text-white);
  border-color: rgba(255, 255, 255, 0.7);
  background: rgba(255, 255, 255, 0.08);
}

/* --- Grid Layouts --- */
.grid-2 {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 1.5rem;
}

.grid-3 {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 1.5rem;
}

.grid-4 {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 1.5rem;
}

/* --- Divider --- */
.divider {
  width: 60px;
  height: 3px;
  background: var(--gradient-cta);
  border-radius: 2px;
  margin: 0 auto 2rem;
}

/* --- Tag / Badge --- */
.tag {
  display: inline-block;
  padding: 0.25rem 0.75rem;
  font-size: 0.75rem;
  font-weight: 600;
  border-radius: var(--radius-full);
  letter-spacing: 0.04em;
}

.tag-blue {
  background: rgba(33, 150, 243, 0.08);
  color: var(--deep-blue);
  border: 1px solid rgba(33, 150, 243, 0.2);
}

.tag-purple {
  background: rgba(92, 107, 192, 0.08);
  color: #3F51B5;
  border: 1px solid rgba(92, 107, 192, 0.2);
}

.tag-orange {
  background: rgba(255, 123, 66, 0.08);
  color: var(--energy-orange);
  border: 1px solid rgba(255, 123, 66, 0.2);
}

/* --- Footer --- */
.footer {
  background: #1A3A8A;
  border-top: none;
  padding: 4rem 2rem 2rem;
}

.footer-inner {
  max-width: var(--content-max);
  margin: 0 auto;
}

.footer-grid {
  display: grid;
  grid-template-columns: 2fr 1fr 1fr 1fr;
  gap: 3rem;
  margin-bottom: 3rem;
}

.footer-brand p {
  font-size: 0.85rem;
  color: rgba(255, 255, 255, 0.6);
  margin-top: 1rem;
  line-height: 1.8;
}

.footer-col h4 {
  font-size: 0.9rem;
  color: var(--text-white);
  margin-bottom: 1.25rem;
  letter-spacing: 0.02em;
}

.footer-col a {
  display: block;
  font-size: 0.83rem;
  color: rgba(255, 255, 255, 0.55);
  padding: 0.35rem 0;
  transition: color var(--duration-fast);
}

.footer-col a:hover {
  color: var(--text-white);
}

.footer-bottom {
  border-top: 1px solid rgba(255, 255, 255, 0.12);
  padding-top: 1.5rem;
  text-align: center;
  font-size: 0.78rem;
  color: rgba(255, 255, 255, 0.45);
}

/* 访问计数器 */
.footer-counter {
  margin-top: 0.8rem;
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 0;
}

.footer-counter .count-label {
  font-size: 0.72rem;
  color: rgba(255, 255, 255, 0.38);
  letter-spacing: 0.08em;
  text-transform: uppercase;
}

.footer-counter .count-divider {
  display: inline-block;
  width: 1px;
  height: 10px;
  margin: 0 0.7rem;
  background: rgba(255, 255, 255, 0.15);
}

.footer-counter .count-num {
  display: inline-flex;
  align-items: center;
  gap: 2px;
}

.footer-counter .count-digit {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-width: 1.15rem;
  height: 1.55rem;
  font-size: 0.85rem;
  font-weight: 600;
  color: rgba(255, 255, 255, 0.8);
  font-family: "SF Mono", "Fira Code", "Consolas", monospace;
  font-variant-numeric: tabular-nums;
  border: 1px solid rgba(255, 255, 255, 0.18);
  border-radius: 3px;
  background: rgba(0, 0, 0, 0.25);
  box-shadow:
    inset 0 1px 3px rgba(0, 0, 0, 0.3),
    0 1px 0 rgba(255, 255, 255, 0.04);
}

/* --- Scroll Animations --- */
.fade-up {
  opacity: 0;
  transform: translateY(30px);
  transition: opacity var(--duration-slow) var(--ease-out),
              transform var(--duration-slow) var(--ease-out);
}

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

/* --- Responsive --- */
@media (max-width: 1024px) {
  :root {
    --section-gap: 70px;
  }
  
  .grid-4 {
    grid-template-columns: repeat(2, 1fr);
  }
  
  .footer-grid {
    grid-template-columns: 1fr 1fr;
  }
}

@media (max-width: 768px) {
  :root {
    --section-gap: 56px;
    --nav-height: 64px;
  }

  .section {
    padding: var(--section-gap) 1.25rem;
  }

  .grid-2, .grid-3, .grid-4 {
    grid-template-columns: 1fr;
    gap: 1rem;
  }

  /* Mobile: 导航栏蓝色半透明背景，白色 Logo / 汉堡按钮 */
  .navbar,
  .navbar.hero-dark {
    background: rgba(26, 58, 138, 0.15);
    backdrop-filter: blur(16px);
    -webkit-backdrop-filter: blur(16px);
  }

  .navbar.scrolled {
    background: rgba(26, 58, 138, 0.65);
  }

  /* 移动端汉堡按钮统一用白色 */
  .nav-toggle span,
  .navbar.hero-dark .nav-toggle span,
  .navbar.scrolled .nav-toggle span {
    background: var(--text-white);
    width: 26px;
    height: 2.5px;
  }

  /* Mobile Nav Dropdown */
  .nav-links {
    position: absolute;
    top: calc(var(--nav-height) - 8px);
    right: 0.75rem;
    left: auto;
    width: max-content;
    min-width: 180px;
    background: #FFFFFF;
    border-radius: var(--radius-lg);
    box-shadow: 0 16px 48px rgba(26, 58, 138, 0.18);
    flex-direction: column;
    justify-content: flex-start;
    align-items: stretch;
    gap: 0;
    padding: 0.5rem;
    max-height: calc(100vh - var(--nav-height) - 2rem);
    overflow-y: auto;
    opacity: 0;
    pointer-events: none;
    transform: translateY(-8px);
    transition: opacity var(--duration-normal) var(--ease-out),
                transform var(--duration-normal) var(--ease-out);
  }

  .nav-links.open {
    opacity: 1;
    pointer-events: all;
    transform: translateY(0);
  }

  .nav-links a {
    font-size: 1rem;
    padding: 0.85rem 1.25rem;
    color: var(--text-secondary);
    border-radius: var(--radius-md);
    text-align: left;
    white-space: nowrap;
    transition: background var(--duration-fast), color var(--duration-fast);
  }

  .nav-links a:hover {
    background: var(--bg-card-hover);
    color: var(--deep-blue);
  }

  .nav-links a.active {
    background: rgba(26, 58, 138, 0.08);
    color: var(--deep-blue);
    font-weight: 600;
  }

  /* 移动端覆盖 hero-dark 的白色文字 */
  .navbar.hero-dark .nav-links a {
    color: var(--text-secondary);
  }

  .navbar.hero-dark .nav-links a:hover,
  .navbar.hero-dark .nav-links a.active {
    color: var(--deep-blue);
  }

  /* 移动端覆盖 scrolled 的白色文字 */
  .navbar.scrolled .nav-links a {
    color: var(--text-secondary);
  }

  .navbar.scrolled .nav-links a:hover,
  .navbar.scrolled .nav-links a.active {
    color: var(--deep-blue);
  }

  .nav-toggle {
    display: flex;
  }

  .page-hero {
    min-height: clamp(260px, 40vw, 480px);
  }

  .hero-text-section {
    padding: 2rem 1.25rem;
  }

  .footer-grid {
    grid-template-columns: 1fr;
    gap: 2rem;
  }
}

@media (max-width: 480px) {
  :root {
    --section-gap: 48px;
  }

  .hero-text-section h1 {
    font-size: 1.75rem;
  }

  .btn-lg {
    padding: 0.8rem 1.8rem;
    font-size: 0.95rem;
  }
}