/* ========================================
   Next-E 战队 — 极简科技风
   字体: Inter + 系统中文
   点缀色: 紫 #7c3aed
   ======================================== */

@import url('https://fonts.googleapis.com/css2?family=Inter:wght@300;400;500;600;700;800;900&display=swap');

/* ===== CSS 变量 ===== */
:root {
  --bg: #fff;
  --bg-alt: #f8f9fb;
  --bg-card: #fff;
  --bg-card-hover: #f5f6fa;
  --border: #e8eaef;
  --border-hover: #d4d7e0;

  --accent: #7c3aed;
  --accent-hover: #6d28d9;
  --accent-light: #f5f3ff;
  --accent-soft: #ede9fe;

  --text: #111827;
  --text-secondary: #6b7280;
  --text-dim: #9ca3af;

  --shadow-sm: 0 1px 2px rgba(0,0,0,0.04);
  --shadow: 0 1px 3px rgba(0,0,0,0.06), 0 1px 2px rgba(0,0,0,0.04);
  --shadow-md: 0 4px 16px rgba(0,0,0,0.06);
  --shadow-lg: 0 12px 40px rgba(0,0,0,0.08);

  --font: 'Inter', -apple-system, BlinkMacSystemFont, 'PingFang SC', 'Microsoft YaHei', 'Noto Sans SC', sans-serif;

  --nav-height: 72px;
  --max-w: 1200px;
  --radius: 8px;
  --radius-lg: 14px;

  --nav-bg: rgba(255,255,255,0.88);
}

/* ===== 暗色模式 ===== */
[data-theme="dark"] {
  --bg: #0e0c18;
  --bg-alt: #141020;
  --bg-card: #161226;
  --bg-card-hover: #1d1830;
  --border: #2a2340;
  --border-hover: #3a3057;

  --accent: #a78bfa;
  --accent-hover: #c4b5fd;
  --accent-light: #221b38;
  --accent-soft: #2b2247;

  --text: #f1eefb;
  --text-secondary: #b7b0d3;
  --text-dim: #8a82ab;

  --shadow-sm: 0 1px 2px rgba(0,0,0,0.45);
  --shadow: 0 1px 3px rgba(0,0,0,0.55), 0 1px 2px rgba(0,0,0,0.45);
  --shadow-md: 0 4px 16px rgba(0,0,0,0.55);
  --shadow-lg: 0 12px 40px rgba(0,0,0,0.65);

  --nav-bg: rgba(14, 12, 24, 0.88);
}

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

html { scroll-behavior: smooth; scroll-padding-top: var(--nav-height); }

body {
  font-family: var(--font);
  background: var(--bg);
  color: var(--text);
  line-height: 1.7;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;

  overflow-x: hidden;
}

a { color: inherit; text-decoration: none; }
ul { list-style: none; }
img { max-width: 100%; display: block; }
button { cursor: pointer; font-family: inherit; border: none; background: none; }
input, select, textarea { font-family: inherit; }

::selection { background: var(--accent-soft); color: var(--accent); }

/* ===== 容器 ===== */
.container { width: 100%; max-width: var(--max-w); margin: 0 auto; padding: 0 32px; }

/* ===== Section 通用 ===== */
.section { padding: 120px 0; }

.section-header { text-align: center; margin-bottom: 72px; }

.section-label {
  display: block;
  font-size: 12px;
  font-weight: 700;
  letter-spacing: 0.18em;
  color: var(--accent);
  margin-bottom: 16px;
  text-transform: uppercase;
}

.section-title {
  font-size: clamp(28px, 4.5vw, 44px);
  font-weight: 800;
  letter-spacing: -0.02em;
  color: var(--text);
  line-height: 1.2;
}

.section-desc {
  color: var(--text-secondary);
  margin-top: 12px;
  font-size: 16px;
  font-weight: 400;
}

/* ===== 导航栏 ===== */
.nav {
  position: fixed;
  top: 0; left: 0; right: 0;
  z-index: 1000;
  height: var(--nav-height);
  background: var(--nav-bg);
  backdrop-filter: blur(16px);
  -webkit-backdrop-filter: blur(16px);
  border-bottom: 1px solid transparent;
  transition: border-color 0.3s, box-shadow 0.3s;
}

.nav.scrolled {
  border-bottom-color: var(--border);
  box-shadow: var(--shadow-sm);
}

/* 顶部（未滚动）时导航透明，贴合 hero 视频背景 */
.nav.nav-transparent {
  background: transparent;
  backdrop-filter: none;
  -webkit-backdrop-filter: none;
  border-bottom-color: transparent;
  box-shadow: none;
}

.nav.nav-transparent .nav-links a {
  color: rgba(255, 255, 255, 0.92);
  text-shadow: 0 1px 6px rgba(0, 0, 0, 0.5);
}

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

.nav.nav-transparent .nav-logo-img {
  filter: brightness(1.7) drop-shadow(0 2px 5px rgba(0, 0, 0, 0.6));
}

.nav.nav-transparent .rm-logo-dark { display: none; }
.nav.nav-transparent .rm-logo-white { display: block; }
.nav.nav-transparent .nav-logo-sep { background: rgba(255, 255, 255, 0.35); }

.nav.nav-transparent .nav-toggle span { background: #fff; }

.nav-inner {
  max-width: var(--max-w);
  margin: 0 auto;
  padding: 0 32px;
  height: 100%;
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.nav-logo {
  display: flex;
  align-items: center;
  gap: 10px;
  z-index: 1001;
}

.nav-logo-sep {
  width: 1px;
  height: 22px;
  background: var(--border);
  margin: 0 4px;
  transition: background 0.3s;
}

.rm-logo {
  height: 18px;
  width: auto;
}

.rm-logo-white { display: none; }

.nav-logo-img {
  height: 36px;
  width: auto;
}

.logo-text {
  font-size: 19px;
  font-weight: 800;
  letter-spacing: -0.02em;
  color: var(--text);
}

.logo-sub {
  display: block;
  font-size: 11px;
  font-weight: 500;
  color: var(--text-dim);
  letter-spacing: 0.06em;
}

.nav-links { display: flex; gap: 36px; }

.nav-links a {
  font-size: 14px;
  font-weight: 500;
  color: var(--text-secondary);
  transition: color 0.2s;
}

.nav-links a:hover { color: var(--accent); }

.nav-toggle {
  display: none;
  flex-direction: column;
  gap: 5px;
  padding: 6px;
  z-index: 1001;
}

.nav-toggle span {
  display: block;
  width: 22px; height: 2px;
  background: var(--text);
  border-radius: 1px;
  transition: transform 0.3s, opacity 0.3s;
}

.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); }

/* ===== 英雄区 ===== */
.hero {
  min-height: 100vh;
  display: flex;
  align-items: center;
  justify-content: center;
  text-align: center;
  padding: 120px 32px 80px;
  position: relative;
  overflow: hidden;
  background: #0c0a1d;
}

.hero-video {
  position: absolute;
  inset: 0;
  width: 100%;
  height: 100%;
  object-fit: cover;
  z-index: 0;
}

.hero-overlay {
  position: absolute;
  inset: 0;
  z-index: 1;
  background: linear-gradient(
    180deg,
    rgba(12, 10, 29, 0.62) 0%,
    rgba(12, 10, 29, 0.38) 45%,
    rgba(12, 10, 29, 0.6) 100%
  );
}

.hero::before {
  content: '';
  position: absolute;
  top: 0; left: 0; right: 0;
  height: 1px;
  background: linear-gradient(90deg, transparent, rgba(124,58,237,0.15), transparent);
}

.hero-title-logo {
  display: block;
  width: clamp(300px, 48vw, 560px);
  height: auto;
  margin: 0 auto;
  filter: drop-shadow(0 4px 18px rgba(0, 0, 0, 0.45));
  animation: fadeInUp 0.8s ease-out;
}

.hero-content { position: relative; z-index: 2; max-width: 700px; margin: 0 auto; }

.hero-badge {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 6px 18px;
  border-radius: 20px;
  font-size: 13px;
  font-weight: 500;
  color: var(--accent);
  background: var(--accent-light);
  margin-bottom: 28px;
  animation: fadeInUp 0.8s ease-out;
}

.badge-dot {
  width: 6px; height: 6px;
  border-radius: 50%;
  background: var(--accent);
}

.hero-title {
  animation: fadeInUp 0.8s ease-out 0.1s both;
}

.title-main {
  display: block;
  font-size: clamp(44px, 9vw, 88px);
  font-weight: 900;
  letter-spacing: -0.03em;
  line-height: 1;
  color: var(--text);
}

.title-sub {
  display: block;
  font-size: clamp(16px, 2.5vw, 20px);
  font-weight: 500;
  color: rgba(255, 255, 255, 0.92);
  letter-spacing: 0.12em;
  margin-top: 12px;
  text-shadow: 0 2px 12px rgba(0, 0, 0, 0.4);
}

.hero-desc {
  font-size: clamp(15px, 2vw, 17px);
  color: rgba(255, 255, 255, 0.88);
  margin-top: 24px;
  line-height: 1.8;
  text-shadow: 0 2px 12px rgba(0, 0, 0, 0.4);
  animation: fadeInUp 0.8s ease-out 0.2s both;
}

.hero-desc .highlight {
  color: #c4b5fd;
  font-weight: 600;
}

.hero-groups {
  display: flex;
  justify-content: center;
  gap: 36px;
  margin-top: 48px;
  flex-wrap: wrap;
  animation: fadeInUp 0.8s ease-out 0.3s both;
}

.hero-group {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 10px;
  min-width: 76px;
}

.hero-group-icon {
  width: 64px; height: 64px;
  border-radius: 18px;
  background: rgba(255, 255, 255, 0.14);
  color: #fff;
  display: flex;
  align-items: center;
  justify-content: center;
  border: 1px solid rgba(255, 255, 255, 0.18);
  backdrop-filter: blur(6px);
  transition: all 0.3s;
}

.hero-group:hover .hero-group-icon {
  background: var(--accent);
  color: #fff;
  border-color: transparent;
  transform: translateY(-3px);
}

.hero-group-svg {
  width: 30px;
  height: 30px;
}

.hero-group-name {
  font-size: 13px;
  font-weight: 600;
  color: rgba(255, 255, 255, 0.85);
  letter-spacing: 0.05em;
  text-shadow: 0 1px 8px rgba(0, 0, 0, 0.5);
}

.hero-actions {
  display: flex;
  justify-content: center;
  gap: 16px;
  margin-top: 40px;
  flex-wrap: wrap;
  animation: fadeInUp 0.8s ease-out 0.4s both;
}

.hero .btn-outline {
  border: 1.5px solid rgba(255, 255, 255, 0.75);
  color: #fff;
  background: rgba(255, 255, 255, 0.08);
  backdrop-filter: blur(6px);
}

.hero .btn-outline:hover {
  border-color: var(--accent);
  color: #fff;
  background: var(--accent);
}

/* ===== 按钮 ===== */
.btn {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 14px 30px;
  font-size: 14px;
  font-weight: 600;
  letter-spacing: 0.02em;
  border-radius: var(--radius);
  transition: all 0.25s;
}

.btn-primary {
  background: var(--accent);
  color: #fff;
  box-shadow: 0 2px 8px rgba(124,58,237,0.25);
}

.btn-primary:hover {
  background: var(--accent-hover);
  box-shadow: 0 4px 16px rgba(124,58,237,0.35);
  transform: translateY(-1px);
}

.btn-outline {
  border: 1.5px solid var(--border);
  color: var(--text);
  background: var(--bg);
}

.btn-outline:hover {
  border-color: var(--accent);
  color: var(--accent);
  background: var(--accent-light);
  transform: translateY(-1px);
}

.btn-primary:active, .btn-outline:active { transform: translateY(0); }

/* ===== 战队介绍 ===== */
.about {
  position: relative;
  background: url('./assets/about-bg.png') center / contain no-repeat;
  background-color: #f5f1fc;
}

.about::before {
  content: '';
  position: absolute;
  inset: 0;
  background: rgba(255, 255, 255, 0.88);
  z-index: 0;
}

.about .container {
  position: relative;
  z-index: 1;
}

.about-text {
  max-width: 860px;
  margin: 0 auto;
  text-align: center;
}

.about-text h3 {
  font-size: 26px;
  font-weight: 800;
  letter-spacing: -0.02em;
  margin-bottom: 20px;
}

.about-text p {
  color: var(--text-secondary);
  margin-bottom: 16px;
  font-size: 15.5px;
  line-height: 1.9;
}

.about-text strong { color: var(--accent); font-weight: 600; }
.about-text em { color: var(--text); font-style: normal; font-weight: 500; }

.about-values {
  display: flex;
  justify-content: center;
  gap: 40px;
  margin-top: 36px;
  flex-wrap: wrap;
}

.value-item {
  display: flex;
  align-items: center;
  gap: 10px;
  padding: 12px 20px;
  border: 1px solid rgba(124, 58, 237, 0.18);
  border-radius: var(--radius);
  background: rgba(255, 255, 255, 0.9);
  color: var(--accent);
  font-size: 14px;
  font-weight: 600;
  box-shadow: var(--shadow-sm);
  transition: all 0.25s;
}

.value-item:hover {
  border-color: var(--accent);
  background: var(--accent-light);
}

.value-icon { display: flex; align-items: center; }

/* ===== 技术组展示 ===== */
.robots { background: var(--bg); }

.tech-carousel {
  position: relative;
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 14px;
}

.carousel-stage {
  position: relative;
  flex: 1;
  height: 450px;
  max-width: 860px;
}

.carousel-arrow {
  flex-shrink: 0;
  width: 52px;
  height: 52px;
  border-radius: 50%;
  border: 1.5px solid var(--border);
  background: var(--bg);
  color: var(--text);
  display: flex;
  align-items: center;
  justify-content: center;
  cursor: pointer;
  transition: all 0.25s;
  z-index: 10;
}

.carousel-arrow:hover {
  background: var(--accent);
  color: #fff;
  border-color: var(--accent);
  box-shadow: 0 4px 16px rgba(124, 58, 237, 0.35);
}

.carousel-arrow:active { transform: scale(0.94); }

.tech-card {
  position: absolute;
  left: 50%;
  top: 50%;
  width: min(680px, 72vw);
  height: 450px;
  padding: 32px 40px;
  box-sizing: border-box;
  background: var(--bg);
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  display: flex;
  flex-direction: column;
  align-items: center;
  text-align: center;
  gap: 16px;
  box-shadow: var(--shadow-sm);
  transition: transform 0.55s cubic-bezier(0.22, 1, 0.36, 1),
              opacity 0.45s ease,
              box-shadow 0.3s,
              border-color 0.3s;
  will-change: transform, opacity;
}

.tech-info {
  flex: 1;
  min-height: 0;
  display: flex;
  flex-direction: column;
  gap: 8px;
  width: 100%;
  max-width: 600px;
}

.tech-card::before {
  content: '';
  position: absolute;
  top: 0; left: 0; right: 0;
  height: 3px;
  background: linear-gradient(90deg, #7c3aed, #6366f1, #a78bfa);
  opacity: 0;
  transition: opacity 0.3s;
}

.tech-card[data-offset="0"] {
  transform: translate(-50%, -50%) scale(1);
  opacity: 1;
  z-index: 5;
  box-shadow: 0 24px 70px rgba(15, 10, 40, 0.14);
  border-color: rgba(124, 58, 237, 0.28);
}

.tech-card[data-offset="0"]::before { opacity: 1; }

.tech-card[data-offset="1"],
.tech-card[data-offset="-1"] {
  transform: translate(calc(-50% + 82%), -50%) scale(0.82);
  opacity: 0.55;
  z-index: 3;
}

.tech-card[data-offset="-1"] {
  transform: translate(calc(-50% - 82%), -50%) scale(0.82);
}

.tech-card[data-offset="2"],
.tech-card[data-offset="-2"] {
  transform: translate(calc(-50% + 160%), -50%) scale(0.72);
  opacity: 0;
  z-index: 1;
  pointer-events: none;
}

.tech-card[data-offset="-2"] {
  transform: translate(calc(-50% - 160%), -50%) scale(0.72);
}

.tech-card[data-offset="0"]:hover {
  border-color: rgba(124,58,237,0.35);
}

.tech-icon {
  width: 88px; height: 88px;
  display: flex;
  align-items: center;
  justify-content: center;
  background: var(--accent-soft);
  border-radius: 18px;
  transition: all 0.35s cubic-bezier(0.4, 0, 0.2, 1);
}

.tech-icon .tech-icon-svg {
  width: 52px;
  height: 52px;
  color: var(--accent);
}

.tech-card:hover .tech-icon {
  background: var(--accent-light);
  transform: scale(1.06) rotate(-2deg);
}

.tech-tag {
  display: inline-block;
  font-size: 10px;
  font-weight: 700;
  color: var(--accent);
  letter-spacing: 0.12em;
  text-transform: uppercase;
  margin-bottom: 2px;
}

.tech-name {
  font-size: 22px;
  font-weight: 800;
  letter-spacing: -0.02em;
  margin: 4px 0 10px;
}

.tech-desc {
  flex: 1;
  min-height: 0;
  font-size: 13.5px;
  color: var(--text-secondary);
  line-height: 1.7;
  text-align: left;
  width: 100%;
  max-width: 600px;
  margin: 0 auto;
  overflow-y: auto;
  padding-right: 10px;
  scrollbar-width: thin;
  scrollbar-color: rgba(124, 58, 237, 0.45) transparent;
}

.tech-desc::-webkit-scrollbar { width: 5px; }
.tech-desc::-webkit-scrollbar-thumb {
  background: rgba(124, 58, 237, 0.35);
  border-radius: 4px;
}
.tech-desc::-webkit-scrollbar-track { background: transparent; }

.tech-desc p + p { margin-top: 10px; }

.tech-desc strong {
  color: var(--accent);
  font-weight: 700;
}



/* ===== 成员网格 ===== */
.members { background: var(--bg); }

.members-grid {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 20px;
}

.member-card {
  background: var(--bg);
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  padding: 36px 20px 28px;
  text-align: center;
  display: flex;
  flex-direction: column;
  align-items: center;
  transition: all 0.3s;
  box-shadow: var(--shadow-sm);
}

.member-card:hover {
  border-color: rgba(124, 58, 237, 0.35);
  box-shadow: var(--shadow-lg);
  transform: translateY(-4px);
}

.member-avatar {
  width: 76px; height: 76px;
  border-radius: 50%;
  background: linear-gradient(135deg, #8b5cf6, #6d28d9);
  margin: 0 auto 18px;
  display: flex;
  align-items: center;
  justify-content: center;
  box-shadow: 0 6px 16px rgba(109, 40, 217, 0.28);
  transition: transform 0.3s, box-shadow 0.3s;
}

.member-card:hover .member-avatar {
  transform: scale(1.05);
  box-shadow: 0 8px 22px rgba(109, 40, 217, 0.4);
}

.avatar-initials {
  font-size: 30px;
  font-weight: 700;
  color: #fff;
}

.member-avatar img {
  width: 100%;
  height: 100%;
  object-fit: cover;
  border-radius: 50%;
  display: block;
}

.member-info h4.member-name {
  font-size: 17px;
  font-weight: 700;
  margin-bottom: 10px;
}

.member-roles {
  display: flex;
  flex-wrap: wrap;
  justify-content: center;
  gap: 6px;
  margin-bottom: 10px;
}

.member-role {
  display: inline-block;
  font-size: 12px;
  font-weight: 600;
  color: var(--accent);
  padding: 3px 10px;
  background: var(--accent-light);
  border-radius: 999px;
}

.member-grade {
  font-size: 13px;
  font-weight: 600;
  color: var(--text-secondary);
  letter-spacing: 0.08em;
}

.member-desc {
  margin-top: 12px;
  font-size: 12.5px;
  color: var(--text-secondary);
  line-height: 1.6;
}

/* ===== 合作伙伴 ===== */
.sponsors { background: var(--bg); }

.sponsors-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 20px;
}

.sponsor-item {
  text-align: center;
  padding: 36px 16px;
  background: var(--bg);
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  transition: all 0.3s;
  box-shadow: var(--shadow-sm);
}

.sponsor-item:hover { box-shadow: var(--shadow-md); }

.sponsor-logo {
  margin-bottom: 12px;
  display: flex;
  justify-content: center;
}

.sponsor-link {
  display: block;
  text-decoration: none;
}

.sponsor-tier {
  font-size: 11px;
  font-weight: 500;
  color: var(--text-dim);
  letter-spacing: 0.04em;
}

.sponsor-name {
  display: block;
  font-size: 14px;
  font-weight: 600;
  color: var(--text);
  margin-bottom: 4px;
}

.sponsor-logo img {
  max-width: 220px;
  max-height: 90px;
  width: auto;
  height: auto;
  object-fit: contain;
}

.sponsor-logo-text {
  font-size: 26px;
  font-weight: 800;
  color: var(--text);
  letter-spacing: 0.02em;
  align-items: center;
}

.sponsor-join {
  border-style: dashed;
  background: linear-gradient(180deg, rgba(255, 255, 255, 0.6), rgba(248, 249, 251, 0.6));
}

.sponsor-join-icon {
  font-size: 40px;
  font-weight: 300;
  color: var(--accent);
  line-height: 1;
}

.sponsors-cta {
  text-align: center;
  margin-top: 52px;
}

.sponsors-cta p {
  color: var(--text-secondary);
  margin-bottom: 16px;
}

/* ===== 联系我们 ===== */
.contact { background: var(--bg-alt); }

.contact-grid {
  display: grid;
  grid-template-columns: 1fr 1.2fr;
  gap: 56px;
  align-items: stretch;
}

.contact-left .section-header {
  text-align: left;
  margin-bottom: 40px;
}

.contact-left .section-header .section-title {
  margin: 0 0 12px;
}

.contact-item {
  display: flex;
  gap: 16px;
  margin-bottom: 24px;
}

.contact-icon {
  flex-shrink: 0;
  width: 46px; height: 46px;
  display: flex;
  align-items: center;
  justify-content: center;
  border-radius: var(--radius);
  background: var(--accent-light);
  color: var(--accent);
}

.contact-item h4 {
  font-size: 14px;
  font-weight: 600;
  margin-bottom: 4px;
}

.contact-item p { font-size: 14px; color: var(--text-secondary); }

.contact-social {
  display: flex;
  gap: 12px;
  margin-top: 28px;
  padding-top: 24px;
  border-top: 1px solid var(--border);
}

.social-link {
  width: 42px; height: 42px;
  display: flex;
  align-items: center;
  justify-content: center;
  border: 1px solid var(--border);
  border-radius: var(--radius);
  color: var(--text-dim);
  transition: all 0.25s;
}

.social-link:hover {
  color: var(--accent);
  border-color: var(--accent);
  background: var(--accent-light);
}

/* 表单 */
.contact-form {
  background: var(--bg);
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  padding: 36px;
  box-shadow: var(--shadow-sm);
}

.form-row {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 16px;
  margin-bottom: 16px;
}

.form-group { margin-bottom: 16px; }

.form-group label {
  display: block;
  font-size: 13px;
  font-weight: 600;
  color: var(--text);
  margin-bottom: 6px;
}

.form-group input,
.form-group select,
.form-group textarea {
  width: 100%;
  padding: 12px 16px;
  background: var(--bg-alt);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  color: var(--text);
  font-size: 14px;
  transition: border-color 0.25s, box-shadow 0.25s;
  outline: none;
}

.form-group input:focus,
.form-group select:focus,
.form-group textarea:focus {
  border-color: var(--accent);
  box-shadow: 0 0 0 3px rgba(124,58,237,0.1);
}

.form-group select {
  cursor: pointer;
  appearance: none;
  background-image: url("data:image/svg+xml,%3Csvg width='12' height='8' viewBox='0 0 12 8' fill='none' xmlns='http://www.w3.org/2000/svg'%3E%3Cpath d='M1 1.5L6 6.5L11 1.5' stroke='%236b7280' stroke-width='1.5' stroke-linecap='round'/%3E%3C/svg%3E");
  background-repeat: no-repeat;
  background-position: right 14px center;
  padding-right: 44px;
}

.form-group select option { background: #fff; color: var(--text); }
.form-group textarea { resize: vertical; min-height: 110px; }

/* ===== 页脚 ===== */
.footer {
  background: #111827;
  color: #e5e7eb;
  padding: 72px 0 36px;
}

.footer-grid {
  display: grid;
  grid-template-columns: 1.1fr 1fr 1fr 2.8fr;
  gap: 48px;
  margin-bottom: 48px;
}

.footer-logo {
  display: flex;
  align-items: center;
  gap: 10px;
  margin-bottom: 16px;
  font-size: 17px;
  font-weight: 700;
  color: #fff;
  letter-spacing: -0.02em;
}

.footer-logo-img { height: 30px; width: auto; }

.footer-brand p {
  font-size: 14px;
  color: #9ca3af;
  line-height: 1.8;
}

.footer-links h4 {
  font-size: 13px;
  font-weight: 600;
  color: #fff;
  margin-bottom: 16px;
}

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

.footer-links a {
  font-size: 14px;
  color: #9ca3af;
  transition: color 0.2s;
}

.footer-links a:hover { color: #c4b5fd; }

.footer-gate {
  display: flex;
  align-items: center;
  justify-content: flex-end;
}

.footer-gate img {
  max-width: 600px;
  width: 100%;
  opacity: 0.95;
}

.footer-bottom {
  padding-top: 28px;
  border-top: 1px solid rgba(255,255,255,0.08);
  text-align: center;
}

.footer-bottom p { font-size: 13px; color: #6b7280; }

.footer-dedication { margin-top: 4px; font-size: 12px !important; }

/* ===== 动画 ===== */
.reveal {
  opacity: 0;
  transform: translateY(36px);
  transition: opacity 0.7s ease, transform 0.7s ease;
}

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

@keyframes fadeInUp {
  from { opacity: 0; transform: translateY(28px); }
  to { opacity: 1; transform: translateY(0); }
}

/* ===== Toast ===== */
.toast {
  position: fixed;
  top: 28px; right: 28px;
  z-index: 9999;
  padding: 14px 24px;
  background: #111827;
  color: #fff;
  font-size: 14px;
  font-weight: 500;
  border-radius: var(--radius);
  box-shadow: 0 8px 32px rgba(0,0,0,0.2);
  animation: slideInRight 0.35s ease-out;
}

.toast.error {
  background: #fef2f2;
  color: #991b1b;
  border: 1px solid #fecaca;
}

@keyframes slideInRight {
  from { opacity: 0; transform: translateX(40px); }
  to { opacity: 1; transform: translateX(0); }
}

.survey-wrap {
  min-height: 0;
}

/* ===== 移动端菜单遮罩 ===== */
.nav-backdrop {
  position: fixed;
  inset: 0;
  background: rgba(8, 6, 18, 0.5);
  backdrop-filter: blur(2px);
  opacity: 0;
  visibility: hidden;
  transition: opacity 0.35s, visibility 0.35s;
  z-index: 999;
}

.nav-backdrop.active { opacity: 1; visibility: visible; }

/* ===== 主题切换按钮 ===== */
.theme-toggle {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 38px;
  height: 38px;
  border-radius: 50%;
  border: 1px solid var(--border);
  color: var(--text-secondary);
  background: transparent;
  transition: all 0.3s;
  z-index: 1001;
}

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

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

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

.nav.nav-transparent .theme-toggle {
  border-color: rgba(255,255,255,0.35);
  color: #fff;
}

/* ===== 暗色补充覆盖 ===== */
[data-theme="dark"] .about { background-color: #141020; }
[data-theme="dark"] .about::before { background: rgba(14, 12, 24, 0.82); }
[data-theme="dark"] .value-item {
  background: rgba(22, 18, 38, 0.9);
  border-color: rgba(167, 139, 250, 0.25);
}
[data-theme="dark"] .survey-iframe { background: #141020; }
[data-theme="dark"] .sponsor-logo:not(.sponsor-logo-text):not(.sponsor-join-icon) {
  background: rgba(255, 255, 255, 0.94);
  border-radius: var(--radius);
  padding: 10px 18px;
}
[data-theme="dark"] .sponsor-join {
  background: linear-gradient(180deg, rgba(22, 18, 38, 0.9), rgba(14, 12, 24, 0.9));
}
[data-theme="dark"] .form-group select option { background: #161226; color: var(--text); }
[data-theme="dark"] .footer { background: #0a0814; }
[data-theme="dark"] .footer-links a:hover { color: var(--accent-hover); }
[data-theme="dark"] .toast { background: #221b38; color: #f1eefb; }

@media (max-width: 768px) {
  [data-theme="dark"] .nav-links {
    background: rgba(14, 12, 24, 0.98);
  }
}

.survey-iframe {
  width: 100%;
  height: 100%;
  min-height: 400px;
  border: 1px solid var(--border);
  border-radius: var(--radius);
  background: #fff;
  display: block;
}

/* ===== 响应式 ===== */
@media (max-width: 1024px) {
  .members-grid { grid-template-columns: repeat(2, 1fr); }
  .sponsors-grid { grid-template-columns: repeat(2, 1fr); }
  .contact-grid { grid-template-columns: 1fr; }
  .footer-grid { grid-template-columns: 1fr 1fr; }
}

@media (max-width: 768px) {
  .section { padding: 80px 0; }

  .nav-links {
    position: fixed;
    top: 0; right: -100%;
    width: min(80vw, 320px); height: 100vh;
    flex-direction: column;
    z-index: 1001;
    background: #fff;
    backdrop-filter: blur(20px);
    padding: 96px 28px 40px;
    gap: 8px;
    transition: right 0.4s ease;
    border-left: 1px solid var(--border);
    box-shadow: -12px 0 40px rgba(0,0,0,0.18);
  }

  .nav-links.active { right: 0; }
  .nav-toggle { display: flex; }

  .hero-groups { gap: 28px; }
  .members-grid { grid-template-columns: repeat(2, 1fr); gap: 14px; }
  .sponsors-grid { grid-template-columns: repeat(2, 1fr); gap: 14px; }
  .tech-card { width: 84vw; padding: 34px 22px; gap: 16px; }
  .carousel-arrow { width: 44px; height: 44px; }
  .tech-carousel { gap: 8px; }
  .form-row { grid-template-columns: 1fr; }
  .footer-grid { grid-template-columns: 1fr 1fr; gap: 32px 28px; }
}

@media (max-width: 480px) {
  .section { padding: 64px 0; }
  .hero-actions { flex-direction: column; align-items: center; }
  .hero-groups { gap: 20px; }
  .about-card { width: 100%; max-width: 320px; }
  .section-header { margin-bottom: 48px; }
}

/* ===== 移动端适配增强 ===== */
@media (max-width: 768px) {
  .container { padding: 0 20px; }
  .nav-inner { padding: 0 16px; }
  .nav-links a { font-size: 15px; font-weight: 600; }

  /* 主页 */
  .hero { padding: 96px 20px 64px; }
  .hero-title-logo { width: clamp(240px, 62vw, 340px); }
  .hero-group-icon { width: 56px; height: 56px; border-radius: 16px; }
  .hero-groups { gap: 24px 18px; margin-top: 36px; }
  .hero-actions { gap: 12px; }
  .hero .btn { padding: 12px 22px; }

  /* 技术组轮播：箭头浮在卡片两侧，舞台全宽 */
  .tech-carousel { gap: 0; }
  .carousel-stage { flex: none; width: 100%; }
  .carousel-arrow {
    position: absolute;
    top: 50%;
    transform: translateY(-50%);
    width: 40px;
    height: 40px;
    z-index: 20;
    box-shadow: var(--shadow-md);
  }
  .carousel-prev { left: 6px; }
  .carousel-next { right: 6px; }
  .tech-card {
    width: 86vw;
    padding: 26px 18px;
    gap: 12px;
  }
  .tech-icon { width: 68px; height: 68px; border-radius: 16px; }
  .tech-icon .tech-icon-svg { width: 38px; height: 38px; }
  .tech-name { font-size: 20px; }
  .tech-desc { font-size: 13px; }

  .nav-links a { font-size: 16px; font-weight: 600; padding: 12px 0; border-bottom: 1px solid var(--border); }

  /* 透明导航态下，展开的菜单内文字必须用深色，否则白底白字 */
  .nav.nav-transparent .nav-links a {
    color: var(--text-secondary);
    text-shadow: none;
  }
  .nav.nav-transparent .nav-links a:hover { color: var(--accent); }
  .nav.nav-transparent .nav-links a.active { color: var(--accent); }

  /* 成员 / 赞助商 2 列 */
  .member-card { padding: 22px 10px 18px; }
  .member-avatar { width: 60px; height: 60px; margin-bottom: 12px; }
  .member-name { font-size: 16px; }
  .member-role, .member-grade { font-size: 12px; }
  .sponsor-item { padding: 22px 10px; }
  .sponsor-logo img { max-width: 150px; max-height: 70px; }
  .sponsor-name { font-size: 13px; }

  /* 页脚：文字左右栏，校门图底部通栏 */
  .footer-gate { grid-column: 1 / -1; justify-content: center; margin-top: 10px; }
  .footer-gate img { max-width: 380px; }

  /* 移动端偏移：±1 露边 63vw，±2 隐藏 */
  .tech-card[data-offset="1"],
  .tech-card[data-offset="-1"] {
    transform: translate(calc(-50% + 63vw), -50%) scale(0.85);
    opacity: 0.5;
  }
  .tech-card[data-offset="-1"] {
    transform: translate(calc(-50% - 63vw), -50%) scale(0.85);
  }
  .tech-card[data-offset="2"],
  .tech-card[data-offset="-2"] {
    transform: translate(-50%, -50%) scale(0.72);
  }

  /* 成员 */
  .member-card { padding: 28px 16px 22px; }
  .member-avatar { width: 68px; height: 68px; }

  /* 联系 */
  .contact-grid { gap: 40px; }
  .survey-wrap { height: 560px; }
  .survey-iframe { min-height: 520px; }

  /* 赞助商 */
  .sponsor-item { padding: 28px 12px; }

  /* 页脚 */
  .footer { padding: 56px 0 28px; }
  .footer-gate { justify-content: center; }
  .footer-gate img { max-width: 320px; }
}

@media (max-width: 480px) {
  .section-header { margin-bottom: 40px; }
  .section-desc { font-size: 14px; }
  .about-values { gap: 20px; }
  .value-item { padding: 10px 16px; font-size: 13px; }
  .tech-card { width: 88vw; padding: 22px 14px; }
  .hero-badge { font-size: 12px; padding: 5px 14px; }
  .contact-social { flex-wrap: wrap; }
}