/* ===== 变量与基础 ===== */
:root {
  --bg-dark: #0d0f14;
  --bg-card: #151820;
  --bg-elevated: #1a1d26;
  --text-primary: #e8eaef;
  --text-secondary: #9ca3b4;
  --accent-blue: #3b82f6;
  --accent-blue-hover: #60a5fa;
  --accent-purple: #8b5cf6;
  --accent-purple-hover: #a78bfa;
  --gradient-cta: linear-gradient(135deg, #3b82f6 0%, #8b5cf6 100%);
  --gradient-bg: radial-gradient(ellipse 80% 60% at 50% 0%, rgba(59, 130, 246, 0.12) 0%, transparent 50%),
    radial-gradient(ellipse 60% 40% at 80% 20%, rgba(139, 92, 246, 0.08) 0%, transparent 40%);
  --font-sans: "Noto Sans SC", -apple-system, BlinkMacSystemFont, sans-serif;
  --shadow-card: 0 4px 24px rgba(0, 0, 0, 0.25);
  --shadow-card-hover: 0 12px 40px rgba(59, 130, 246, 0.15);
  --radius: 12px;
  --header-h: 64px;
}

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

html {
  scroll-behavior: smooth;
}

body {
  margin: 0;
  font-family: var(--font-sans);
  font-size: 16px;
  line-height: 1.6;
  color: var(--text-primary);
  background-color: var(--bg-dark);
  overflow-x: hidden;
}

/* ===== 加载动画 ===== */
.loader {
  position: fixed;
  inset: 0;
  z-index: 9999;
  display: flex;
  align-items: center;
  justify-content: center;
  background: var(--bg-dark);
  transition: opacity 0.4s ease, visibility 0.4s ease;
}

.loader.is-hidden {
  opacity: 0;
  visibility: hidden;
  pointer-events: none;
}

.loader-inner {
  width: 48px;
  height: 48px;
  border: 3px solid var(--bg-elevated);
  border-top-color: var(--accent-blue);
  border-radius: 50%;
  animation: loader-spin 0.8s linear infinite;
}

@keyframes loader-spin {
  to { transform: rotate(360deg); }
}

/* ===== 导航 ===== */
.header {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  z-index: 100;
  height: var(--header-h);
  background: rgba(13, 15, 20, 0.9);
  backdrop-filter: blur(12px);
  border-bottom: 1px solid rgba(255, 255, 255, 0.06);
  transition: background 0.2s ease;
}

.header-inner {
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 24px;
  height: 100%;
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.logo {
  font-weight: 700;
  font-size: 1.125rem;
  color: var(--text-primary);
  text-decoration: none;
  letter-spacing: 0.02em;
}

.logo:hover {
  color: var(--accent-blue);
}

.nav-toggle {
  display: none;
  width: 40px;
  height: 40px;
  padding: 0;
  border: none;
  background: transparent;
  cursor: pointer;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: 6px;
}

.nav-toggle::before,
.nav-toggle::after,
.nav-toggle span {
  content: "";
  display: block;
  width: 22px;
  height: 2px;
  background: var(--text-primary);
  border-radius: 1px;
  transition: transform 0.2s ease, opacity 0.2s ease;
}

.nav-toggle span {
  width: 18px;
  margin: 0 auto;
}

.nav-toggle[aria-expanded="true"]::before {
  transform: translateY(4px) rotate(45deg);
}

.nav-toggle[aria-expanded="true"]::after {
  transform: translateY(-4px) rotate(-45deg);
}

.nav-toggle[aria-expanded="true"] span {
  opacity: 0;
}

.nav-list {
  display: flex;
  align-items: center;
  gap: 8px;
  list-style: none;
  margin: 0;
  padding: 0;
}

.nav-item {
  position: relative;
}

.nav-link {
  display: block;
  padding: 10px 16px;
  color: var(--text-secondary);
  text-decoration: none;
  font-weight: 500;
  font-size: 0.9375rem;
  border-radius: var(--radius);
  transition: color 0.2s ease, background 0.2s ease;
}

.nav-link:hover {
  color: var(--text-primary);
  background: rgba(255, 255, 255, 0.06);
}

.nav-dropdown {
  position: absolute;
  top: 100%;
  left: 0;
  min-width: 160px;
  padding: 8px 0;
  margin-top: 4px;
  background: var(--bg-elevated);
  border-radius: var(--radius);
  box-shadow: var(--shadow-card);
  list-style: none;
  opacity: 0;
  visibility: hidden;
  transform: translateY(-8px);
  transition: opacity 0.2s ease, transform 0.2s ease, visibility 0.2s ease;
}

.nav-item:hover .nav-dropdown,
.nav-item:focus-within .nav-dropdown {
  opacity: 1;
  visibility: visible;
  transform: translateY(0);
}

.nav-dropdown a {
  display: block;
  padding: 10px 16px;
  color: var(--text-secondary);
  text-decoration: none;
  font-size: 0.875rem;
  transition: color 0.2s ease, background 0.2s ease;
}

.nav-dropdown a:hover {
  color: var(--accent-blue);
  background: rgba(59, 130, 246, 0.1);
}

/* ===== 通用区块 ===== */
.section {
  padding: 80px 0;
}

.container {
  max-width: 1100px;
  margin: 0 auto;
  padding: 0 24px;
}

.section-title {
  margin: 0 0 40px;
  font-size: 1.75rem;
  font-weight: 700;
  text-align: center;
  color: var(--text-primary);
}

/* ===== Hero ===== */
.hero {
  position: relative;
  min-height: 100vh;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  padding: var(--header-h) 24px 60px;
  overflow: hidden;
}

.hero-bg {
  position: absolute;
  inset: 0;
  background-image: linear-gradient(
      to bottom,
      rgba(13, 15, 20, 0.72),
      rgba(13, 15, 20, 0.78)
    ),
    url("../assets/imgs/网站文案规范1.jpg");
  background-size: cover;
  background-position: center;
  background-repeat: no-repeat;
  pointer-events: none;
}

.hero-compliance {
  margin-top: 40px;
  max-width: 520px;
  margin-left: auto;
  margin-right: auto;
  padding: 14px 20px;
  background: rgba(26, 29, 38, 0.85);
  border-radius: var(--radius);
  border: 1px solid rgba(59, 130, 246, 0.2);
  text-align: left;
}

.hero-compliance-title {
  margin: 0 0 6px;
  font-size: 0.8125rem;
  font-weight: 600;
  color: var(--accent-blue);
}

.hero-compliance-desc {
  margin: 0;
  font-size: 0.75rem;
  color: var(--text-secondary);
  line-height: 1.5;
}

.hero-compliance strong {
  color: var(--text-primary);
}

.hero-content {
  position: relative;
  z-index: 1;
  text-align: center;
  max-width: 720px;
}

.hero-title {
  margin: 0 0 20px;
  font-size: clamp(1.75rem, 4vw, 2.5rem);
  font-weight: 700;
  line-height: 1.25;
  color: var(--text-primary);
  letter-spacing: 0.02em;
}

.hero-subtitle {
  margin: 0 0 32px;
  font-size: 1.0625rem;
  color: var(--text-secondary);
  max-width: 520px;
  margin-left: auto;
  margin-right: auto;
}

.hero-actions {
  display: flex;
  flex-wrap: wrap;
  gap: 16px;
  justify-content: center;
}

/* ===== 按钮 ===== */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  padding: 14px 28px;
  font-family: var(--font-sans);
  font-size: 1rem;
  font-weight: 600;
  text-decoration: none;
  border-radius: var(--radius);
  border: none;
  cursor: pointer;
  transition: transform 0.2s ease, box-shadow 0.2s ease, opacity 0.2s ease;
}

.btn:active {
  transform: scale(0.98);
}

.btn--primary {
  background: var(--gradient-cta);
  color: #fff;
  box-shadow: 0 4px 20px rgba(59, 130, 246, 0.35);
}

.btn--primary:hover {
  box-shadow: 0 8px 32px rgba(59, 130, 246, 0.45);
  opacity: 0.95;
}

.btn--secondary {
  background: transparent;
  color: var(--accent-blue);
  border: 2px solid var(--accent-blue);
}

.btn--secondary:hover {
  background: rgba(59, 130, 246, 0.12);
  color: var(--accent-blue-hover);
  border-color: var(--accent-blue-hover);
}

.btn--download {
  flex-direction: column;
  align-items: center;
  gap: 4px;
  min-width: 140px;
}

.btn-platform {
  font-size: 1rem;
}

.btn-version {
  font-size: 0.75rem;
  font-weight: 400;
  opacity: 0.9;
}

/* ===== About ===== */
.about {
  background: var(--bg-card);
}

.about-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 48px;
  align-items: center;
}

.about-content .section-title {
  text-align: left;
  margin-bottom: 20px;
}

.about-text {
  margin: 0 0 16px;
  color: var(--text-secondary);
  font-size: 1rem;
}

.about-text strong {
  color: var(--accent-blue);
}

.about-compliance {
  margin: 0;
  padding: 16px;
  background: rgba(59, 130, 246, 0.08);
  border-radius: var(--radius);
  border-left: 4px solid var(--accent-blue);
  font-size: 0.9375rem;
  color: var(--text-secondary);
}

.about-compliance strong {
  color: var(--text-primary);
}

.about-placeholder {
  aspect-ratio: 16/10;
  background: var(--bg-elevated);
  border-radius: var(--radius);
  border: 1px dashed rgba(255, 255, 255, 0.12);
  display: flex;
  align-items: center;
  justify-content: center;
  color: var(--text-secondary);
  font-size: 0.9375rem;
}

/* ===== Features ===== */
section.features {
  position: relative;
  background-image: linear-gradient(
      to bottom,
      rgba(13, 15, 20, 0.5),
      rgba(13, 15, 20, 0.55)
    ),
    url("../assets/imgs/网站文案规范2.png");
  background-size: cover;
  background-position: center;
  background-repeat: no-repeat;
}

.features-title {
  margin-bottom: 48px;
}

.features-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 24px;
  list-style: none;
  margin: 0;
  padding: 0;
}

.feature-card {
  padding: 28px 24px;
  background: var(--bg-card);
  border-radius: var(--radius);
  border: 1px solid rgba(255, 255, 255, 0.06);
  transition: transform 0.25s ease, box-shadow 0.25s ease, border-color 0.2s ease;
}

.feature-card:hover {
  transform: translateY(-4px);
  box-shadow: var(--shadow-card-hover);
  border-color: rgba(59, 130, 246, 0.25);
}

.feature-icon {
  display: block;
  width: 44px;
  height: 44px;
  margin-bottom: 16px;
  background: var(--gradient-cta);
  border-radius: 10px;
  opacity: 0.9;
}

.feature-icon--img {
  width: 100%;
  max-width: 120px;
  height: auto;
  background: none;
  border-radius: 8px;
  overflow: hidden;
}

.feature-icon--img img {
  display: block;
  width: 100%;
  height: auto;
  object-fit: contain;
  vertical-align: middle;
}

.feature-title {
  margin: 0 0 10px;
  font-size: 1.0625rem;
  font-weight: 600;
  color: var(--text-primary);
}

.feature-desc {
  margin: 0;
  font-size: 0.875rem;
  color: var(--text-secondary);
  line-height: 1.55;
}

/* ===== Testimonials ===== */
.testimonials {
  background: var(--bg-card);
}

.testimonials-carousel {
  position: relative;
  max-width: 640px;
  margin: 0 auto;
  overflow: hidden;
}

.testimonials-track {
  display: flex;
  transition: transform 0.4s ease;
}

.testimonial-card {
  flex: 0 0 100%;
  padding: 32px;
  background: var(--bg-elevated);
  border-radius: var(--radius);
  border: 1px solid rgba(255, 255, 255, 0.06);
}

.testimonial-header {
  display: flex;
  align-items: center;
  gap: 16px;
  margin-bottom: 16px;
}

.testimonial-avatar {
  width: 48px;
  height: 48px;
  border-radius: 50%;
  background: var(--gradient-cta);
  display: flex;
  align-items: center;
  justify-content: center;
  font-weight: 700;
  color: #fff;
  font-size: 1rem;
}

.testimonial-name {
  font-weight: 600;
  color: var(--text-primary);
}

.testimonial-stars {
  font-size: 0.875rem;
  color: #fbbf24;
  letter-spacing: 2px;
}

.testimonial-text {
  margin: 0;
  color: var(--text-secondary);
  font-size: 0.9375rem;
  line-height: 1.6;
}

.testimonials-dots {
  display: flex;
  justify-content: center;
  gap: 10px;
  margin-top: 24px;
}

.testimonials-dots button {
  width: 10px;
  height: 10px;
  padding: 0;
  border: none;
  border-radius: 50%;
  background: rgba(255, 255, 255, 0.2);
  cursor: pointer;
  transition: background 0.2s ease, transform 0.2s ease;
}

.testimonials-dots button:hover {
  background: rgba(255, 255, 255, 0.4);
}

.testimonials-dots button.is-active {
  background: var(--accent-blue);
  transform: scale(1.2);
}

/* ===== Download ===== */
.download-desc {
  text-align: center;
  color: var(--text-secondary);
  margin: 0 0 32px;
}

.download-buttons {
  display: flex;
  flex-wrap: wrap;
  gap: 20px;
  justify-content: center;
  margin-bottom: 40px;
}

.download-changelog {
  max-width: 560px;
  margin: 0 auto;
  padding: 24px;
  background: var(--bg-card);
  border-radius: var(--radius);
  border: 1px solid rgba(255, 255, 255, 0.06);
}

.download-changelog-title {
  margin: 0 0 12px;
  font-size: 1rem;
  font-weight: 600;
  color: var(--text-primary);
}

.download-changelog-text {
  margin: 0;
  font-size: 0.875rem;
  color: var(--text-secondary);
  line-height: 1.6;
}

/* ===== Footer ===== */
.footer {
  padding: 40px 0;
  background: var(--bg-elevated);
  border-top: 1px solid rgba(255, 255, 255, 0.06);
}

.footer-links {
  display: flex;
  justify-content: center;
  gap: 32px;
  margin-bottom: 20px;
}

.footer-links a {
  color: var(--text-secondary);
  text-decoration: none;
  font-size: 0.9375rem;
  transition: color 0.2s ease;
}

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

.footer-copy {
  margin: 0;
  text-align: center;
  font-size: 0.8125rem;
  color: var(--text-secondary);
  line-height: 1.6;
  max-width: 640px;
  margin-left: auto;
  margin-right: auto;
}

/* ===== 滚动渐入（由 JS 添加 .is-visible） ===== */
.section.reveal {
  opacity: 0;
  transform: translateY(24px);
  transition: opacity 0.6s ease, transform 0.6s ease;
}

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

.feature-card.reveal {
  opacity: 0;
  transform: translateY(20px);
  transition: opacity 0.5s ease, transform 0.5s ease;
}

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

/* ===== 响应式 ===== */
@media (max-width: 900px) {
  .features-grid {
    grid-template-columns: repeat(2, 1fr);
  }

  .about-grid {
    grid-template-columns: 1fr;
    gap: 32px;
  }

  .about-content .section-title {
    text-align: center;
  }

  .about-text,
  .about-compliance {
    text-align: left;
  }
}

@media (max-width: 640px) {
  .nav-toggle {
    display: flex;
  }

  .nav {
    position: absolute;
    top: 100%;
    left: 0;
    right: 0;
    background: var(--bg-elevated);
    border-bottom: 1px solid rgba(255, 255, 255, 0.06);
    padding: 16px;
    display: none;
  }

  .nav.is-open {
    display: block;
  }

  .nav-list {
    flex-direction: column;
    align-items: stretch;
  }

  .nav-dropdown {
    position: static;
    opacity: 1;
    visibility: visible;
    transform: none;
    margin-top: 4px;
    margin-left: 16px;
    padding: 8px 0;
    background: transparent;
    box-shadow: none;
    display: none;
  }

  .nav-item.is-open .nav-dropdown {
    display: block;
  }

  .nav-item:hover .nav-dropdown {
    transform: none;
  }

  .hero-compliance {
    margin-top: 28px;
    max-width: none;
  }

  .hero-actions {
    flex-direction: column;
  }

  .btn {
    width: 100%;
    max-width: 280px;
  }

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

  .section {
    padding: 56px 0;
  }

  .download-buttons {
    flex-direction: column;
    align-items: center;
  }

  .footer-links {
    flex-direction: column;
    align-items: center;
    gap: 12px;
  }
}