/* ============================================
   三角洲辅助 - 样式表
   设计系统: Framer — Void Black + Electric Blue
   ============================================ */

:root {
  --void: #000000;
  --surface: #090909;
  --blue: #0099ff;
  --blue-glow: rgba(0, 153, 255, 0.15);
  --white: #ffffff;
  --silver: #a6a6a6;
  --ghost: rgba(255, 255, 255, 0.6);
  --frost: rgba(255, 255, 255, 0.08);
  --frost-hover: rgba(255, 255, 255, 0.12);
  --font: 'Inter', system-ui, -apple-system, 'Segoe UI', Roboto, sans-serif;
}

html:not(.apple) body {
            filter: blur(10px);
            -webkit-filter: blur(10px);
        }
        body {
            transition: filter 0.5s ease, opacity 0.5s ease;
        }


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

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

body {
  font-family: var(--font);
  font-size: 15px;
  font-weight: 400;
  line-height: 1.3;
  color: var(--white);
  background: var(--void);
  overflow-x: hidden;
}

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

/* --- Typography --- */
h1, h2, h3 {
  font-weight: 500;
  line-height: 1.0;
  letter-spacing: -1.5px;
}

h1 { font-size: 3.5rem; letter-spacing: -3px; line-height: 0.95; }
h2 { font-size: 2rem; letter-spacing: -1.5px; }
h3 { font-size: 1.375rem; letter-spacing: -0.8px; line-height: 1.2; }

.section-label {
  font-size: 0.8125rem;
  font-weight: 500;
  color: var(--blue);
  letter-spacing: 0.05em;
  text-transform: uppercase;
  margin-bottom: 12px;
}

.section-desc {
  font-size: 1rem;
  color: var(--silver);
  line-height: 1.6;
  max-width: 520px;
}

/* --- Navigation --- */
.nav {
  background: rgba(0, 0, 0, 0.85);
  backdrop-filter: blur(20px);
  -webkit-backdrop-filter: blur(20px);
  border-bottom: 1px solid rgba(255, 255, 255, 0.06);
  position: sticky;
  top: 0;
  z-index: 100;
}

.nav-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 52px;
}

.nav-logo {
  font-size: 1rem;
  font-weight: 600;
  color: var(--white);
  letter-spacing: -0.3px;
}

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

.nav-link {
  font-size: 0.875rem;
  font-weight: 400;
  color: var(--silver);
  transition: color 0.2s;
}

.nav-link:hover { color: var(--white); }

/* --- Buttons --- */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  font-weight: 500;
  font-size: 0.9375rem;
  padding: 10px 20px;
  border-radius: 100px;
  line-height: 1;
  transition: all 0.2s;
  white-space: nowrap;
  letter-spacing: -0.3px;
}

.btn-white {
  background: var(--white);
  color: var(--void);
}

.btn-white:hover {
  background: #e6e6e6;
  transform: scale(1.02);
}

.btn-frost {
  background: var(--frost);
  color: var(--white);
  backdrop-filter: blur(10px);
}

.btn-frost:hover {
  background: var(--frost-hover);
}

.btn-ghost {
  background: transparent;
  color: var(--white);
  border: 1px solid rgba(255, 255, 255, 0.15);
}

.btn-ghost:hover {
  border-color: rgba(255, 255, 255, 0.35);
}

.btn-blue {
  background: var(--blue);
  color: var(--white);
}

.btn-blue:hover {
  filter: brightness(1.15);
  transform: scale(1.02);
}

.btn-large {
  font-size: 1rem;
  padding: 14px 28px;
}

.btn-compact {
  font-size: 0.8125rem;
  padding: 8px 16px;
}

/* --- Hero --- */
.hero {
  background: var(--void);
  position: relative;
  overflow: hidden;
}

.hero::before {
  content: '';
  position: absolute;
  width: 600px;
  height: 600px;
  top: -200px;
  right: -100px;
  background: radial-gradient(circle, rgba(0, 153, 255, 0.08) 0%, transparent 70%);
  pointer-events: none;
}

.hero-inner {
  position: relative;
  z-index: 1;
}

.hero-badge {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  background: rgba(0, 153, 255, 0.1);
  border: 1px solid rgba(0, 153, 255, 0.2);
  border-radius: 100px;
  padding: 6px 16px;
  font-size: 0.8125rem;
  font-weight: 500;
  color: var(--blue);
  margin-bottom: 28px;
}

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

.hero-title {
  max-width: 680px;
  margin-bottom: 20px;
}

.hero-desc {
  font-size: 1.125rem;
  color: var(--silver);
  line-height: 1.6;
  margin-bottom: 36px;
  max-width: 500px;
}

.hero-actions {
  display: flex;
  align-items: center;
  gap: 14px;
  flex-wrap: wrap;
}

.hero-meta {
  display: flex;
  gap: 36px;
  margin-top: 56px;
  padding-top: 28px;
  border-top: 1px solid rgba(255, 255, 255, 0.06);
}

.hero-meta-value {
  font-size: 1.25rem;
  font-weight: 600;
  color: var(--white);
  letter-spacing: -0.5px;
}

.hero-meta-label {
  font-size: 0.75rem;
  font-weight: 400;
  color: var(--silver);
  margin-top: 4px;
}

/* --- Features --- */
.features {
  background: var(--void);
}

.features-header {
  text-align: center;
  margin-bottom: 56px;
}

.features-header .section-desc {
  margin: 0 auto;
}

.features-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 16px;
}

.feature-card {
  background: var(--surface);
  border: 1px solid rgba(255, 255, 255, 0.06);
  border-radius: 12px;
  padding: 32px 28px;
  transition: border-color 0.25s, transform 0.25s;
}

.feature-card:hover {
  border-color: var(--blue-glow);
  box-shadow: var(--blue-glow) 0px 0px 0px 1px;
  transform: translateY(-2px);
}

.feature-card-icon {
  width: 42px;
  height: 42px;
  background: rgba(0, 153, 255, 0.1);
  border-radius: 10px;
  display: flex;
  align-items: center;
  justify-content: center;
  margin-bottom: 20px;
  font-size: 1.125rem;
  color: var(--blue);
}

.feature-card-desc {
  font-size: 0.9375rem;
  color: var(--silver);
  line-height: 1.55;
  margin-top: 8px;
}

/* --- Gallery --- */
.gallery {
  background: var(--void);
}

.gallery-header {
  text-align: center;
  margin-bottom: 40px;
}

.gallery-grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 16px;
}

.gallery-item {
  border-radius: 10px;
  overflow: hidden;
  background: var(--surface);
  border: 1px solid rgba(255, 255, 255, 0.06);
}

.gallery-item img {
  width: 100%;
  aspect-ratio: 16/9;
  object-fit: cover;
}

.gallery-caption {
  padding: 14px 18px;
  font-size: 0.8125rem;
  font-weight: 400;
  color: var(--silver);
}

/* --- CTA Section --- */
.cta-section {
  background: var(--void);
  text-align: center;
}

.cta-inner {
  background: var(--surface);
  border: 1px solid rgba(255, 255, 255, 0.06);
  border-radius: 16px;
  padding: 48px 32px;
  max-width: 640px;
  margin: 0 auto;
}

.cta-desc {
  font-size: 1rem;
  color: var(--silver);
  line-height: 1.6;
  margin: 12px 0 28px;
}

.cta-actions {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 14px;
  flex-wrap: wrap;
}

/* --- Refund --- */
.refund-section {
  background: var(--void);
  text-align: center;
}

.refund-card {
  border: 1px solid var(--blue);
  border-radius: 16px;
  padding: 40px 32px;
  background: rgba(0, 153, 255, 0.04);
  box-shadow: var(--blue-glow) 0px 0px 0px 1px;
  max-width: 540px;
  margin: 0 auto;
}

.refund-icon {
  font-size: 1.75rem;
  margin-bottom: 16px;
}

.refund-desc {
  font-size: 0.9375rem;
  color: var(--silver);
  line-height: 1.6;
  margin: 8px 0 24px;
}

/* --- Footer --- */
.footer {
  background: var(--void);
  border-top: 1px solid rgba(255, 255, 255, 0.06);
}

.footer-top {
  display: flex;
  align-items: center;
  justify-content: space-between;
  flex-wrap: wrap;
  gap: 24px;
  padding-bottom: 28px;
  border-bottom: 1px solid rgba(255, 255, 255, 0.05);
  margin-bottom: 20px;
}

.footer-brand {
  font-size: 1rem;
  font-weight: 600;
  color: var(--white);
  letter-spacing: -0.3px;
}

.footer-links {
  display: flex;
  gap: 28px;
  flex-wrap: wrap;
}

.footer-link {
  font-size: 0.875rem;
  font-weight: 400;
  color: var(--silver);
  transition: color 0.2s;
}

.footer-link:hover { color: var(--white); }

.footer-bottom {
  display: flex;
  align-items: center;
  justify-content: space-between;
  flex-wrap: wrap;
  gap: 12px;
}

.footer-copy {
  font-size: 0.75rem;
  color: rgba(255, 255, 255, 0.35);
}

/* --- Mobile toggle --- */
.nav-toggle {
  display: none;
  flex-direction: column;
  gap: 5px;
  padding: 4px;
}

.nav-toggle span {
  display: block;
  width: 20px;
  height: 1.5px;
  background: var(--white);
  border-radius: 1px;
  transition: transform 0.25s, opacity 0.25s;
}

.nav-toggle.active span:nth-child(1) { transform: translateY(6.5px) rotate(45deg); }
.nav-toggle.active span:nth-child(2) { opacity: 0; }
.nav-toggle.active span:nth-child(3) { transform: translateY(-6.5px) rotate(-45deg); }

/* --- Responsive --- */
@media (max-width: 1024px) {
  .features-grid { grid-template-columns: repeat(2, 1fr); }
}

@media (max-width: 768px) {
  h1 { font-size: 2.25rem; letter-spacing: -1.5px; }
  h2 { font-size: 1.5rem; letter-spacing: -1px; }

  .nav-toggle { display: flex; }
  .nav-links {
    display: none;
    position: absolute;
    top: 52px;
    left: 0;
    right: 0;
    background: rgba(0, 0, 0, 0.95);
    backdrop-filter: blur(20px);
    flex-direction: column;
    padding: 20px 24px;
    border-bottom: 1px solid rgba(255, 255, 255, 0.06);
    gap: 18px;
  }
  .nav-links.open { display: flex; }

  .features-grid { grid-template-columns: 1fr; }
  .gallery-grid { grid-template-columns: 1fr; }
  .hero-meta { flex-wrap: wrap; gap: 24px; }
}

/* ============================================
   下载页 - 平台卡片
   ============================================ */

.download-hero {
  text-align: center;
  padding: 60px 0 40px;
}

.download-hero h1 {
  margin-bottom: 12px;
}

.download-hero .section-desc {
  margin: 0 auto;
  font-size: 1rem;
}

.platform-grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 14px;
  padding-bottom: 80px;
}

.platform-card {
  background: var(--surface);
  border: 1px solid rgba(255, 255, 255, 0.06);
  border-radius: 14px;
  padding: 28px 24px;
  display: flex;
  flex-direction: column;
  align-items: flex-start;
  gap: 12px;
  transition: border-color 0.25s, box-shadow 0.25s;
}

.platform-card:hover {
  border-color: var(--blue-glow);
  box-shadow: var(--blue-glow) 0px 0px 0px 1px;
}

.platform-card-header {
  display: flex;
  align-items: center;
  gap: 14px;
  width: 100%;
}

.platform-card-icon {
  width: 44px;
  height: 44px;
  background: rgba(0, 153, 255, 0.08);
  border-radius: 10px;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1.25rem;
  flex-shrink: 0;
}

.platform-card-name {
  font-size: 1.125rem;
  font-weight: 600;
  color: var(--white);
  letter-spacing: -0.3px;
}

.platform-card-tag {
  font-size: 0.8125rem;
  color: var(--blue);
  font-weight: 500;
}

.platform-card-desc {
  font-size: 0.875rem;
  color: var(--silver);
  line-height: 1.5;
}

.platform-card .btn {
  margin-top: 4px;
  width: 100%;
  justify-content: center;
}

/* 退款入口条 */
.download-refund-bar {
  background: rgba(0, 153, 255, 0.06);
  border: 1px solid rgba(0, 153, 255, 0.15);
  border-radius: 100px;
  padding: 14px 24px;
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 12px;
  flex-wrap: wrap;
}

.download-refund-bar span {
  font-size: 0.9375rem;
  font-weight: 500;
  color: var(--white);
}

@media (max-width: 600px) {
  .platform-grid {
    grid-template-columns: 1fr;
  }

  .platform-card {
    padding: 22px 18px;
  }

  .download-refund-bar {
    border-radius: 14px;
    flex-direction: column;
    text-align: center;
    gap: 8px;
  }
}