:root {
  --bg: #121826;
  --card: #1e2635;
  --text: #e8ecf1;
  --muted: #bcc6d3;
  --primary: #4ba3ff;
  --primary-600: #2f86e6;
  --ring: rgba(75, 163, 255, 0.4);
  --border: #2f3a52;
}

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

html, body {
  margin: 0;
  padding: 0;
  background: linear-gradient(180deg, #141b2b, #1b2437 40%, #141b2b 100%);
  color: var(--text);
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, "Noto Sans", "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", sans-serif;
  line-height: 1.6;
}

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

.container {
  width: 100%;
  max-width: 1100px;
  margin: 0 auto;
  padding: 0 20px;
}

.site-header {
  position: sticky;
  top: 0;
  z-index: 20;
  background: rgba(13, 15, 20, 0.7);
  backdrop-filter: blur(10px);
  border-bottom: 1px solid var(--border);
}

.header-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 64px;
}

.logo {
  font-weight: 700;
  letter-spacing: 0.3px;
}

.nav a {
  color: var(--muted);
  text-decoration: none;
  margin-left: 18px;
  transition: color .2s ease;
}

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

.hero {
  padding: 56px 0 20px;
}

.hero-inner {
  display: grid;
  grid-template-columns: 1.1fr 0.9fr;
  gap: 28px;
  align-items: center;
}

.hero-text h1 {
  font-size: 40px;
  line-height: 1.15;
  margin: 10px 0 12px;
}

.hero-text p {
  color: var(--muted);
  margin: 0 0 20px;
}

.cta {
  display: flex;
  gap: 12px;
  flex-wrap: wrap;
}

.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  height: 40px;
  padding: 0 16px;
  border-radius: 10px;
  background: #1a2130;
  color: var(--text);
  border: 1px solid var(--border);
  text-decoration: none;
  transition: transform .06s ease, box-shadow .2s ease, border-color .2s ease;
  will-change: transform;
}

.btn:hover {
  transform: translateY(-1px);
  border-color: #2a3142;
  box-shadow: 0 6px 24px rgba(0,0,0,0.25);
}

.btn.primary {
  background: linear-gradient(180deg, var(--primary), var(--primary-600));
  border-color: transparent;
  color: #fff;
  box-shadow: 0 10px 30px var(--ring);
}

.hero-visual {
  display: grid;
  place-items: center;
  background: radial-gradient(80% 80% at 50% 50%, rgba(75,163,255,0.08), transparent 60%);
}
.hero-visual img {
  width: 75%;
  max-width: 75%;
  transition: transform .3s ease, filter .3s ease;
  will-change: transform;
}
.hero-visual img:hover {
  transform: translateY(-4px) scale(1.03);
  filter: drop-shadow(0 10px 24px rgba(75,163,255,0.25));
}

.section {
  padding: 56px 0;
}

.section.alt {
  background: linear-gradient(180deg, rgba(33,39,54,0.5), rgba(33,39,54,0.25));
  border-top: 1px solid var(--border);
  border-bottom: 1px solid var(--border);
}
.section.bright {
  background: linear-gradient(180deg, rgba(255,255,255,0.06), rgba(255,255,255,0.03));
  border-top: 1px solid var(--border);
  border-bottom: 1px solid var(--border);
}

/* Alternate backgrounds: one light, one dark per section */
main > section:nth-of-type(odd) {
  background: linear-gradient(180deg, rgba(255,255,255,0.08), rgba(255,255,255,0.04));
}
main > section:nth-of-type(even) {
  background: linear-gradient(180deg, rgba(33,39,54,0.5), rgba(33,39,54,0.25));
}

h2 {
  font-size: 28px;
  margin: 0 0 20px;
}

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

.feature-card {
  background: var(--card);
  border: 1px solid var(--border);
  border-radius: 12px;
  padding: 16px;
  box-shadow: 0 10px 24px rgba(0,0,0,0.25);
}

.feature-card h3 {
  margin: 0 0 6px;
  font-size: 18px;
}

.feature-card p {
  margin: 0;
  color: var(--muted);
}

.gallery-grid {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 10px;
}

.gallery-item {
  position: relative;
  border-radius: 10px;
  overflow: hidden;
  border: 1px solid var(--border);
  background: #0f1420;
}

.gallery-item img {
  width: 100%;
  height: 100%;
  object-fit: cover;
  transition: transform .25s ease;
}

.gallery-item:hover img {
  transform: scale(1.03);
}

.notes {
  margin: 0;
  padding-left: 18px;
  color: var(--muted);
}

.site-footer {
  border-top: 1px solid var(--border);
  padding: 22px 0;
}

.footer-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 10px;
  color: var(--muted);
}

.back-to-top {
  color: var(--muted);
  text-decoration: none;
  border: 1px solid var(--border);
  border-radius: 50%;
  width: 36px;
  height: 36px;
  display: inline-grid;
  place-items: center;
}

/* Lightbox */
.lightbox {
  position: fixed;
  inset: 0;
  background: rgba(0, 0, 0, 0.7);
  display: none;
  align-items: center;
  justify-content: center;
  z-index: 100;
  padding: 20px;
}

.lightbox.open {
  display: flex;
}

.lightbox-image {
  max-width: 92vw;
  max-height: 86vh;
  border-radius: 12px;
  border: 1px solid var(--border);
  background: #000;
}

.lightbox-close {
  position: absolute;
  top: 14px;
  right: 14px;
  width: 40px;
  height: 40px;
  border-radius: 8px;
  border: 1px solid var(--border);
  background: var(--card);
  color: var(--text);
  cursor: pointer;
  font-size: 22px;
}

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

@media (max-width: 768px) {
  .hero-inner {
    grid-template-columns: 1fr;
  }
  .nav a {
    margin-left: 12px;
  }
}