:root {
  --ink: #12161c;
  --ink-soft: #2a3340;
  --mist: #e8eef4;
  --paper: #f7f9fb;
  --sky: #6f8fad;
  --sky-deep: #3d5f7c;
  --line: rgba(18, 22, 28, 0.1);
  --glow: rgba(111, 143, 173, 0.35);
  --display: "Songti SC", "STSong", "Noto Serif CJK SC", "Source Han Serif SC", serif;
  --body: "PingFang SC", "Hiragino Sans GB", "Noto Sans SC", "Microsoft YaHei", sans-serif;
}

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

html {
  scroll-behavior: smooth;
}

body {
  margin: 0;
  color: var(--ink);
  font-family: var(--body);
  background: var(--paper);
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
}

a {
  color: inherit;
  text-decoration: none;
}

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

/* —— Top bar —— */
.top {
  position: fixed;
  inset: 0 0 auto;
  z-index: 20;
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 18px clamp(20px, 4vw, 48px);
  mix-blend-mode: difference;
  color: #fff;
  pointer-events: none;
}

.top a {
  pointer-events: auto;
}

.top-brand {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  font-family: var(--display);
  font-size: 1.15rem;
  letter-spacing: 0.18em;
}

.top-brand img {
  width: 36px;
  height: 36px;
  object-fit: contain;
  filter: invert(1);
}

.top-nav {
  display: flex;
  align-items: center;
  gap: 18px;
  font-size: 0.92rem;
  letter-spacing: 0.08em;
}

.top-cta {
  padding: 8px 14px;
  border: 1px solid rgba(255, 255, 255, 0.45);
  border-radius: 999px;
  transition: background 0.25s ease, color 0.25s ease;
}

.top-cta:hover {
  background: #fff;
  color: #111;
  mix-blend-mode: normal;
}

/* —— Hero —— */
.hero {
  position: relative;
  min-height: 100svh;
  display: grid;
  place-items: center;
  overflow: hidden;
  color: #fff;
}

.hero-media {
  position: absolute;
  inset: 0;
}

.hero-photo {
  width: 100%;
  height: 100%;
  object-fit: cover;
  transform: scale(1.08);
  animation: drift 28s ease-in-out infinite alternate;
}

.hero-veil {
  position: absolute;
  inset: 0;
  background:
    linear-gradient(180deg, rgba(10, 14, 20, 0.55) 0%, rgba(10, 14, 20, 0.28) 42%, rgba(10, 14, 20, 0.72) 100%),
    radial-gradient(ellipse 70% 50% at 50% 35%, transparent 0%, rgba(8, 12, 18, 0.35) 100%);
}

.hero-grain {
  position: absolute;
  inset: 0;
  opacity: 0.18;
  mix-blend-mode: soft-light;
  background-image: url("data:image/svg+xml,%3Csvg viewBox='0 0 200 200' xmlns='http://www.w3.org/2000/svg'%3E%3Cfilter id='n'%3E%3CfeTurbulence type='fractalNoise' baseFrequency='0.85' numOctaves='4' stitchTiles='stitch'/%3E%3C/filter%3E%3Crect width='100%25' height='100%25' filter='url(%23n)'/%3E%3C/svg%3E");
  pointer-events: none;
}

.hero-inner {
  position: relative;
  z-index: 1;
  width: min(920px, calc(100% - 40px));
  text-align: center;
  padding: 100px 0 80px;
}

.hero-mark {
  width: clamp(120px, 22vw, 188px);
  height: auto;
  margin: 0 auto 22px;
  filter: drop-shadow(0 18px 40px rgba(0, 0, 0, 0.35));
  animation: rise 1.1s cubic-bezier(0.22, 1, 0.36, 1) both;
}

.hero-brand {
  margin: 0;
  font-family: var(--display);
  font-weight: 600;
  font-size: clamp(3.4rem, 11vw, 6.4rem);
  letter-spacing: 0.34em;
  text-indent: 0.34em;
  line-height: 1;
  text-shadow: 0 10px 40px rgba(0, 0, 0, 0.35);
  animation: rise 1.1s cubic-bezier(0.22, 1, 0.36, 1) 0.08s both;
}

.hero-line {
  margin: 22px auto 0;
  max-width: 28em;
  font-size: clamp(1rem, 2.4vw, 1.2rem);
  letter-spacing: 0.14em;
  color: rgba(255, 255, 255, 0.86);
  animation: rise 1.1s cubic-bezier(0.22, 1, 0.36, 1) 0.16s both;
}

.hero-actions {
  display: flex;
  flex-wrap: wrap;
  justify-content: center;
  gap: 12px;
  margin-top: 36px;
  animation: rise 1.1s cubic-bezier(0.22, 1, 0.36, 1) 0.24s both;
}

.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-height: 48px;
  padding: 0 22px;
  border-radius: 999px;
  font-size: 0.95rem;
  letter-spacing: 0.08em;
  transition: transform 0.25s ease, background 0.25s ease, border-color 0.25s ease, color 0.25s ease;
}

.btn:hover {
  transform: translateY(-2px);
}

.btn-primary {
  background: #fff;
  color: var(--ink);
}

.btn-primary:hover {
  background: #f0f4f8;
}

.btn-ghost {
  border: 1px solid rgba(255, 255, 255, 0.45);
  color: #fff;
  background: rgba(255, 255, 255, 0.04);
  backdrop-filter: blur(8px);
}

.btn-ghost:hover {
  border-color: #fff;
  background: rgba(255, 255, 255, 0.12);
}

.btn-wide {
  min-width: min(280px, 100%);
}

.hero-scroll {
  position: absolute;
  left: 50%;
  bottom: 28px;
  z-index: 1;
  width: 24px;
  height: 38px;
  margin-left: -12px;
  border: 1px solid rgba(255, 255, 255, 0.45);
  border-radius: 999px;
}

.hero-scroll span {
  position: absolute;
  left: 50%;
  top: 8px;
  width: 4px;
  height: 8px;
  margin-left: -2px;
  border-radius: 999px;
  background: #fff;
  animation: scrollDot 1.6s ease-in-out infinite;
}

/* —— About —— */
.about {
  padding: clamp(72px, 12vw, 128px) clamp(20px, 6vw, 80px);
  max-width: 820px;
  margin: 0 auto;
  text-align: center;
}

.about-kicker {
  margin: 0 0 14px;
  color: var(--sky-deep);
  letter-spacing: 0.28em;
  font-size: 0.78rem;
  text-transform: uppercase;
}

.about-title {
  margin: 0;
  font-family: var(--display);
  font-size: clamp(1.8rem, 4.5vw, 2.6rem);
  font-weight: 600;
  letter-spacing: 0.08em;
  line-height: 1.35;
}

.about-copy {
  margin: 22px auto 0;
  max-width: 34em;
  color: var(--ink-soft);
  font-size: 1.05rem;
  line-height: 1.9;
}

/* —— Download —— */
.download {
  padding: 0 clamp(20px, 6vw, 80px) clamp(88px, 12vw, 140px);
}

.download-panel {
  max-width: 720px;
  margin: 0 auto;
  padding: clamp(36px, 6vw, 56px) clamp(24px, 5vw, 48px);
  text-align: center;
  border-radius: 28px;
  background:
    radial-gradient(ellipse 80% 70% at 50% 0%, rgba(111, 143, 173, 0.16), transparent 60%),
    linear-gradient(180deg, #ffffff 0%, #f3f6f9 100%);
  border: 1px solid var(--line);
  box-shadow: 0 30px 80px rgba(18, 22, 28, 0.06);
}

.download-panel h2 {
  margin: 0;
  font-family: var(--display);
  font-size: clamp(1.6rem, 3.5vw, 2.1rem);
  letter-spacing: 0.1em;
}

.download-panel p {
  margin: 14px auto 0;
  max-width: 28em;
  color: var(--ink-soft);
  line-height: 1.75;
}

.download-panel .btn {
  margin-top: 28px;
}

.download-note {
  margin-top: 16px !important;
  font-size: 0.86rem !important;
  color: #7a8694 !important;
}

/* —— Footer —— */
.foot {
  padding: 48px 24px 56px;
  text-align: center;
  background: #0f1419;
  color: rgba(255, 255, 255, 0.78);
}

.foot-brand {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  font-family: var(--display);
  letter-spacing: 0.22em;
  color: #fff;
}

.foot-brand img {
  width: 28px;
  height: 28px;
  filter: invert(1);
}

.foot-tag {
  margin: 12px 0 0;
  letter-spacing: 0.12em;
  font-size: 0.86rem;
  color: rgba(255, 255, 255, 0.55);
}

.foot-links {
  display: flex;
  justify-content: center;
  gap: 22px;
  margin-top: 22px;
  font-size: 0.9rem;
}

.foot-links a {
  border-bottom: 1px solid transparent;
  transition: border-color 0.2s ease, color 0.2s ease;
}

.foot-links a:hover {
  color: #fff;
  border-bottom-color: rgba(255, 255, 255, 0.5);
}

.foot-copy {
  margin: 28px 0 0;
  font-size: 0.8rem;
  color: rgba(255, 255, 255, 0.38);
}

@keyframes rise {
  from {
    opacity: 0;
    transform: translateY(18px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

@keyframes drift {
  from {
    transform: scale(1.08) translate3d(0, 0, 0);
  }
  to {
    transform: scale(1.14) translate3d(-1.5%, -1%, 0);
  }
}

@keyframes scrollDot {
  0%,
  100% {
    opacity: 0.35;
    transform: translateY(0);
  }
  50% {
    opacity: 1;
    transform: translateY(12px);
  }
}

@media (max-width: 640px) {
  .top-nav a:not(.top-cta) {
    display: none;
  }

  .hero-brand {
    letter-spacing: 0.22em;
    text-indent: 0.22em;
  }

  .hero-line {
    letter-spacing: 0.06em;
  }

  .hero-actions {
    flex-direction: column;
    align-items: stretch;
  }
}

@media (prefers-reduced-motion: reduce) {
  .hero-photo,
  .hero-mark,
  .hero-brand,
  .hero-line,
  .hero-actions,
  .hero-scroll span {
    animation: none !important;
  }

  .hero-photo {
    transform: none;
  }
}