* {
  box-sizing: border-box;
}

html,
body {
  margin: 0;
  width: 100%;
  min-height: 100%;
  overflow: hidden;
  font-family:
    "Noto Sans SC",
    system-ui,
    sans-serif;
  color: #ffffff;
  background: #050607;
}

main {
  position: relative;
  width: 100vw;

  /* 旧浏览器回退 */
  height: 100vh;

  /* 实际可见区域，会随浏览器工具栏变化 */
  height: 100dvh;

  overflow: hidden;
}

.loading-screen {
  position: fixed;
  inset: 0;
  z-index: 999;
  display: grid;
  place-items: center;
  color: #ffffff;
  background: #000000;
  font-size: clamp(22px, 3vw, 36px);
  font-weight: 700;
  letter-spacing: 0.12em;
  transition:
    opacity 0.35s ease,
    visibility 0.35s ease;
}

.loading-screen.is-hidden {
  visibility: hidden;
  opacity: 0;
}

.page {
  position: absolute;
  inset: 0;
  width: 100%;

  /* 旧浏览器回退 */
  height: 100vh;

  /* 修复 Chrome 地址栏导致的底部裁剪 */
  height: 100dvh;

  overflow: hidden;
  pointer-events: none;
  visibility: hidden;
}

.page.is-active,
.page.is-leaving {
  visibility: visible;
}

.page.is-active {
  z-index: 2;
  pointer-events: auto;
}

.page.is-leaving {
  z-index: 1;
}

.page-bg {
  position: absolute;
  inset: 0;
  opacity: 0;
  transform: scale(1.02);
  transition:
    opacity 0.55s ease,
    transform 0.75s ease;
  will-change: opacity, transform;
}

.page-bg::after {
  position: absolute;
  inset: 0;
  content: "";
  background:
    linear-gradient(90deg, rgba(0, 0, 0, 0.58), rgba(0, 0, 0, 0.12) 48%, rgba(0, 0, 0, 0.48)),
    radial-gradient(circle at 50% 22%, rgba(255, 255, 255, 0.12), transparent 32%),
    linear-gradient(to bottom, rgba(5, 7, 9, 0.12), rgba(5, 6, 7, 0.68));
}

.page-bg-image {
  position: absolute;
  inset: 0;
  width: 100%;
  height: 100%;
  object-fit: cover;
}

.is-active .page-bg {
  opacity: 1;
  transform: scale(1);
}

.is-leaving .page-bg {
  opacity: 0;
  transform: scale(1.015);
}

.hero-image {
  position: absolute;
  inset: 0;
  width: 100%;
  height: 100%;
  object-fit: cover;
  opacity: 0;
  transform: scale(1.02);
  transition:
    opacity 0.85s ease,
    transform 0.85s ease;
}

body.is-loaded .hero-image {
  opacity: 1;
  transform: scale(1);
}

.overview-page .page-bg {
  background: #07090b;
}

.features-page .page-bg {
  background: #050807;
}

.packs-page .page-bg {
  background: #060608;
}

.download-page .page-bg {
  background: #050607;
}

.text-block,
.text-line {
  position: relative;
  z-index: 3;
}

.text-line {
  opacity: 0;
  transform: translate(var(--line-base-x, 0px), calc(var(--line-base-y, 0px) + 18px));
  transition:
    opacity 0.62s ease,
    transform 0.72s cubic-bezier(0.22, 1, 0.36, 1);
  transition-delay: 0ms;
  will-change: opacity, transform;
}

body.is-loaded .is-active .text-line {
  opacity: 1;
  transform: translate(var(--line-base-x, 0px), var(--line-base-y, 0px));
  transition-delay: calc(var(--line-index, 0) * 90ms + 180ms);
}

body.is-loaded .is-leaving .text-line {
  opacity: 0;
  transform: translate(var(--line-base-x, 0px), calc(var(--line-base-y, 0px) - 14px));
  transition-delay: calc(var(--line-index, 0) * 55ms);
}

.hero-title {
  position: absolute;
  top: clamp(32px, 6vw, 88px);
  left: clamp(32px, 6vw, 88px);
  color: #ffffff;
}

.hero-title p,
.hero-title h1,
.section-copy p,
.section-copy h2,
.download-panel p,
.download-info p {
  margin: 0;
}

.mobile-recommendation {
  display: none;
}

.hero-kicker,
.section-kicker {
  color: #ffffff;
  font-size: clamp(11px, 1vw, 14px);
  font-weight: 700;
  letter-spacing: 0.34em;
}

.hero-kicker {
  --line-base-x: 3px;
  --line-base-y: 5px;
}

.hero-title h1 {
  margin-top: clamp(14px, 2vw, 24px);
  font-weight: 900;
  line-height: 0.98;
  letter-spacing: -0.04em;
}

.hero-title-small,
.hero-title-large {
  display: block;
}

.hero-title-small {
  font-size: clamp(34px, 4.6vw, 58px);
}

.hero-title-large {
  font-size: clamp(48px, 7vw, 88px);
  --line-base-x: -8px;
  --line-base-y: 9px;
}

.hero-meta {
  margin-top: clamp(18px, 2vw, 30px);
  color: #ffffff;
  font-size: clamp(10px, 0.95vw, 13px);
  font-weight: 700;
  letter-spacing: 0.3em;
  --line-base-x: -1px;
  --line-base-y: 31px;
}

.hero-subtitle {
  position: absolute;
  right: clamp(24px, 5vw, 72px);
  bottom: clamp(34px, 7vw, 84px);
  margin: 0;
  color: #ffffff;
  font-size: clamp(18px, 2.4vw, 30px);
  font-weight: 700;
  letter-spacing: 0.04em;
}

.scroll-hint {
  position: absolute;
  bottom: 24px;
  left: 50%;
  margin: 0;
  color: rgba(255, 255, 255, 0.72);
  font-size: 12px;
  letter-spacing: 0.24em;
  transform: translate(-50%, 18px);
}

body.is-loaded .is-active .scroll-hint.text-line {
  transform: translate(-50%, 0);
}

body.is-loaded .is-leaving .scroll-hint.text-line {
  transform: translate(-50%, -14px);
}

.section-copy {
  position: absolute;
  max-width: min(760px, 86vw);
}

.align-left {
  left: clamp(32px, 6vw, 88px);
}

.align-right {
  right: clamp(32px, 6vw, 88px);
}

.section-copy.align-left {
  top: clamp(56px, 12vh, 132px);
}

.section-copy.align-right {
  top: clamp(46px, 10vh, 112px);
  text-align: right;
}

.section-copy.lower {
  top: auto;
  bottom: clamp(70px, 13vh, 140px);
}

.section-copy.top {
  top: clamp(42px, 8vh, 96px);
}

.section-title {
  margin-top: clamp(18px, 2.4vw, 34px);
  color: #ffffff;
  font-size: clamp(48px, 7.6vw, 112px);
  font-weight: 900;
  line-height: 0.96;
  letter-spacing: -0.06em;
}

.section-title .text-line {
  display: block;
}

.section-side-note,
.feature-list,
.download-panel,
.download-info,
.pack-list {
  position: absolute;
  width: min(520px, 44vw);
}

.section-side-note {
  bottom: clamp(54px, 10vh, 112px);
}

.section-side-note p,
.download-panel p {
  color: rgba(255, 255, 255, 0.86);
  font-size: clamp(18px, 2vw, 28px);
  font-weight: 700;
  line-height: 1.55;
}

.metric-row {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
  justify-content: flex-end;
  margin-top: 28px;
}

.metric-row span {
  padding: 10px 14px;
  border: 1px solid rgba(255, 255, 255, 0.34);
  border-radius: 999px;
  color: #ffffff;
  font-size: 13px;
  font-weight: 700;
  letter-spacing: 0.08em;
}

.feature-list {
  top: clamp(64px, 13vh, 146px);
  display: grid;
  gap: 24px;
}

.feature-list article {
  display: grid;
  gap: 8px;
  padding-left: 24px;
  border-left: 3px solid rgba(255, 255, 255, 0.82);
}

.feature-list strong {
  color: #ffffff;
  font-size: clamp(24px, 2.7vw, 42px);
  line-height: 1;
}

.feature-list span {
  color: rgba(255, 255, 255, 0.78);
  font-size: clamp(15px, 1.5vw, 18px);
  line-height: 1.7;
}

.pack-list {
  bottom: clamp(48px, 10vh, 108px);
  display: grid;
  gap: 14px;
  margin: 0;
  padding: 0;
  list-style: none;
}

.pack-list li,
.pack-list a {
  color: #ffffff;
  font-size: clamp(26px, 3.4vw, 52px);
  font-weight: 900;
  line-height: 1.05;
  letter-spacing: -0.04em;
}

.pack-list a {
  text-decoration: none;
  pointer-events: auto;
  transition:
    opacity 0.2s ease,
    transform 0.2s ease;
}

.pack-list a:hover {
  opacity: 0.78;
}

.download-panel {
  bottom: clamp(34px, 7vh, 74px);
  text-align: left;
}

.download-info {
  bottom: clamp(34px, 7vh, 74px);
}

.download-button {
  display: flex;
  align-items: center;
  justify-content: center;
  width: fit-content;
  max-width: 100%;
  min-width: min(100%, 300px);
  margin: 0 0 22px;
  padding: 17px 34px;
  border: 1px solid rgba(255, 255, 255, 0.9);
  border-radius: 999px;
  color: #050607;
  background: #ffffff;
  font-size: clamp(18px, 2vw, 24px);
  font-weight: 900;
  text-decoration: none;
  transition:
    opacity 0.62s ease,
    transform 0.72s cubic-bezier(0.22, 1, 0.36, 1),
    background 0.2s ease;
  pointer-events: auto;
}

.download-button.text-line {
  transform: translate(var(--line-base-x, 0px), calc(var(--line-base-y, 0px) + 18px)) scale(0.98);
}

body.is-loaded .is-active .download-button.text-line {
  transform: translate(var(--line-base-x, 0px), var(--line-base-y, 0px)) scale(1);
}

body.is-loaded .is-leaving .download-button.text-line {
  transform: translate(var(--line-base-x, 0px), calc(var(--line-base-y, 0px) - 14px)) scale(0.98);
}

.download-button:hover {
  transform: translate(var(--line-base-x, 0px), calc(var(--line-base-y, 0px) - 2px)) scale(1.02);
  background: #e8eef3;
}

.download-meta {
  margin-top: 10px;
  color: rgba(255, 255, 255, 0.62);
  font-size: 12px;
  font-weight: 700;
  letter-spacing: 0.04em;
}

.source-link {
  display: inline-block;
  margin-top: 24px;
  color: rgba(255, 255, 255, 0.76);
  font-size: 13px;
  font-weight: 700;
  letter-spacing: 0.12em;
  text-decoration: none;
  text-transform: uppercase;
  pointer-events: auto;
}

.source-link:hover {
  color: #ffffff;
}

@media (max-width: 820px) {
  .hero-title {
    left: 32px;
  }

  .hero-subtitle {
    top: 31.2vh;
    right: 32px;
    bottom: auto;
    left: 32px;
    font-size: clamp(16px, 4.8vw, 22px);
  }

  .hero-meta {
    margin-top: clamp(110px, 18vw, 150px);
  }

  .section-side-note,
  .feature-list,
  .download-panel,
  .download-info,
  .pack-list {
    width: auto;
    max-width: calc(100vw - 64px);
    left: 32px;
    right: 32px;
  }

  .section-side-note,
  .feature-list,
  .download-panel,
  .download-info,
  .pack-list {
    bottom: 44px;
    top: auto;
  }

  .section-copy.align-right {
    left: 32px;
    right: 32px;
    text-align: left;
  }

  .section-copy.align-left,
  .section-copy.align-right,
  .features-page .section-copy.lower {
    top: clamp(42px, 8vh, 96px);
    bottom: auto;
  }

  .download-page .download-panel {
    top: 50%;
    bottom: auto;
    text-align: center;
    transform: translateY(-50%);
  }

  .download-page .download-button {
    margin-right: auto;
    margin-left: auto;
  }

  .desktop-recommendation {
    display: none;
  }

  .mobile-recommendation {
    display: inline;
  }

  .metric-row {
    justify-content: flex-start;
  }

}