:root {
  color: #141414;
  background: #f1f8ff;
  font-family: "Alibaba PuHuiTi", "PingFang SC", "Microsoft YaHei", system-ui, sans-serif;
  font-synthesis: none;
  text-rendering: optimizeLegibility;
  -webkit-font-smoothing: antialiased;
}

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

html {
  scroll-behavior: smooth;
}

body {
  min-width: 320px;
  background: #f1f8ff;
}

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

.page-shell {
  position: relative;
  min-height: 100vh;
  overflow: hidden;
  background-color: #f1f8ff;
  background-image: linear-gradient(rgba(7, 107, 255, 0.72), rgba(241, 248, 255, 0) 860px), url("./assets/bg.webp");
  background-repeat: no-repeat;
  background-position: top center;
  /* background-size: min(1920px, 130vw) auto; */
  background-size: cover;
}

.site-header {
  position: fixed;
  z-index: 20;
  inset: 0 0 auto;
  display: flex;
  align-items: center;
  justify-content: flex-end;
  gap: clamp(22px, 4vw, 48px);
  height: 64px;
  padding: 0 clamp(22px, 7vw, 140px);
  color: #fff;
  transition: background 0.3s ease, color 0.3s ease, backdrop-filter 0.3s ease;
}

.site-header.is-fixed {
  color: #141414;
  background: rgba(255, 255, 255, 0.82);
  backdrop-filter: blur(8px);
  box-shadow: 0 10px 30px rgba(20, 70, 160, 0.08);
}

.header-logo {
  position: absolute;
  left: clamp(22px, 4vw, 60px);
  width: 108px;
  height: 42px;
  object-fit: contain;
  opacity: 0;
  transform: translateY(-8px);
  transition: opacity 0.3s ease, transform 0.3s ease;
}

.site-header.is-fixed .header-logo {
  opacity: 1;
  transform: translateY(0);
}

.site-header nav {
  display: flex;
  align-items: center;
  gap: clamp(18px, 4vw, 42px);
  font-size: clamp(15px, 1.2vw, 20px);
}

.site-header a {
  white-space: nowrap;
  transition: opacity 0.2s ease;
}

.site-header a:hover {
  opacity: 0.68;
}

main {
  position: relative;
  z-index: 2;
}

#features,
#engine,
#faq {
  scroll-margin-top: 76px;
}

.hero {
  min-height: clamp(920px, 88vh, 1900px);
  padding-top: clamp(136px, 7vh, 240px);
}

.hero-title {
  color: #fff;
  text-transform: uppercase;
  letter-spacing: 0;
  padding-left: clamp(24px, 10vw, 360px);
  font-size: clamp(46px, 6.4vw, 172px);
  font-weight: 900;
  line-height: 1.12;
}

.hero-title + .hero-title {
  margin-top: clamp(28px, 5vw, 74px);
}

.hero-title-right {
  padding-right: clamp(24px, 8vw, 300px);
  padding-left: 0;
  text-align: right;
}

.hero-title span {
  display: inline-block;
}

.hero-desc {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 20px;
  margin-top: clamp(70px, 7vw, 180px);
  color: #fff;
  font-size: clamp(16px, 1.35vw, 34px);
}

.hero-desc span:first-child {
  display: flex;
  align-items: center;
  gap: 12px;
}

.hero-desc span:first-child::before,
.hero-desc span:first-child::after {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-width: 58px;
  min-height: 44px;
  padding: 0 10px;
  border-radius: 8px;
  background: #f5bf00;
  color: #fff;
  font-size: clamp(15px, 1.1vw, 28px);
  font-weight: 700;
}

.hero-desc span:first-child::before {
  content: "游戏";
}

.download-btn {
  display: grid;
  place-items: center;
  width: min(300px, calc(100vw - 48px));
  height: 84px;
  margin: 54px auto 176px;
  border-radius: 50px;
  background: url("./assets/download-bg.webp") center / contain no-repeat;
  filter: drop-shadow(3px 3px 10px rgba(0, 0, 0, 0.22));
  cursor: pointer;
}

.download-btn span {
  position: absolute;
  width: 1px;
  height: 1px;
  overflow: hidden;
  clip: rect(0 0 0 0);
}

.feature-cards {
  display: grid;
  grid-template-columns: repeat(4, minmax(220px, 420px));
  justify-content: center;
  gap: clamp(20px, 4vw, 108px);
  padding: 0 clamp(20px, 4vw, 72px);
}

.feature-card {
  min-height: 350px;
  padding: 58px 20px 34px;
  border-radius: 20px;
  color: #fff;
  text-align: center;
  box-shadow: 5px 10px 18px rgba(0, 0, 0, 0.2);
  opacity: 0;
  visibility: hidden;
}

.no-js-animate .feature-card,
.no-js-animate .engine-img,
.no-js-animate .question {
  opacity: 1;
  visibility: visible;
  transform: none;
}

.feature-card h2 {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 12px;
  font-size: clamp(28px, 2.4vw, 40px);
  line-height: 1.1;
}

.feature-card h2 img {
  width: 34px;
  height: 34px;
  object-fit: contain;
  flex: 0 0 34px;
}

.card-icon {
  display: grid;
  place-items: center;
  width: 34px;
  height: 34px;
  border-radius: 50%;
  background: rgba(255, 255, 255, 0.22);
  font-size: 22px;
}

.card-tip {
  margin: 10px 0 54px;
  font-size: 18px;
}

.feature-card p:last-child {
  font-size: 14px;
  line-height: 1.65;
}

.built-in {
  background: #1c54ee;
}

.rhythm {
  background: #080b12;
}

.sync {
  background: #d800d8;
}

.game {
  background: #ffc804;
}

.line-title {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: clamp(18px, 4vw, 62px);
  margin: 160px 0 92px;
}

.line-title i {
  position: relative;
  width: min(28vw, 503px);
  height: 2px;
  background: #aed6ff;
}

.line-title i::before,
.line-title i::after {
  content: "";
  position: absolute;
  top: -4px;
  width: 10px;
  height: 10px;
  border-radius: 50%;
  background: inherit;
}

.line-title i::before {
  left: -4px;
}

.line-title i::after {
  right: -4px;
}

.line-title span {
  color: #101010;
  white-space: nowrap;
  font-size: clamp(26px, 2.5vw, 38px);
  font-weight: 900;
}

.engine-section {
  text-align: center;
}

.engine-img {
  width: min(1800px, 92vw);
  aspect-ratio: 16 / 10;
  object-fit: contain;
  opacity: 0;
  transform: scale(0);
  border-radius: 10px;
  filter: drop-shadow(0 24px 44px rgba(20, 70, 160, 0.16));
}

.question-grid {
  display: grid;
  grid-template-columns: repeat(3, minmax(240px, 560px));
  justify-content: center;
  gap: clamp(20px, 1.5vw, 36px);
  padding: 0 clamp(20px, 4vw, 72px) 100px;
}

.question {
  min-height: 270px;
  padding: 40px 30px;
  border-radius: 20px;
  background: #fff;
  box-shadow: 5px 8px 18px rgba(0, 0, 0, 0.15);
  opacity: 0;
  visibility: hidden;
}

.question h3 {
  margin-bottom: 30px;
  color: #202020;
  font-size: clamp(20px, 1.7vw, 24px);
  font-weight: 500;
  line-height: 1.35;
}

.question p {
  color: #202020;
  font-size: clamp(19px, 1.7vw, 24px);
  font-weight: 700;
  line-height: 1.45;
}

.site-footer {
  position: relative;
  min-height: 722px;
  overflow: hidden;
  border-radius: 80px 80px 0 0;
  background: #1c54ee;
  color: #fff;
}

.footer-title {
  margin: 80px 0;
}

.footer-title span {
  color: #fff;
}

.footer-title i {
  background: #fff;
}

.footer-content {
  display: flex;
  flex-wrap: wrap;
  /* justify-content: center; */
  gap: clamp(36px, 2.6vw, 96px);
  /* justify-content: center; */
  /* gap: clamp(56px, 4vw, 200px); */
  max-width: 2360px;
  margin: 0 auto;
  padding: 0 clamp(32px, 7vw, 260px);
}

.footer-content img {
  /* width: 180px; */
  /* height: 50px; */
  max-width: clamp(180px, 10vw, 320px);
  max-height: clamp(58px, 3.5vw, 104px);
  object-fit: contain;
  margin-bottom: 30px;
}

.footer-content > div:first-child {
  max-width: 660px;
}

.footer-content h2 {
  margin-bottom: 24px;
  font-size: clamp(30px, 2.8vw, 40px);
}

.footer-content p {
  font-size: clamp(20px, 2vw, 28px);
  line-height: 1.4;
}

.qr-pair {
  display: flex;
  gap: 60px;
}

.qr-card {
  display: grid;
  justify-items: center;
  gap: 12px;
  color: #fff;
  text-align: center;
}

.qr-card span {
  display: grid;
  place-items: center;
  width: 240px;
  height: 240px;
  border-radius: 24px;
  background:
    linear-gradient(90deg, rgba(255, 255, 255, 0.18) 50%, transparent 0) 0 0 / 28px 28px,
    linear-gradient(rgba(255, 255, 255, 0.18) 50%, transparent 0) 0 0 / 28px 28px,
    #0d2fb2;
  font-size: 54px;
  font-weight: 900;
}

.qr-card p {
  font-size: 24px;
}

.footer-bottom {
  position: absolute;
  inset: auto 0 0;
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 10px;
  height: 100px;
  background: #141414;
  color: #8d8d8d;
  user-select: none;
}

@media (max-width: 1180px) {
  .feature-cards,
  .question-grid {
    grid-template-columns: repeat(2, minmax(260px, 420px));
  }

  .footer-content {
    flex-direction: column;
    align-items: center;
    text-align: center;
  }
}

@media (min-width: 1920px) {
  .site-header {
    height: clamp(64px, 3.8vw, 96px);
    padding: 0 clamp(140px, 7vw, 268px);
  }

  .header-logo {
    left: clamp(60px, 4vw, 150px);
    width: clamp(108px, 5.8vw, 176px);
    height: clamp(42px, 2.4vw, 72px);
  }

  .download-btn {
    width: clamp(300px, 15vw, 480px);
    height: clamp(84px, 4.2vw, 134px);
    margin-top: clamp(54px, 3vw, 104px);
    margin-bottom: clamp(176px, 8vw, 300px);
  }

  .feature-card {
    min-height: clamp(350px, 18vw, 520px);
    padding: clamp(58px, 3.1vw, 92px) clamp(20px, 1.4vw, 42px) clamp(34px, 2vw, 64px);
    border-radius: clamp(20px, 1vw, 28px);
  }

  .feature-card h2 {
    font-size: clamp(40px, 2vw, 56px);
  }

  .feature-card h2 img {
    width: clamp(34px, 1.7vw, 52px);
    height: clamp(34px, 1.7vw, 52px);
    flex-basis: clamp(34px, 1.7vw, 52px);
  }

  .card-tip {
    margin: clamp(10px, 0.8vw, 22px) 0 clamp(54px, 3vw, 92px);
    font-size: clamp(18px, 1vw, 28px);
  }

  .feature-card p:last-child {
    font-size: clamp(14px, 0.78vw, 22px);
  }

  .line-title {
    margin: clamp(160px, 8vw, 260px) 0 clamp(92px, 4.8vw, 154px);
  }

  .line-title span {
    font-size: clamp(38px, 1.9vw, 58px);
  }

  .question {
    min-height: clamp(270px, 14vw, 410px);
    padding: clamp(40px, 2.2vw, 74px) clamp(30px, 1.8vw, 58px);
    border-radius: clamp(20px, 1vw, 28px);
  }

  .question h3 {
    margin-bottom: clamp(30px, 1.8vw, 58px);
    font-size: clamp(24px, 1.25vw, 34px);
  }

  .question p {
    font-size: clamp(24px, 1.25vw, 34px);
  }

  .site-footer {
    min-height: clamp(722px, 37vw, 1120px);
    border-radius: clamp(80px, 4vw, 150px) clamp(80px, 4vw, 150px) 0 0;
  }

  .footer-title {
    margin: clamp(80px, 4vw, 140px) 0;
  }

  .footer-bottom {
    height: clamp(100px, 5vw, 160px);
    font-size: clamp(16px, 0.85vw, 26px);
  }
}

@media (min-width: 2560px) {
  .feature-cards {
    grid-template-columns: repeat(4, minmax(360px, 500px));
  }

  .question-grid {
    grid-template-columns: repeat(3, minmax(460px, 650px));
  }

  .engine-img {
    width: min(2160px, 84vw);
  }

  .footer-content {
    max-width: 2800px;
  }
}

@media (max-width: 720px) {
  .site-header {
    justify-content: center;
    height: 58px;
    padding: 0 16px;
  }

  .header-logo {
    display: none;
  }

  .hero {
    min-height: 770px;
    padding-top: 118px;
  }

  .hero-title,
  .hero-title-right {
    padding: 0 22px;
    text-align: left;
  }

  .hero-desc {
    flex-direction: column;
    align-items: flex-start;
    padding: 0 22px;
  }

  .download-btn {
    margin-bottom: 118px;
  }

  .feature-cards,
  .question-grid {
    grid-template-columns: 1fr;
  }

  .feature-card {
    min-height: 290px;
    padding-top: 42px;
  }

  .line-title {
    gap: 16px;
    margin: 96px 0 54px;
  }

  .line-title i {
    width: 18vw;
  }

  .question {
    min-height: 220px;
  }

  .site-footer {
    border-radius: 42px 42px 0 0;
  }

  .qr-pair {
    flex-direction: column;
  }

  .qr-card span {
    width: 210px;
    height: 210px;
  }
}