/* ========== Reset & Base ========== */
*, *::before, *::after {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

html {
  /* 设计基准：1440 宽下 1rem = 10px */
  font-size: clamp(8px, 0.694444vw, 10px);
  scroll-behavior: smooth;
  scroll-padding-top: 6rem;
}

body {
  background: #000;
  color: #fff;
  font-family: "PingFang SC", "Microsoft YaHei", "Helvetica Neue", Arial, sans-serif;
  line-height: 1.6;
  overflow-x: hidden;
}

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

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

button {
  border: none;
  background: none;
  cursor: pointer;
  color: inherit;
  font-family: inherit;
}

/* ========== 吸顶导航栏：通栏纯黑50%透明 ========== */
.nav-header {
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  z-index: 1000;
  background: rgba(0, 0, 0, 0.5);
  height: 6.4rem;
}

.nav-inner {
  width: 100%;
  max-width: 144rem;
  margin: 0 auto;
  height: 100%;
  display: flex;
  align-items: center;
  padding: 0 4rem;
}

.nav-logo img {
  height: 4.4rem;
  width: auto;
}

.nav-menu {
  display: flex;
  align-items: center;
  gap: 3.2rem;
  margin-left: 13rem;
  margin-right: auto;
}

.nav-link {
  font-size: 1.4rem;
  color: rgba(255, 255, 255, 0.7);
  transition: color 0.3s;
  letter-spacing: 0.1rem;
}

.nav-link:hover,
.nav-link.active {
  color: #fff;
}

/* ========== 首屏 Hero ========== */
.hero-section {
  position: relative;
  width: 100%;
  height: 100vh;
  min-height: 80rem;
  display: flex;
  align-items: flex-end;
  justify-content: center;
  overflow: hidden;
}

.hero-video {
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  object-fit: cover;
  pointer-events: none;
}

.hero-overlay {
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  background: linear-gradient(
    to bottom,
    rgba(0, 0, 0, 0.3) 0%,
    rgba(0, 0, 0, 0) 15%,
    rgba(0, 0, 0, 0) 70%,
    rgba(0, 0, 0, 0.6) 100%
  );
}

.hero-content {
  position: relative;
  z-index: 2;
  text-align: center;
  width: 100%;
  padding-bottom: 12rem;
  display: flex;
  flex-direction: column;
  align-items: center;
}

/* ========== 首屏平台按钮 ========== */
.hero-platforms {
  display: flex;
  align-items: center;
  gap: 1.6rem;
  margin-top: 15rem;
}

/* 单个平台按钮：固定宽度211px，高度57px */
.platform-btn {
  position: relative;
  width: 21.1rem;
  height: 5.7rem;
  display: flex;
  align-items: center;
  justify-content: center;
  transition: transform 0.2s;
}

.platform-btn:hover:not(.disabled) {
  transform: translateY(-0.2rem);
}

.platform-btn:active:not(.disabled) {
  transform: scale(0.97);
}

.platform-btn.disabled {
  cursor: not-allowed;
}

.btn-bg {
  position: absolute;
  top: 0;
  left: 0;
  width: 21.1rem;
  height: 5.7rem;
}

.btn-bg-active {
  display: none;
}

.btn-bg-normal {
  display: block;
}

.platform-btn.active .btn-bg-active {
  display: block;
}

.platform-btn.active .btn-bg-normal {
  display: none;
}

.btn-icon {
  position: relative;
  z-index: 1;
  height: 2.6rem;
  width: auto;
  object-fit: contain;
}

/* ========== 二维码悬浮容器 ========== */
.qrcode-floating {
  position: absolute;
  top: 0;
  left: 0;
  display: none;
  pointer-events: none;
  flex-direction: column;
  align-items: center;
  width: 20rem;
  height: 21.8rem;
  padding: 2rem;
  background: #705C42;
  border-radius: 0.4rem;
  gap: 0.8rem;
  animation: fadeIn 0.3s ease;
}

.qrcode-floating.show {
  display: flex;
}

@keyframes fadeIn {
  from { opacity: 0; transform: translateY(0.8rem); }
  to { opacity: 1; transform: translateY(0); }
}

.qrcode-img {
  width: 16rem;
  height: 16rem;
  border-radius: 0.2rem;
}

.qrcode-tip {
  font-size: 1.2rem;
  line-height: 1.5;
  color: rgba(255, 255, 255, 0.85);
  letter-spacing: 0.1rem;
}

/* ========== 通用分屏 ========== */
.section-screen {
  padding: 8rem 0;
  background: #000;
}

.section-title-wrap {
  text-align: center;
  margin-bottom: 4.8rem;
}

.section-title-img {
  height: 3.2rem;
  width: auto;
  margin: 0 auto;
}

.section-img-wrap {
  max-width: 144rem;
  margin: 0 auto;
}

.section-full-img {
  width: 100%;
  height: auto;
  display: block;
}

.art-desc-wrap {
  text-align: center;
  margin-top: 4.8rem;
  padding: 0 4rem;
}

.art-desc-img {
  height: 5.3rem;
  width: auto;
  margin: 0 auto;
  max-width: 100%;
}

/* ========== 底部教学视频 ========== */
.section-tutorial {
  background: #000;
}

.video-player-wrap {
  position: relative;
  width: 144rem;
  height: 81rem;
  max-width: 100%;
  margin: 0 auto;
  border-radius: 0.8rem;
  overflow: hidden;
  background: #0a0a0a;
  box-shadow: 0 1.6rem 4.8rem rgba(0, 0, 0, 0.6);
}

.tutorial-video {
  width: 100%;
  height: 100%;
  display: block;
  object-fit: cover;
  background: #000;
  cursor: pointer;
}

.video-controls {
  position: absolute;
  left: 0;
  right: 0;
  bottom: 0;
  display: flex;
  align-items: center;
  gap: 1.2rem;
  padding: 1rem 1.6rem;
  background: rgba(10, 10, 10, 0.95);
}

.video-btn {
  width: 3rem;
  height: 3rem;
  display: flex;
  align-items: center;
  justify-content: center;
  color: rgba(255, 255, 255, 0.8);
  transition: color 0.3s;
  flex-shrink: 0;
}

.video-btn:hover {
  color: #A0825F;
}

.video-btn svg {
  width: 1.8rem;
  height: 1.8rem;
}

.progress-wrap {
  flex: 1;
  cursor: pointer;
  padding: 1rem 0;
}

.progress-bar {
  width: 100%;
  height: 0.3rem;
  background: rgba(255, 255, 255, 0.15);
  border-radius: 0.2rem;
  transition: height 0.2s;
}

.progress-wrap:hover .progress-bar {
  height: 0.5rem;
}

.progress-filled {
  height: 100%;
  background: #A0825F;
  border-radius: 0.2rem;
  width: 0%;
  transition: width 0.1s linear;
  position: relative;
}

.progress-filled::after {
  content: "";
  position: absolute;
  right: -0.5rem;
  top: 50%;
  transform: translateY(-50%) scale(0);
  width: 1rem;
  height: 1rem;
  border-radius: 50%;
  background: #A0825F;
  transition: transform 0.2s;
}

.progress-wrap:hover .progress-filled::after {
  transform: translateY(-50%) scale(1);
}

.time-display {
  font-size: 1.2rem;
  color: rgba(255, 255, 255, 0.5);
  white-space: nowrap;
  min-width: 8.5rem;
  text-align: right;
  flex-shrink: 0;
}

.video-player-wrap:fullscreen {
  display: flex;
  flex-direction: column;
  justify-content: center;
  background: #000;
  border-radius: 0;
}

.video-player-wrap:fullscreen .tutorial-video {
  flex: 1;
}

.video-player-wrap:fullscreen .video-controls {
  padding: 1.2rem 2.4rem;
}

/* ========== 底部版权：严格按设计稿 ========== */
.site-footer {
  background: #000;
  height: 22rem;
  padding: 0 4rem;
  display: flex;
  align-items: center;
}

.footer-inner {
  max-width: 144rem;
  width: 100%;
  margin: 0 auto;
  display: grid;
  grid-template-columns: 24rem 1fr 36rem;
  align-items: start;
  column-gap: 4rem;
}

.footer-brand-img {
  width: 17.5rem;
  height: 7.5rem;
}

.footer-col-middle,
.footer-col-right {
  font-size: 1.4rem;
  color: #A0825F;
  line-height: 1.9;
  display: flex;
  flex-direction: column;
  gap: 0.6rem;
}

.footer-line {
  margin: 0;
  white-space: nowrap;
  display: flex;
  align-items: center;
}

.footer-line img {
  width: 1.4rem;
  height: 1.4rem;
  margin-right: 0.6rem;
}

.footer-line a {
  color: #A0825F;
  font-size: 1.4rem;
  transition: opacity 0.3s;
}

.footer-line a:hover {
  opacity: 0.6;
}

.footer-line span {
  color: rgba(160, 130, 95, 0.4);
  margin: 0 0.6rem;
}

/* ========== 滚动动画 ========== */
.fade-in {
  opacity: 0;
  transform: translateY(2rem);
  transition: opacity 0.6s ease, transform 0.6s ease;
}

.fade-in.visible {
  opacity: 1;
  transform: translateY(0);
}

/* ========== 响应式 ========== */
@media (max-width: 96rem) {
  .nav-menu {
    margin-left: 2.4rem;
  }

  .hero-platforms {
    flex-wrap: wrap;
    justify-content: center;
    gap: 1.2rem;
    padding: 0 2rem;
  }

  .qrcode-floating {
    display: none !important;
  }

  .section-screen {
    padding: 6rem 0;
  }

  .video-player-wrap {
    width: 100%;
    height: auto;
    aspect-ratio: 16 / 9;
  }

  .footer-inner {
    grid-template-columns: 1fr;
    row-gap: 1.6rem;
  }

  .site-footer {
    height: auto;
    padding: 2rem;
    align-items: flex-start;
  }
}