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

:root {
  --color-white: #FFFFFF;
  --color-orange: #FF6F00;
  --color-gray-black: #2A2D33;
  --color-tiffany: #A8DCD6;
  --color-text: #333333;
  --color-border: #E0E0E0;
  --nav-height: 64px;
}

html {
  scroll-behavior: smooth;
}

body {
  font-family: -apple-system, "Microsoft YaHei", sans-serif;
  color: var(--color-text);
  background: var(--color-white);
  padding-top: var(--nav-height);
}

.site-nav {
  position: fixed;
  top: 0;
  left: 0;
  z-index: 1000;
  width: 100%;
  height: var(--nav-height);
  background: var(--color-white);
  border-bottom: 1px solid var(--color-border);
  transition: box-shadow 0.3s ease;
}

.site-nav.nav-scrolled {
  box-shadow: 0 2px 12px rgba(0, 0, 0, 0.08);
}

.nav-inner {
  width: min(1180px, calc(100% - 48px));
  height: 100%;
  margin: 0 auto;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 32px;
}

.logo {
  flex: 0 0 auto;
  color: var(--color-orange);
  font-size: 22px;
  font-weight: 700;
  line-height: 1;
  text-decoration: none;
  white-space: nowrap;
}

.nav-menu {
  display: flex;
  align-items: center;
  justify-content: flex-end;
  gap: 28px;
  list-style: none;
}

.nav-menu a {
  color: var(--color-text);
  font-size: 15px;
  line-height: 1;
  text-decoration: none;
  transition: color 0.2s ease;
  white-space: nowrap;
}

.nav-menu a:hover,
.nav-menu a:focus,
.nav-menu a.nav-active {
  color: var(--color-orange);
}

.hero-section {
  min-height: calc(100vh - var(--nav-height));
  background: var(--color-white);
  scroll-margin-top: var(--nav-height);
}

.hero-inner {
  width: min(960px, calc(100% - 48px));
  min-height: calc(100vh - var(--nav-height));
  margin: 0 auto;
  padding: 72px 0 64px;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  text-align: center;
}

.hero-inner h1 {
  color: var(--color-gray-black);
  font-size: clamp(36px, 4vw, 48px);
  font-weight: 700;
  line-height: 1.28;
}

.hero-line {
  width: 60px;
  height: 4px;
  margin: 24px 0 40px;
  background: var(--color-orange);
}

.contest-image {
  width: 100%;
  max-width: 720px;
  height: auto;
  border-radius: 12px;
  box-shadow: 0 4px 24px rgba(0, 0, 0, 0.12);
  display: block;
  margin: 0 auto;
}

.contest-intro {
  width: min(800px, 100%);
  margin-top: 28px;
  color: var(--color-text);
  font-size: 18px;
  line-height: 1.9;
}

.content-section,
.section-placeholder {
  min-height: 1px;
  scroll-margin-top: var(--nav-height);
}

.content-section {
  background: var(--color-white);
  padding: 96px 0;
  opacity: 0;
  transform: translateY(30px);
}

.content-section.section-visible {
  opacity: 1;
  transform: translateY(0);
  transition: opacity 0.6s ease, transform 0.6s ease;
}

.section-inner {
  width: min(1080px, calc(100% - 48px));
  margin: 0 auto;
}

.section-title {
  color: var(--color-gray-black);
  font-size: 36px;
  font-weight: 700;
  line-height: 1.25;
  text-align: center;
}

.section-line {
  width: 60px;
  height: 4px;
  margin: 20px auto 36px;
  background: var(--color-orange);
}

.section-subtitle {
  margin: -12px 0 40px;
  color: var(--color-gray-black);
  font-size: 18px;
  line-height: 1.7;
  text-align: center;
}

.about-text {
  max-width: 800px;
  margin: 0 auto;
  color: var(--color-text);
  font-size: 18px;
  line-height: 1.9;
  text-align: center;
}

.business-grid {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 24px;
}

.business-card {
  min-height: 100%;
  padding: 32px;
  background: var(--color-white);
  border: 1px solid var(--color-border);
  border-radius: 12px;
  transition: transform 0.3s ease, box-shadow 0.3s ease;
}

.business-card:hover {
  box-shadow: 0 4px 16px rgba(0, 0, 0, 0.08);
  transform: translateY(-4px);
}

.card-icon {
  width: 56px;
  height: 56px;
  display: flex;
  align-items: center;
  justify-content: center;
  color: var(--color-white);
  background: var(--color-orange);
  border-radius: 50%;
  font-size: 24px;
  font-weight: 700;
  line-height: 1;
}

.business-card h3 {
  margin-top: 24px;
  color: var(--color-gray-black);
  font-size: 20px;
  font-weight: 700;
  line-height: 1.35;
}

.business-card p {
  margin-top: 14px;
  color: var(--color-text);
  font-size: 15px;
  line-height: 1.8;
}

.brands-section {
  background: var(--color-tiffany);
}

.brands-section .section-line {
  background: var(--color-gray-black);
}

.brand-grid {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 24px;
}

.brand-card {
  padding: 0;
  background: var(--color-white);
  border-radius: 12px;
  overflow: hidden;
}

.brand-image {
  width: 100%;
  height: 260px;
  object-fit: contain;
  background: #F5F5F5;
  padding: 16px;
  display: block;
  margin: 0 0 24px;
}

.brand-card h3 {
  padding: 0 32px;
  color: var(--color-gray-black);
  font-size: 24px;
  font-weight: 700;
  line-height: 1.3;
}

.brand-card p {
  margin-top: 12px;
  padding: 0 32px 32px;
  color: var(--color-text);
  font-size: 15px;
  line-height: 1.8;
}

.award-grid {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 24px;
}

.award-card {
  padding: 32px;
  color: var(--color-white);
  background: var(--color-gray-black);
  border-radius: 12px;
}

.award-label {
  color: var(--color-orange);
  font-size: 14px;
  font-weight: 700;
  line-height: 1.4;
}

.award-card h3 {
  margin-top: 14px;
  color: var(--color-white);
  font-size: 24px;
  font-weight: 700;
  line-height: 1.3;
}

.award-card p:not(.award-label) {
  margin-top: 14px;
  color: var(--color-white);
  font-size: 15px;
  line-height: 1.8;
}

.contact-section {
  color: var(--color-white);
  background: var(--color-gray-black);
}

.contact-section .section-title {
  color: var(--color-white);
}

.contact-section .section-title,
.contact-section .section-subtitle {
  width: min(920px, 100%);
  margin-left: auto;
  margin-right: auto;
}

.contact-section .section-subtitle {
  color: rgba(255, 255, 255, 0.7);
}

.contact-grid {
  display: grid;
  grid-template-columns: minmax(0, 1.35fr) minmax(260px, 0.65fr);
  gap: 48px;
  max-width: 920px;
  margin: 0 auto;
}

.contact-list {
  display: grid;
  gap: 22px;
}

.contact-item dt {
  color: var(--color-orange);
  font-size: 15px;
  font-weight: 700;
  line-height: 1.4;
}

.contact-item dd {
  margin-top: 8px;
  color: var(--color-white);
  font-size: 17px;
  line-height: 1.8;
}

.qr-code {
  width: 80px;
  height: 80px;
  margin-top: 28px;
  border-radius: 8px;
  border: 1px solid rgba(255, 255, 255, 0.2);
  display: block;
}

.qr-tip {
  width: 80px;
  margin-top: 8px;
  color: rgba(255, 255, 255, 0.6);
  font-size: 13px;
  line-height: 1.5;
  text-align: center;
}

.site-footer {
  padding: 24px 0;
  background: #171717;
}

.footer-inner {
  width: min(1080px, calc(100% - 48px));
  margin: 0 auto;
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 32px;
  color: rgba(255, 255, 255, 0.5);
  font-size: 14px;
  line-height: 1.7;
  text-align: center;
}

.footer-inner p + p::before {
  content: "·";
  margin-right: 32px;
}

.back-to-top {
  position: fixed;
  right: 32px;
  bottom: 32px;
  z-index: 900;
  width: 48px;
  height: 48px;
  color: var(--color-white);
  background: var(--color-gray-black);
  border: 0;
  border-radius: 50%;
  cursor: pointer;
  font-size: 24px;
  line-height: 1;
  opacity: 0;
  visibility: hidden;
  transition: all 0.3s ease;
}

.back-to-top:hover,
.back-to-top:focus {
  background: var(--color-orange);
}

.back-to-top.back-to-top-visible {
  opacity: 1;
  visibility: visible;
}

@media (max-width: 900px) {
  .nav-inner {
    width: min(100% - 32px, 720px);
    gap: 18px;
  }

  .nav-menu {
    gap: 16px;
    overflow-x: auto;
    -webkit-overflow-scrolling: touch;
    scrollbar-width: none;
  }

  .nav-menu::-webkit-scrollbar {
    display: none;
  }

  .nav-menu a {
    font-size: 14px;
  }

  .hero-inner {
    width: min(100% - 32px, 720px);
    padding: 56px 0 48px;
  }

  .contest-image {
    max-width: 680px;
  }

  .section-inner {
    width: min(100% - 32px, 720px);
  }

  .business-grid {
    grid-template-columns: 1fr;
  }

  .brand-grid,
  .award-grid {
    grid-template-columns: 1fr;
  }

  .contact-grid {
    grid-template-columns: 1fr;
    gap: 36px;
  }

  .footer-inner {
    flex-direction: column;
    gap: 6px;
  }

  .footer-inner p + p::before {
    content: none;
    margin-right: 0;
  }
}

@media (max-width: 600px) {
  .nav-inner {
    width: calc(100% - 24px);
    gap: 14px;
  }

  .nav-menu {
    flex: 1 1 auto;
    justify-content: flex-start;
    gap: 14px;
  }

  .nav-menu li:first-child {
    border-left: 1px solid var(--color-border);
    padding-left: 14px;
  }

  .hero-section,
  .hero-inner {
    min-height: calc(100vh - var(--nav-height));
  }

  .hero-inner h1 {
    font-size: 34px;
  }

  .contest-intro {
    font-size: 16px;
    line-height: 1.8;
  }

  .content-section {
    padding: 64px 0;
  }

  .section-inner {
    width: calc(100% - 48px);
  }

  .section-title {
    font-size: 30px;
  }

  .about-text {
    font-size: 16px;
    line-height: 1.85;
  }

  .business-card {
    padding: 28px;
  }

  .award-card {
    padding: 28px;
  }

  .brand-card h3 {
    padding: 0 28px;
  }

  .brand-card p {
    padding: 0 28px 28px;
  }

  .section-subtitle {
    margin-bottom: 32px;
  }

  .back-to-top {
    right: 20px;
    bottom: 20px;
    width: 40px;
    height: 40px;
    font-size: 20px;
  }
}

@media (prefers-reduced-motion: reduce) {
  html {
    scroll-behavior: auto;
  }

  *,
  *::before,
  *::after {
    transition: none !important;
    animation: none !important;
  }

  .content-section {
    opacity: 1;
    transform: none;
  }
}