/* ============================================================
   每日大赛品牌联名任务赛中心 — 商务公文风（Corporate Brief Style）
   设计哲学：Swiss International Style × Corporate Identity
   主色调：高级灰 + 品牌橙，信息层级严格分明
   ============================================================ */

:root {
  --primary: #374151;
  --secondary: #F97316;
  --bg: #F7F7F5;
  --card: #FFFFFF;
  --accent: #111827;
  --text: #1F2937;
  --text-light: #6B7280;
  --border: #E5E7EB;
  --radius: 14px;
  --shadow: 0 10px 30px rgba(0,0,0,0.12);
  --shadow-sm: 0 4px 12px rgba(0,0,0,0.06);
  --shadow-hover: 0 14px 40px rgba(0,0,0,0.16);
  --ease-out: cubic-bezier(0.23, 1, 0.32, 1);
  --ease-in-out: cubic-bezier(0.77, 0, 0.175, 1);
  --font-heading: "Noto Sans SC", -apple-system, BlinkMacSystemFont, sans-serif;
  --font-body: "Noto Sans SC", -apple-system, BlinkMacSystemFont, sans-serif;
  --font-mono: "JetBrains Mono", "SF Mono", "Fira Code", monospace;
  --max-width: 1200px;
  --header-height: 72px;
}

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

html {
  font-size: 16px;
  scroll-behavior: smooth;
  -webkit-text-size-adjust: 100%;
}

body {
  font-family: var(--font-body);
  color: var(--text);
  background-color: var(--bg);
  line-height: 1.75;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

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

a {
  color: var(--secondary);
  text-decoration: none;
  transition: color 0.2s var(--ease-out);
}

a:hover { color: var(--accent); }

h1, h2, h3, h4, h5, h6 {
  font-family: var(--font-heading);
  font-weight: 700;
  color: var(--accent);
  line-height: 1.3;
}

h1 { font-size: 2.5rem; margin-bottom: 1rem; }
h2 { font-size: 1.875rem; margin-bottom: 0.875rem; }
h3 { font-size: 1.375rem; margin-bottom: 0.75rem; }
h4 { font-size: 1.125rem; margin-bottom: 0.5rem; }

p { margin-bottom: 1rem; }

ul, ol { padding-left: 1.5rem; margin-bottom: 1rem; }
li { margin-bottom: 0.5rem; }

/* === Layout === */
.container {
  width: 100%;
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 1.25rem;
}

.section {
  padding: 4rem 0;
}

.section-title {
  text-align: center;
  margin-bottom: 3rem;
  position: relative;
}

.section-title::after {
  content: "";
  display: block;
  width: 48px;
  height: 4px;
  background: var(--secondary);
  margin: 0.75rem auto 0;
  border-radius: 2px;
}

.section-subtitle {
  color: var(--text-light);
  font-size: 1rem;
  margin-top: 0.5rem;
}

/* === Header === */
.site-header {
  position: sticky;
  top: 0;
  z-index: 1000;
  background: var(--card);
  border-bottom: 1px solid var(--border);
  height: var(--header-height);
  display: flex;
  align-items: center;
  backdrop-filter: blur(12px);
}

.header-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  width: 100%;
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 1.25rem;
}

.site-logo {
  font-size: 1.25rem;
  font-weight: 700;
  color: var(--accent);
  display: flex;
  align-items: center;
  gap: 0.5rem;
}

.site-logo .logo-icon {
  width: 36px;
  height: 36px;
  background: var(--secondary);
  border-radius: 8px;
  display: flex;
  align-items: center;
  justify-content: center;
  color: #fff;
  font-weight: 900;
  font-size: 1rem;
}

.main-nav { display: flex; align-items: center; gap: 1.5rem; }
.main-nav a {
  color: var(--text);
  font-size: 0.9375rem;
  font-weight: 500;
  transition: color 0.2s var(--ease-out);
}
.main-nav a:hover { color: var(--secondary); }

.nav-toggle {
  display: none;
  background: none;
  border: none;
  cursor: pointer;
  width: 32px;
  height: 32px;
  flex-direction: column;
  justify-content: center;
  align-items: center;
  gap: 5px;
}
.nav-toggle span {
  display: block;
  width: 22px;
  height: 2px;
  background: var(--accent);
  transition: transform 0.3s var(--ease-out);
}

/* === Hero === */
.hero {
  position: relative;
  padding: 5rem 0 4rem;
  overflow: hidden;
  background: linear-gradient(135deg, var(--primary) 0%, #1F2937 100%);
  color: #fff;
}

.hero-bg {
  position: absolute;
  inset: 0;
  opacity: 0.15;
  background-size: cover;
  background-position: center;
}

.hero-content {
  position: relative;
  z-index: 2;
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 3rem;
  align-items: center;
}

.hero-left h1 {
  color: #fff;
  font-size: 2.75rem;
  margin-bottom: 1rem;
}

.hero-left .hero-subtitle {
  color: rgba(255,255,255,0.85);
  font-size: 1.125rem;
  margin-bottom: 1.5rem;
  line-height: 1.7;
}

.hero-badge {
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
  background: var(--secondary);
  color: #fff;
  padding: 0.5rem 1rem;
  border-radius: 24px;
  font-size: 0.875rem;
  font-weight: 600;
  margin-bottom: 1.5rem;
}

.hero-right {
  background: var(--card);
  border-radius: var(--radius);
  padding: 2rem;
  color: var(--text);
  box-shadow: var(--shadow);
}

.hero-right h3 { color: var(--accent); margin-bottom: 1rem; }

.hero-cta {
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
  background: var(--secondary);
  color: #fff;
  padding: 0.875rem 2rem;
  border-radius: 8px;
  font-weight: 600;
  font-size: 1rem;
  border: none;
  cursor: pointer;
  transition: transform 0.16s var(--ease-out), box-shadow 0.2s var(--ease-out);
}

.hero-cta:hover {
  transform: translateY(-2px);
  box-shadow: 0 8px 24px rgba(249,115,22,0.35);
  color: #fff;
}

.hero-cta:active { transform: scale(0.97); }

/* === Brief Card === */
.brief-card {
  background: var(--card);
  border-radius: var(--radius);
  padding: 1.75rem;
  border-left: 4px solid var(--secondary);
  box-shadow: var(--shadow-sm);
  transition: transform 0.3s var(--ease-out), box-shadow 0.3s var(--ease-out);
}

.brief-card:hover {
  transform: translateY(-4px);
  box-shadow: var(--shadow-hover);
}

.brief-card-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-bottom: 1rem;
}

.brief-card-title {
  font-size: 1.125rem;
  font-weight: 700;
  color: var(--accent);
}

.brief-card-status {
  font-size: 0.75rem;
  font-weight: 600;
  padding: 0.25rem 0.75rem;
  border-radius: 12px;
  text-transform: uppercase;
}

.status-active { background: #ECFDF5; color: #059669; }
.status-pending { background: #FFF7ED; color: #EA580C; }
.status-closed { background: #F3F4F6; color: #6B7280; }

.brief-card-meta {
  display: flex;
  gap: 1.5rem;
  margin-top: 1rem;
  font-size: 0.875rem;
  color: var(--text-light);
}

.brief-card-meta .mono {
  font-family: var(--font-mono);
  color: var(--secondary);
  font-weight: 600;
}

/* === Task Cards Grid === */
.task-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(320px, 1fr));
  gap: 1.5rem;
}

/* === Rewards Showcase === */
.rewards-showcase {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 2rem;
}

.reward-item {
  text-align: center;
  padding: 2rem 1.5rem;
  background: var(--card);
  border-radius: var(--radius);
  box-shadow: var(--shadow-sm);
  transition: transform 0.3s var(--ease-out), box-shadow 0.3s var(--ease-out);
}

.reward-item:hover {
  transform: translateY(-6px);
  box-shadow: var(--shadow);
}

.reward-icon {
  width: 64px;
  height: 64px;
  margin: 0 auto 1rem;
  background: linear-gradient(135deg, var(--secondary), #FB923C);
  border-radius: 16px;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1.75rem;
}

.reward-title {
  font-size: 1.125rem;
  font-weight: 700;
  margin-bottom: 0.5rem;
}

/* === Process Flow === */
.process-flow {
  display: flex;
  justify-content: space-between;
  align-items: flex-start;
  gap: 1rem;
  position: relative;
}

.process-flow::before {
  content: "";
  position: absolute;
  top: 32px;
  left: 10%;
  right: 10%;
  height: 3px;
  background: var(--border);
  z-index: 0;
}

.process-step {
  flex: 1;
  text-align: center;
  position: relative;
  z-index: 1;
}

.process-step-num {
  width: 64px;
  height: 64px;
  border-radius: 50%;
  background: var(--primary);
  color: #fff;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1.25rem;
  font-weight: 700;
  margin: 0 auto 1rem;
  transition: background 0.3s var(--ease-out), transform 0.3s var(--ease-out);
}

.process-step.active .process-step-num {
  background: var(--secondary);
  transform: scale(1.1);
}

.process-step-title {
  font-weight: 600;
  margin-bottom: 0.25rem;
}

.process-step-desc {
  font-size: 0.8125rem;
  color: var(--text-light);
}

/* === Delivery Checklist === */
.checklist {
  background: var(--card);
  border-radius: var(--radius);
  padding: 2rem;
  box-shadow: var(--shadow-sm);
}

.checklist-item {
  display: flex;
  align-items: center;
  gap: 0.75rem;
  padding: 0.875rem 0;
  border-bottom: 1px solid var(--border);
}

.checklist-item:last-child { border-bottom: none; }

.checklist-check {
  width: 24px;
  height: 24px;
  border-radius: 6px;
  border: 2px solid var(--border);
  display: flex;
  align-items: center;
  justify-content: center;
  flex-shrink: 0;
  transition: all 0.2s var(--ease-out);
  cursor: pointer;
}

.checklist-check.checked {
  background: var(--secondary);
  border-color: var(--secondary);
  background: var(--secondary);
  border-color: var(--secondary);
}

.checklist-check.checked::after {
  content: "✓";
  color: #fff;
  font-size: 0.875rem;
  font-weight: 700;
}

/* === Case Showcase === */
.case-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
  gap: 1.5rem;
}

.case-card {
  background: var(--card);
  border-radius: var(--radius);
  overflow: hidden;
  box-shadow: var(--shadow-sm);
  transition: transform 0.3s var(--ease-out), box-shadow 0.3s var(--ease-out);
}

.case-card:hover {
  transform: translateY(-4px);
  box-shadow: var(--shadow);
}

.case-card-img {
  width: 100%;
  height: 180px;
  object-fit: cover;
}

.case-card-body { padding: 1.25rem; }

/* === FAQ === */
.faq-list { max-width: 800px; margin: 0 auto; }

.faq-item {
  background: var(--card);
  border-radius: var(--radius);
  margin-bottom: 1rem;
  box-shadow: var(--shadow-sm);
  overflow: hidden;
}

.faq-question {
  padding: 1.25rem 1.5rem;
  font-weight: 600;
  cursor: pointer;
  display: flex;
  justify-content: space-between;
  align-items: center;
  transition: background 0.2s;
}

.faq-question:hover { background: #FAFAFA; }

.faq-question::after {
  content: "+";
  font-size: 1.25rem;
  color: var(--secondary);
  font-weight: 700;
  transition: transform 0.3s var(--ease-out);
}

.faq-item.open .faq-question::after { transform: rotate(45deg); }

.faq-answer {
  padding: 0 1.5rem;
  max-height: 0;
  overflow: hidden;
  transition: max-height 0.4s var(--ease-out), padding 0.3s;
}

.faq-item.open .faq-answer {
  max-height: 500px;
  padding: 0 1.5rem 1.25rem;
}

/* === APP Section === */
.app-section {
  background: linear-gradient(135deg, var(--primary), #1F2937);
  color: #fff;
  text-align: center;
}

.app-section h2 { color: #fff; }
.app-section p { color: rgba(255,255,255,0.8); }

.app-btn {
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
  background: var(--secondary);
  color: #fff;
  padding: 0.875rem 2rem;
  border-radius: 8px;
  font-weight: 600;
  transition: transform 0.16s var(--ease-out), box-shadow 0.2s;
}

.app-btn:hover {
  transform: translateY(-2px);
  box-shadow: 0 8px 24px rgba(249,115,22,0.35);
  color: #fff;
}

/* === Footer === */
.site-footer {
  background: var(--accent);
  color: rgba(255,255,255,0.7);
  padding: 3rem 0 1.5rem;
}

.footer-grid {
  display: grid;
  grid-template-columns: 2fr 1fr 1fr 1fr;
  gap: 2rem;
  margin-bottom: 2rem;
}

.footer-brand { font-size: 1.25rem; font-weight: 700; color: #fff; margin-bottom: 0.75rem; }
.footer-desc { font-size: 0.875rem; line-height: 1.6; }

.footer-col h4 { color: #fff; font-size: 0.9375rem; margin-bottom: 1rem; }
.footer-col a {
  display: block;
  color: rgba(255,255,255,0.6);
  font-size: 0.875rem;
  margin-bottom: 0.5rem;
  transition: color 0.2s;
}
.footer-col a:hover { color: var(--secondary); }

.footer-bottom {
  border-top: 1px solid rgba(255,255,255,0.1);
  padding-top: 1.5rem;
  text-align: center;
  font-size: 0.8125rem;
}

/* === Breadcrumb === */
.breadcrumb {
  padding: 1rem 0;
  font-size: 0.875rem;
  color: var(--text-light);
}

.breadcrumb a { color: var(--text-light); }
.breadcrumb a:hover { color: var(--secondary); }
.breadcrumb span { margin: 0 0.5rem; }

/* === Page Header === */
.page-header {
  background: var(--primary);
  color: #fff;
  padding: 3rem 0;
  text-align: center;
}

.page-header h1 { color: #fff; font-size: 2.25rem; }
.page-header p { color: rgba(255,255,255,0.8); margin-top: 0.5rem; }

/* === Content Block === */
.content-block {
  background: var(--card);
  border-radius: var(--radius);
  padding: 2rem;
  margin-bottom: 2rem;
  box-shadow: var(--shadow-sm);
}

/* === Related Links === */
.related-links {
  display: flex;
  flex-wrap: wrap;
  gap: 0.75rem;
  margin-top: 1.5rem;
}

.related-links a {
  padding: 0.5rem 1rem;
  background: var(--bg);
  border-radius: 8px;
  font-size: 0.875rem;
  color: var(--text);
  transition: background 0.2s, color 0.2s;
}

.related-links a:hover {
  background: var(--secondary);
  color: #fff;
}

/* === Search === */
.search-input {
  width: 100%;
  padding: 1rem 1.5rem;
  border: 2px solid var(--border);
  border-radius: var(--radius);
  font-size: 1rem;
  font-family: var(--font-body);
  outline: none;
  transition: border-color 0.2s;
}

.search-input:focus { border-color: var(--secondary); }

.search-results { margin-top: 2rem; }

.search-result-item {
  padding: 1.25rem;
  border-bottom: 1px solid var(--border);
}

.search-result-item h3 a { color: var(--accent); }
.search-result-item h3 a:hover { color: var(--secondary); }
.search-result-item .result-path { font-size: 0.8125rem; color: var(--text-light); font-family: var(--font-mono); }
.search-result-item .result-tag {
  display: inline-block;
  padding: 0.125rem 0.5rem;
  background: #FFF7ED;
  color: var(--secondary);
  border-radius: 4px;
  font-size: 0.75rem;
  font-weight: 600;
  margin-top: 0.5rem;
}

/* === Animations === */
@media (prefers-reduced-motion: no-preference) {
  .fade-in {
    opacity: 0;
    transform: translateY(20px);
    transition: opacity 0.6s var(--ease-out), transform 0.6s var(--ease-out);
  }
  .fade-in.visible {
    opacity: 1;
    transform: translateY(0);
  }
  .stagger-1 { transition-delay: 0.08s; }
  .stagger-2 { transition-delay: 0.16s; }
  .stagger-3 { transition-delay: 0.24s; }
  .stagger-4 { transition-delay: 0.32s; }
  .stagger-5 { transition-delay: 0.40s; }
}

/* === Responsive === */
@media (max-width: 768px) {
  h1 { font-size: 1.875rem; }
  h2 { font-size: 1.5rem; }

  .hero-content {
    grid-template-columns: 1fr;
    gap: 2rem;
  }

  .hero-left h1 { font-size: 2rem; }

  .footer-grid {
    grid-template-columns: 1fr 1fr;
    gap: 1.5rem;
  }

  .rewards-showcase {
    grid-template-columns: 1fr;
  }

  .process-flow {
    flex-direction: column;
    align-items: center;
  }

  .process-flow::before {
    top: 0;
    bottom: 0;
    left: 32px;
    right: auto;
    width: 3px;
    height: auto;
  }

  .process-step {
    display: flex;
    align-items: center;
    gap: 1rem;
    text-align: left;
  }

  .process-step-num { margin: 0; flex-shrink: 0; }

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

  .nav-toggle { display: flex; }

  .main-nav {
    position: fixed;
    top: var(--header-height);
    left: 0;
    right: 0;
    background: var(--card);
    flex-direction: column;
    padding: 1.5rem;
    gap: 1rem;
    border-bottom: 1px solid var(--border);
    transform: translateY(-100%);
    opacity: 0;
    pointer-events: none;
    transition: transform 0.3s var(--ease-out), opacity 0.3s;
  }

  .main-nav.open {
    transform: translateY(0);
    opacity: 1;
    pointer-events: all;
  }
}

@media (max-width: 480px) {
  .container { padding: 0 1rem; }
  .section { padding: 2.5rem 0; }
  .hero { padding: 3rem 0 2.5rem; }
  .footer-grid { grid-template-columns: 1fr; }
}

/* === Utility === */
.text-center { text-align: center; }
.text-mono { font-family: var(--font-mono); }
.text-secondary { color: var(--secondary); }
.text-light { color: var(--text-light); }
.mt-1 { margin-top: 0.5rem; }
.mt-2 { margin-top: 1rem; }
.mt-3 { margin-top: 1.5rem; }
.mb-2 { margin-bottom: 1rem; }
.mb-3 { margin-bottom: 1.5rem; }
.grid-2 { display: grid; grid-template-columns: 1fr 1fr; gap: 1.5rem; }
.grid-3 { display: grid; grid-template-columns: repeat(3, 1fr); gap: 1.5rem; }

@media (max-width: 768px) {
  .grid-2, .grid-3 { grid-template-columns: 1fr; }
}