/* ============================================================
   四项户外体能挑战站 - 全站样式表
   设计风格：档案馆柔光摄影画面，语气科技效率
   CSS前缀：b2s01k06n01-summit-
   断点：480px / 768px / 992px / 1200px (Mobile-First)
   ============================================================ */

/* --- Reset & Base --- */
*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }
html { font-size: 16px; scroll-behavior: smooth; }
body {
  font-family: "Noto Sans SC", "Helvetica Neue", Arial, sans-serif;
  line-height: 1.75;
  color: #2c2c2c;
  background: #faf9f7;
}
img { max-width: 100%; height: auto; display: block; }
a { color: #1a5276; text-decoration: none; transition: color .2s; }
a:hover { color: #d35400; }
ul, ol { list-style: none; }

/* --- Typography --- */
h1, h2, h3, h4, h5, h6 {
  font-weight: 700;
  line-height: 1.3;
  color: #1b2631;
}
h1 { font-size: 2rem; margin-bottom: 1rem; }
h2 { font-size: 1.6rem; margin-bottom: .8rem; }
h3 { font-size: 1.3rem; margin-bottom: .6rem; }
p { margin-bottom: 1rem; }

/* --- Layout --- */
.b2s01k06n01-summit-container-wrapper {
  width: 100%;
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 1rem;
}

/* --- Header --- */
.b2s01k06n01-summit-header {
  background: rgba(255,255,255,.97);
  border-bottom: 1px solid #e8e4df;
  position: sticky;
  top: 0;
  z-index: 1000;
  backdrop-filter: blur(6px);
}
.b2s01k06n01-summit-header-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: .8rem 1rem;
  max-width: 1200px;
  margin: 0 auto;
}
.b2s01k06n01-summit-logo img { height: 40px; width: auto; }
.b2s01k06n01-summit-nav-list {
  display: none;
  flex-direction: column;
  gap: 0;
  position: absolute;
  top: 100%;
  left: 0;
  right: 0;
  background: #fff;
  border-bottom: 1px solid #e8e4df;
  padding: 1rem;
}
.b2s01k06n01-summit-nav-list.active { display: flex; }
.b2s01k06n01-summit-nav-item { padding: .5rem 0; }
.b2s01k06n01-summit-link-element {
  font-size: .95rem;
  font-weight: 500;
  color: #2c3e50;
  transition: color .2s;
}
.b2s01k06n01-summit-link-element:hover,
.b2s01k06n01-summit-link-element.active { color: #d35400; }
.b2s01k06n01-summit-menu-toggle {
  display: block;
  background: none;
  border: none;
  font-size: 1.5rem;
  cursor: pointer;
  color: #2c3e50;
}

/* --- Hero / Banner --- */
.b2s01k06n01-summit-hero {
  position: relative;
  min-height: 420px;
  display: flex;
  align-items: center;
  justify-content: center;
  text-align: center;
  overflow: hidden;
  background: #1b2631;
}
.b2s01k06n01-summit-hero img {
  position: absolute;
  inset: 0;
  width: 100%;
  height: 100%;
  object-fit: cover;
  opacity: .55;
}
.b2s01k06n01-summit-hero-content {
  position: relative;
  z-index: 2;
  color: #fff;
  padding: 2rem 1rem;
}
.b2s01k06n01-summit-hero-content h1 { color: #fff; font-size: 2.2rem; }
.b2s01k06n01-summit-hero-content p { color: rgba(255,255,255,.9); font-size: 1.1rem; max-width: 600px; margin: .5rem auto 1.5rem; }
.b2s01k06n01-summit-cta-btn {
  display: inline-block;
  padding: .75rem 2rem;
  background: #d35400;
  color: #fff;
  border-radius: 4px;
  font-weight: 600;
  transition: background .2s, transform .15s;
}
.b2s01k06n01-summit-cta-btn:hover { background: #e67e22; transform: translateY(-2px); color: #fff; }

/* --- Section --- */
.b2s01k06n01-summit-section {
  padding: 3rem 0;
}
.b2s01k06n01-summit-section:nth-child(even) { background: #f4f1ec; }
.b2s01k06n01-summit-section-title {
  text-align: center;
  margin-bottom: 2rem;
  position: relative;
}
.b2s01k06n01-summit-section-title::after {
  content: '';
  display: block;
  width: 60px;
  height: 3px;
  background: #d35400;
  margin: .6rem auto 0;
}

/* --- Cards Grid --- */
.b2s01k06n01-summit-grid {
  display: grid;
  gap: 1.5rem;
  grid-template-columns: 1fr;
}
.b2s01k06n01-summit-card {
  background: #fff;
  border-radius: 6px;
  overflow: hidden;
  box-shadow: 0 2px 12px rgba(0,0,0,.06);
  transition: transform .2s, box-shadow .2s;
}
.b2s01k06n01-summit-card:hover { transform: translateY(-4px); box-shadow: 0 6px 20px rgba(0,0,0,.1); }
.b2s01k06n01-summit-card img { width: 100%; height: 200px; object-fit: cover; }
.b2s01k06n01-summit-card-body { padding: 1.2rem; }
.b2s01k06n01-summit-card-body h3 { font-size: 1.1rem; margin-bottom: .4rem; }
.b2s01k06n01-summit-card-body p { font-size: .9rem; color: #555; }
.b2s01k06n01-summit-card-meta { font-size: .8rem; color: #888; margin-top: .5rem; }

/* --- FAQ --- */
.b2s01k06n01-summit-faq-item { border-bottom: 1px solid #e8e4df; padding: 1.2rem 0; }
.b2s01k06n01-summit-faq-item h3 { font-size: 1rem; color: #1a5276; cursor: pointer; }
.b2s01k06n01-summit-faq-item p { margin-top: .5rem; font-size: .92rem; color: #444; }

/* --- Footer --- */
.b2s01k06n01-summit-footer {
  background: #1b2631;
  color: #ccc;
  padding: 3rem 0 1.5rem;
  font-size: .88rem;
}
.b2s01k06n01-summit-footer a { color: #f0c27f; }
.b2s01k06n01-summit-footer a:hover { color: #fff; }
.b2s01k06n01-summit-footer-grid {
  display: grid;
  gap: 2rem;
  grid-template-columns: 1fr;
  margin-bottom: 2rem;
}
.b2s01k06n01-summit-footer-col h4 { color: #fff; margin-bottom: .8rem; font-size: .95rem; }
.b2s01k06n01-summit-footer-col ul li { margin-bottom: .4rem; }
.b2s01k06n01-summit-footer-bottom {
  border-top: 1px solid rgba(255,255,255,.1);
  padding-top: 1.2rem;
  text-align: center;
  color: #888;
}

/* --- Breadcrumb --- */
.b2s01k06n01-summit-breadcrumb {
  padding: .8rem 0;
  font-size: .85rem;
  color: #666;
}
.b2s01k06n01-summit-breadcrumb a { color: #1a5276; }
.b2s01k06n01-summit-breadcrumb span { margin: 0 .4rem; color: #999; }

/* --- Article --- */
.b2s01k06n01-summit-article { max-width: 800px; margin: 0 auto; padding: 2rem 1rem; }
.b2s01k06n01-summit-article-meta { font-size: .85rem; color: #888; margin-bottom: 1.5rem; }
.b2s01k06n01-summit-article img { border-radius: 6px; margin: 1.5rem 0; }

/* --- Form --- */
.b2s01k06n01-summit-form { max-width: 600px; margin: 0 auto; }
.b2s01k06n01-summit-form label { display: block; font-weight: 600; margin-bottom: .3rem; font-size: .9rem; }
.b2s01k06n01-summit-form input,
.b2s01k06n01-summit-form textarea,
.b2s01k06n01-summit-form select {
  width: 100%;
  padding: .7rem;
  border: 1px solid #ddd;
  border-radius: 4px;
  margin-bottom: 1rem;
  font-size: .95rem;
  font-family: inherit;
}
.b2s01k06n01-summit-form button {
  padding: .75rem 2rem;
  background: #d35400;
  color: #fff;
  border: none;
  border-radius: 4px;
  font-weight: 600;
  cursor: pointer;
  transition: background .2s;
}
.b2s01k06n01-summit-form button:hover { background: #e67e22; }

/* --- Video --- */
.b2s01k06n01-summit-video-wrap {
  position: relative;
  padding-bottom: 56.25%;
  height: 0;
  overflow: hidden;
  border-radius: 6px;
  margin: 1.5rem 0;
}
.b2s01k06n01-summit-video-wrap video {
  position: absolute;
  top: 0; left: 0;
  width: 100%; height: 100%;
  object-fit: cover;
}

/* --- Timeline --- */
.b2s01k06n01-summit-timeline { position: relative; padding-left: 2rem; }
.b2s01k06n01-summit-timeline::before {
  content: '';
  position: absolute;
  left: .5rem;
  top: 0; bottom: 0;
  width: 2px;
  background: #d35400;
}
.b2s01k06n01-summit-timeline-item { margin-bottom: 2rem; position: relative; }
.b2s01k06n01-summit-timeline-item::before {
  content: '';
  position: absolute;
  left: -1.6rem;
  top: .4rem;
  width: 12px; height: 12px;
  background: #d35400;
  border-radius: 50%;
}
.b2s01k06n01-summit-timeline-item h4 { font-size: 1rem; color: #1b2631; }
.b2s01k06n01-summit-timeline-item p { font-size: .9rem; color: #555; }

/* --- Trust Badge --- */
.b2s01k06n01-summit-trust-badges {
  display: flex;
  flex-wrap: wrap;
  gap: 1rem;
  justify-content: center;
  padding: 1.5rem 0;
}
.b2s01k06n01-summit-badge {
  background: #fff;
  border: 1px solid #e8e4df;
  border-radius: 6px;
  padding: .8rem 1.2rem;
  font-size: .85rem;
  color: #333;
  text-align: center;
}

/* --- Interactive Tool --- */
.b2s01k06n01-summit-tool-box {
  background: #fff;
  border: 1px solid #e8e4df;
  border-radius: 8px;
  padding: 2rem;
  max-width: 700px;
  margin: 0 auto;
}

/* ============================================================
   Responsive Breakpoints (Mobile-First)
   ============================================================ */
@media (min-width: 480px) {
  .b2s01k06n01-summit-grid { grid-template-columns: repeat(2, 1fr); }
  .b2s01k06n01-summit-footer-grid { grid-template-columns: repeat(2, 1fr); }
}

@media (min-width: 768px) {
  h1 { font-size: 2.4rem; }
  .b2s01k06n01-summit-hero { min-height: 500px; }
  .b2s01k06n01-summit-hero-content h1 { font-size: 2.8rem; }
  .b2s01k06n01-summit-grid { grid-template-columns: repeat(2, 1fr); }
  .b2s01k06n01-summit-footer-grid { grid-template-columns: repeat(2, 1fr); }
}

@media (min-width: 992px) {
  .b2s01k06n01-summit-nav-list {
    display: flex;
    flex-direction: row;
    position: static;
    background: transparent;
    border: none;
    padding: 0;
    gap: 1.5rem;
  }
  .b2s01k06n01-summit-menu-toggle { display: none; }
  .b2s01k06n01-summit-grid { grid-template-columns: repeat(3, 1fr); }
  .b2s01k06n01-summit-footer-grid { grid-template-columns: repeat(4, 1fr); }
}

@media (min-width: 1200px) {
  .b2s01k06n01-summit-container-wrapper { padding: 0 2rem; }
  .b2s01k06n01-summit-hero { min-height: 560px; }
  .b2s01k06n01-summit-hero-content h1 { font-size: 3.2rem; }
}