/* ----------------------------------------------------------------
   common.css — base typography, layout primitives, header & footer
   ---------------------------------------------------------------- */

html { scroll-behavior: smooth; }

body {
  font-family: var(--font-base);
  font-size: 16px;
  line-height: 1.7;
  color: var(--color-text-1);
  background: var(--color-bg);
  font-feature-settings: "kern", "liga";
}

/* ---------- Layout primitives ---------- */

.container {
  width: 100%;
  max-width: var(--container-max);
  margin: 0 auto;
  padding: 0 var(--gutter);
}

.section {
  padding: var(--space-9) 0;
}
.section--soft   { background: var(--color-bg-soft); }
.section--dark   { background: var(--color-bg-dark); color: #FFFFFF; }
.section--primary{ background: var(--color-primary-soft); }

.section-head {
  text-align: center;
  max-width: 720px;
  margin: 0 auto var(--space-7);
}
.section-head--left { text-align: left; margin-left: 0; }
.section-eyebrow {
  display: inline-flex;
  align-items: center;
  gap: var(--space-2);
  color: var(--color-primary);
  font-size: 14px;
  font-weight: 600;
  letter-spacing: 2px;
  text-transform: uppercase;
}
.section-eyebrow::before {
  content: "";
  width: 24px;
  height: 2px;
  background: var(--color-accent);
  display: inline-block;
}
/* 眉标与下方标题共用同一中心轴：仅改变对齐与位置，不改颜色/字号/字重/字距/间距 */
.section-eyebrow--center {
  width: 100%;
  justify-content: center;
}
.section-title {
  font-size: clamp(28px, 3vw, 40px);
  font-weight: 700;
  color: var(--color-text-1);
  margin: var(--space-3) 0 var(--space-4);
  line-height: 1.25;
}
.section-title span { color: var(--color-primary); }
.section-desc {
  font-size: 16px;
  color: var(--color-text-2);
  line-height: 1.7;
}

/* ---------- Typography ---------- */

h1, h2, h3, h4, h5, h6 { font-family: var(--font-base); font-weight: 700; line-height: 1.25; color: var(--color-text-1); }
h1 { font-size: clamp(36px, 4.5vw, 56px); }
h2 { font-size: clamp(28px, 3vw, 40px); }
h3 { font-size: clamp(22px, 2.2vw, 28px); }
h4 { font-size: 20px; }
p { color: var(--color-text-2); }
strong, b { color: var(--color-text-1); font-weight: 600; }
.text-gradient {
  background: var(--gradient-accent);
  -webkit-background-clip: text;
  background-clip: text;
  color: transparent;
}

/* ---------- Buttons ---------- */

.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: var(--space-2);
  padding: 12px 22px;
  border-radius: var(--radius-pill);
  font-weight: 600;
  font-size: 15px;
  letter-spacing: 0.5px;
  transition: transform var(--duration-base) var(--ease-out),
              box-shadow var(--duration-base) var(--ease-out),
              background var(--duration-base) var(--ease-out),
              color var(--duration-base) var(--ease-out);
  cursor: pointer;
  white-space: nowrap;
}
.btn--primary {
  background: var(--color-primary);
  color: #FFFFFF;
  box-shadow: 0 6px 16px rgba(30, 98, 217, 0.32);
}
.btn--primary:hover { background: #1656BA; transform: translateY(calc(-1 * var(--lift-sm))); box-shadow: 0 10px 24px rgba(30, 98, 217, 0.45); }
.btn--ghost {
  background: rgba(255, 255, 255, 0.12);
  color: #FFFFFF;
  border: 1px solid rgba(255, 255, 255, 0.4);
  backdrop-filter: blur(6px);
}
.btn--ghost:hover { background: rgba(255,255,255,0.22); }
.btn--outline {
  background: transparent;
  color: var(--color-primary);
  border: 1.5px solid var(--color-primary);
}
.btn--outline:hover { background: var(--color-primary); color: #FFFFFF; }
.btn--light {
  background: #FFFFFF;
  color: var(--color-primary);
  box-shadow: var(--shadow-card);
}
.btn--light:hover { transform: translateY(calc(-1 * var(--lift-sm))); box-shadow: var(--shadow-hover); }
.btn .btn-icon { width: 18px; height: 18px; }
.btn--lg { padding: 14px 28px; font-size: 16px; }

/* ---------- Header / Navigation ---------- */

.site-header {
  position: sticky;
  top: 0;
  left: 0;
  right: 0;
  z-index: var(--z-nav);
  background: rgba(255, 255, 255, 0.85);
  backdrop-filter: saturate(1.4) blur(12px);
  border-bottom: 1px solid transparent;
  transition: background var(--duration-base) var(--ease-out),
              border-color var(--duration-base) var(--ease-out),
              box-shadow var(--duration-base) var(--ease-out);
}
.site-header.is-scrolled {
  background: rgba(255, 255, 255, 0.95);
  border-bottom-color: var(--color-border);
  box-shadow: var(--shadow-sm);
}

.nav-bar {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 72px;
  gap: var(--space-5);
}
.nav-logo {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  flex: 0 0 auto;               /* 不参与挤压，始终固定在左上角 */
  gap: var(--space-2);
  font-weight: 700;
  font-size: 18px;
  color: var(--color-primary-deep);
  /* 移除画框式底衬，使图标与导航栏背景自然融合 */
  padding: 8px 16px;
  margin-right: clamp(8px, 1.6vw, 24px);
  border-radius: 16px;
  border: none;
  background: transparent;
  box-shadow: none;
  transition: transform var(--duration-base) var(--ease-out);
}
.nav-logo:hover {
  transform: translateY(-1px);
  box-shadow: none;
}
.nav-logo img {
  display: block;
  height: 52px;                 /* 36px → 52px，仍小于原图 124px 高，属下采样，不模糊 */
  width: auto;                  /* 宽度自适应，比例恒定不变形 */
  max-width: 100%;
}

.nav-list {
  display: flex;
  align-items: center;
  gap: var(--space-6);
  list-style: none;
  padding: 0;
  margin: 0;
}
.nav-list a {
  position: relative;
  padding: 8px 4px;
  font-weight: 500;
  font-size: 15px;
  color: var(--color-text-1);
  transition: color var(--duration-base) var(--ease-out);
}
.nav-list a::after {
  content: "";
  position: absolute;
  bottom: 0;
  left: 50%;
  width: 0;
  height: 2px;
  background: var(--color-primary);
  transition: width var(--duration-base) var(--ease-out),
              left var(--duration-base) var(--ease-out);
}
.nav-list a:hover, .nav-list a.is-active { color: var(--color-primary); }
.nav-list a:hover::after, .nav-list a.is-active::after { width: 100%; left: 0; }

.nav-cta { display: flex; align-items: center; gap: var(--space-3); }

.nav-toggle {
  display: none;
  width: 40px;
  height: 40px;
  align-items: center;
  justify-content: center;
  border-radius: var(--radius-sm);
}
.nav-toggle span {
  display: block;
  width: 22px;
  height: 2px;
  background: var(--color-primary-deep);
  position: relative;
  transition: transform var(--duration-base) var(--ease-out);
}
.nav-toggle span::before, .nav-toggle span::after {
  content: "";
  position: absolute;
  left: 0;
  width: 22px;
  height: 2px;
  background: var(--color-primary-deep);
  transition: transform var(--duration-base) var(--ease-out);
}
.nav-toggle span::before { top: -7px; }
.nav-toggle span::after  { top: 7px; }
.nav-toggle.is-open span { background: transparent; }
.nav-toggle.is-open span::before { top: 0; transform: rotate(45deg); }
.nav-toggle.is-open span::after  { top: 0; transform: rotate(-45deg); }

/* ---------- Footer ---------- */

.site-footer {
  background: var(--color-bg-dark);
  color: #CFD8E5;
  padding: var(--space-8) 0 var(--space-5);
  font-size: 14px;
}
.footer-grid {
  display: grid;
  /* 共 6 个子项：品牌列 + 4 个链接列 + 二维码列。
     链接列与二维码列按内容宽度收敛（空间不足时回落到 min-content 换行，避免溢出），
     品牌列弹性吸收剩余空间，使各列紧凑并排在同一行。 */
  grid-template-columns: minmax(200px, 1fr) repeat(5, minmax(min-content, max-content));
  gap: var(--space-7);
  align-items: start;
  padding-bottom: var(--space-7);
  border-bottom: 1px solid rgba(255,255,255,0.08);
}
.footer-brand h3 {
  color: #FFFFFF;
  margin-bottom: var(--space-3);
  font-size: 18px;
}
.footer-brand p { color: #9AAAC1; max-width: 320px; }
/* 页脚品牌图标：与首页导航同源 logo.png，等比缩放保证清晰 */
.footer-brand .footer-logo {
  display: block;
  height: 40px;
  width: auto;
  margin-bottom: var(--space-4);
}
.footer-col h4 {
  color: #FFFFFF;
  font-size: 15px;
  font-weight: 600;
  margin-bottom: var(--space-4);
}
.footer-col ul { list-style: none; padding: 0; margin: 0; display: flex; flex-direction: column; gap: var(--space-2); }
.footer-col a {
  color: #9AAAC1;
  font-size: 14px;
  transition: color var(--duration-base) var(--ease-out);
}
.footer-col a:hover { color: var(--color-accent); }
.footer-contact {
  display: flex;
  align-items: flex-start;
  gap: var(--space-2);
  color: #9AAAC1;
}
.footer-contact strong { display: block; color: #FFFFFF; font-weight: 500; }
.footer-bottom {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding-top: var(--space-5);
  color: #6F7E96;
  font-size: 13px;
}
.footer-bottom .legal a { color: #6F7E96; margin-left: var(--space-4); }
.footer-bottom .legal a:hover { color: var(--color-accent); }

/* ---------- Footer QR column ---------- */
/* 二维码作为 footer-grid 的最后一列，与「走进涌智 / 资源中心 / 联系方式」同行并排 */
.footer-col--qr .footer-qr-row {
  display: flex;
  flex-direction: row;
  align-items: flex-start;
  gap: var(--space-4);
}
.footer-qr-item {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: var(--space-2);
}
.footer-qr-frame {
  /* 外框 96px + 7px 内边距 → 码图 82px（原 108px 的 76%），兼顾扫码识别与页脚文字的视觉比例 */
  width: 96px;
  height: 96px;
  padding: 7px;
  border-radius: var(--radius-md);
  background: #FFFFFF;
  box-shadow: 0 4px 14px rgba(0,0,0,0.12);
  display: flex;
  align-items: center;
  justify-content: center;
}
.footer-qr-frame img {
  width: 100%;
  height: 100%;
  object-fit: contain;
  display: block;
}
.footer-qr-item p {
  color: #9AAAC1;
  font-size: 13px;
  line-height: 1.4;
  margin: 0;
  text-align: center;
  white-space: nowrap;
}

/* ---------- Misc utility ---------- */

.grid { display: grid; gap: var(--space-5); }
.grid-2 { grid-template-columns: repeat(2, minmax(0, 1fr)); }
.grid-3 { grid-template-columns: repeat(3, minmax(0, 1fr)); }
.grid-4 { grid-template-columns: repeat(4, minmax(0, 1fr)); }
.flex { display: flex; }
.flex-col { display: flex; flex-direction: column; }
.center { display: flex; align-items: center; justify-content: center; }
.gap-3 { gap: var(--space-3); }
.gap-4 { gap: var(--space-4); }
.gap-5 { gap: var(--space-5); }
.text-center { text-align: center; }
.text-muted { color: var(--color-text-2); }
.text-accent { color: var(--color-primary); }

.divider {
  width: 60px;
  height: 4px;
  background: var(--gradient-accent);
  border-radius: var(--radius-pill);
  margin: var(--space-3) 0;
}
.divider.center { margin-left: auto; margin-right: auto; }

/* Tag */
.tag {
  display: inline-block;
  padding: 4px 10px;
  border-radius: var(--radius-pill);
  background: var(--color-primary-soft);
  color: var(--color-primary);
  font-size: 12px;
  font-weight: 600;
  letter-spacing: 0.5px;
}
.tag--accent  { background: var(--color-accent-soft); color: #0E5C8C; }
.tag--ghost   { background: rgba(255,255,255,0.1); color: #FFFFFF; border: 1px solid rgba(255,255,255,0.25); }

/* back to top */
.back-to-top {
  position: fixed;
  right: 24px;
  bottom: 24px;
  width: 44px;
  height: 44px;
  border-radius: 50%;
  background: var(--color-primary);
  color: #FFFFFF;
  display: flex;
  align-items: center;
  justify-content: center;
  box-shadow: var(--shadow-hover);
  opacity: 0;
  pointer-events: none;
  transform: translateY(8px);
  transition: opacity var(--duration-base) var(--ease-out),
              transform var(--duration-base) var(--ease-out),
              background var(--duration-base) var(--ease-out);
  z-index: 90;
}
.back-to-top.is-visible { opacity: 1; pointer-events: auto; transform: translateY(0); }
.back-to-top:hover { background: #1656BA; }
.back-to-top svg { width: 18px; height: 18px; }