/* One public header for every page, including accounts and nested articles. */
.site-nav { position: relative; z-index: 2000; border-bottom: 1px solid var(--border-primary); }
.site-nav [hidden] { display: none !important; }
.footer-column[hidden] { display: none !important; }
.site-nav .admin-nav-link { color: var(--primary-500); }
.site-nav:not([data-session-state]) .account-nav-link { visibility: hidden; }
.site-nav .nav-content { gap: 24px; min-height: 70px; }
.site-nav .logo { flex-shrink: 0; white-space: nowrap; }
.site-nav .nav-menu { margin-left: auto; gap: clamp(14px, 1.7vw, 26px); }
.site-nav .nav-link { white-space: nowrap; font-weight: 600; }
.site-nav .logo-stickman { width: 32px; height: 32px; }
.site-nav .space-nav-link { color: var(--text-primary); }
.site-nav .account-nav-link { padding: 8px 13px; border: 1px solid var(--border-primary); border-radius: 10px; font-size: 14px; }
.site-nav .account-nav-link:hover, .site-nav .account-nav-link.is-signed-in { border-color: var(--primary-500); color: var(--primary-500); }
.site-nav .account-nav-link.active::after { display: none; }
.site-nav-learning-entry { display: flex; align-items: center; gap: 5px; }
.site-nav-caret { display: grid; place-items: center; width: 26px; height: 32px; border: 0; border-radius: 6px; color: var(--text-secondary); background: transparent; cursor: pointer; }
.site-nav-caret:hover { color: var(--primary-500); background: var(--bg-tertiary); }
.site-nav-chevron { display: inline-block; width: 6px; height: 6px; margin: -3px 3px 0; border: solid currentColor; border-width: 0 1.5px 1.5px 0; transform: rotate(45deg); transition: transform .18s ease; }
.site-nav .is-open .site-nav-chevron { transform: rotate(225deg); margin-top: 3px; }
.site-nav .dropdown-menu { display: block; min-width: 184px; }
.site-nav .nav-dropdown:not(.is-open) .dropdown-menu { opacity: 0; visibility: hidden; transform: translateY(8px); }
.site-nav .nav-dropdown.is-open .dropdown-menu { opacity: 1; visibility: visible; transform: none; }
.site-nav .dropdown-item[aria-current="page"] { color: var(--primary-500); background: var(--bg-tertiary); font-weight: 700; }
.site-nav .theme-toggle { flex-shrink: 0; }
.site-nav .site-nav-moon { display: block; }
.site-nav .site-nav-sun { display: none; }
[data-theme="dark"] .site-nav .site-nav-moon { display: none; }
[data-theme="dark"] .site-nav .site-nav-sun { display: block; }
.site-nav :is(a, button):focus-visible { outline: 2px solid var(--primary-500); outline-offset: 4px; }
.site-nav .site-nav-learning-menu { width: min(620px, calc(100vw - 32px)); padding: 22px; border: 1px solid var(--border-primary); border-radius: 12px; }
.site-nav-menu-intro { display: flex; align-items: baseline; gap: 12px; padding: 0 6px 16px; border-bottom: 1px solid var(--border-primary); color: var(--text-primary); }
.site-nav-menu-intro span { color: var(--text-secondary); font-size: 13px; }
.site-nav-menu-groups { display: grid; grid-template-columns: repeat(3, minmax(0, 1fr)); gap: 12px; padding-top: 16px; }
.site-nav-menu-group { min-width: 0; }
.site-nav-menu-label { display: block; padding: 0 12px 8px; color: var(--text-secondary); font-size: 12px; font-weight: 700; }
.site-nav .site-nav-menu-group .dropdown-item { padding: 10px 12px; border-radius: 6px; color: var(--text-primary); font-size: 14px; }
.site-nav .site-nav-menu-group .dropdown-item:hover { color: var(--primary-500); }

@media (min-width: 1281px) {
  .site-nav .nav-toggle { display: none; }
}
@media (max-width: 1280px) {
  .site-nav .nav-toggle { display: block; margin-left: auto; flex-shrink: 0; }
  .site-nav .nav-menu { position: fixed; top: 70px; right: 0; bottom: 0; left: 0; display: flex; flex-direction: column; align-items: stretch; gap: 8px; width: 100vw; max-width: 100vw; height: calc(100dvh - 70px); max-height: calc(100dvh - 70px); margin: 0; padding: 18px max(18px, min(7vw, 72px)) 34px; border-top: 1px solid var(--border-primary); background: var(--bg-secondary); box-shadow: 0 18px 40px rgba(15,23,42,.2); overflow-x: hidden; overflow-y: auto; overscroll-behavior: contain; transform: translateX(100%); visibility: hidden; transition: transform .2s ease, visibility .2s ease; z-index: 2100; }
  .site-nav .nav-menu.active { transform: none; visibility: visible; }
  .site-nav .nav-link { display: block; min-height: 48px; padding: 13px 10px; font-size: 16px; line-height: 1.35; }
  .site-nav .nav-link.active::after { display: none; }
  .site-nav .nav-dropdown { width: 100%; }
  .site-nav-learning-entry { min-height: 48px; justify-content: space-between; }
  .site-nav-learning-entry > a { flex: 1; }
  .site-nav .site-nav-learning-menu { width: 100%; padding: 12px; }
  .site-nav-menu-intro { display: none; }
  .site-nav-menu-groups { display: block; padding-top: 0; }
  .site-nav-menu-group + .site-nav-menu-group { margin-top: 14px; padding-top: 12px; border-top: 1px solid var(--border-primary); }
  .site-nav-menu-label { padding: 0 14px 4px; }
  .site-nav .dropdown-toggle { display: flex; width: 100%; align-items: center; justify-content: space-between; }
  .site-nav-caret { width: 48px; height: 48px; }
  .site-nav .dropdown-menu { position: static; display: none; width: 100%; padding: 6px; border-radius: 10px; box-shadow: none; background: var(--bg-tertiary); }
  .site-nav .nav-dropdown.is-open .dropdown-menu { display: block; }
  .site-nav .dropdown-item { display: block; min-height: 44px; padding: 12px 14px; line-height: 1.35; }
  .site-nav .account-nav-link { align-self: stretch; padding: 12px 15px; margin-top: 8px; text-align: center; }
  .site-nav .theme-toggle { align-self: flex-start; margin-top: 8px; }
  body.nav-menu-open { overflow: hidden; }
}
@media (prefers-reduced-motion: reduce) {
  .site-nav *, .site-nav *::before, .site-nav *::after { transition: none !important; }
}

/* The compact contact interaction is shared by every page. */
.wechat-modal { position: fixed; inset: 0; z-index: 5000; display: grid; place-items: center; padding: 20px; background: rgba(15,23,42,.58); backdrop-filter: blur(5px); }
.wechat-modal[hidden] { display: none; }
.wechat-modal-card { position: relative; width: min(100%, 420px); padding: 30px; border: 1px solid var(--border-primary); border-radius: 22px; color: var(--text-primary); background: var(--bg-secondary); box-shadow: 0 24px 80px rgba(15,23,42,.3); }
.wechat-modal-close { position: absolute; top: 12px; right: 12px; width: 38px; height: 38px; border: 0; border-radius: 50%; color: var(--text-secondary); background: transparent; font-size: 1.4rem; cursor: pointer; }
.wechat-modal-close:hover { color: var(--text-primary); background: var(--bg-tertiary); }
.wechat-modal-icon { display: grid; place-items: center; width: 52px; height: 52px; border-radius: 16px; color: #fff; background: linear-gradient(135deg, #10b981, #0ea5e9); font-size: 1.45rem; }
.wechat-modal-card h2 { margin-top: 18px; color: var(--text-primary); font-size: 1.45rem; }
.wechat-modal-card p { margin-top: 8px; color: var(--text-secondary); line-height: 1.7; }
.wechat-id-row { display: grid; grid-template-columns: auto minmax(0, 1fr) auto; gap: 12px; align-items: center; margin-top: 24px; padding: 12px 12px 12px 16px; border: 1px solid var(--border-primary); border-radius: 13px; background: var(--bg-tertiary); }
.wechat-id-label { color: var(--text-tertiary); font-size: .84rem; }
.wechat-id-value { min-width: 0; overflow-wrap: anywhere; color: var(--text-primary); font-weight: 800; letter-spacing: .02em; }
.wechat-copy-action { min-height: 40px; padding: 8px 13px; border: 1px solid var(--primary-500); border-radius: 9px; color: #fff; background: var(--primary-500); font: inherit; font-size: .86rem; font-weight: 700; cursor: pointer; }
.wechat-copy-action:hover, .wechat-copy-action.copied { background: var(--primary-600, #4f46e5); }
@media (max-width: 420px) { .wechat-modal-card { padding: 26px 20px 22px; }.wechat-id-row { grid-template-columns: 1fr auto; }.wechat-id-label { grid-column: 1 / -1; }.wechat-copy-action { grid-column: 2; grid-row: 2; } }