:root { --control-height: 2.75rem; --text-ui: .9375rem; --text-small: .875rem; --radius: 100px; }

  .header {
    position: sticky;
    top: 0;
    z-index: 1000;
    padding-top: env(safe-area-inset-top, 0px);
    background: var(--bg);
    border-bottom: 1px solid var(--border);
  }
  .header-container {
    display: flex;
    align-items: center;
    justify-content: space-between;
    flex-wrap: wrap;
    gap: var(--space-sm) var(--space-md);
    min-height: var(--header-height);
    padding-block: var(--space-sm);
    padding-inline-start: max(var(--page-gutter), env(safe-area-inset-left, 0px));
    padding-inline-end: max(var(--page-gutter), env(safe-area-inset-right, 0px));
  }
  .header-brand {
    display: inline-flex;
    align-items: center;
    min-width: 0;
    gap: var(--space-sm);
    color: var(--fg);
    font: 800 1rem/1.2 var(--display);
    letter-spacing: -.025em;
    text-decoration: none;
  }
  .header-brand > span:last-child { overflow-wrap: anywhere; }
  .brand-logo { display: block; flex: 0 0 2rem; width: 2rem; height: 2rem; }
  .mobile-menu-btn {
    display: inline-grid;
    place-items: center;
    flex: 0 0 var(--control-height);
    width: var(--control-height);
    height: var(--control-height);
    padding: 0;
    border: 0;
    border-radius: var(--radius-sm);
    background: transparent;
    color: var(--fg);
    cursor: pointer;
  }
  .close-icon { display: none; }
  .mobile-menu-btn[aria-expanded="true"] .close-icon { display: block; }
  .mobile-menu-btn[aria-expanded="true"] .menu-icon { display: none; }
  .header-nav { display: none; flex-basis: 100%; min-width: 0; }
  .header.is-menu-open .header-nav {
    display: grid;
    gap: var(--space-sm);
    padding-top: var(--space-md);
    padding-bottom: var(--space-md);
    border-top: 1px solid var(--border);
    max-height: calc(100dvh - var(--header-height) - env(safe-area-inset-top, 0px));
    overflow-y: auto;
    overscroll-behavior: contain;
  }
  .nav-link, .nav-app, summary {
    display: flex;
    align-items: center;
    min-height: var(--control-height);
    padding: .625rem var(--space-md);
    border-radius: var(--radius-sm);
    font-size: var(--text-ui);
    font-weight: 500;
    line-height: 1.4;
    text-decoration: none;
  }
  .nav-link { color: var(--fg); }
  .nav-app { justify-content: center; background: var(--fg); color: var(--bg); border-radius: var(--radius); font-weight: 700; }
  .desktop-label { display: none; }
  .language-picker { position: relative; min-width: 0; }
  summary { justify-content: space-between; gap: var(--space-sm); color: var(--fg-muted); list-style: none; cursor: pointer; }
  summary::-webkit-details-marker { display: none; }
  summary svg { flex-shrink: 0; }
  .language-picker[open] summary { color: var(--fg); }
  .language-picker[open] summary svg { transform: rotate(180deg); }
  .language-options { display: grid; grid-template-columns: repeat(2, minmax(0, 1fr)); gap: var(--space-sm); padding-top: var(--space-sm); }
  .language-options a {
    display: flex;
    align-items: center;
    min-height: var(--control-height);
    min-width: 0;
    padding: .625rem .875rem;
    border-radius: var(--radius-sm);
    color: var(--fg-muted);
    font-size: var(--text-small);
    line-height: 1.4;
    text-decoration: none;
    overflow-wrap: anywhere;
  }
  .language-options a[aria-current] { color: var(--fg); background: var(--surface); }
  @media (hover: hover) {
    .nav-link:hover, summary:hover, .mobile-menu-btn:hover, .language-options a:hover { color: var(--fg); background: var(--surface); }
    .header-brand:hover, .nav-app:hover { opacity: .85; }
  }
  @media (min-width: 60rem) {
    .header-container { flex-wrap: nowrap; padding-inline: max(var(--space-2xl), env(safe-area-inset-left, 0px)); }
    .header-brand { font-size: 1.45rem; gap: .7rem; white-space: nowrap; }
    .brand-logo { flex-basis: 2.375rem; width: 2.375rem; height: 2.375rem; }
    .mobile-menu-btn, .mobile-label { display: none; }
    .desktop-label { display: inline; }
    .header .header-nav { display: flex; align-items: center; flex-basis: auto; gap: var(--space-sm); max-height: none; overflow: visible; padding: 0; border: 0; }
    .nav-link { padding-inline: .5rem; }
    .nav-app { padding-inline: 1.25rem; }
    summary { padding-inline: .75rem; }
    .language-options {
      position: absolute;
      inset-inline-end: 0;
      top: calc(100% + var(--space-sm));
      z-index: 1;
      grid-template-columns: 1fr;
      min-width: 11rem;
      max-height: min(65dvh, 32rem);
      overflow-y: auto;
      overscroll-behavior: contain;
      padding: var(--space-sm);
      border: 1px solid var(--border);
      border-radius: var(--radius-sm);
      background: var(--bg);
      box-shadow: 0 12px 32px #0004;
    }
  }

.brand-logo { color: var(--blue); }
.brand-logo svg { display: block; width: 100%; height: 100%; }