.surface-header {
  position: sticky;
  top: 0;
  z-index: 20;
  display: grid;
  grid-template-columns: 1fr auto 1fr;
  align-items: center;
  min-height: 62px;
  gap: 16px;
  padding: 10px 28px;
}

.surface-header-left,
.surface-header-actions {
  display: flex;
  align-items: center;
  gap: 8px;
}

.surface-header-left { grid-column: 1; }
.surface-header-actions { grid-column: 3; }
.surface-header-actions { justify-content: flex-end; }

.surface-brand {
  position: absolute;
  top: 50%;
  left: 50%;
  display: block;
  line-height: 0;
  transform: translate(-50%, -50%);
}

.surface-brand img {
  display: block;
  width: 118px;
  height: auto;
}

:root[data-theme="dark"] .surface-brand img { filter: invert(1); }

.icon-button {
  display: inline-grid;
  place-items: center;
  width: 38px;
  height: 38px;
  padding: 0;
  border: 1px solid var(--line-strong);
  border-radius: 2px;
  background: transparent;
  color: var(--ink);
}

.icon-button:hover { background: var(--row-hover); }
.icon-button svg { width: 18px; height: 18px; }

.nav-shell { position: relative; }
.surface-nav {
  position: absolute;
  top: calc(100% + 10px);
  left: 0;
  width: min(300px, calc(100vw - 32px));
  padding: 7px;
  border: 1px solid var(--line-strong);
  border-radius: 2px;
  background: var(--panel);
  box-shadow: var(--shadow, 0 24px 70px rgba(27, 27, 25, 0.14));
}

.surface-nav[hidden] { display: none; }
.surface-nav a {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 20px;
  padding: 10px 11px;
  border-left: 2px solid transparent;
  color: var(--ink);
  font-family: var(--label);
  font-size: 10px;
  font-weight: 600;
  letter-spacing: 0.14em;
  text-decoration: none;
  text-transform: uppercase;
}

.surface-nav a:hover,
.surface-nav a[aria-current="page"] {
  border-left-color: var(--signal);
  background: var(--row-hover);
  color: var(--ink-strong);
}

.surface-nav a span:last-child {
  color: var(--muted);
  font-family: var(--mono);
  font-size: 9px;
  letter-spacing: 0;
}

.surface-search {
  display: flex;
  align-items: center;
  width: 38px;
  height: 38px;
  padding: 0;
  gap: 0;
  overflow: hidden;
  border: 1px solid var(--line-strong);
  border-radius: 2px;
  background: var(--paper);
  transition: width 180ms ease;
}

.surface-search[data-expanded="true"],
.surface-search:focus-within {
  width: min(360px, calc(100vw - 190px));
}

.surface-search .search-toggle {
  flex: 0 0 36px;
  width: 36px;
  height: 36px;
  border: 0;
}

.surface-search input {
  min-width: 0;
  width: 100%;
  padding: 8px 12px 8px 2px;
  border: 0;
  outline: 0;
  background: transparent;
  opacity: 0;
  font-size: 14px;
  transition: opacity 120ms ease;
}

.surface-search[data-expanded="true"] input,
.surface-search:focus-within input { opacity: 1; }

.theme-icon-sun { display: none; }
:root[data-theme="dark"] .theme-icon-sun { display: block; }
:root[data-theme="dark"] .theme-icon-moon { display: none; }

@media (max-width: 620px) {
  .surface-header { min-height: 58px; padding: 9px 16px; }
  .surface-brand img { width: 104px; }
  .surface-search[data-expanded="true"],
  .surface-search:focus-within {
    position: absolute;
    right: 62px;
    width: calc(100vw - 132px);
    z-index: 2;
  }
}

@media (prefers-reduced-motion: reduce) {
  .surface-search,
  .surface-search input { transition: none; }
}