/* HZF Portfolio v7.0 — foundation, global navigation and accessibility */
*, *::before, *::after { box-sizing: border-box; }
html { scroll-behavior: smooth; scroll-padding-top: calc(var(--nav-height) + 1.25rem); background: var(--color-canvas); }
body {
  margin: 0;
  min-width: 20rem;
  background: var(--color-canvas);
  color: var(--color-text-primary);
  font-family: var(--font-body);
  font-size: var(--text-body);
  line-height: 1.72;
  text-rendering: optimizeLegibility;
  -webkit-font-smoothing: antialiased;
}
img, video, svg, canvas { display: block; max-width: 100%; }
img, video { height: auto; }
button, input, select, textarea { font: inherit; }
a { color: inherit; text-decoration-thickness: .08em; text-underline-offset: .2em; }
p, h1, h2, h3, h4, h5, h6, figure, dl, dd { margin-top: 0; }
::selection { background: var(--color-accent); color: var(--color-on-inverse); }

.skip-link {
  position: fixed;
  z-index: 10000;
  inset: .75rem auto auto .75rem;
  transform: translateY(-180%);
  padding: .65rem .9rem;
  border-radius: .5rem;
  background: var(--color-inverse);
  color: var(--color-on-inverse);
  transition: transform var(--transition-fast);
}
.skip-link:focus { transform: translateY(0); }

:where(a, button, input, select, textarea, [tabindex]):focus-visible {
  outline: 2px solid var(--color-accent);
  outline-offset: 3px;
}

.site-header {
  position: sticky;
  top: 0;
  z-index: 900;
  min-height: var(--nav-height);
  border-bottom: 1px solid color-mix(in srgb, var(--color-border) 82%, transparent);
  background: color-mix(in srgb, var(--color-canvas) 90%, transparent);
  backdrop-filter: blur(16px);
  -webkit-backdrop-filter: blur(16px);
}
.site-nav {
  width: min(calc(100% - 2 * var(--page-gutter)), var(--content-max-width));
  min-height: var(--nav-height);
  margin-inline: auto;
  display: flex;
  align-items: center;
  gap: var(--space-8);
}
.brand {
  display: inline-flex;
  align-items: baseline;
  gap: .55rem;
  min-height: 2.75rem;
  font-weight: 600;
  text-decoration: none;
  letter-spacing: -.02em;
  white-space: nowrap;
}
.brand-mark { font-size: .75rem; font-weight: 500; letter-spacing: .04em; color: var(--color-text-secondary); }
.brand-name { font-size: 1.05rem; }
.nav-links { margin-left: auto; display: flex; align-items: center; gap: .25rem; }
.nav-links > a,
.lang-switch {
  min-height: 2.5rem;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  padding: .5rem .8rem;
  border: 1px solid transparent;
  border-radius: .5rem;
  background: transparent;
  color: var(--color-text-secondary);
  font-size: .875rem;
  font-weight: 500;
  text-decoration: none;
  transition: background var(--transition-fast), color var(--transition-fast), border-color var(--transition-fast);
}
.nav-links > a:hover,
.nav-links > a[aria-current="page"],
.nav-links > a.is-active,
.lang-switch:hover { color: var(--color-text-primary); background: var(--color-surface-soft); }
.nav-resume { border-color: var(--color-border) !important; }
.lang-switch { cursor: pointer; }
.lang-option[aria-current="true"], .lang-switch[aria-pressed="true"] .lang-option[data-lang-code="en"], .lang-switch:not([aria-pressed="true"]) .lang-option[data-lang-code="zh"] { color: var(--color-text-primary); font-weight: 700; }
.lang-separator { margin-inline: .25rem; color: var(--color-border-strong); }
.nav-toggle { display: none; width: 2.75rem; height: 2.75rem; margin-left: auto; border: var(--border-default); border-radius: var(--radius-control); background: var(--color-surface); cursor: pointer; }
.nav-toggle span { width: 1rem; height: 1px; background: currentColor; transition: transform var(--transition-fast); }

.shell,
.page-shell,
.case-page,
.site-footer > .shell,
.footer-grid {
  width: min(calc(100% - 2 * var(--page-gutter)), var(--content-max-width));
  margin-inline: auto;
}

.site-footer { border-top: var(--border-default); margin-top: var(--space-24); padding-block: var(--space-8); color: var(--color-text-secondary); }
.footer-grid { display: flex; justify-content: space-between; gap: var(--space-6); font-size: var(--text-meta); }

.text-link { color: var(--color-text-primary); text-decoration: none; border-bottom: 1px solid currentColor; }
.text-link:hover { color: var(--color-accent); }

[hidden] { display: none !important; }

@media (max-width: 800px) {
  :root { --nav-height: 4rem; }
  .site-nav { gap: var(--space-4); }
  .brand-name { display: none; }
  .nav-toggle { display: inline-flex; flex-direction: column; align-items: center; justify-content: center; gap: .32rem; }
  .nav-links {
    position: fixed;
    top: calc(var(--nav-height) + .5rem);
    left: var(--page-gutter);
    right: var(--page-gutter);
    display: grid;
    gap: .25rem;
    padding: .75rem;
    border: var(--border-default);
    border-radius: var(--radius-card);
    background: var(--color-surface);
    box-shadow: var(--shadow-float);
    opacity: 0;
    visibility: hidden;
    transform: translateY(-.5rem);
    transition: opacity var(--transition-fast), transform var(--transition-fast), visibility var(--transition-fast);
  }
  .nav-links[data-open="true"] { opacity: 1; visibility: visible; transform: translateY(0); }
  .nav-links > a, .lang-switch { width: 100%; min-height: 2.75rem; justify-content: flex-start; }
  .lang-switch { border-top: var(--border-default); border-radius: 0; margin-top: .25rem; padding-top: .75rem; }
  .footer-grid { flex-direction: column; }
}

@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  *, *::before, *::after { animation-duration: .01ms !important; animation-iteration-count: 1 !important; transition-duration: .01ms !important; }
}

@media print {
  .site-header, .toolbar, .section-nav, .scroll-cue, .page-bar { display: none !important; }
  body { background: #fff; color: #000; font-size: 10.5pt; }
  .page-shell { width: 100%; }
}