*, *::before, *::after {
  box-sizing: border-box;
}

/* The [hidden] attribute must always win over component display rules
   (e.g. .alert { display: flex }) — otherwise a "hidden" error/processing
   box still renders as an empty flex/grid box. */
[hidden] {
  display: none !important;
}

html {
  -webkit-text-size-adjust: 100%;
}

body {
  margin: 0;
  background: var(--color-background);
  color: var(--color-text);
  font-family: var(--font-family-base);
  font-size: 16px;
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
}

img, svg, canvas {
  max-width: 100%;
  display: block;
}

h1, h2, h3, h4 {
  line-height: 1.25;
  font-weight: 700;
  color: var(--color-text);
  margin: 0 0 var(--space-4);
}

h1 { font-size: clamp(1.9rem, 1.5rem + 1.6vw, 2.75rem); }
h2 { font-size: clamp(1.5rem, 1.3rem + 0.8vw, 2rem); }
h3 { font-size: 1.25rem; }
h4 { font-size: 1.05rem; }

p {
  margin: 0 0 var(--space-4);
  color: var(--color-text);
}

a {
  color: var(--color-primary);
  text-decoration-thickness: 1.5px;
  text-underline-offset: 2px;
}

a:hover {
  color: var(--color-primary-hover);
}

ul, ol {
  padding-left: 1.25em;
}

code, kbd {
  font-family: var(--font-family-mono);
  font-size: 0.9em;
}

hr {
  border: none;
  border-top: 1px solid var(--color-border);
  margin: var(--space-6) 0;
}

/* Visible, consistent focus ring everywhere; never remove focus outlines. */
:focus-visible {
  outline: 3px solid var(--color-focus-ring);
  outline-offset: 2px;
  border-radius: var(--radius-sm);
}

.visually-hidden {
  position: absolute;
  width: 1px;
  height: 1px;
  padding: 0;
  margin: -1px;
  overflow: hidden;
  clip: rect(0, 0, 0, 0);
  white-space: nowrap;
  border: 0;
}

.skip-link {
  position: absolute;
  left: var(--space-3);
  top: -100px;
  background: var(--color-surface);
  color: var(--color-text);
  padding: var(--space-3) var(--space-4);
  border-radius: var(--radius-sm);
  box-shadow: var(--shadow-md);
  z-index: 1000;
  transition: top var(--transition-fast);
}

.skip-link:focus {
  top: var(--space-3);
}

@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after {
    animation-duration: 0.01ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.01ms !important;
    scroll-behavior: auto !important;
  }
}