/* ==========================================================================
   BASE.CSS — reset e stili generali
   ========================================================================== */

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

html {
  scroll-behavior: smooth;
  scroll-padding-top: calc(var(--header-h) + 1rem);
  -webkit-text-size-adjust: 100%;
  color-scheme: light;
}
:root[data-theme="dark"] { color-scheme: dark; }

body {
  margin: 0;
  font-family: var(--font-sans);
  font-size: var(--fs-base);
  line-height: 1.65;
  color: var(--text);
  background-color: var(--bg);
  /* Griglia di sfondo, stile "carta millimetrata" */
  background-image:
    linear-gradient(var(--bg-grid) 1px, transparent 1px),
    linear-gradient(90deg, var(--bg-grid) 1px, transparent 1px);
  background-size: 40px 40px;
  -webkit-font-smoothing: antialiased;
  transition: background-color var(--transition), color var(--transition);
}

h1, h2, h3, h4 { line-height: 1.2; margin: 0; font-weight: 650; letter-spacing: -0.01em; }
p { margin: 0 0 var(--space-4); }
ul, ol { margin: 0; padding: 0; list-style: none; }
img { max-width: 100%; display: block; }
a { color: var(--accent); text-decoration: none; }
a:hover { text-decoration: underline; text-underline-offset: 3px; }
button { font: inherit; color: inherit; cursor: pointer; }
code, kbd, .mono { font-family: var(--font-mono); }

kbd {
  font-size: 0.72rem;
  padding: 0.1rem 0.4rem;
  border: 1px solid var(--border-strong);
  border-bottom-width: 2px;
  border-radius: 4px;
  background: var(--surface-2);
  color: var(--text-muted);
}

::selection { background: var(--accent); color: var(--accent-contrast); }

:focus-visible {
  outline: 2px solid var(--accent);
  outline-offset: 3px;
  border-radius: 4px;
}

.skip-link {
  position: absolute;
  left: -999px;
  top: 0;
  background: var(--accent);
  color: var(--accent-contrast);
  padding: var(--space-2) var(--space-4);
  z-index: 200;
}
.skip-link:focus { left: var(--space-4); }

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

/* Comparsa allo scroll (gestita da ui.js). Senza JS il contenuto resta visibile. */
.js .reveal { opacity: 0; transform: translateY(14px); transition: opacity 550ms ease, transform 550ms ease; }
.js .reveal.is-visible { opacity: 1; transform: none; }

@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  .js .reveal { opacity: 1; transform: none; transition: none; }
  *, *::before, *::after { animation: none !important; }
}