/* ============================================================
   CSS Semantico — la pagina è essa stessa una demo del libro:
   @layer per l'architettura, custom properties come token,
   nesting nativo, clamp() per tutto ciò che è fluido,
   griglie intrinseche, :has() e :user-invalid nel form.
   Zero media query dimensionali.
   ============================================================ */
@layer tokens, base, components;

@layer tokens {
  :root {
    /* Token di brand: tutte le varianti derivano da --brand con color-mix (cap. 5) */
    --brand: #E8564A;
    --brand-dark: color-mix(in oklch, var(--brand) 62%, black);
    --brand-deep: color-mix(in oklch, var(--brand) 82%, black);
    --brand-tint: color-mix(in oklch, var(--brand) 9%, white);
    --brand-tint-2: color-mix(in oklch, var(--brand) 16%, white);
    --bg: #FBF7F2;
    --ink: #221B19;
    --ink-soft: #5C514D;
    --code-bg: #241D1B;
    --code-ink: #F4E9E4;
    --radius: 14px;
    /* Scala tipografica fluida: niente breakpoint, solo clamp() (cap. 4) */
    --step-0: clamp(1rem, 0.95rem + 0.3vw, 1.125rem);
    --step-1: clamp(1.15rem, 1.05rem + 0.5vw, 1.4rem);
    --step-2: clamp(1.4rem, 1.2rem + 1vw, 1.9rem);
    --step-3: clamp(1.9rem, 1.5rem + 2vw, 2.8rem);
    --step-4: clamp(2.6rem, 1.8rem + 4.2vw, 4.6rem);
    --space: clamp(1rem, 0.8rem + 1vw, 1.75rem);
    --section-pad: clamp(3.5rem, 2.5rem + 5vw, 7rem);
    --measure: 62ch;
    font-family: "Sora", "Helvetica Neue", sans-serif;
  }
}

@layer base {
  * { box-sizing: border-box; margin: 0; }
  html { scroll-behavior: smooth; }
  @media (prefers-reduced-motion: reduce) {
    html { scroll-behavior: auto; }
    * { transition: none !important; animation: none !important; }
  }
  body { background: var(--bg); color: var(--ink); font-size: var(--step-0); line-height: 1.6; -webkit-font-smoothing: antialiased; }
  a { color: var(--brand-dark); text-underline-offset: 3px; }
  a:hover { color: var(--brand); }
  :focus-visible { outline: 3px solid var(--brand); outline-offset: 3px; border-radius: 4px; }
  code, pre { font-family: "JetBrains Mono", monospace; }
  .wrap { max-width: 68rem; margin-inline: auto; padding-inline: var(--space); }
}

@layer components {
  /* Il pattern-manifesto del libro: classi semantiche componibili,
     varianti col nesting nativo — esattamente il codice del cap. 2 */
  .button {
    --button-bg: var(--brand-tint-2);
    --button-ink: var(--brand-deep);
    display: inline-block;
    background: var(--button-bg);
    color: var(--button-ink);
    font: 600 var(--step-0) "Sora", sans-serif;
    padding: 0.85em 1.7em;
    border: 0;
    border-radius: 999px;
    text-decoration: none;
    cursor: pointer;
    transition: filter 0.15s, translate 0.15s;

    &.primary { --button-bg: var(--brand); --button-ink: white; }
    &.inverse { --button-bg: white; --button-ink: var(--brand-dark); }
    &:hover { filter: brightness(1.07); translate: 0 -1px; }
  }

  .hero {
    background: var(--brand);
    color: white;
    position: relative;
    overflow: clip;
    padding-block: var(--section-pad);

    /* Le graffe della copertina come motivo decorativo */
    & .brace {
      position: absolute;
      font: 700 clamp(14rem, 30vw, 30rem)/1 "JetBrains Mono", monospace;
      color: color-mix(in oklch, white 10%, transparent);
      user-select: none;
      pointer-events: none;
    }
    & .brace.open { top: -0.18em; left: -0.12em; }
    & .brace.close { bottom: -0.22em; right: -0.1em; }

    & .hero-grid {
      display: flex;
      flex-wrap: wrap; /* le colonne si impilano da sole: niente breakpoint */
      align-items: center;
      gap: clamp(2rem, 5vw, 5rem);
      position: relative;
    }
    & .hero-copy { flex: 1 1 24rem; }
    & .kicker {
      font: 700 0.8rem "JetBrains Mono", monospace;
      letter-spacing: 0.14em;
      text-transform: uppercase;
      opacity: 0.85;
    }
    & h1 { font-size: var(--step-4); font-weight: 800; line-height: 1.02; letter-spacing: -0.02em; margin-block: 0.35em 0.4em; }
    & .subtitle { font-size: var(--step-1); font-weight: 600; max-width: 26ch; text-wrap: balance; }
    & .hook { margin-block: 1.4em 2em; max-width: 46ch; opacity: 0.94; text-wrap: pretty; }
  }

  /* Mockup 3D dell'e-book: solo transform CSS, nessuna libreria */
  .book-scene { flex: 0 1 auto; perspective: 1400px; margin-inline: auto; }
  .book {
    position: relative;
    width: clamp(180px, 24vw, 260px);
    aspect-ratio: 2 / 3;
    transform-style: preserve-3d;
    transform: rotateY(-24deg) rotateX(4deg);

    /* Il dorso: un solo pseudo-elemento ruotato di 90° */
    &::before {
      content: "";
      position: absolute;
      inset: 0 auto 0 0;
      width: 34px;
      background: var(--brand-deep);
      transform: rotateY(-90deg) translateX(-17px);
      transform-origin: left;
      border-radius: 3px 0 0 3px;
    }
    /* L'ombra a terra */
    &::after {
      content: "";
      position: absolute;
      inset: auto -12% -7% -18%;
      height: 8%;
      background: color-mix(in oklch, black 32%, transparent);
      filter: blur(18px);
      transform: translateZ(-40px);
      border-radius: 50%;
    }
  }
  /* Copertina resa in CSS. Per usare la vera copertina (file cover.png, proporzione 2:3):
     sostituisci il contenuto di .cover con un semplice tag img */
  .cover {
    position: absolute;
    inset: 0;
    width: 100%;
    height: 100%;
    object-fit: cover;
    border-radius: 4px 10px 10px 4px;
    box-shadow: 0 30px 60px -20px color-mix(in oklch, black 45%, transparent), inset 4px 0 8px color-mix(in oklch, black 20%, transparent);
  }

  .section { padding-block: var(--section-pad); }
  .section-title { font-size: var(--step-3); font-weight: 800; letter-spacing: -0.02em; line-height: 1.1; text-wrap: balance; }
  .section-lead { color: var(--ink-soft); max-width: var(--measure); margin-top: 0.8em; text-wrap: pretty; }

  /* Confronto prima/dopo: griglia intrinseca, si impila da sola */
  .compare {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(min(100%, 22rem), 1fr));
    gap: var(--space);
    margin-top: clamp(2rem, 4vw, 3.5rem);
  }
  .code-panel {
    background: var(--code-bg);
    color: var(--code-ink);
    border-radius: var(--radius);
    overflow: hidden;

    & .code-head {
      display: flex;
      justify-content: space-between;
      gap: 1rem;
      padding: 0.7rem 1.2rem;
      font: 700 0.72rem "JetBrains Mono", monospace;
      letter-spacing: 0.1em;
      text-transform: uppercase;
      background: color-mix(in oklch, var(--code-bg) 80%, white);
    }
    & pre { padding: 1.2rem 1.4rem; overflow-x: auto; font-size: clamp(0.78rem, 0.7rem + 0.35vw, 0.95rem); line-height: 1.7; }
    & figcaption { padding: 0.9rem 1.4rem 1.1rem; font-size: 0.85rem; color: color-mix(in oklch, var(--code-ink) 70%, var(--code-bg)); border-top: 1px solid color-mix(in oklch, white 8%, transparent); }
  }
  /* Tema chiaro dei pannelli, pilotato da un data-attribute */
  [data-code-theme="crema"] .code-panel {
    --code-bg: #F4EBE2;
    --code-ink: #3A2E2A;
    box-shadow: inset 0 0 0 1px color-mix(in oklch, var(--ink) 12%, transparent);
  }
  /* Syntax highlighting fatto a mano, solo span + token */
  .tok-tag { color: #F2A29A; } .tok-attr { color: #EFC88B; } .tok-str { color: #A8D8A0; }
  .tok-com { color: color-mix(in oklch, var(--code-ink) 52%, var(--code-bg)); font-style: italic; }
  .tok-sel { color: #F2A29A; } .tok-prop { color: #9BC8EA; } .tok-val { color: #A8D8A0; } .tok-amp { color: #EFC88B; font-weight: 700; }
  [data-code-theme="crema"] :is(.tok-tag, .tok-sel) { color: #B33A2F; }
  [data-code-theme="crema"] :is(.tok-attr, .tok-amp) { color: #8A6117; }
  [data-code-theme="crema"] :is(.tok-str, .tok-val) { color: #2F6B3A; }
  [data-code-theme="crema"] .tok-prop { color: #1F5C8A; }

  /* Indice: numeri decorativi grandi nel rosso brand */
  .toc { display: grid; gap: clamp(2rem, 4vw, 3rem); margin-top: clamp(2rem, 4vw, 3.5rem); }
  .toc-part > h3 { font: 700 0.8rem "JetBrains Mono", monospace; letter-spacing: 0.14em; text-transform: uppercase; color: var(--brand-dark); margin-bottom: 1.2rem; }
  .chapter-list { list-style: none; padding: 0; display: grid; gap: 1.1rem; }
  .chapter {
    display: grid;
    grid-template-columns: auto 1fr;
    gap: 1.1rem;
    align-items: baseline;
    max-width: var(--measure);

    & .num { font: 800 var(--step-3)/1 "Sora", sans-serif; color: var(--brand); min-width: 1.4em; }
    & h4 { font-size: var(--step-1); font-weight: 700; }
    & h4 em { font-style: normal; font-weight: 400; font-size: 0.8em; color: var(--ink-soft); }
    & p { color: var(--ink-soft); margin-top: 0.25em; font-size: 0.95em; text-wrap: pretty; }
  }
  .chapter-row { list-style: none; padding: 0; display: flex; flex-wrap: wrap; gap: 0.6rem 1.8rem; max-width: 54rem; }
  .chapter-row li { font-weight: 600; white-space: nowrap; }
  .chapter-row .num { color: var(--brand); font-weight: 800; margin-right: 0.4em; }
  .toc-more { margin-top: 2.2rem; font-style: italic; color: var(--ink-soft); max-width: var(--measure); text-wrap: pretty; }

  /* Tre punti di forza: auto-fit, la griglia decide da sola le colonne */
  .points {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(min(100%, 15rem), 1fr));
    gap: var(--space);
    margin-top: clamp(2rem, 4vw, 3rem);
  }
  .point {
    background: white;
    border: 1px solid color-mix(in oklch, var(--ink) 10%, transparent);
    border-radius: var(--radius);
    padding: clamp(1.4rem, 3vw, 2rem);

    & .point-brace { font: 700 1.6rem/1 "JetBrains Mono", monospace; color: var(--brand); }
    & h3 { font-size: var(--step-1); margin-block: 0.6em 0.4em; }
    & p { color: var(--ink-soft); font-size: 0.95em; text-wrap: pretty; }
  }

  /* Form: tinta chiara derivata dal brand; validazione con :user-invalid e :has() */
  .signup {
    background: var(--brand-tint);
    border-radius: calc(var(--radius) * 1.6);
    padding: var(--section-pad) var(--space);
    text-align: center;

    & form {
      display: flex;
      flex-wrap: wrap;
      justify-content: center;
      gap: 0.8rem;
      max-width: 34rem;
      margin: 2.2rem auto 0;
    }
    & label { position: absolute; width: 1px; height: 1px; overflow: hidden; clip-path: inset(50%); }
    & input {
      flex: 1 1 16rem;
      font: 400 var(--step-0) "Sora", sans-serif;
      padding: 0.85em 1.3em;
      border: 2px solid color-mix(in oklch, var(--ink) 18%, transparent);
      border-radius: 999px;
      background: white;
      color: var(--ink);

      /* :user-invalid scatta solo dopo l'interazione: niente rosso al primo paint (cap. 6) */
      &:user-invalid { border-color: var(--brand-dark); background: color-mix(in oklch, var(--brand) 6%, white); }
    }
    & .invalid-hint { display: none; flex-basis: 100%; color: var(--brand-dark); font-weight: 600; font-size: 0.9em; }
    /* :has() sul form: il messaggio appare quando un campo è :user-invalid */
    & form:has(:user-invalid) .invalid-hint { display: block; }
    & .microcopy { margin-top: 1.2rem; font-size: 0.85em; color: var(--ink-soft); }
    & .thanks { margin-top: 2.2rem; font-weight: 700; color: var(--brand-dark); font-size: var(--step-1); }
  }

  footer.site {
    padding-block: clamp(2rem, 4vw, 3.5rem);
    color: var(--ink-soft);
    font-size: 0.9em;

    & .foot-row { display: flex; flex-wrap: wrap; gap: 0.5rem 2rem; justify-content: space-between; align-items: baseline; }
  }
}