/* =========================================================
   Piston — foglio di stile
   Palette: alluminio, ghisa, inchiostro tecnico blu,
   giallo dei segni di serraggio, rosso solo per il limitatore.
   ========================================================= */

:root {
  --alluminio: #E4E8EA;
  --carta: #F5F7F8;
  --ghisa: #22282C;
  --grafite: #58626A;
  --linea: #C3CBD0;
  --blu: #1D3557;
  --blu-tenue: #D3DCE6;
  --giallo: #E3A008;
  --giallo-tenue: #F6DE9C;
  --rosso: #B3261E;
  --su-blu: #EEF2F6;
  --targa: #1D3557;

  --testo: "Archivo", "Helvetica Neue", Arial, sans-serif;
  --serif: "Source Serif 4", Georgia, serif;
  --misura: 72rem;
  --raggio: 3px;
}

@media (prefers-color-scheme: dark) {
  :root:not([data-theme="light"]) {
    --alluminio: #161A1D;
    --carta: #1F2529;
    --ghisa: #E5E9EB;
    --grafite: #A3ADB4;
    --linea: #343C42;
    --blu: #9DBCE0;
    --blu-tenue: #263445;
    --giallo: #F0B429;
    --giallo-tenue: #4A3A12;
    --rosso: #F2685F;
    --su-blu: #0F1A27;
    --targa: #1C2C42;
  }
}
:root[data-theme="dark"] {
  --alluminio: #161A1D; --carta: #1F2529; --ghisa: #E5E9EB; --grafite: #A3ADB4;
  --linea: #343C42; --blu: #9DBCE0; --blu-tenue: #263445; --giallo: #F0B429;
  --giallo-tenue: #4A3A12; --rosso: #F2685F; --su-blu: #0F1A27; --targa: #1C2C42;
}

*, *::before, *::after { box-sizing: border-box; }
html { -webkit-text-size-adjust: 100%; }
body {
  margin: 0;
  background: var(--alluminio);
  color: var(--ghisa);
  font-family: var(--testo);
  font-size: 1.0625rem;
  line-height: 1.5;
  font-variant-numeric: tabular-nums;
}
a { color: var(--blu); text-decoration-thickness: 1px; text-underline-offset: 3px; }
a:hover { text-decoration-color: var(--giallo); text-decoration-thickness: 2px; }
:focus-visible { outline: 3px solid var(--giallo); outline-offset: 2px; }
img, svg { max-width: 100%; }
h1, h2, h3 { font-family: var(--testo); line-height: 1.1; margin: 0; }
h1 { font-stretch: 125%; font-weight: 800; letter-spacing: -0.01em; font-size: clamp(2.1rem, 5.4vw, 4rem); }
h2 { font-stretch: 112%; font-weight: 700; font-size: 1.35rem; }
h3 { font-size: 1rem; font-weight: 600; }

.riga { max-width: var(--misura); margin: 0 auto; padding: 0 16px; }
@media (min-width: 720px) { .riga { padding: 0 32px; } }
.stretta { max-width: 46rem; }

.salta { position: absolute; left: -999px; top: 8px; background: var(--giallo); color: #000; padding: .5rem 1rem; z-index: 10; }
.salta:focus { left: 8px; }

/* ---------- Testata ---------- */
.testata { border-bottom: 1px solid var(--linea); background: var(--carta); }
.testata .riga { display: flex; flex-wrap: wrap; align-items: center; justify-content: space-between; gap: .5rem 2rem; padding-top: .9rem; padding-bottom: .9rem; }
.marchio { display: inline-flex; align-items: center; gap: .55rem; text-decoration: none; color: var(--ghisa); font-stretch: 125%; font-weight: 800; font-size: 1.35rem; }
.marchio-icona { width: 26px; height: 26px; fill: none; stroke: var(--blu); stroke-width: 2; }
.marchio-icona .pistone { fill: var(--blu); }
.menu { display: flex; flex-wrap: wrap; gap: .25rem 1.25rem; }
.menu a { color: var(--grafite); text-decoration: none; font-weight: 500; padding: .25rem 0; border-bottom: 2px solid transparent; }
.menu a:hover { color: var(--ghisa); }
.menu a[aria-current="page"] { color: var(--ghisa); border-bottom-color: var(--giallo); }

/* ---------- Apertura ---------- */
.apertura { padding: clamp(2.5rem, 7vw, 5rem) 0 2rem; }
.apertura h1 { max-width: 14ch; }
.sottotitolo { color: var(--grafite); font-size: 1.15rem; max-width: 60ch; margin: 1rem 0 0; }

/* ---------- Filtri ---------- */
.filtri { display: grid; grid-template-columns: repeat(auto-fill, minmax(10.5rem, 1fr)); gap: .75rem 1rem; align-items: end; padding: 1.25rem; background: var(--carta); border: 1px solid var(--linea); border-radius: var(--raggio); }
.filtri label { display: flex; flex-direction: column; gap: .3rem; font-size: .875rem; color: var(--grafite); font-weight: 500; }
.filtri .cerca { grid-column: 1 / -1; }
.filtri .spunta { flex-direction: row; align-items: center; gap: .5rem; color: var(--ghisa); padding-bottom: .6rem; }
.filtri input[type="search"], .filtri select, .scelte select {
  font: inherit; color: var(--ghisa); background: var(--alluminio);
  border: 1px solid var(--linea); border-radius: var(--raggio); padding: .55rem .6rem; width: 100%;
}
.filtri input[type="search"] { font-size: 1.15rem; padding: .7rem .8rem; }
.filtri input[type="checkbox"] { width: 1.1rem; height: 1.1rem; accent-color: var(--blu); }
@media (max-width: 560px) { .filtri { grid-template-columns: 1fr 1fr; padding: 1rem; } .filtri .spunta { grid-column: 1 / -1; } }
.conteggio { color: var(--grafite); margin: 1.5rem 0 .5rem; font-size: .95rem; }

/* ---------- Elenco motori ---------- */
.elenco { margin-bottom: 4rem; }
.elenco-testa, .voce a {
  display: grid;
  grid-template-columns: 64px minmax(0, 1fr) 7.5rem 11rem 6.5rem 4.5rem;
  gap: 1rem; align-items: center;
}
.elenco-testa { padding: .5rem .75rem; border-bottom: 2px solid var(--ghisa); font-size: .85rem; color: var(--grafite); }
.elenco-testa button { font: inherit; font-weight: 600; color: var(--grafite); background: none; border: 0; padding: 0; cursor: pointer; text-align: left; }
.elenco-testa button.num { text-align: right; }
.elenco-testa button[aria-pressed="true"] { color: var(--ghisa); }
.elenco-testa button[data-verso="su"]::after { content: " \2191"; }
.elenco-testa button[data-verso="giu"]::after { content: " \2193"; }
.elenco-righe { list-style: none; margin: 0; padding: 0; }
.voce { border-bottom: 1px solid var(--linea); }
.voce a { padding: .45rem .75rem; text-decoration: none; color: var(--ghisa); border-left: 3px solid transparent; }
.voce a:hover, .voce a:focus-visible { background: var(--carta); border-left-color: var(--giallo); }
.voce-disegno .cilindro { width: 64px; height: 57px; display: block; }
.voce-disegno .cilindro text { display: none; }
.voce-nome { display: flex; flex-direction: column; min-width: 0; }
.voce-nome strong { font-weight: 600; font-size: 1.05rem; }
.voce-nome span { color: var(--grafite); font-size: .875rem; overflow: hidden; text-overflow: ellipsis; white-space: nowrap; }
.voce-anni em { font-style: normal; color: var(--blu); font-weight: 600; }
.voce-arch { color: var(--grafite); font-size: .925rem; }
.num { text-align: right; }
.voce-cv { font-stretch: 112%; font-weight: 700; font-size: 1.1rem; }
.vuoto { padding: 2rem 0; color: var(--grafite); }
@media (max-width: 760px) {
  .elenco-testa, .voce a { grid-template-columns: 52px minmax(0, 1fr) 4rem; gap: .25rem .75rem; }
  .nasconde-piccolo, .elenco-testa button[data-ordina="cc"], .voce a > .num:not(.voce-cv) { display: none; }
  .voce-anni { grid-column: 2; grid-row: 2; font-size: .85rem; color: var(--grafite); }
  .voce-cv { grid-column: 3; grid-row: 1 / span 2; }
  .voce-disegno { grid-row: 1 / span 2; }
  .elenco-testa button[data-ordina="inizio"] { display: none; }
}

/* ---------- Disegno del cilindro ---------- */
.cilindro { overflow: visible; }
.cilindro .volume { fill: var(--giallo-tenue); stroke: none; }
.cilindro .camicia { fill: none; stroke: var(--blu); stroke-width: 2.5; }
.cilindro path.camicia { stroke-width: 2.5; }
.cilindro .pistone { fill: var(--blu); }
.cilindro .asse { fill: var(--blu); }
.cilindro .quota { stroke: var(--grafite); stroke-width: 1; }
.cilindro text { font-family: var(--testo); font-size: 9px; fill: var(--grafite); font-variant-numeric: tabular-nums; }

/* ---------- Scheda motore ---------- */
.targhetta { background: var(--targa); color: #EEF2F6; }
.targhetta { display: grid; gap: 1.5rem 3rem; grid-template-columns: minmax(0, 1fr); padding: clamp(2rem, 5vw, 3.5rem) max(16px, calc((100vw - var(--misura)) / 2 + 32px)); }
@media (min-width: 900px) { .targhetta { grid-template-columns: minmax(0, 1fr) auto; align-items: end; } }
.targhetta a { color: #EEF2F6; }
.percorso { margin: 0 0 .75rem; font-size: .95rem; opacity: .85; }
.targhetta h1 { color: #fff; }
.codice { margin: .9rem 0 0; font-size: 1.05rem; }
.stato { display: inline-block; margin-left: .4rem; padding: .05rem .5rem; border-radius: var(--raggio); background: var(--giallo); color: #1A1A1A; font-weight: 600; font-size: .85rem; }
.cifre { display: flex; flex-wrap: wrap; gap: 1.5rem 2.25rem; margin: 0; }
.cifre div { border-top: 3px solid var(--giallo); padding-top: .5rem; }
.cifre dt { font-size: .85rem; opacity: .85; }
.cifre dd { margin: 0; font-stretch: 125%; font-weight: 700; font-size: clamp(1.6rem, 3.5vw, 2.25rem); line-height: 1.1; }
.cifre small { font-size: .5em; font-weight: 500; font-stretch: 100%; }

.motore-corpo { max-width: var(--misura); margin: 0 auto; padding: 2.5rem 16px 4rem; display: grid; gap: 2.5rem; grid-template-columns: minmax(0, 1fr); }
@media (min-width: 720px) { .motore-corpo { padding-left: 32px; padding-right: 32px; } }
@media (min-width: 960px) { .motore-corpo { grid-template-columns: 17rem minmax(0, 1fr); gap: 3.5rem; } .tavola { position: sticky; top: 1.5rem; align-self: start; } }
.tavola figure + figure { margin-top: 1rem; }
.tavola figure { max-width: 22rem; margin: 0; background: var(--carta); border: 1px solid var(--linea); border-radius: var(--raggio); padding: 1.25rem 1rem 1rem; }
.tavola .cilindro { width: 100%; height: auto; display: block; }
.tavola figcaption { font-size: .875rem; color: var(--grafite); margin-top: .75rem; }
.contagiri { margin-top: 1.25rem; }
.contagiri-scala { position: relative; height: 10px; border-radius: 5px; background: linear-gradient(90deg, var(--linea) 0 75%, color-mix(in srgb, var(--rosso) 35%, var(--linea)) 75% 100%); overflow: hidden; }
.contagiri-ago { position: absolute; inset: 0 auto 0 0; background: var(--blu); border-right: 3px solid var(--rosso); }
.contagiri p { margin: .5rem 0 0; font-size: .9rem; }
.contagiri p strong { font-stretch: 112%; font-size: 1.15rem; color: var(--rosso); }
.contagiri p span { display: block; color: var(--grafite); font-size: .8rem; }

.schede > section, .doppia > section { margin-bottom: 2.5rem; }
.schede h2 { padding-bottom: .5rem; margin-bottom: 1rem; border-bottom: 1px solid var(--linea); }
.specifiche, .versioni { width: 100%; border-collapse: collapse; }
.specifiche th { text-align: left; font-weight: 500; color: var(--grafite); width: 40%; padding: .5rem 1rem .5rem 0; vertical-align: top; }
.specifiche td { padding: .5rem 0; }
.specifiche tr + tr th, .specifiche tr + tr td { border-top: 1px solid var(--linea); }
.tabella-scorre { overflow-x: auto; }
.versioni { min-width: 34rem; font-size: .95rem; }
.versioni th { text-align: left; font-size: .85rem; color: var(--grafite); font-weight: 600; padding: .4rem .75rem .4rem 0; border-bottom: 2px solid var(--ghisa); }
.versioni td { padding: .6rem .75rem .6rem 0; border-bottom: 1px solid var(--linea); vertical-align: top; }
.versioni th.num, .versioni td.num { text-align: right; }
.versioni td.num { font-weight: 700; font-stretch: 112%; }
.versioni .nota { color: var(--grafite); font-size: .9rem; }
.anni { color: var(--grafite); white-space: nowrap; }
.modelli, .altri { list-style: none; padding: 0; margin: 0; }
.modelli li, .altri li { display: flex; justify-content: space-between; gap: 1rem; padding: .5rem 0; border-bottom: 1px solid var(--linea); }
.storia p, .doppia p, .curiosita, .testo-lungo { font-family: var(--serif); font-size: 1.125rem; line-height: 1.65; max-width: 66ch; }
.doppia { display: grid; gap: 0 2.5rem; }
@media (min-width: 760px) { .doppia { grid-template-columns: 1fr 1fr; } }
.doppia ul { padding-left: 1.1rem; margin: 0; }
.doppia li { margin-bottom: .5rem; }
.avviso h2 { border-bottom-color: var(--giallo); border-bottom-width: 2px; }
.curiosita { padding-left: 1.1rem; }
.curiosita li { margin-bottom: .5rem; }
.bottone { display: inline-block; padding: .7rem 1.1rem; border: 2px solid var(--blu); border-radius: var(--raggio); text-decoration: none; font-weight: 600; }
.bottone:hover { background: var(--blu); color: var(--alluminio); }

/* ---------- Pagine di raggruppamento ---------- */
.pagina { padding-top: clamp(2rem, 5vw, 3.5rem); padding-bottom: 4rem; }
.pagina > h1 + .sottotitolo { margin-bottom: 2rem; }
.indice-lettere { display: flex; flex-wrap: wrap; gap: .4rem .9rem; margin-bottom: 2.5rem; padding-bottom: 1.25rem; border-bottom: 1px solid var(--linea); }
.gruppo { margin-bottom: 3rem; scroll-margin-top: 1rem; }
.gruppo h2 { display: flex; align-items: baseline; gap: .6rem; font-size: 1.6rem; font-stretch: 125%; }
.quanti { font-size: .9rem; font-stretch: 100%; font-weight: 500; color: var(--grafite); }
.nota-paese, .spiegazione { color: var(--grafite); margin: .35rem 0 1rem; max-width: 66ch; }
.schedine { list-style: none; padding: 0; margin: 0; display: grid; grid-template-columns: repeat(auto-fill, minmax(14rem, 1fr)); gap: 1px; background: var(--linea); border: 1px solid var(--linea); }
.schedine a { display: grid; grid-template-columns: 60px minmax(0, 1fr); grid-template-rows: auto 1fr; column-gap: .75rem; padding: .85rem; height: 100%; background: var(--carta); text-decoration: none; color: var(--ghisa); }
.schedine a:hover { background: var(--alluminio); }
.schedine .cilindro { grid-row: 1 / span 2; width: 60px; height: 53px; }
.schedine .cilindro text { display: none; }
.schedine strong { font-weight: 600; line-height: 1.25; }
.schedine span { color: var(--grafite); font-size: .875rem; }

/* ---------- Cronologia ---------- */
.cronologia { list-style: none; padding: 0; margin: 0; }
.cronologia .anno { display: grid; grid-template-columns: 5rem minmax(0, 1fr); gap: 1rem; padding: .75rem 0; border-top: 1px solid var(--linea); }
.cronologia h2 { font-stretch: 125%; font-size: 1.4rem; color: var(--blu); }
.cronologia ul, .scala-anni { list-style: none; padding: 0; margin: 0; }
.cronologia ul li, .scala-anni { display: grid; grid-template-columns: minmax(0, 15rem) minmax(0, 1fr) 11rem; gap: 1rem; align-items: center; padding: .3rem 0; }
.scala-anni { margin-left: 6rem; font-size: .8rem; color: var(--grafite); }
.scala-anni .traccia { position: relative; height: 1.2rem; }
.scala-anni i { position: absolute; font-style: normal; }
.durata { display: block; height: 8px; background: var(--carta); border-radius: 4px; }
.durata span { display: block; height: 100%; background: var(--blu); border-radius: 4px; }
.durata span.aperta { background: linear-gradient(90deg, var(--blu) 70%, var(--giallo)); }
.periodo { color: var(--grafite); font-size: .875rem; }
@media (max-width: 760px) {
  .cronologia .anno { grid-template-columns: 1fr; gap: .25rem; }
  .cronologia ul li { grid-template-columns: 1fr; gap: .2rem; padding: .5rem 0; }
  .scala-anni { display: none; }
}

/* ---------- Confronto ---------- */
.scelte { display: grid; grid-template-columns: repeat(auto-fill, minmax(14rem, 1fr)); gap: 1rem; margin-bottom: 2rem; }
.scelte label { display: flex; flex-direction: column; gap: .3rem; font-size: .875rem; color: var(--grafite); font-weight: 500; }
.confronto-teste, .confronto-riga { display: grid; grid-template-columns: 11rem repeat(var(--colonne), minmax(0, 1fr)); gap: 1.25rem; align-items: center; }
.confronto-teste { grid-template-columns: repeat(var(--colonne), minmax(0, 1fr)); margin-left: 12.25rem; margin-bottom: 1rem; align-items: end; }
.confronto-teste div { display: flex; flex-direction: column; gap: .2rem; }
.confronto-teste span { color: var(--grafite); font-size: .9rem; }
.confronto-teste .cilindro { width: 100%; max-width: 170px; height: auto; margin-top: .5rem; }
.confronto-riga { padding: .7rem 0; border-top: 1px solid var(--linea); }
.confronto-riga h3 { font-weight: 500; color: var(--grafite); font-size: .95rem; }
.confronto-riga.testo p { margin: 0; font-size: .95rem; }
.barra { position: relative; }
.barra span { display: block; height: 6px; background: var(--blu-tenue); border-radius: 3px; margin-bottom: .35rem; }
.barra.prima span { background: var(--blu); }
.barra b { font-stretch: 112%; font-size: 1.1rem; }
.barra small { font-weight: 500; font-stretch: 100%; color: var(--grafite); font-size: .8rem; }
@media (max-width: 760px) {
  .confronto-teste { margin-left: 0; }
  .confronto-riga { grid-template-columns: repeat(var(--colonne), minmax(0, 1fr)); }
  .confronto-riga h3 { grid-column: 1 / -1; }
}

/* ---------- Glossario e testi ---------- */
.glossario div { padding: 1rem 0; border-top: 1px solid var(--linea); }
.glossario dt { font-weight: 700; font-stretch: 112%; font-size: 1.1rem; }
.glossario dd { margin: .35rem 0 0; font-family: var(--serif); font-size: 1.1rem; line-height: 1.6; }
.testo-lungo h1 { margin-bottom: 1.5rem; }
.testo-lungo h2 { margin: 2rem 0 .5rem; }
.testo-lungo code { font-size: .9em; background: var(--carta); padding: .1rem .3rem; border-radius: var(--raggio); }

/* ---------- Piede ---------- */
.piede { border-top: 1px solid var(--linea); background: var(--carta); padding: 2rem 0; color: var(--grafite); font-size: .925rem; }
.piede p { max-width: 70ch; margin: 0 0 .5rem; }

@media (prefers-reduced-motion: reduce) { * { transition: none !important; scroll-behavior: auto !important; } }

/* ---------- Dati in rilievo ---------- */
.rilievo { background: var(--carta); border-bottom: 1px solid var(--linea); }
.rilievo ul { list-style: none; margin: 0 auto; max-width: var(--misura); padding: 1.5rem 16px; display: grid; gap: 1.25rem 2.5rem; grid-template-columns: repeat(auto-fit, minmax(14rem, 1fr)); }
@media (min-width: 720px) { .rilievo ul { padding: 1.75rem 32px; } }
.rilievo li { display: flex; flex-direction: column; gap: .3rem; padding-left: 1rem; border-left: 4px solid var(--giallo); }
.rilievo strong { font-stretch: 125%; font-weight: 800; font-size: clamp(1.5rem, 3vw, 2rem); line-height: 1.05; color: var(--blu); }
.rilievo span { color: var(--ghisa); font-size: .975rem; line-height: 1.4; max-width: 34ch; }

/* ---------- Schema disposizione cilindri ---------- */
.schema { width: 100%; height: auto; display: block; }
.schema .canna { fill: var(--alluminio); stroke: var(--blu); stroke-width: 2.5; }
.schema .pistone { fill: var(--blu); }
.schema .biella { stroke: var(--grafite); stroke-width: 3; stroke-linecap: round; }
.schema .albero { fill: var(--giallo-tenue); stroke: var(--blu); stroke-width: 2.5; }
.schema .perno { fill: var(--blu); }
.schema .angolo { font-family: var(--testo); font-size: 13px; font-weight: 700; fill: var(--rosso); }
.schema .pianta circle { fill: var(--giallo-tenue); stroke: var(--blu); stroke-width: 1.5; }
@media (max-width: 959px) {
  .tavola { display: grid; grid-template-columns: 1fr 1fr; gap: 1rem; align-items: start; }
  .tavola figure { max-width: none; padding: .75rem; }
  .tavola figure + figure { margin-top: 0; }
  .tavola figcaption { font-size: .8rem; }
  .contagiri { grid-column: 1 / -1; margin-top: 0; }
}

/* ---------- Foto ---------- */
.tavola .foto { padding: 0; overflow: hidden; }
.tavola .foto img { display: block; width: 100%; height: auto; aspect-ratio: 4 / 3; object-fit: cover; background: var(--alluminio); }
.tavola .foto figcaption { padding: .6rem .8rem .75rem; margin-top: 0; font-size: .78rem; }
@media (max-width: 959px) { .tavola .foto { grid-column: 1 / -1; } }


.altra-marca { display: inline-block; margin-left: .4rem; padding: 0 .4rem; border-radius: var(--raggio); background: var(--giallo-tenue); color: var(--ghisa); font-size: .78rem; font-weight: 600; white-space: nowrap; }