/* ============================================================
   tech-extras.css — aggiunte "disegno tecnico" per le pagine
   interne del sito (si somma a main.css + pages.css, già
   ricolorati in bianco/rosso/nero). Contiene: rail persistente
   col Violino Andrea Amati che si disegna scorrendo, griglia
   millimetrata, crocette di riferimento, costruzioni geometriche
   animate, barra di avanzamento, reveal-on-scroll aggiuntivo.
   Va caricato DOPO main.css e pages.css.
============================================================ */
:root{
  --rosso:#d81324;
  --rosso-vivo:#ff1f36;
  --nero-t:#0b0b0c;
  --bianco-t:#faf9f6;
  --linea-t:rgba(11,11,12,.14);
  --linea-bianca-t:rgba(250,249,246,.16);
  --ease-t:cubic-bezier(.22,1,.36,1);
}

@media(min-width:1181px){
  body{padding-right:132px}
  nav{right:132px}
  .lang-bar{right:132px}
}

/* ============================================================
   BARRA PROGRESSO SCROLL
============================================================ */
#progress{
  position:fixed;top:0;left:0;height:3px;width:0%;
  background:var(--rosso);z-index:999;
  transition:width .08s linear;
}
@media(min-width:1181px){ #progress{right:132px;width:auto} }

/* ============================================================
   GRIGLIA TECNICA + CROCETTE
============================================================ */
.grid-bg{
  position:absolute;inset:0;
  background-image:
    linear-gradient(var(--linea-t) 1px, transparent 1px),
    linear-gradient(90deg, var(--linea-t) 1px, transparent 1px);
  background-size:48px 48px;
  opacity:.4;
  pointer-events:none;
}
.grid-bg.dark{
  background-image:
    linear-gradient(var(--linea-bianca-t) 1px, transparent 1px),
    linear-gradient(90deg, var(--linea-bianca-t) 1px, transparent 1px);
}
.crop{
  position:absolute;width:14px;height:14px;pointer-events:none;opacity:.55;z-index:2;
}
.crop::before,.crop::after{content:'';position:absolute;background:currentColor}
.crop::before{left:50%;top:0;width:1px;height:100%;transform:translateX(-50%)}
.crop::after{top:50%;left:0;height:1px;width:100%;transform:translateY(-50%)}

/* ============================================================
   RAIL — il Violino Andrea Amati (Traité de Lutherie §9) che
   si disegna man mano che si scorre la pagina.
============================================================ */
#rail{display:none}
@media(min-width:1181px){
  #rail{
    display:block;position:fixed;top:0;right:0;width:132px;height:100vh;
    background:var(--nero-t);z-index:450;
    border-left:1px solid rgba(216,19,36,.45);
    overflow:hidden;
  }
}
#rail .grid-bg{opacity:.2}
.rail-violin{position:absolute;top:50%;left:50%;width:78px;transform:translate(-50%,-50%)}
.rail-violin svg{width:100%;height:auto;overflow:visible;display:block}
#railViolinPath{
  fill:none;stroke:var(--rosso-vivo);stroke-width:2.6;
  stroke-linecap:round;stroke-linejoin:round;
  filter:drop-shadow(0 0 7px rgba(255,31,54,.5));
  stroke-dasharray:900;stroke-dashoffset:900;
}
.rail-ghost{fill:none;stroke:rgba(250,249,246,.1);stroke-width:1}
.rail-arc{position:absolute;border:1px solid rgba(216,19,36,.22);border-radius:50%;animation:railspin 46s linear infinite}
.rail-arc.a2{border-color:rgba(250,249,246,.14);animation-duration:64s;animation-direction:reverse}
@keyframes railspin{to{transform:rotate(360deg)}}
.rail-formula{
  position:absolute;left:50%;transform:translateX(-50%);
  font-family:var(--mono);font-size:.56rem;letter-spacing:.03em;
  color:rgba(250,249,246,.4);white-space:nowrap;
  animation:raildrift 6.5s ease-in-out infinite;
}
@keyframes raildrift{
  0%,100%{transform:translateX(-50%) translateY(0);opacity:.3}
  50%{transform:translateX(-50%) translateY(-7px);opacity:.75}
}
.rail-tick{position:absolute;left:50%;width:16px;height:1px;background:rgba(250,249,246,.28);transform:translateX(-50%)}
.rail-caption{
  position:absolute;bottom:36px;left:50%;
  transform:translateX(-50%) rotate(-90deg);transform-origin:center;
  font-family:var(--mono);font-size:.58rem;letter-spacing:.14em;text-transform:uppercase;
  color:rgba(250,249,246,.4);white-space:nowrap;
}
.rail-pct{position:absolute;top:26px;left:0;right:0;text-align:center;font-family:var(--mono);font-size:.62rem;letter-spacing:.03em;color:var(--rosso-vivo)}
.rail-pct small{display:block;margin-top:3px;font-size:.52rem;letter-spacing:.1em;text-transform:uppercase;color:rgba(250,249,246,.4)}

/* ============================================================
   COSTRUZIONI GEOMETRICHE ANIMATE (a compasso e riga) —
   inseribili come divisori di sezione su qualunque pagina.
============================================================ */
.construct-wrap{
  position:relative;border:1px solid var(--linea-t);padding:30px 20px 46px;
  background:
    linear-gradient(var(--linea-t) 1px, transparent 1px),
    linear-gradient(90deg, var(--linea-t) 1px, transparent 1px);
  background-size:24px 24px;
  margin:5rem 0;
}
.construct-wrap.on-dark{border-color:var(--linea-bianca-t)}
.construct-cap{
  font-family:var(--mono);font-size:.64rem;letter-spacing:.06em;color:var(--fog, #726f6a);
  text-align:center;margin-top:14px;
}
.construct-cap b{color:var(--rosso);font-weight:500}
.gsec{fill:none;stroke:var(--nero-t);stroke-width:1}
.gsec.red{stroke:var(--rosso)}
.gsec.white{stroke:rgba(250,249,246,.5)}
.gsec-txt{
  font-family:var(--mono);font-size:10px;fill:var(--fog,#726f6a);
  transform-origin:center;animation:t-labelbob 5s ease-in-out infinite 2.4s;
}
.gsec-txt.red{fill:var(--rosso)}
.gsec-txt.white{fill:rgba(250,249,246,.7)}
.tick-t{stroke:var(--nero-t);stroke-width:1}
.gsec-pulse{fill:none;stroke:var(--rosso);stroke-width:1;opacity:0;animation:t-pulsering 4s ease-out infinite 2.6s}
@keyframes t-pulsering{0%{opacity:.6;r:3}70%{opacity:0;r:16}100%{opacity:0;r:16}}
@keyframes t-labelbob{0%,100%{transform:translateY(0)}50%{transform:translateY(-3px)}}
.gsec-spin{animation:railspin 60s linear infinite;transform-origin:center}

/* ============================================================
   REVEAL ON SCROLL (nuove classi, in aggiunta a reveal-up/left/right)
============================================================ */
.reveal{opacity:0;transform:translateY(28px);transition:opacity .8s var(--ease-t),transform .8s var(--ease-t)}
.reveal.in{opacity:1;transform:translateY(0)}
.reveal-l{opacity:0;transform:translateX(-32px);transition:opacity .8s var(--ease-t),transform .8s var(--ease-t)}
.reveal-l.in{opacity:1;transform:translateX(0)}
.reveal-r{opacity:0;transform:translateX(32px);transition:opacity .8s var(--ease-t),transform .8s var(--ease-t)}
.reveal-r.in{opacity:1;transform:translateX(0)}

@media(prefers-reduced-motion:reduce){
  #railViolinPath,.rail-arc,.rail-formula,.gsec-txt,.gsec-pulse,.gsec-spin{animation:none!important}
  .proc-frame img{transition:opacity .25s linear!important;transform:none!important}
}

/* ============================================================
   PROCESS SLIDESHOW — sequenza fotografica "dal legno al
   violino" con transizione a dissolvenza incrociata + filmstrip.
============================================================ */
.proc-section{margin:6rem 0}
.proc-lead{
  font-size:.95rem;color:var(--fog,#726f6a);max-width:640px;
  margin-top:1rem;line-height:1.85;
}

.proc-stage{
  position:relative;margin-top:3rem;
  aspect-ratio:16/9;
  background:var(--nero-t);
  overflow:hidden;
  border:1px solid rgba(11,11,12,.14);
  outline:none;
}
.proc-stage .grid-bg{opacity:.16}
.proc-stage .crop{color:rgba(250,249,246,.35);z-index:4}

.proc-frame{position:absolute;inset:0}
.proc-frame img{
  position:absolute;inset:0;width:100%;height:100%;object-fit:contain;
  background:#000;
  opacity:0;transform:scale(1.045);
  transition:opacity 1.15s var(--ease-t), transform 1.7s var(--ease-t);
  will-change:opacity,transform;
}
.proc-frame img.active{opacity:1;transform:scale(1);z-index:1}

.proc-arrow{
  position:absolute;top:50%;transform:translateY(-50%);
  width:42px;height:42px;border:1px solid rgba(250,249,246,.32);
  background:rgba(11,11,12,.3);color:var(--bianco-t);
  display:flex;align-items:center;justify-content:center;
  cursor:pointer;font-size:1rem;line-height:1;
  transition:background .2s,border-color .2s;
  backdrop-filter:blur(2px);
  z-index:5;
}
.proc-arrow:hover{background:var(--rosso);border-color:var(--rosso)}
.proc-arrow.prev{left:14px}
.proc-arrow.next{right:14px}

.proc-meta{
  position:absolute;left:0;right:0;bottom:0;
  display:flex;align-items:center;gap:1rem;
  padding:.9rem 1.1rem;
  background:linear-gradient(0deg, rgba(11,11,12,.8), transparent);
  font-family:var(--mono);font-size:.66rem;letter-spacing:.06em;
  color:rgba(250,249,246,.85);
  z-index:5;
}
.proc-count{white-space:nowrap;min-width:60px}
.proc-bar{flex:1;height:2px;background:rgba(250,249,246,.2);position:relative}
.proc-bar-fill{
  position:absolute;left:0;top:0;bottom:0;
  background:var(--rosso-vivo);width:0%;
  transition:width .5s var(--ease-t);
}
.proc-play{
  width:24px;height:24px;flex-shrink:0;
  border:1px solid rgba(250,249,246,.32);background:transparent;color:var(--bianco-t);
  display:flex;align-items:center;justify-content:center;cursor:pointer;font-size:.58rem;
  transition:background .2s,border-color .2s;
}
.proc-play.playing{background:var(--rosso);border-color:var(--rosso)}

.proc-strip{
  display:flex;gap:6px;margin-top:10px;overflow-x:auto;padding-bottom:6px;
  scrollbar-width:thin;
}
.proc-strip::-webkit-scrollbar{height:5px}
.proc-strip::-webkit-scrollbar-thumb{background:rgba(11,11,12,.22)}
.proc-strip img{
  width:64px;height:48px;object-fit:cover;flex-shrink:0;cursor:pointer;
  opacity:.42;filter:grayscale(65%);
  transition:opacity .25s,filter .25s,outline-color .25s;
  outline:2px solid transparent;outline-offset:-2px;
}
.proc-strip img:hover{opacity:.8}
.proc-strip img.active{opacity:1;filter:grayscale(0%);outline-color:var(--rosso)}

@media(max-width:700px){
  .proc-arrow{width:34px;height:34px;font-size:.85rem}
  .proc-meta{font-size:.58rem;padding:.7rem}
  .proc-strip img{width:46px;height:34px}
}