/* ==========================================================================
   TRANSIZIONI — aspetto degli effetti di apertura (logica in js/transizioni.js).
   Tempi e colori si ritoccano qui; i colori arrivano da css/theme.css.
   ========================================================================== */

/* ---- Velo di partenza (dalla home): copre lo schermo prima di cambiare pagina ---- */
.tr-velo { position: fixed; inset: 0; z-index: 100; opacity: 0; transition: opacity .4s ease; }
.tr-velo.is-su { opacity: 1; }
.tr-velo--libretto { background: var(--c-salvia-scuro); }
.tr-velo--cartolina { background: var(--c-rosa); }

/* ---- LIBRETTO: due metà di copertina che si aprono dal centro ---- */
.tr-libro { position: fixed; inset: 0; z-index: 100; perspective: 2200px; pointer-events: none; }
.tr-libro__meta { position: absolute; top: 0; bottom: 0; width: 50%; overflow: hidden; backface-visibility: hidden;
  transition: transform 1.2s cubic-bezier(.6, .05, .25, 1); background: var(--c-salvia-scuro); }
.tr-libro__meta--sx { left: 0; transform-origin: left center; }
.tr-libro__meta--dx { right: 0; transform-origin: right center; }
.tr-libro__cop { width: 100vw; height: 100%; display: grid; place-items: center; color: var(--c-su-accento);
  box-shadow: inset 0 0 0 .9rem var(--c-salvia-scuro), inset 0 0 0 1rem var(--c-accento-chiaro);
  background: radial-gradient(circle at 50% 45%, rgba(255,255,255,.12), transparent 60%); }
.tr-libro__meta--dx .tr-libro__cop { margin-left: -50vw; }
.tr-libro__cop span { font: 400 clamp(3rem, 16vw, 7rem)/1 var(--f-corsivo); text-shadow: 0 2px 12px rgba(0,0,0,.25); }
.tr-libro__meta::after { content: ""; position: absolute; top: 0; bottom: 0; width: 1.5rem; pointer-events: none; }   /* ombra del dorso */
.tr-libro__meta--sx::after { right: 0; background: linear-gradient(90deg, transparent, rgba(0,0,0,.35)); }
.tr-libro__meta--dx::after { left: 0; background: linear-gradient(270deg, transparent, rgba(0,0,0,.35)); }
.tr-libro.is-aperto .tr-libro__meta--sx { transform: rotateY(-112deg); }
.tr-libro.is-aperto .tr-libro__meta--dx { transform: rotateY(112deg); }
body.tr-in-corso .libretto, body.tr-in-corso .cartolina { animation: sale 1.4s var(--curva) both; }
@keyframes sale { from { opacity: .0; transform: scale(.94); } to { opacity: 1; transform: none; } }

/* ---- CARTOLINA: appare, si gira, si dissolve sulla pagina ---- */
.tr-cart { position: fixed; inset: 0; z-index: 100; display: grid; place-items: center; background: var(--c-rosa); perspective: 1800px;
  transition: opacity .7s ease; }
.tr-cart.is-esci { opacity: 0; }
.tr-cart__card { position: relative; width: min(82vw, 30rem); aspect-ratio: 3 / 2; transform-style: preserve-3d;
  transform: scale(.7) rotate(-6deg); opacity: 0; transition: transform 1s var(--curva), opacity .5s ease; }
.tr-cart.is-in .tr-cart__card { transform: scale(1) rotate(-2deg); opacity: 1; }
.tr-cart.is-giro .tr-cart__card { transform: scale(1.05) rotate(0) rotateY(180deg); transition: transform 1.1s cubic-bezier(.5, 0, .2, 1); }
.tr-cart__faccia { position: absolute; inset: 0; backface-visibility: hidden; border-radius: .6rem; box-shadow: 0 30px 60px -20px rgba(60, 20, 30, .5); }
.tr-cart__fronte { display: grid; align-content: end; justify-items: center; text-align: center; padding: 1.25rem; color: var(--c-su-immagine);
  background-color: var(--c-accento); background-image: var(--velo-copertina), var(--img, none); background-size: cover; background-position: center;
  border: .6rem solid var(--c-superficie); }
.tr-cart__nomi { margin: 0; font: 400 clamp(2.4rem, 11vw, 4rem)/1 var(--f-corsivo); }
.tr-cart__fronte p:last-child { margin: .25rem 0 0; font-size: .8rem; letter-spacing: .3em; text-transform: uppercase; }
.tr-cart__retro { transform: rotateY(180deg); padding: 1.4rem 1.5rem; background: var(--c-superficie); border: 1px solid var(--c-linea); border-radius: var(--raggio); }
.tr-cart__retro::before { content: ""; position: absolute; inset: .4rem; border: 1px dashed var(--c-rosa); border-radius: calc(var(--raggio) - .4rem); pointer-events: none; }
.tr-cart__sopra { margin: 0; font-size: .6rem; letter-spacing: .25em; text-transform: uppercase; color: var(--c-salvia-scuro); }
.tr-cart__titolo { margin: .3rem 0 .9rem; max-width: 70%; font: 400 clamp(1.9rem, 8vw, 3rem)/1 var(--f-corsivo); color: var(--c-accento); }
.tr-cart__riga { display: block; height: 1px; margin: .55rem 0; background: var(--c-linea); }
.tr-cart__riga--corta { width: 60%; }
.tr-cart__francobollo { position: absolute; top: 1rem; right: 1rem; width: 2.6rem; height: 3.25rem; background: var(--francobollo) center / 100% 100% no-repeat; filter: drop-shadow(0 1px 1px rgba(0,0,0,.18)); }

@media (prefers-reduced-motion: reduce) { .tr-libro, .tr-cart, .tr-velo { display: none; } }