/* Bouton to-top — thème Orange */
:root{
  --brand:#F97316;     /* orange principal */
  --brand-2:#EA580C;   /* orange foncé */
  --ring:#FCD34D;      /* halo focus */
}

.to-top{
  position: fixed;
  right: 16px;
  bottom: calc(16px + env(safe-area-inset-bottom, 0));
  width: 44px; height: 44px;
  display: inline-flex; align-items: center; justify-content: center;
  border: 1px solid color-mix(in oklab, var(--brand) 35%, #0000);
  border-radius: 999px;
  background: linear-gradient(135deg, var(--brand), var(--brand-2));
  color: #fff;
  box-shadow: 0 14px 28px color-mix(in oklab, var(--brand) 25%, transparent);
  cursor: pointer;
  z-index: 999;

  /* caché par défaut (pas de saut de layout) */
  opacity: 0; visibility: hidden; pointer-events: none;
  transform: translateY(8px);
  transition: opacity .22s ease, transform .22s ease, visibility 0s linear .22s;
}

.to-top.show{
  opacity: 1; visibility: visible; pointer-events: auto;
  transform: translateY(0);
  transition: opacity .22s ease, transform .22s ease;
}

.to-top:hover{ filter: brightness(1.02); transform: translateY(-1px); }
.to-top:active{ transform: translateY(0); }
.to-top:focus-visible{
  outline: none;
  box-shadow: 0 0 0 4px color-mix(in oklab, var(--ring) 60%, transparent),
              0 14px 28px color-mix(in oklab, var(--brand) 25%, transparent);
}

/* Mode sombre auto (optionnel) */
@media (prefers-color-scheme: dark){
  .to-top{
    border-color: color-mix(in oklab, var(--brand) 30%, #fff0);
    box-shadow: 0 14px 28px rgba(0,0,0,.45);
  }
}