/*
 * La coque : split view à trois colonnes (rail des modules · liste · fil),
 * toute la hauteur, aucune barre de défilement de page. Sous 900 px la liste
 * et le fil se relaient (une seule colonne visible, `.app.conv-ouverte`).
 */
.page-app { height: 100dvh; overflow: hidden; }
.app { display: grid; grid-template-columns: var(--tb-rail) var(--tb-liste) minmax(0, 1fr); height: 100dvh; background: var(--tb-fond); }

/* Rail des modules */
.rail { display: flex; flex-direction: column; align-items: stretch; gap: 6px; padding: 12px 10px; background: var(--tb-surface); border-right: 1px solid var(--tb-bordure); }
.rail-logo { display: grid; place-items: center; height: 44px; margin-bottom: 6px; }
.rail-logo img { border-radius: 8px; }
.rail-btn { position: relative; display: flex; flex-direction: column; align-items: center; gap: 4px; padding: 9px 2px 7px; border-radius: var(--tb-rayon); color: var(--tb-texte-2); font-size: 10.5px; font-weight: 500; line-height: 1; transition: background var(--tb-duree), color var(--tb-duree); }
.rail-btn:hover { background: var(--tb-surface-3); color: var(--tb-texte); text-decoration: none; }
.rail-btn.est-actif { background: var(--tb-surface-3); color: var(--tb-texte); }
.rail-lib { max-width: 100%; overflow: hidden; text-overflow: ellipsis; white-space: nowrap; }
.rail-badge { position: absolute; top: 4px; right: 6px; min-width: 18px; height: 18px; padding: 0 5px; border-radius: 9px; background: var(--tb-danger); color: #fff; font-size: 11px; font-weight: 700; line-height: 18px; text-align: center; }
.rail-fin { margin-top: auto; display: flex; flex-direction: column; gap: 4px; }
.rail-moi .avatar { margin-bottom: 1px; }

/* Liste */
.liste { display: flex; flex-direction: column; min-height: 0; background: var(--tb-fond); border-right: 1px solid var(--tb-bordure); }
.liste-tete { display: flex; align-items: center; gap: 4px; padding: 16px 12px 10px 18px; }
.liste-titre { flex: 1; font-size: 19px; font-weight: 700; letter-spacing: -.02em; }
.liste-corps { flex: 1; min-height: 0; overflow-y: auto; padding: 0 8px 12px; }

/* Fil */
.fil { position: relative; display: flex; flex-direction: column; min-width: 0; min-height: 0; background: var(--tb-surface); }
.fil-vide { flex: 1; display: flex; flex-direction: column; align-items: center; justify-content: center; gap: 14px; color: var(--tb-texte-2); text-align: center; padding: 24px; }
.fil-vide-logo { border-radius: 14px; opacity: .9; }
.fil-conv { display: flex; flex-direction: column; flex: 1; min-height: 0; }
.fil-tete { display: flex; align-items: center; gap: 12px; padding: 10px 18px; min-height: 60px; background: var(--tb-surface); border-bottom: 1px solid var(--tb-bordure); }
.fil-messages { flex: 1; min-height: 0; overflow-y: auto; padding: 16px 20px 8px; overscroll-behavior: contain; scroll-behavior: smooth; }
@media (prefers-reduced-motion: reduce) { .fil-messages { scroll-behavior: auto; } }
.fil-tape { min-height: 20px; padding: 0 22px; font-size: 12px; color: var(--tb-texte-3); }

/* Étroit : une colonne à la fois */
.btn-retour { display: none; }
@media (max-width: 900px) {
  .app { grid-template-columns: var(--tb-rail) minmax(0, 1fr); }
  .liste { grid-column: 2; }
  .fil { grid-column: 2; grid-row: 1; display: none; }
  .app.conv-ouverte .liste { display: none; }
  .app.conv-ouverte .fil { display: flex; }
  .btn-retour { display: inline-flex; }
}
@media (max-width: 560px) {
  :root { --tb-rail: 52px; }
  .rail-lib { display: none; }
  .rail-btn { padding: 10px 0; }
  .fil-messages { padding: 12px 12px 6px; }
}

/* Porte (connexion, 404) */
.page-porte { display: grid; place-items: center; min-height: 100dvh; padding: 24px; background: var(--tb-surface); }
.porte-carte { width: min(400px, 100%); display: flex; flex-direction: column; gap: 14px; padding: 36px 32px 26px; background: var(--tb-surface); border: 1px solid var(--tb-bordure); border-radius: 14px; }
.porte-logo { border-radius: 11px; }
.porte-titre { font-size: 22px; }
.porte-intro { color: var(--tb-texte-2); margin-bottom: 6px; }
.porte-pied { margin-top: 10px; font-size: 11.5px; color: var(--tb-texte-3); text-align: center; }