:root{
  --bg:#f7f8fb; --card:#fff; --muted:#6b7280; --accent:#0366d6; --radius:10px;
  --gap:10px;
}
*{box-sizing:border-box}
body{font-family:Inter,system-ui,Arial,Helvetica,sans-serif;margin:0;background:var(--bg);color:#0f172a;-webkit-font-smoothing:antialiased}
header{position:sticky;top:0;z-index:20;background:linear-gradient(180deg,#fff,#fbfdff);display:flex;justify-content:space-between;align-items:center;padding:10px 12px;border-bottom:1px solid rgba(2,6,23,0.04)}
.hdr-left{display:flex;align-items:center;gap:10px}
.hdr-left h1{margin:0;font-size:18px}
.icon-btn{background:transparent;border:0;font-size:20px;padding:6px;border-radius:8px}
.breadcrumb{font-size:13px;color:var(--muted);max-width:60vw;overflow:hidden;text-overflow:ellipsis;white-space:nowrap}

main{padding:12px 10px 80px}
.toolbar{display:flex;gap:8px;align-items:center;flex-wrap:wrap;margin-bottom:12px}
#search{flex:1;min-width:0;padding:10px;border-radius:10px;border:1px solid rgba(15,23,42,0.06);background:white}
.controls{display:flex;gap:8px;align-items:center}
.controls select, .controls button{padding:8px 10px;border-radius:10px;border:1px solid rgba(15,23,42,0.06);background:white;font-size:14px}

#files{display:grid;gap:var(--gap);align-items:start}
#files.grid{grid-template-columns:repeat(2,minmax(0,1fr))}
#files.list{grid-template-columns:1fr}

.card{
  background:var(--card);padding:10px;border-radius:var(--radius);box-shadow:0 6px 18px rgba(16,24,40,0.04);
  display:flex;flex-direction:column;gap:8px;min-height:120px;cursor:pointer;overflow:hidden;
  transition:transform .12s ease,box-shadow .12s ease;
}
.card:active{transform:scale(.998)}
.card.row{flex-direction:row;align-items:center;gap:12px;padding:10px}

.thumb-wrap{width:100%;height:140px;border-radius:8px;background:linear-gradient(90deg,#eef2ff,#f8fafc);display:flex;align-items:center;justify-content:center;overflow:hidden;position:relative}
.thumb{width:100%;height:100%;object-fit:cover;display:block;opacity:0;transition:opacity .28s ease}
.thumb.small{width:88px;height:88px;border-radius:8px;object-fit:cover}
.skeleton{position:absolute;inset:0;background:linear-gradient(90deg,rgba(255,255,255,0.0),rgba(255,255,255,0.5),rgba(255,255,255,0.0));animation:shimmer 1.1s linear infinite;transition:opacity .25s ease}
@keyframes shimmer{0%{transform:translateX(-100%)}100%{transform:translateX(100%)}}

/* when image loads we add .loaded class (JS) */
.thumb.loaded{opacity:1}
.skeleton.hidden{opacity:0;pointer-events:none;}

/* existing styles kept */
.card .meta{font-size:12px;color:var(--muted)}
.card .name{font-weight:600;font-size:14px;line-height:1.1}
.card .row .thumb.small{flex:0 0 auto}
.card .info{display:flex;flex-direction:column;gap:6px}
.actions{display:flex;gap:8px;align-items:center;margin-top:auto}
.actions a, .actions button{padding:6px 8px;border-radius:8px;border:1px solid rgba(2,6,23,0.06);background:white;font-size:13px;text-decoration:none;color:inherit}
.empty{padding:18px;background:var(--card);border-radius:8px;color:var(--muted);text-align:center}

/* preview overlay */
#preview{position:fixed;inset:0;background:rgba(0,0,0,0.6);display:flex;align-items:center;justify-content:center;padding:18px}
#preview.hidden{display:none}
.preview-content{background:white;border-radius:10px;max-width:980px;max-height:88vh;overflow:auto;padding:12px}
#preview-close{position:absolute;top:18px;right:18px;color:white;font-size:22px;border:0;background:transparent}

/* responsive */
@media (min-width:640px){
  #files.grid{grid-template-columns:repeat(3,minmax(0,1fr))}
}
@media (min-width:980px){
  #files.grid{grid-template-columns:repeat(4,minmax(0,1fr))}
  main{padding:18px 26px}
}

/* preview header (close/download) */
.preview-header{display:flex;align-items:center;gap:8px;margin-bottom:10px}
.preview-header .btn{padding:6px 10px;border-radius:8px;border:1px solid rgba(2,6,23,0.06);background:white;font-size:14px;cursor:pointer}
.preview-body{max-height:78vh;overflow:auto}