body.research main {
  max-width: 1200px;
  margin: 0 auto;
  padding: 3rem;
}

.subtitle {
  margin-bottom: 3rem;
  color: #ccc;
}

/* folders */
.folder-grid {
  display: flex;
  flex-wrap: nowrap;
  gap: 2rem;
  margin: 3rem 0;
}

.folder {
  flex: 0 0 170px;
  width: 170px;
  height: 130px;
  border-radius: 10px;
  border: 1px solid #ae30e9;
  position: relative;
  overflow: hidden;
  cursor: pointer;
  display: flex;
  align-items: flex-end;
  justify-content: center;
  background: #111;
}

.folder-preview {
  position: absolute;
  inset: 0;
  width: 100%;
  height: 100%;
  object-fit: cover;
  opacity: 0.35;
}

.folder-name {
  position: relative;
  z-index: 2;
  font-size: 0.9rem;
  padding: 10px;
  background: rgba(0,0,0,0.55);
  width: 100%;
  text-align: center;
}

/* popup */
.popup-overlay {
  display: none;
  position: fixed;
  inset: 0;
  background: rgba(10,10,10,0.95);
  backdrop-filter: blur(5px);
  z-index: 1000;
  justify-content: center;
  align-items: center;
}

.popup-content {
  background: #111;
  border: 1px solid #444;
  border-radius: 10px;
  padding: 2rem;
  width: 80%;
  max-width: 800px;
  max-height: 80%;
  overflow-y: auto;
  position: relative;
}

.popup-close {
  position: absolute;
  top: 1rem;
  right: 1rem;
  font-size: 1.5rem;
  cursor: pointer;
  color: #f00;
}

.file-list li {
  padding: 0.5rem 0;
  border-bottom: 1px solid #333;
}

.file-list a {
  color: #0ff;
  text-decoration: none;
}

/* responsive */
@media (max-width: 850px) {
  .folder-grid {
    flex-wrap: wrap;
  }
}