#framesPreview img {
    display: inline-block;
    margin-right: 10px;
}

.preview-frame {
    max-width: 200px;   /* or whatever size you want */
    max-height: 200px;
    object-fit: contain; /* important: keeps full image visible */
    cursor: pointer;
    border: 2px solid transparent;
    outline-offset: 0;
    transition: outline-offset 0.3s ease-in-out;
}

.preview-frame.selected {
  outline: rgba(255,255,255,.6) solid 4px;
  outline-offset: .2em; 
  border-radius: .2em;
}