ul, li  {
    list-style-type: none;
}

img {
    width: 150px;
    opacity: .5;
}
img:hover   {
    opacity: 1;
}

.portfolio    {
    display: flex;
    flex-direction: column;
    justify-content: space-evenly;
    align-content: center;
    gap: 0px;
    opacity: 1;
}

.image-gallery {
    display: flex;
    flex-wrap: wrap;
    justify-content: center;
    gap: 10px;
  }
  
  .image-gallery > li {
    flex-basis: 150px;
  }
  
  .image-gallery li img {
    object-fit: cover;
    max-width: 100%;
    height: auto;
    vertical-align: middle;
    border-radius: 5px;
    cursor: pointer;
  }