html {
  background-color: #efffff;

}
h1 {
  font-family: 'Baloo', cursive;
  text-align: center;
  font-size: 350%;
}

h4 {
  font-family: sans-serif;
  text-align: center;
}


#gallery {
  margin: auto;
  max-width: 780px;
}

.thumbnail {
  display: inline-block;
  position: relative;
  width: 250px;
  height: 250px;
  overflow: hidden;
  border-radius: 50%;
  margin: 5px;
}
.thumbnail img {
  position: absolute;
  left: 50%;
  top: 50%;
  height: 100%;
  width: auto;
  -webkit-transform: translate(-50%,-50%);
      -ms-transform: translate(-50%,-50%);
          transform: translate(-50%,-50%);
}

.thumbnail:hover .overlay {
  opacity: 1;
}

.overlay {
  position: absolute;
  top: 0;
  bottom: 0;
  left: 0;
  right: 0;
  height: 100%;
  width: 100%;
  opacity: 0;
  transition: .5s ease;
  background-color: #429bed;
}

.title {
  color: #efffff;
  font-size: 20px;
  position: absolute;
  text-align: center;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%);
  -ms-transform: translate(-50%, -50%);
}