/* Three image containers (use 25% for four, and 50% for two, etc) */
.column {
  float: left;
  padding: 5px;
}

/* Clear floats after image containers */
.row::after {
  content: "";
  clear: both;
  display: table;
}

.logo {
    -webkit-filter: grayscale(100%);
    -webkit-transition: .5s ease-in-out;
    -moz-filter: grayscale(100%); 
    -moz-transition: .5s ease-in-out;
    -o-filter: grayscale(100%); 
    -o-transition: .5s ease-in-out;
}

.logo:hover {
    -webkit-filter: grayscale(0%);
    -webkit-transition: .2s ease-in-out;
    -moz-filter: grayscale(0%);
    -moz-transition: .2s ease-in-out;
    -o-filter: grayscale(0%);
    -o-transition: .2s ease-in-out;
}