.item12 {
    float: left;
}


.grid-sizer { width: 25%; }
.item12 { width: 25%; padding: 10px; }

.item12>div
{
	position: relative;
	 transition: all 0.4s ease-in-out;
    -webkit-transition: all 0.4s ease-in-out;
    -moz-transition: all 0.4s ease-in-out;
}

@media screen and (max-width: 1224px) {
  /* 10 columns for larger screens */
  .grid-sizer { width: 25%; }
  .item12 { width: 25%; }
}

@media screen and (max-width: 720px) {
  /* 10 columns for larger screens */
  .grid-sizer { width: 50%; }
  .item12 { width: 50%; }
}

@media screen and (max-width: 480px) {
  /* 10 columns for larger screens */
  .grid-sizer { width: 100%; }
  .item12 { width: 100%; }
}

.image{
    max-width: 100%;
    margin: 0;
    display: block;
    filter: none;
    -moz-filter: none;
    -webkit-filter: none;
    filter: grayscale(0);
    -moz-filter: grayscale(0);
    -webkit-filter: grayscale(0);
}

.image:hover
{
    filter: gray;
    -moz-filter: gray;
    -webkit-filter: gray;
    filter: grayscale(1);
    -webkit-filter: grayscale(1);
    -moz-filter: grayscale(1);
    transition: all 0.3s ease-in-out;
    -webkit-transition: all 0.3s ease-in-out;
    -moz-transition: all 0.3s ease-in-out;
}

.image:after {
    clear:both;
}

.overlay {
    width: 100%;
    height: 100%;
    background-color: rgba(0,0,0,0.4);
    position: absolute;
    top: 0;
    left: 0;
    text-decoration: none;
    color: #fff;
    display:none;
     transition: all 0.4s ease-in-out;
    -webkit-transition: all 0.4s ease-in-out;
    -moz-transition: all 0.4s ease-in-out;
}

.overlay .title {
    text-align: center;
    font-size: 24px;
    padding-top:20px;
}

.item12>div:hover .overlay
{
    display:block;
}