list5a {
    padding:0;
    list-style: none;
}    
.list5a li {
    position: relative;
    padding: 2px 20px;
    background: linear-gradient(to left, #ADCEE9 0%, #FFF, #ADCEE9);
    border: 2px solid #337AB7;
    color: #506a6b;
    box-shadow: 0 5px 5px 0 rgba(0,0,0, .2);
    margin-bottom: 5px;
  /*  text-align:center;*/
    background-size: 100% 100%;
    z-index: 1;
    list-style-type: none;
}
.list5a li:before {
    content: "";
    position:absolute;
    width: 0;
    height: 100%;
    top: 50%;
    left: 50%;
    background: linear-gradient(to left, #EBF3FA 0%, #FFF, #EBF3FA);
    opacity: 0;
    -webkit-transform: translateX(-50%) translateY(-50%);
    -moz-transform: translateX(-50%) translateY(-50%);
    -ms-transform: translateX(-50%) translateY(-50%);
    transform: translateX(-50%) translateY(-50%);
    -webkit-transition: all 0.3s;
    -moz-transition: all 0.3s;
    transition: all 0.3s;
    z-index: -1;
}
.list5a li:hover:before {
    width: 100%;
    opacity: 1;
}
Вариант 5b: