.fav_btn{/*周りの凹み*/
    display: inline-block;
    position: relative;
    text-decoration: none;
    color: rgba(255, 193, 7, 1);
    width: 80px;
    height: 80px;
    z-index: 2;
    /*border-radius: 50%;*/
    text-align: center;
    /*background: #f7f7f7;*/
    /*box-shadow: inset 0 0 4px rgba(0, 0, 0, 0.08);*/
    
    
    position: fixed;
    bottom: 16px;
    right: 16px;
}
.fav_btn .fa {/*ボタン自体*/
    position: absolute;
    content: '';
    width: 60px;
    height: 60px;
    line-height: 60px;
    vertical-align: middle; 
    left: 10px;
    top: 9px;
    border-radius: 50%;
    font-size: 30px;
    background-image: -webkit-linear-gradient(#e8e8e8 0%, #d6d6d6 100%);
    background-image: linear-gradient(#e8e8e8 0%, #d6d6d6 100%);
    text-shadow: 1px 1px 1px rgba(255, 255, 255, 0.66);
    box-shadow: inset 0 2px 0 rgba(255,255,255,0.5), 0 2px 2px rgba(0, 0, 0, 0.19);
    border-bottom: solid 2px #b5b5b5;
  }

.fav_btn .fa:active{
    background-image: -webkit-linear-gradient(#efefef 0%, #d6d6d6 100%);
    box-shadow: inset 0 1px 0 rgba(255,255,255,0.5), 0 2px 2px rgba(0, 0, 0, 0.19);
    border-bottom: solid 2px #d8d8d8;
}

.fav_btn a
{
    display: block;
    text-decoration: none;
}
.fav_btn:hover
{
    opacity: 0.85 ;
}