html{
   max-width: 640px;
   margin: 0 auto;
}
body.hidden{overflow:hidden;}

header{
    display: flex;
    top: 0px;
    width: 100%;
    height: 60px;
    padding: 0 4% 0 4%;
    z-index:100;
    background-color: #fff;
    border-top:1px solid #eee;
    border-bottom:1px solid #eee;
}
header .left{
    width: 30%;
    height: 100%;
}
header .left img{
    width: 62%;
    max-width: 65px;
    vertical-align: middle;
}
header .center{
    height: 100%;
    margin: 0 20px;
    text-align: center;
    flex: 1;
   display: flex;
   justify-content: center;
   align-items: center;
}
header .center img.logo{
    width: 120px;
    max-width: 150px;
    cursor: pointer;
    margin-top: -4px;
    margin-left: 5px;
}
header .right{
    width: 30%;
    height: 100%;
    text-align: right;
}
header .right img.menu-open{
    width: 25%;
    max-width: 30px;
    cursor: pointer;
}
header .left span, header .center span, header .right span{
    height: 100%;
    overflow: hidden;
    display: inline-block;
    vertical-align: middle;
}

footer{
    bottom:0px;
    width: 100%;
    height: 60px;
    background-color: #1a1b23;
}
footer p{
    font-size: 1.1em;
    color: #797a81;
    text-align: center;
    vertical-align: middle;
    font-family: nanumgothic-regular,sans-serif;
    line-height:58px;
}
footer span{
    font-weight: bold;
    color: #fff;
}

.back-to-top{
    position: fixed;
    display: none;
    right: 0px;
    bottom: 110px;
    width: 42px;
    height: 42px;
    font-size: 1.1em;
    font-weight: bold;
    color: #fff;
    text-align: center;
    line-height: 42px;
    background-color: #202020;
    opacity:0.4;
    border-top:1px solid #ccc;
    border-bottom:1px solid #ccc;
    border-left:1px solid #ccc;
    border-radius: 6px 3px 3px 6px;
    padding-left: 3px;
    text-shadow:0px 0px 3px #f8305f, 0px 0px 100px #f8305f, 0px 0px 72px #f8305f,0px 0px 200px #f8305f;
    cursor: pointer;
}