/* PC版 */
body{
    height:100%;
    margin:0;
    display:flex;
    flex-direction:column;
}
#wrapper{
    display:flex;
    flex-direction:column;
    min-height:100vh;
}
#main_body{
    position:relative;
    width:1000px;
    margin:0 auto;
    flex:1;
}

#footer{
    width:1000px;
    background:#4c4c4e;
    margin:0 auto;
    color:white;
    text-align:center;
}
#footer a{
    color:white;
}
/* pc版メニュー */
#top_menu{
    background-color:silver;
    margin:0 auto;
    filter: drop-shadow(10px 10px 10px #424242);
}

#top_menu a{
    color:white;
    text-decoration:none;
    font-size:x-large;
    margin:20px;
}

/* ボックス */
.half_box{
    width:50%;
    height:100%;
    display:flex;
    flex-direction: column; 
    justify-content: center; 
    align-items: center; 
}