.header {
    position: fixed;
    top: 5px;
    width: 100%;
    height: 50px;
    background-color: darkgrey;
    }

.main {
    padding-top: 0px;
    overflow: auto;
    }

.footer {
    position: fixed;
    bottom: 0;
    width: 100%;
    height: 50px;
    background-color: darkgrey;
    }

h1 {
    /*線の種類（二重線）太さ 色*/
    border-bottom: double 5px darkgray;
    }