*{margin:0;padding:0;box-sizing:border-box}body{display:flex;flex-direction:column;height:100%;width:100%;overflow:hidden}main{height:80%;width:100%}header{flex-shrink:0;height:10%;display:flex;align-items:center;padding:0 20px;background:#111;color:#fff}header>h1{width:100%;font-size:80%}footer{flex-shrink:0;height:10%;display:flex;align-items:center;padding:0 20px;background:#111;color:#fff}#c{flex:1;display:block;width:100%}