*{
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}
header{
background-color: blue;
padding: 3em;
color: #fff;
text-align: center;

}
section>nav{
    float: left;
    width: 30%;
    background-color: blanchedalmond;
    padding: 1.5em;
    height: 250px;

}
section>nav>ul{
    list-style: none;

}
section>nav>ul>li>a{
    text-decoration: none;
    color: black;
}
article{
    float: left;
    padding: 20px;
    width: 70%;
    /* background-color: aqua; */
}
footer{
    background-color: #ccc;
    padding: 20px;
    text-align: center;
}

.clearfix::after{
    content: '';
    display: block;
    clear: both;
    overflow: hidden;
}

/* 반응형웹 */
@media screen and (max-width:600px) {
    section> nav, article{
      /* background-color: aqua; */
        width: 100%;
        height: auto;
    }
}