layoutelement.css

*{
    box-sizing: border-box;
    margin: 0;
    padding: 0;
}

body{
    font-family: Arial, Helvetica, sans-serif;
    font-size: 15px;
    line-height: 1.5em;
}

img{
    max-width: 100%;
}

header{
    background: #fadadd;
    padding: 20px;
}

header img{
    margin-top: 20px;
    width: 250px;
    margin: 0 auto;
    display: block;
}

#main_menu{
    list-style: none;
    text-align: center; 
}

#main_menu li{
    display: inline-block;
    margin: 0 5px 10px;
}

#main_menu a{
    background: #e8336d;
    font-size: 14px;
    color: #fff;
    padding: 5px 15px;
    text-decoration: none;
    
}

section{
    background: #cdeaff;
    display: flex;
}

div{
    padding: 20px;
    width: 60%;
}

div h1{
    margin-bottom: 20px;
}

aside{
    padding: 20px;
    width: 40%;
}

aside ul{
    margin-left: 20px;
    margin-top: 10px;
}

footer{
    background: #eaffcd;
    padding: 20px;

}

footer p {
    font-size: 12px;
}