#nav_menu ul { 
display: flex;
flex-basis: 100%;
justify-content: space-around;
background-color: black; 
list-style-type: none;
margin: 0;
padding: 0;
}
#nav_menu a { color: #FFFFFF;
text-decoration: none; }
#nav_menu ul li { flex-basis: 20%; }
main { display: flex; }
article {flex-basis: 60%;
margin: 1.5em 2.52525% 0 2.0202% }

aside { flex-basis: 40%;
padding: 2.0202%;
max-width:200px;
min-height:180px;
background-color:#ffebc6;
margin: 1.5em 2.0202% 0 0; }

article img { max-width: 100%; margin-bottom: 1em; }
footer { background-color: pink; }