Make main menu stick to top

assets/style.scss

@@ -31,15 +31,18 @@ body {
 }
 
 header, footer {
-	padding: 0 1rem;
+	padding: 1rem;
 }
 
 header {
 	align-items: center;
+	background: $color-background;
 	display: flex;
 	flex-wrap: wrap;
 	justify-content: space-between;
-	margin-top: 1rem;
+	position: sticky;
+	top: 0;
+	z-index: 1;
 
 	a img {
 		display: block;
@@ -89,7 +92,7 @@ header {
 }
 
 main {
-	padding: 1rem;
+	padding: 0 1rem;
 
 	& > :last-child {
 		margin-bottom: 0 !important;
@@ -100,17 +103,13 @@ main {
 	}
 }
 
-footer {
-	margin-bottom: 1rem;
-
-	nav {
+footer nav {
 	align-items: end;
 
 	@media screen and (min-width: $small) {
 		align-items: normal;
 		justify-content: end;
 	}
-	}
 }
 
 nav {