added some style variables

src/style/variables.scss

@@ -1,6 +1,14 @@
 //SIZE
 $mobile-width: 31.25em;
 
+$content-wide: 80%;
+$content-semi-wide: 70%;
+$content-thin: 60%;
+
+//MARGINS
+$single-margin: 2.5em;
+$double-margin: 5em;
+
 //COLOR
 $dark-color: hsl(0, 0%, 20%);
 $darker-color: hsl(0, 0%, 10%);