Added colour variables

styles.css

@@ -1,4 +1,10 @@
 :root {
+    --header-colour: #00000031;
+    --main-colour: #393e41;
+    --footer-colour: #00000031;
+    --text-colour: #f6f7eb;
+    --text-accent-colour: #e94f37;
+
     --header-size: 100px;
 }
 
@@ -11,11 +17,11 @@ html, body {
 }
 
 body {
-    background-color: #000000;
-    color: #FFFFFF;
+    color: var(--text-colour);
     font-family: sans-serif;
     display: flex;
     flex-flow: column;
+    background-color: var(--main-colour);
 }
 
 
@@ -27,6 +33,7 @@ header main footer {
 header {
     position: fixed;
     top: 0;
+    background-color: var(--header-colour);
 }
 
 /* Required to set the width and height of the header, as `fixed` elements can't have their size set. */
@@ -39,11 +46,13 @@ main {
     flex: 1 1 auto;
     margin-top: var(--header-size);
     text-align: center;
+    background-color: var(--main-colour);
 }
 
 footer {
     flex: 0 1 auto;
     display: flex;
+    background-color: var(--footer-colour);
 }
 
 footer > div {