Feature/tweaks (#8)

* show copy button on focs

* change base link styling

* text-decoration underline on basic links

* basic hover and focus styles on button and tabs

* add links in footer

* change breakpoints vars

* medium breakpoint on footer

packages/dev-tools-pages/ts/components/Code.tsx

@@ -21,6 +21,9 @@ const Button = styled(BaseButton)`
     top: 1rem;
     right: 1rem;
     transition: opacity 0.2s;
+    :focus {
+        opacity: 1;
+    }
 `;
 
 const Base =