refactor component styles to use type-safe stitches tokens

https://stitches.dev/docs/typescript#stricter-experience

components/Content/Content.tsx

@@ -1,9 +1,9 @@
-import { styled } from "../../lib/styles/stitches.config";
+import { styled, theme } from "../../lib/styles/stitches.config";
 
 const Content = styled("div", {
   fontSize: "0.9em",
   lineHeight: 1.7,
-  color: "$text",
+  color: theme.colors.text,
 
   "@medium": {
     fontSize: "0.925em",