Change body font-family and add font-weight styles

Updated font-family for body and added font-weight styles for headings and links.

Author: fwanderlingh

css/styles.css

@@ -53,14 +53,30 @@ html {
 
 body {
   margin: 0;
-  font-family: Inter, ui-sans-serif, system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
+  font-family: "Fira Sans", ui-sans-serif, system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
   color: var(--text);
   min-height: 100vh;
   line-height: 1.6;
   overflow-x: hidden;
   transition: background 220ms ease, color 220ms ease;
 }
 
+h1, h2, h3 {
+  font-weight: 700;
+  letter-spacing: -0.02em;
+}
+
+body {
+  font-weight: 400;
+}
+
+.nav a,
+.button,
+.card-link,
+.final-info-link {
+  font-weight: 500;
+}
+
 body:not(.dark-theme) {
   background:
     radial-gradient(circle at top left, rgba(43, 187, 216, 0.12), transparent 30%),