upd

frontend/app/assets/styles/main.scss

@@ -1,4 +1,23 @@
-* {
+@import url('https://fonts.googleapis.com/css2?family=Newsreader:ital,opsz,wght@0,6..72,300;0,6..72,400;1,6..72,400&family=JetBrains+Mono:wght@400&display=swap');
+
+:root {
+  --canvas:         #FBFBFA;
+  --surface:        #FFFFFF;
+  --surface-subtle: #F7F6F3;
+  --border:         #EAEAEA;
+  --text-primary:   #111111;
+  --text-secondary: #787774;
+  --text-muted:     #C2BFBB;
+  --font-sans:      'Helvetica Neue', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
+  --font-serif:     'Newsreader', Georgia, 'Times New Roman', serif;
+  --font-mono:      'JetBrains Mono', 'SF Mono', Consolas, 'Courier New', monospace;
+  --radius-sm:      4px;
+  --radius-md:      8px;
+}
+
+*,
+*::before,
+*::after {
   box-sizing: border-box;
 }
 
@@ -7,4 +26,14 @@ body {
   margin: 0;
   padding: 0;
   height: 100%;
+  font-family: var(--font-sans);
+  background: var(--canvas);
+  color: var(--text-primary);
+  -webkit-font-smoothing: antialiased;
+  -moz-osx-font-smoothing: grayscale;
+}
+
+::selection {
+  background: #111111;
+  color: #FFFFFF;
 }