fixed colors and added assets

src/styles/global.css

@@ -1,5 +1,9 @@
 body {
-  background: var(--color-bg);
+  background-image: url('../assets/common/background.jpeg');
+  background-size: cover;
+  background-position: center;
+  background-repeat: no-repeat;
+  background-attachment: fixed;
   color: var(--color-text);
   font-family: var(--font-family-base);
   line-height: 1.5;