Add patterned shadow.

source/scss/components/_listenbrainz.scss

@@ -1,10 +1,16 @@
+@use 'mixins';
+
 .listenbrainz {
+  @include mixins.patterned-shadow(0.5rem);
+
   align-items: center;
+  background-color: var(--background-1);
   border: 2px solid var(--foreground-1);
   display: grid;
   grid-template-columns: min-content auto;
   margin-top: 1rem;
   padding: 1rem;
+  width: fit-content;
 
   a {
     width: fit-content;

source/scss/components/_page-main.scss

@@ -15,6 +15,9 @@
     }
 
     a {
+      @include mixins.patterned-shadow(0.5rem);
+
+      background-color: var(--background-1);
       border: 2px solid var(--foreground-1);
       padding: 1rem;
     }

source/scss/mixins.scss

@@ -10,3 +10,20 @@ $large-breakpoint: 1200px;
     width: 100%;
   }
 }
+
+@mixin patterned-shadow($size) {
+  position: relative;
+
+  &::after {
+    --shadow-size: #{$size};
+
+    background: url('/assets/shadow-pattern.png') repeat;
+    content: '';
+    height: 100%;
+    left: var(--shadow-size);
+    position: absolute;
+    top: var(--shadow-size);
+    width: 100%;
+    z-index: -1;
+  }
+}