use transparency for alert background colors

Author: mydea

src/components/alert/styles.scss

@@ -41,10 +41,12 @@
 
 .alert-info {
   background: var(--desatPurple15);
+  background: color-mix(in srgb, var(--desatPurple15), transparent 10%);
 }
 
 .alert-warning {
   background: var(--desatFlame8);
+  background: color-mix(in srgb, var(--desatFlame8), transparent 10%);
 
   > .alert-icon {
     color: var(--flame5);