Remove unused styles and prevent postcss from purging relevant ones

modules/webapp/src/main/styles/index.css

@@ -133,32 +133,4 @@
         @apply bg-lime-200 dark:bg-lightblue-700 italic font-bold px-1;
     }
 
-
-    .tag::before {
-        position: absolute;
-        transform: translateY(-50%) translateX(50%) rotate(-45deg);
-        top: 50%;
-        right: 100%;
-        content: '';
-        background-color: inherit;
-        background-image: none;
-        border-color: inherit;
-        width: 1.2em;
-        height: 1.2em;
-        border-radius: 4px;
-    }
-
-    .tag::after {
-        position: absolute;
-        content: '';
-        top: 50%;
-        left: -.25em;
-        margin-top: -.25em;
-        background-color: #fff;
-        width: .4em;
-        height: .4em;
-        box-shadow: 0 -1px 1px 0 rgba(0,0,0,.3);
-        border-radius: 500rem;
-    }
-
 }

modules/webapp/src/main/styles/keep.txt

@@ -0,0 +1,33 @@
+- KEEP THIS
+
+this is only to prevent postcss-purge from removing these classes from
+the final css. These are provided by an elm component, that generates
+them using string concatenation, which cannot be detected by postcss.
+
+
+   elm-datepicker--container
+   elm-datepicker--input
+   elm-datepicker--picker
+   elm-datepicker--picker-header
+   elm-datepicker--prev-container
+   elm-datepicker--prev
+   elm-datepicker--month-container
+   elm-datepicker--month
+   elm-datepicker--year
+   elm-datepicker--year-menu
+   elm-datepicker--next-container
+   elm-datepicker--next
+   elm-datepicker--table
+   elm-datepicker--weekdays
+   elm-datepicker--dow
+   elm-datepicker--days
+   elm-datepicker--row
+   elm-datepicker--day
+   elm-datepicker--other-month
+   elm-datepicker--day
+   elm-datepicker--row
+   elm-datepicker--day
+   elm-datepicker--day
+   elm-datepicker--today
+   elm-datepicker--day
+   elm-datepicker--other-month

postcss.config.js

@@ -16,6 +16,7 @@ const prodPlugins =
           require("@fullhuman/postcss-purgecss")({
               content: [
                   "./modules/webapp/src/main/elm/**/*.elm",
+                  "./modules/webapp/src/main/styles/keep.txt",
                   "./modules/restserver/src/main/templates/*.html"
               ],
               defaultExtractor: content => content.match(/[A-Za-z0-9-_:/\.]+/g) || []