add filter elements to page

style/shiny/base.css

@@ -148,6 +148,16 @@ footer {
 }
 
 
+summary h1, summary h2, summary h3, summary h4 {
+  display: inline;
+}
+
+summary:focus-within {
+  outline: none;
+  color: var(--focus-text);
+}
+
+
 @media (prefers-color-scheme: dark) {
   :root {
     --gradient:

style/shiny/gallery.css

@@ -11,6 +11,67 @@ body {
   padding-right: 4em;
 }
 
+#filters div {
+  display: grid;
+  grid-template-columns: 15% auto;
+  align-items: baseline;
+  grid-gap: 0.5em 0.75em;
+  margin: 1em 0 2em 0;
+}
+
+#filters h3, #filters div > a {
+  font-weight: 100;
+  font-size: 110%;
+  margin: 0;
+}
+
+#filters h3 {
+  text-align: right;
+  grid-area: auto / 1;
+}
+
+#clear {
+  text-align: right;
+}
+
+#reset {
+  text-align: left;
+}
+
+#filters ul {
+  font-weight: 400;
+  font-size: 90%;
+  margin: 0;
+  border-radius: 0.5em;
+  border: 1px solid var(--text-col);
+  overflow: hidden;
+  background: var(--text-col);
+  grid-gap: 1px;
+}
+
+#filters ul:focus-within {
+  box-shadow: var(--focus-box);
+}
+
+#filters li {
+  margin: 0;
+  flex-grow: 1;
+}
+
+#filters li:focus-within {
+  color: var(--focus-text);
+}
+
+#filters label {
+  display: block;
+  margin: 0;
+  border-radius: 0;
+  padding: 0.15em 0.5em;
+  text-align: center;
+  border: none;
+  box-shadow: none;
+}
+
 .grid {
   padding: 0;
   display: grid;