Add klmn

docs/_javascript/klmn.js

@@ -0,0 +1,40 @@
+document.addEventListener('DOMContentLoaded', () => {
+
+  const $klmnColumns = Array.prototype.slice.call(document.querySelectorAll('.bd-klmn-columns'), 0);
+  const $klmnGaps = Array.prototype.slice.call(document.querySelectorAll('.bd-klmn-gap'), 0);
+  const $klmnValue = document.getElementById('klmnValue');
+
+  $klmnGaps.forEach(el => {
+    el.addEventListener('mouseenter', () => {
+      const index = el.dataset.value;
+      selectGap(index);
+    });
+  });
+
+  function resetGaps() {
+    $klmnGaps.forEach(el => {
+      el.classList.remove('bd-is-selected');
+    });
+  }
+
+  function setColumns(n) {
+    $klmnColumns.forEach(el => {
+      el.className = `columns is-variable bd-klmn-columns is-${n}`;
+    });
+  }
+
+  function setValue(n) {
+    const rem = `${n * 0.25}rem`;
+    $klmnValue.innerHTML = rem;
+  }
+
+  function selectGap(n) {
+    resetGaps();
+    $klmnGaps[n].classList.add('bd-is-selected');
+    setColumns(n);
+    setValue(n);
+  }
+
+  selectGap(3);
+
+});