Mobile ui (#227)

* Basic grid setup

* Fixing thumb on two-up

* Adding margin so you can still access the two-up

* Allow multi-panel to keep one open only

* Edge cases for one-open

* Abstracting results so it can be used as a heading.

* Ordering of items in mobile view. Changing scrolling element.

* Adding labels to collapsed view

* Adding height animation to multi-panel

* Fixing animation bugs

* Expand/collapse icon

* Allow two-up and pinch-zoom to work beneath controls

* Range bubble now behaves properly on mobile

* No longer need this.

* Prevent options overflow at larger widths

src/lib/util.ts

@@ -258,3 +258,43 @@ export function konami(): Promise<void> {
     window.addEventListener('keydown', listener);
   });
 }
+
+interface TransitionOptions {
+  from?: number;
+  to?: number;
+  duration?: number;
+  easing?: string;
+}
+
+export async function transitionHeight(el: HTMLElement, opts: TransitionOptions): Promise<void> {
+  const {
+    from = el.getBoundingClientRect().height,
+    to = el.getBoundingClientRect().height,
+    duration = 1000,
+    easing = 'ease-in-out',
+  } = opts;
+
+  if (from === to || duration === 0) {
+    el.style.height = to + 'px';
+    return;
+  }
+
+  el.style.height = from + 'px';
+  // Force a style calc so the browser picks up the start value.
+  getComputedStyle(el).transform;
+  el.style.transition = `height ${duration}ms ${easing}`;
+  el.style.height = to + 'px';
+
+  return new Promise<void>((resolve) => {
+    const listener = (event: Event) => {
+      if (event.target !== el) return;
+      el.style.transition = '';
+      el.removeEventListener('transitionend', listener);
+      el.removeEventListener('transitioncancel', listener);
+      resolve();
+    };
+
+    el.addEventListener('transitionend', listener);
+    el.addEventListener('transitioncancel', listener);
+  });
+}