adjust font size

app/javascript/elements/page_container.js

@@ -0,0 +1,14 @@
+export default class extends HTMLElement {
+  connectedCallback () {
+    this.image.addEventListener('load', (e) => {
+      this.image.setAttribute('width', e.target.naturalWidth)
+      this.image.setAttribute('height', e.target.naturalHeight)
+
+      this.style.aspectRatio = `${e.target.naturalWidth} / ${e.target.naturalHeight}`
+    })
+  }
+
+  get image () {
+    return this.querySelector('img')
+  }
+}