src/components/bottom-app-bar.js

@@ -11,6 +11,8 @@ const template = `
 `;
 const style = `
   :host {
+    position: fixed;
+    bottom: 20px;
     display: flex;
     height: 42px;
     width: 80%;

src/css/index.css

@@ -16,5 +16,4 @@ footer {
   display: grid;
   place-items: center;
   width: 100%;
-  height: calc(42px + 20px + 20px);
 }