Hide hex dump and disk info until disk is loaded

src/components/PlaygroundView.vue

@@ -75,17 +75,21 @@ function onReadProgress(read: number, total: number) {
       <div v-else>No disk loaded</div>
     </div>
   </section>
-  <section>
+  <section v-if="diskReadyState === 'read-success'">
     <h2>Disk Hex Dump</h2>
     <HexDump :buffer="diskData" />
   </section>
-  <section>
+  <section v-if="diskReadyState === 'read-success'">
     <h2>Disk Info</h2>
     <DiskInfo :data="diskData" />
   </section>
 </template>
 
 <style scoped>
+nav {
+  margin-bottom: 1rem;
+}
+
 .cols {
   display: flex;
   flex-direction: row;