optimize Mastering Bitcoin excerpt image

index.md

@@ -20,9 +20,12 @@ A practical explanation of how weak entropy can ruin your day - and your savings
 - Think of this as securing your online bank account with a password manager that creates a long random password, but it often creates the same passwords for every user. Malicious people have figured this out and drained funds on any account they can find.
 
 ## How?
-<div style="float: left; margin-right:40px;margin-left:20px; margin-top:20px;margin-bottom:30px; width: 50%">
-    <img width="100%" src="/assets/base/bx-mastering-bitcoin.png" />
-    <div style="font-size: 12px">
+<div style="float: left; margin-right:40px;margin-left:20px; margin-top:20px;margin-bottom:30px; width: 50%; display:table;">
+    <div style="display:table-row; justify-content: space-around;">
+      <img style="display: table-cell; vertical-align: middle;" width="25%" src="/assets/base/bx-mastering-bitcoin_left.jpg" />
+      <img style="display: table-cell; vertical-align: middle;" width="75%" src="/assets/base/bx-mastering-bitcoin_right.jpg" />
+    </div>
+    <div style="display: table-footer;" style="font-size: 12px; margin-top: 10px;">
         Mastering Bitcoin - Second Edition by Andreas M. Antonopoulos LLC is licensed under a Creative Commons Attribution-ShareAlike 4.0 International License.
     </div>
 </div>