Bug 1589324 - Restore max-width on .container. r=jaws

Differential Revision: https://phabricator.services.mozilla.com/D49654

--HG--
extra : moz-landing-system : lando

browser/components/aboutlogins/content/components/login-item.css

@@ -4,7 +4,7 @@
 
 :host {
   overflow: auto;
-  display: flex;
+  padding: 40px;
 
   --reveal-checkbox-opacity: .8;
   --reveal-checkbox-opacity-hover: .6;
@@ -26,8 +26,9 @@
 }
 
 .container {
-  flex-basis: 700px;
-  padding: 40px;
+  box-sizing: border-box;
+  height: 100%;
+  max-width: 700px;
   display: flex;
   flex-direction: column;
 }