Bug 1576599 - Calculate the flex-basis of the login-item detail rows from the left (start) side to keep the copy buttons aligned in small windows. r=ntim

Differential Revision: https://phabricator.services.mozilla.com/D44037

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

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

@@ -114,7 +114,7 @@ input[type="url"][readOnly]:hover:active {
 .detail-row-contents {
   display: flex;
   align-items: end;
-  flex-basis: calc(100% - 360px); /* Adds a 360px flexible spacer to the right */
+  flex-basis: 340px; /* Allows for 360px of flex on the end (700px (the default 100% width) - 340px) */
   max-width: 100%;
 }