I don't had the problem when I tested the css the problem but that depend on the browser. 

If you know how to fix it that would be awesome!
 Just saw the PR thanks!
 Probably after this change there will be still horizontal scroll-bar because I saw some other elements longer then 100% (with padding, margins and borders) . Even if they are - they will not be as significant as ones solved in PR.

Javadoc CSS width issue
There is some minor problem with element width (CSS) on javadoc site.
Some elements are too wide and are causing horizontal scroll bar to show up.

I post picture to show what is going on.

https://s9.postimg.io/xlbg2e0ul/mockito_javadoc.png

src/javadoc/stylesheet.css
src/javadoc/stylesheet.css
diff --git a/src/javadoc/stylesheet.css b/src/javadoc/stylesheet.css
index b33442208a..f4b3dd7fd5 100644
--- a/src/javadoc/stylesheet.css
+++ b/src/javadoc/stylesheet.css
@@ -246,15 +246,16 @@ Heading styles
 ul.blockList ul.blockList li.blockList h3, ul.blockList ul.blockList li.blockList h3 {
     background:#E0E6DF;
     border:1px solid #C0C0C0;
-    width: 110%;
-    margin-left: -1em;
-    padding-left: 1em;
+    width: 100%;
+    margin-left: 0;
+    padding-left: 0;
 }
 div.summary ul.blockList ul.blockList li.blockList h3 {
     background:#E0E6DF;
-    border:0;
-    border:1px solid #C0C0C0;
-    padding-left:5px;
+    border: 0 solid #C0C0C0;
+    padding: 0;
+    margin: 0;
+    width: 100%;
 }
 div.summary ul.blockList ul.blockList ul.blockList li.blockList h3 {
     background:#E0E6DF;
