TYPO3 Core

Yes, this needs to be fixed before release of 6.2.

This is the CSS added by phpinfo() (i.e. in PHP 5.4.4):

body {background-color: #ffffff; color: #000000;}
body, td, th, h1, h2 {font-family: sans-serif;}
pre {margin: 0px; font-family: monospace;}
a:link {color: #000099; text-decoration: none; background-color: #ffffff;}
a:hover {text-decoration: underline;}
table {border-collapse: collapse;}
.center {text-align: center;}
.center table { margin-left: auto; margin-right: auto; text-align: left;}
.center th { text-align: center !important; }
td, th { border: 1px solid #000000; font-size: 75%; vertical-align: baseline;}
h1 {font-size: 150%;}
h2 {font-size: 125%;}
.p {text-align: left;}
.e {background-color: #ccccff; font-weight: bold; color: #000000;}
.h {background-color: #9999cc; font-weight: bold; color: #000000;}
.v {background-color: #cccccc; color: #000000;}
.vr {background-color: #cccccc; text-align: right; color: #000000;}
img {float: right; border: 0px;}
hr {width: 600px; background-color: #cccccc; border: 0px; height: 1px; color: #000000;}

Some of these is still required for the table styling, but some interfere with out styles.

A quick&dirty solution is indeed to manipulate this part before outputting: i.e. remove all attributes "font-family", "font-size" or prefix the selectors with a common class or identifier and make sure this output is included in such a DIV.

A more error prone solution could be to load this phpinfo() inside an IFRAME which then has no impact at all on the Install Tool styling. This IFRAME URL still needs authenticated Install Tool login, of course. And we have to cope with the IFRAME limitations (fixed height).

Patch set 1 for branch master of project Packages/TYPO3.CMS has been pushed to the review server.
It is available at https://review.typo3.org/28225

Applied in changeset 97aa83fc26c21f794bb1fd3ffa44142af6cbe077.