Revert "change the defult fontsize"

This reverts commit 26f0512cfd0e1ef8d9259de57ca2a4f6259e7861.
Revert "Merge remote-tracking branch 'origin/master' into learndoor_bbb_branch"

This reverts commit ddd1a162422604deabfdf92fa13539ae9a877ae4, reversing
changes made to a79e224f4bbe5a6e196007aada69014e4cfe222a.
Revert "Revert "change the defult fontsize""

This reverts commit ddbbd04ef23c621fee1d430d294e8a8878d9c9a1.