Revert "Revert "added reference images""

This reverts commit 1c6819b0a8f96aa502f38810c0a07b1c3ee3dd53.
Merge branch 'master' into referenciak-#48

Conflicts:
	index.php
added some "logos" to Referenciak #48
added reference boxes and aligned in 80-89em #48
fixed box width in 64-80em #48
fixed box margin-top in 80-89em #48
fixed box margin-top in 89-100em #48
replaced box background to gradient one #48
replaced small boxes background to gradient one #48
modified colors #48
using different colors #48
Revert "using different colors #48"

This reverts commit 9dbfb7cf89ec61825224500ea47c583068a72013.
added links to box-text #48
changed links #48
Merge branch 'master' into referenciak-#48
added more references to 3rd slide #48
modifed some align in every >64em viewport #48
modified positions & aligns in mobile 30em viewport #48
modified positions & aligns in 30-48em viewport #48
modified aligns in 48-64em viewport #48