2.26.2

Fixed: the hidden preheader no longer carries a tiny invisible font

The preheader the renderer injects into layouts without their own {{ preheader }} (and the one
in the block layouts) was styled font-size:1px;line-height:1px, the block layouts also with the
page colour as text colour. That is the combination SpamAssassin's FONT_INVIS_MSGID (2.5 points)
looks for. The three properties are gone; display:none, max-height:0, overflow:hidden,
mso-hide:all and opacity:0 still hide the snippet, and inbox clients still read it as the
preview text. Same change as email-templates 2.8.1.