<img tal:define="size info/thumbSize;
margin_top python:(slide_size - size['height']) / 2"
tal:attributes="src python:info['src'] if info['displayed'] else blank_img;
<img tal:define="size info/thumbSize;
margin_top python:(slide_size - size['height']) / 2"
tal:attributes="src python:info['src'] if info['displayed'] else blank_img;