Hello,
Please check file in components/com_booking/views/reservation/tmpl/default.php
There is line at the end: <div class="clr></div>
Repair it to: <div class="clr"></div>
It should repair your bug.
And you can set time format in configuration page. It is in tab Main and there are those fields (with examples of settings):
Date format:
Use custom formats
Long format:
j.n.Y G:i
Normal format:
j.n.Y
Format daily/weekly calendar:
j.n.
Format monthly calendar:
j.n.
Time:
G:i
If you want to set your own formats, please check
PHP Date - Manual