Hello, since a few weeks ago, (since the update of thunderbird to version 78 in particular), we are having problems with the display of emails made with mjml (https://mjml.io/), that did not happen with previous versions. So we have seen, Thunderbird html/css render removes the css with media queries, (the html email code sent and received in thunderbird has the media query, but if I check with the developer tools the code doesn't show up ). This occurs with media queries that use @media, like "@media (min-width:600px)", "@media only screen and (min-width:600px)"... , if the styles are created with <style type="/text/css" media="(min-width:600px)" >, it displays the emails correctly. 600px is just an example, we have tested other breakpoints. This is not an addon problem, we have opened Thunderbird in safe mode and it keeps not showing well the emails. Environment: Windows 10 Pro 64bits Thunderbird 78.1.1 (32-bits)