My current project involves sending verification emails to users using the php mail function. The email is styled with html and css, and while most of the styling appears correctly when the email is received, I noticed that certain flex commands such as flex-direction are not rendering properly. Upon inspecting the email code, I realized that these specific CSS properties were missing from the sent email. Here is a snippet of the HTML code:
<!DOCTYPE html>
<html lang="en">
...
// Complete HTML code goes here
...
</html>
Expected outcome: https://i.sstatic.net/Yn6qm.png
Actual Gmail display: https://i.sstatic.net/3I3Z0.png
Upon inspecting Gmail's code, I found that certain flex properties like flex-direction were missing. How can I resolve this issue?