how to make a transparent div?

Answer 1

Use the hexadecimal Color values and rgba property as shown in the code. The last number can be between 0.1 and 1.0.
https://code.sololearn.com/W939Sfgdzc7J/?ref=app

Answer 2

Use opacity property.

Answer 3

opacity: 0;

Answer 4

A div is transparent. Unless you style it.