Microsoft Windows and Apple Mac are two of the most widely used desktop operating systems worldwide, the only drawback of these two operating systems is that they’re not free (Mac is now free but you can only deploy it on an Apple product so it’s not totally free) but if you’re looking for a free and open source operating system then look no further than Linux. But it might be a little bit tempting for beginners to choose a proper Linux distro to start with.
If you’re new to Linux and wondering what a Linux distro is; think of a distro as a distinct flavor of Linux that has its own advantages and in some cases its uses. For example Kali Linux is a Linux distro that is optimized for offensive security. But the best Linux distro for beginners is Linux Mint.
This post will present a step by step guide on how to change the panel’s color and make it transparent/semi-transparent in Linux Mint.
Step One: Press Alt-F2, type gksu gedit and press Enter.

Step Two: Browse to the folder /usr/share/themes/Linux Mint/cinnamon under “File System” and open this file cinnamon.css

Step Three: Search for a section beginning with (#panel).

Step Four: After the last line within the section, insert a new line for example background-color: rgba(,0,0,0.1); (The alpha value ranges from 0 [full transparency] to 1 [full opacity].).
Example – background-color: rgba(215,40,40,0.1);
215,40,40 = The first 3 number column is the color code. 215,40,40 will give you a sort of red color. The last column, is the opacity. In this case, 0.1 makes it really transparent. If you want opacity to be at 100%, you would then change the numbers to background-color: rgba(215,40,40,1);

Step Five: Click Save and close the file.
Step Six: Now, you have to switch to another theme and back to the Linux Mint theme to see the result.
That was it, now you have successfully changed the transparency of any panel in Linux Mint.