Issue in changing angle of diagonal border

Hello,
I’m trying to change the angle of my diagonal angles and I found the code line in the shortcodes.css.
I tried copying the css in a new css folder in my child them, no change. I tried adding the code to the custom.css with important, no change. i finally change the initial css and still no change… does anybody know what to do?
Thanks in advance :-)

.avia_transform .av-extra-border-element.border-extra-diagonal .av-extra-border-inner {
-webkit-transform: rotate(2deg)!important;
transform: rotate(2deg)!important;
}
.avia_transform .av-extra-border-element.border-extra-diagonal.border-extra-diagonal-inverse .av-extra-border-inner{
-webkit-transform: rotate(-2deg)!important;
transform: rotate(-2deg)!important;
}