I’d like to clarify here that it’s actually alt-[number of whatever alt-bg you’ve chosen] that you have to use in the css…
This is my code now:
/* Remove white triangle on full-width items */
.alt-one.full-width-text:after, .alt-two.full-width-text:after, .alt-three.full-width-text:after, .alt-four.full-width-text:after, .alt-five.full-width-text:after, .alt-six.full-width-text:after, .alt-seven.full-width-text:after, .alt-eight.full-width-text:after, .alt-nine.full-width-text:after, .alt-ten.full-width-text:after {
display: none;
}