ENFOLD – fix element at the bottom of a Colour Section / browser

Hey there. i got a problem:
I want a special element, that is fixed at the bottom of the browser.

I have a Page, with a colourSection element. In this colour section element is a textbox, that contains a shortcode. for this Textbox i set a custom class named “slide_face”

How can i set via custom css, that the whole textbox is set to the bottom of the page?
(i tried the following, but has no effect)

.slide_face {
position:fixed;
bottom:0;
}

do you have any further hints for me!?

much thanks in advance for your help