Formatting Fonts in image blocks (poster) Vertical center align

Site URL: http://switch.squarespace.com

Need help with the following- 

1. vertical centering the text in all 3 boxes
2. making it so it doesn't overflow the boxes when they're sized down (see image 2)
3. Changing the font color in box 1 & 3 to black but keeping font white in center box

(maybe a better way to say this: i basically want it to look like the first image at all times, but with black text over the 2 white boxes)

thanks in advance for any help you guys can throw my way!! 🙏🙏

Add to Home > Design > Custom CSS

div#block-yui_3_17_2_1_1586818319104_30084+.row>.span-4:first-child *, div#block-yui_3_17_2_1_1586818319104_30084+.row>.span-4:last-child * {
    color: black;
     background-image: linear-gradient(to right, black, black);
}
/* align */
div#block-yui_3_17_2_1_1586818319104_30084+.row>.span-4:first-child .image-subtitle.sqs-dynamic-text, div#block-yui_3_17_2_1_1586818319104_30084+.row>.span-4:last-child .image-subtitle.sqs-dynamic-text {
	display: flex;
}