I'm starting to customize my site at https://micro-flex.myshopify.com/, and I need to resize the banner. It's currently forcing the banner to be 920px wide, even though the original images are 1170px wide. I've change the CSS for the divs that hold the image, and I tried re-uploading the pictures after making those changes, but it's still forcing the image to be 920px wide. Any ideas on how to fix this?
look at the root src of the img in the code and you'll see that the image is in fact 920px --- so when you say that you re-uploaded some original images that are 1170px they are not being refrenced in the slideshow -- perhaps it has something to do with the way you choose files in the theme customization settings. you may need to remove the old images and then select files again to try and get a fresh start -- especially if the file names of the 920px images and the 1170px images are the same.
Otherwise, you can check in the theme config file to find the inputs for the slider images to see if they are trimming your upload files (possible, but unlikely)