Index Gallery Mobile Resize HELP PLEASE

Site URL: https://dog-clavichord-beac.squarespace.com

Hi There! 

I hope someone can help me here. Im designing a testimonial slider on my home page using a Gallery Page through my index Home page. I am having trouble resizing for mobile. I was able to achieve the tablet and desktop view but For some reason I can't resize the mobile view. The code I used for the table goes as follows: 

@media only screen and (min-width: 640px) and (max-width: 950px){.Index-gallery-item-image img {width: 150% !important;
  padding-left: 85px;}}

When I attempted to do for the mobile no matter what I change the width to nothing happened it's just giant. I tried playing with the margins and padding and it just breaks. Can someone please help me solve this issue? If it can't be resized is there a way I can replace the image for mobile only? 

In addition to resizing it is there a way to get rid of the top space on mobile only? I have attached a screenshot so you can see what I mean. 

Here is the link to site: https://dog-clavichord-beac.squarespace.com/

Password: lookingforhelp

Incorrect password. Can you check again?