css样式，改变一个图像样式，而不是所有

I'm really new to CSS and I have a sticky header menu with our company's logo in it where the menu and the image shrink to 48 pixels high once the user scrolls down. My code I use to shrink the logo is below, but how can I change just the logo image and include the .sticky to the logo image without changing all the images like I've done below with I'm really new to CSS and I have a sticky heade