BlueGriffon HELP - Images in a row that realign depending on window size

I am completely new to this so bare with if it's obvious.

I have three images in a row at full screen which I want to realign in accordance to the window size, i.e. go to two, then one (while always centred). The other images then being displayed underneath vertically.

This is what the code looks like (with the image location removed)

<div class="img_container"> <img id="img2" alt="" src="IMAGE">

#im1 {
display: block;
top: 250px;
background-color: white;
width: 250px;
height: 250px;
position: absolute;
left: 558px;
}

thank you!!