Toggle 5 columns in big screen to 3 columns in mobile

Hi!
I have to display 3 columns per row on the mobile. I entered this code

@media only screen and (max-width:767px) {
.tech-boll-mobile-box {
width:32%!important;
}
.tech-boll-mobile-box.av_one_fifth{
margin-left:1%!important;
clear: none;
float: left;
}}

<img src="<img src=”https://i.ibb.co/64PpxxX/1.jpg&#8221; alt=”1″ border=”0″ />” alt=”null” />

but it doesn’t work correctly. The columns are not aligned and there are white spaces.

You can help me?