bootstrap columns css code example
Example 1: .col-12 bootstrap
.col-12{
flex: 0 0 100%;
max-width: 100%;
}
Example 2: bootstrap grid class
col-12 col-sm-4 col-md-3 col-lg-12 col-xl-12
Example 3: .row bootstrap
.row{
display: flex;
flex-wrap: wrap;
margin-right: -15px;
margin-left: -15px;
}