Magento 2 arranging form fields column wise and full width

For changing layout of a list form to column wise we need to change the display to flex and flex-warp to wrap state.

For example:

this form was created using the following css: (to the main div)

.contactus .amcform-page-wrap {
display: flex;
flex-wrap: wrap;

}

for the sub divisions:

.contactus .rendered-form .fieldset .fields .field.form-group {
margin-bottom: -13px;
flex: 0 0 50%;
max-width: 50%;
padding: 10px 10px;
}

width 100% and flex 0 0 50% :for the column display

width:50% and flex 0 0 100% for full stretchered form.