Edit in JSFiddle

<div>
    <input type="checkbox" name="q[]" id="q1" /><label for="q1">小宝3225</label>
    <input type="checkbox" name="q[]" id="q2" /><label for="q2">王老白白白</label>
    <input type="checkbox" name="q[]" id="q3" /><label for="q3">空夫31</label>
    <input type="checkbox" name="q[]" id="q4" /><label for="q4">谷大白话</label>
    <input type="checkbox" name="q[]" id="q5" /><label for="q5">Meathill</label>
    <input type="checkbox" name="q[]" id="q6" /><label for="q6">一毛不拔大师</label>
    <hr />
</div>

div {
    display:flex;
    flex-direction:row;
    flex-wrap:wrap;
    font: 14px/25px Arial;
}
div:first-line {
    color:#F30;
}
input[type=checkbox],
label {
    order:2;
}
label {
    min-width:100px;
    margin-right:5px;
}
hr {
    width: 100%;
    order: 1;
    display:none;
}
input[type=checkbox]:checked {
    order:0;
}
input[type=checkbox]:checked + label {
    order:0;
}
input[type=checkbox]:checked ~ hr {
    display:block;
}