How can i add border to a form box ?

i want to add border to the bootstrap form box.i had added border style properties but its not working . suggest please

thia is the form box class:

<div class="form-box">
                   <div class="form-top">
                                <div class="form-top-left">

And this is the css :

.form-box {
    margin-top: 0px;
      border-radius: 25px;
    border-bottom-style: solid;
    border-color: #50e54b;

}