The box’s height is 130px, couldn’t figure out why?

    <style>
        .box {
            line-height: 120px;
            background-color: #cd0000;
            color: #fff;
        }

        .content {
            display: inline-block;
            line-height: 20px;
        }
    </style>

    <div class="box">
        <div class="content">1<br />2<br />3<br />1</div>
    </div>

Set .box’s height 120px,it will be 120px, but I don’t know why the 130px happen?