why not use flexbox ? so wrap them into another div like that
.flexContainer { _x000D_
_x000D_
margin: 2px 10px;_x000D_
display: flex;_x000D_
} _x000D_
_x000D_
.left {_x000D_
flex-basis : 30%;_x000D_
}_x000D_
_x000D_
.right {_x000D_
flex-basis : 30%;_x000D_
}
_x000D_
<form id="new_production" class="simple_form new_production" novalidate="novalidate" method="post" action="/projects/1/productions" accept-charset="UTF-8">_x000D_
<div style="margin:0;padding:0;display:inline">_x000D_
<input type="hidden" value="?" name="utf8">_x000D_
<input type="hidden" value="2UQCUU+tKiKKtEiDtLLNeDrfBDoHTUmz5Sl9+JRVjALat3hFM=" name="authenticity_token">_x000D_
</div>_x000D_
<div class="flexContainer">_x000D_
<div class="left">Proj Name:</div>_x000D_
<div class="right">must have a name</div>_x000D_
</div>_x000D_
<div class="input string required"> </div>_x000D_
</form>
_x000D_
feel free to play with flex-basis percentage to get more customized space.