<div class="use-float">

    <div></div>

    <div></div>

</div>

.use-float>div:first-child{

    width:100px;

    float:left;

}

.use-float>div:last-child{

    overflow:hidden;

}

<table class="use-table">

    <tr>

        <td></td>

        <td></td>

    </tr>

</table>

.use-table{

    border-collapse:collapse;

    width:100%;

}

.use-table>tbody>tr>td:first-child{

    width:100px;

}

<div class="use-mock-table">

    <div></div>

    <div></div>

</div>

.use-mock-table{

    display:table;

    width:100%;

}

.use-mock-table>div{

    display:table-cell;

}

.use-mock-table>div:first-child{

    width:100px;

}

<div class="use-flex">

    <div></div>

    <div></div>

</div>

.use-flex{

    display:flex;

}

.use-flex>div:first-child{

    flex:none;

    width:100px;

}

.use-flex>div:last-child{

    flex:;

}