CSS - ayuda con css en bootstrap

<div class="container">

    <div id="signupbox" style="margin-top:50px" class="mainbox col-md-6 col-md-offset-3 col-sm-8 col-sm-offset-2">

        <div class="panel panel-info">

            <div class="panel-heading">

                <div class="panel-title">Reg&iacute;strate</div>

                <div style="float:right; font-size: 85%; position: relative; top:-10px"><a id="signinlink" href="index.php">Iniciar Sesi&oacute;n</a></div>

            </div>