<style>
.alert{
position: absolute; top: 0px; left: 0px; display: block; width: 100%; height: 100%;
}
.alert1{
width: 300px; background: #E7F0F5; padding: 10px; border: 1px Solid #95BED6;
}
</style>

<div class="alert" id="alert"><table width="100%" height="100%">
<tr><td align="center"><div class="alert1"><span style="color: #ff0000; font-size: 20pt; font-weight: bold; font-family: Verdana;">!!!</span><br><br>
ТЕКСТ<br><br><input type="button" value="OK" style="width: 60px;" onClick="document.getElementById('alert').style.display = 'none';" id="alert_kill"></div></td></tr></table></div>