📄 pos.css

html,body {
    box-sizing: border-box;
	padding:3px;
    margin:0;
    height:100%;
	width:100%;
}

button.calcbutton {
	display: inline-block;
	position: relative;
	padding: 0;
	line-height: normal;
	cursor: pointer;
	vertical-align: middle;
	text-align: center;
	overflow: visible; /* removes extra width in IE */
	width:24%;
	height:24%;
	font-weight: bold;
	color: #555555;
}

button.calcbutton2 {
	display: inline-block;
	position: relative;
	padding: 0;
	line-height: normal;
	cursor: pointer;
	vertical-align: middle;
	text-align: center;
	overflow: visible; /* removes extra width in IE */
	width:24%;
	height:24%;
	font-weight: bold;
	color: #555555;
}

button.calcbutton3 {
	display: inline-block;
	position: relative;
	padding: 0;
	line-height: normal;
	cursor: pointer;
	vertical-align: middle;
	text-align: center;
	font-size:120%;
	overflow: visible; /* removes extra width in IE */
	width:12%;
	height:24%;
}

button.actionbutton {
	display: inline-block;
	position: relative;
	padding: 0;
	line-height: normal;
	cursor: pointer;
	vertical-align: middle;
	text-align: center;
	overflow: visible; /* removes extra width in IE */
	width:33%;
	height:33%;
}

div.wrapper{
	float:left; /* important */
	position:relative; /* important(so we can absolutely position the description div */
	width:25%;
	height:25%;
	margin:0;
	padding:1px;
	border: 0.1em solid;
	box-shadow: 3px 3px 2px #888;
	text-align: center;
	box-sizing: border-box;
	background-color:#f0eeee;
}

div.wrapper2{
	float:left; /* important */
	position:relative; /* important(so we can absolutely position the description div */
	width:12.5%;
	height:25%;
	margin:0;
	padding:1px;
	border: 0.1em solid;
	box-shadow: 2px 2px 1px #888;
	text-align: center;
	box-sizing: border-box;
	background-color:#f0eeee;
}

button:active{
    background:black;
	color: white;
}

div.description{
	position:absolute; /* absolute position (so we can position it where we want)*/
	bottom:0px; /* position will be on bottom */
	left:0px;
	width:100%;
	/* styling below */
	background-color:black;
	font-family: 'tahoma';
	color:white;
	opacity:0.8; /* transparency */
	filter:alpha(opacity=80); /* IE transparency */
	text-align:center;
}

@media only screen and (max-aspect-ratio: 6/4) {
	div.description{
	min-height:20%;
	}
}

.container{
	width: 100%;
	height: 100%;
	margin: 0 auto;
	overflow: visible;
	box-sizing: border-box;
}

.row1{
	margin: 0 auto;
	width: 100%;
	height: 34%;
}

.row2{
	margin: 0 auto;
	width: 100%;
	height: 66%;
}

.div1{
	height:100%;
	width: 34%;
	float: left;
	text-align: center;
	box-sizing: border-box;
	overflow: auto;
	background-color:white;
}

.div2{
	height: 100%;
	width: 33%;
	font-size: 0;
	float: left;
	padding-left: 10px;
	box-sizing: border-box;
}

.div3{
	height: 100%;
	width: 33%;
	float: left;
	box-sizing: border-box;
}

.div4{
	height: 100%;
	width: 34%;
	float: left;
	box-sizing: border-box;
	font-size: 6px;
	padding:3px;
}

.div5{
	height: 100%;
	width: 66%;
	float: left;
	box-sizing: border-box;
	font-size: 6px;
	padding:10px;
}

p.description_content{
	padding:10px;
	margin:0px;

}

@media screen and (min-width: 892px) {
	.calcbutton{
		font-size: 18px;
	}
	.calcbutton2{
		font-size: 14px;
	}
	.actionbutton{
		font-size: 13px;
	}
	div.description{
		font-size: 15px;
	}
	.invoice{
		font-size: 14px;
	}
}

@media (max-width: 891px) and (min-width: 386px) {
	.calcbutton{
		font-size: 12px;
	}
	.calcbutton2{
		font-size: 9px;
	}
	.actionbutton{
		font-size: 12px;
	}
	div.description{
		font-size: 13px;
	}
	.invoice{
		font-size: 12px;
	}
}

@media screen and (max-width: 385px){
	.calcbutton{
		font-size: 8px;
	}
	.calcbutton2{
		font-size: 7px;
	}
	.actionbutton{
		font-size: 10px;
	}
	div.description{
		font-size: 11px;
	}
	.invoice{
		font-size: 10px;
	}
}