For your plan B (to center the text within the triangle both vertically and horizontally), which I prefer as solution, you could add this css rule:
.up p {
text-align: center;
top: 80px;
left: -47px;
position: relative;
width: 93px;
height: 93px;
margin: 0px;
}
Try it here:
.up {
width: 0px;
height: 0px;
border-style: inset;
border-width: 0 100px 173.2px 100px;
border-color: transparent transparent #007bff transparent;
float: left;
transform: rotate(360deg);
-ms-transform: rotate(360deg);
-moz-transform: rotate(360deg);
-webkit-transform: rotate(360deg);
-o-transform: rotate(360deg);
}
.up p {
text-align: center;
top: 80px;
left: -47px;
position: relative;
width: 93px;
height: 93px;
margin: 0px;
}
<div class="up">
<p>some information text goes here
<p>
</div>