If the Hans Christian Andersen is the sample page, adding the margin left and width to your existing rule should do it
.single-post .page-title {
font-family:lato;
padding-top: 0.2cm;
font-size:calc(1.4em + 0.7vw);
padding-bottom:0.9em;
text-align:center;
line-height:1.3;
color:#353535;
margin-top:0.8em;
margin-left: -96px;
width: 930px;
}
The margin left should be half the difference between the normal width and the new one (930)