Correct for our cursors' extra width

Unfortunately not as easy for the borders of the fragment selection; for
now just making those stay 'inside' the selection (through box-sizing).

app/assets/main.css

@@ -118,6 +118,7 @@ input#volume:focus {
 
 .playlist .selection.point {
 	width: 2px !important;
+	transform: translateX(-0.5px); /* Correct for the extra 1px of width we add. */
 }
 
 .playlist .selection.point::after {
@@ -137,6 +138,7 @@ input#volume:focus {
 	background: #f006;
 	border-left: 2px solid red;
 	border-right: 2px solid red;
+	box-sizing: border-box;
 }
 
 .playlist .selection.segment:before {
@@ -173,6 +175,7 @@ input#volume:focus {
 
 .playlist .cursor {
 	width: 2px !important;
+	transform: translateX(-0.5px); /* Correct for the extra 1px of width we add. */
 	background: #666;
 }