Ah, I forgot you were using an OLED, which unfortunately rules out colours.
I'd be tempted to draw a single-pixel line (instead of the ">" character, or the "-" character you've used). I'd keep the highlight personally - but YMMV.
I've actually switched away from an OLED for my project - partly because they're expensive for their size (I was using Adafruit's 128x128 display, which costs a little over £20/unit); now I use a 128x160 TFT: The per unit price is around £6.00 (from a reputable supplier), I get a whole pile of colours, and some extra pixels to boot. Yeah, the viewing angle isn't as good as OLED, but that doesn't seem to be a problem in normal use.