While French nouns generally have a gender, "surligneur" is considered common gender. This means it can be used with either masculine or feminine articles and adjectives depending on the context.
For example:
* Un surligneur jaune: A yellow highlighter (masculine article)
* Une surligneur rose: A pink highlighter (feminine article)
However, it's more common to use the masculine article "un" with "surligneur", even if the color is associated with femininity.