Ramallah is a diverse city and it is common to see a variety of different attires around the city. However, it is best to be aware of the cultural norms and dressing modestly is recommended. For women, less attention will be drawn if your shoulders and knees are covered. Transparent tops, spaghetti straps, low necklines, and short skirts and shorts are unusual here except for in bars and some restaurants. Ramallah is accustomed to a regular amount of tourists and it is unlikely that your attire will cause problems but it may make your stay more enjoyable to dress like the locals and people will be less inclined to harass or make comments.
For men, longer shorts are permissible, but be aware that shorter shorts are not culturally normative.