Since the name is for a girl, I would suggest 婕然婕然 instead of 捷然, unless you have attached a story or meaning to the latter.
婕 - handsome. (婕妤 - the official name of the female officer in the Han Dynasty)
然 is a sex-neutral word with many good meanings such as certainly, pledge, promise, understand, agree, fit, ... (the most associated words - 自然, 天然...)
Another suggestion will be "潔然", 取義於"簡潔自然".