Sentence:  Byron was insouciant towards the risks he took. Many of his best passages are strikingly joyous and carefree, in prose that's <WSD>lambent</WSD>, simple and brilliantly observed, as in this conclusion to a sunset at the shrine of Niamatullah: ... 
Meaning of the word marked with <WSD> tags:  Exhibiting lightness or brilliance of wit; clever or witty without unkindness.