The Gītā with Rāmānuja's commentary, everything clickable. Every word of the verses and of the Śrī-bhāṣya-school commentary opens its sandhi-split, grammar and meaning; every block of commentary carries an English and a বাংলা translation. देवनागरी / বাংলা changes script throughout, popups included. Rāmānuja comments on runs of verses, so a block is printed once, headed with the range it covers.

Typing Sanskrit: the A button by the search box turns on typing in the script the page is showing — A ⇄ अ in Devanāgarī, A ⇄ অ in Bengali. A bare consonant carries its own a, so yog gives योग / যোগ; a comma is the halant, so dhr,m gives धर्म / ধর্ম. The ⌃ button hides this whole bar; on a phone it also slides away as you scroll down.