Condensed Statements of Convertible Preferred Stock and Stockholders' Equity (Deficit) (Unaudited) - USD ($) shares in Thousands, $ in Thousands	Total	Common Stock	Additional Paid-in Capital	Accumulated Other Comprehensive Loss	Accumulated Deficit	Convertible Preferred Stock
Balance at Dec. 31, 2019	$ (65,357)		$ (43,172)		$ (22,185)
Temporary equity, balance, Shares at Dec. 31, 2019						37,267
Temporary equity, balance at Dec. 31, 2019						$ 134,720
Balance, Shares at Dec. 31, 2019		2,989
Issuance of common stock upon exercise of stock options, net of repurchases	16		16
Issuance of common stock upon exercise of stock options, net of repurchases, Shares		41
Vesting of early exercise options	14		14
Issuance of Series C convertible preferredstock, net of issuance costs of $100						$ 2,200
Issuance of Series C convertible preferred stock, net of issuance costs, Shares						538
Stock-based compensation	449		449
Net loss	(6,085)				(6,085)
Balance at Mar. 31, 2020	(70,963)		(42,693)		(28,270)
Temporary equity, balance, Shares at Mar. 31, 2020						37,805
Temporary equity, balance at Mar. 31, 2020						$ 136,920
Balance, Shares at Mar. 31, 2020		3,030
Balance at Dec. 31, 2020	306,223	$ 4	372,764	$ (5)	(66,540)
Balance, Shares at Dec. 31, 2020		37,569
Issuance of common stock upon exercise of stock options	$ 24		24
Issuance of common stock upon exercise of stock options, Shares	31	31
Vesting of early exercise options	$ 10		10
Stock-based compensation	3,701		3,701
Net loss	(23,844)				(23,844)
Other comprehensive gain	2			2
Balance at Mar. 31, 2021	$ 286,116	$ 4	$ 376,499	$ (3)	$ (90,384)
Balance, Shares at Mar. 31, 2021		37,600