Demonstration
Step-by-step guide
1
Aim crosshair
Place your crosshair here

2
Throw
Press the keys to throw the grenade
Left clickRight click
Hint
Break the glass first, then take the alt mid position from the preview, aim at the marked point and throw with left click — standing, no jump.
Practice from exact position
Paste in CS2 developer console to teleport to the throw spot