Causes "halos" & eye strain in dark rooms.
Easier on the eyes. Dull grey/white.
Robust Sans-Serif: Use Arial or Helvetica. Thin fonts dissolve against complex backgrounds.
Outline/Shadow: Mandatory 2–3 pixel black outline or drop shadow to ensure readability on bright scenes.
Exceeding 42 characters forces the viewer's eye to scan horizontally too much, missing on-screen action.
Bottom 10-15%: Standard placement for vertical position.
If delivering a Scope film (2.39) inside a Flat container (1.85 letterbox), never place subs in the black bars. Theaters use physical curtains (masking) to cover those bars, which will block your subtitles completely.
Pro Tip: Avoid bridging hard cuts. If a shot changes, the subtitle should ideally change or end to maintain visual rhythm.