ALMA continuum map in band 8 (410 GHz; top) and in Band 6 (230 GHz, bottom). Black solid contours are at levels of 1 and 2σ, where i.e σ = 40μJy/beam and σ = 7μJy/beam in the two bands, respectively. Dashed contours trace negative levels at –1 and –2σ. The synthesised beams are shown in the bottom left corners. The position of BDF-3299 measured in the HST Y-band is marked with a cross. The square mark shows the location of the [C ii] detection.