When I build in the Builder's Guild Phase, does the new building colors have to match strictly the color upper or lower or it doesn't matter where the color is, upper or lower? For example if I have a lumber mill with red (upper) and purple (lower) and I want to build a card that has purple (upper) and blue (lower), can I build it next to my lumber mill? Or it has to match the exact purple color on the upper side of the card?
If I want to build two buildings in the same round. I put the first one the left side of the lumber mill. Am I allowed to put the second building on the left side of the first building, or do I have to build it on the right side of the lumber mill?