Is it better for a girl not to wear red? What if a garmant has just a red stripe? Does this apply to everything, including pyjamas and clothing just worn around the house?

Shalom U'varacha The prohibition against wearing red is in fact a prohibition against wearing "loud" clothing that draws attention to the woman wearing it. If one wears clothing that has red in it but is still modest then it is permitted. This is also the case regarding any clothing worn at home or in a private place. Kol Tuv Rabbi Gideon Weitzman