secure https address is changes from green to yellow while reading e-mail is this normal

when I open my hotmail, the https is green, but as soon as it connects, it goes yellow, or it might stay a green https but changes to yellow while I checking my different e-mails. Am I safe to read and send e-mails if it is not showing a green https? I usually google stuuf from this hot mail page. Am i safe doing so.