Images and text not resizing automatically when web browers is made smaller

Site URL: http://www.sisudesignstudio.co.uk

Hi There

is anyone able to help with my coding issue?

on three pages I have text that sites over an image block, it is responsive and resizes for mobile but when the web browser is made smaller or you look at my website on a laptop it is not. I would be really grateful if anyone has any suggestions. 

Hi. Try using rem or vw, instead of px

#home-services h3 {
    font-size: 4rem;
}