How to extend header to the full page width? [duplicate]
问题 This question already has answers here : Removing body margin in CSS (10 answers) Closed 23 days ago . How can I extend my header to the full page? I have tried margin-left & right but that doesn't work. Header.css background: green; height: 70px; width: 100%; display: flex; justify-content: space-between; margin-bottom: 25px; left: 0; right: 0; } .header-right { float: right; } @media screen and (max-width: 500px) { .header-right { float: none; } } Here's my app.tsx file: const Header = () =