1. viewport
<!DOCTYPE html> <html lang="en"> <head> … <meta name="viewport" content="width=device-width, initialscale=1"> … </head>
2.disable the user's ability to zoom the viewport
• minimum-scale,
• maximum-scale,
• user-scalable.
3. img
img { max-width: 100%; display: block; }
layout: width better use XX%， other than XXpx;
4.