when I use position:fixed in the head, I operate the page drop-down in the web page. The head is fixed and does not follow the page drop-down. Android will not, but iOS will. Have you ever encountered 
 
 this is the time of drop-down
 this is the time of drop-down 
 when I use position:fixed in the head, I operate the page drop-down in the web page. The head is fixed and does not follow the page drop-down. Android will not, but iOS will. Have you ever encountered 
 
 this is the time of drop-down
 this is the time of drop-down 
use absolute positioning to simulate. Ios cannot be fixed on
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