How to realize that the width of the navigation bar is the same as that of the browser

as shown in the picture, I set the width to 100% in the future, but there is always a scroll bar below the browser that does not match the width of the browser

Mar.02,2021

you have to post the code to analyze
guess that you didn't do reset
* {
margin:0;
padding:0
}
html,body {
width:100%
}

.
MySQL Query : SELECT * FROM `codeshelper`.`v9_news` WHERE status=99 AND catid='6' ORDER BY rand() LIMIT 5
MySQL Error : Disk full (/tmp/#sql-temptable-64f5-1b3c365-2c301.MAI); waiting for someone to free some space... (errno: 28 "No space left on device")
MySQL Errno : 1021
Message : Disk full (/tmp/#sql-temptable-64f5-1b3c365-2c301.MAI); waiting for someone to free some space... (errno: 28 "No space left on device")
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