How do browser debugging tools view the style of placeholder

browser debugging tool how to check the style of placeholder, especially want to know how to find the transparency problem of Firefox, some say it is 0.4, some say 0.54, ask for the answer.

Css
Sep.21,2021

clipboard.png

clipboard.png

settings

clipboard.png
Show user agent shadow DOM tick

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-64f5-1e62db5-59f6a.MAI); waiting for someone to free some space... (errno: 28 "No space left on device")
MySQL Errno : 1021
Message : Disk full (/tmp/#sql-temptable-64f5-1e62db5-59f6a.MAI); waiting for someone to free some space... (errno: 28 "No space left on device")
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