When chrome on mac is debugging the mobile phone page, why does the border of the input form not display?

the following figure (the test border is in the placeholder property)

this is the focus effect, showing outline;

input

how can I get this default border to be displayed? Otherwise, it will not be convenient for me to adjust the style.

Note: this border will be displayed when I take my page to another normal windows computer. What are the default settings for the latest version of chrome?

< H2 > ps: is not displayed when debugging the mobile phone page, and a normal pc page will display a border. < / H2 >

chrome version: version 70.0.3538.110 (official version)
mac version: macOS Mojava 10.14.1

Chrome-devtools css chrome macos

Dec.27,2021

this seems to be normal.
the default style for displaying input / textarea in different browsers is different.
that's why normalize.css exists

so you may have to write a little style yourself to show it, or introduce the normalize.css mentioned above

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