Search setting alignment layout

I wanted to center my search settings in the folowwing format :
– Computer : 3 columns that are centered (this is what my website is currently showing)
– Mobile : One column with centered items (Not working, they are on the left)

I added the following Custom CSS

/* Center the parent container horizontally on all devices */
#ajaxsearchprobsettings1_1 {
text-align: center;
max-width: 1000; /* Adjust this value to your preference */
margin: 0 auto;
}

/* Adjust the positioning of the fieldsets */
#ajaxsearchprobsettings1_1 form {
/* Set the form to occupy the full width of the parent container */
width: 100%;
max-width: 1000; /* Adjust this value to your preference */
}

#ajaxsearchprobsettings1_1 fieldset {
/* Adjust the fieldsets to be displayed as block elements */
display: block;
margin: 0 auto;
max-width: 1000; /* Adjust this value to your preference */
margin-bottom: 20px; /* Adjust this value to control the spacing between fieldsets */
}

Could you help me fix it ?