Problem with CSS, please help!

It’s supposed to be a style that replaces the look of the standard checkbox. To remove it, add this custom css using a css plugin:

input[type="radio"] + span:before, 
input[type="checkbox"] + span:before,
input[type="radio"] + span:after, 
input[type="checkbox"] + span:after {
    display: none;
}

Wow! That was it! Thanks!:-)))
One last question so that I better understand:
I pasted your code in the theme editor and it didn’t work.
Then I downloaded a CSS plugin and put the code there and it worked.
How come?

Hi all,
I think my problem is similar.
My contact form is https://www.newhorizon.ac.nz/enrol/ (although you have to scroll down to see)
Am using it as an application form.
Two separate issues (both which I can’t work out an answer to despite having read everything I can)

Issue 1: I receive a message that have 2 unresolved errors. BUT I have no idea what they are. They’re not highlighted so I don’t want to risk making changes solely because I have a message that somewhere I have some errors.

Issue 2: My checkboxes don’t retain the check in them even though I’ve ticked exclusive (from after the question ‘Would you stay with a student from another country?’ These could possibly be the two errors, but I think I’ve looked at the source card hard enough and it seems fine, but I would absolutely appreciate any help, I’ve exhausted my options and my brain!

Code:
<h5> 1: Personal Details </h5>
<p>Family Name<br />
[text* your-name] </p>
<p>First Name(s)<br />
[text* your-name] </p>
<p>Date of Birth<br />
[date date-569] </p>

[checkbox checkbox-896 exclusive “Male” “Female”]

<p>Nationality<br />[text text-232]

<p>Passport Number<br />[text text-232]

<p>Address<br />[textarea textarea-344]

<p>Country<br />[text* text-608]

<p>Telephone<br />[tel tel-986]

<p>Your Email<br />[email* your-email] </p>

<h5> 2: Qualification/Courses </h5>

<p>Course Start Date<br />[date* date-771]

<p>Course End Date<br />[date* date-771]

<p>Number of Weeks<br />[text text-402]

<p>Course Type<br />[select* menu-860 “Full time” “Part time (mornings)” “Part time (afternoons)” “Part time (evenings)”]

<p>Level<br />[select* menu-715 “Beginner” “Elementary” “Pre-Intermediate” “Intermediate” “Upper-Intermediate” “Advanced”]

<h5> 3: Insurance</h5>

<p>Do you need insurance?<br />[checkbox* checkbox-874 exclusive “Yes” “No”]

<h5> 4: Accommodation </h5>

<p>Do you need a homestay arranged for you?<br />[checkbox* checkbox-243 exclusive “Yes ” “No”]

<p>If “Yes”<br />
<p>Homestay type?<br />[checkbox* checkbox-243 exclusive “With children” “No children” “I don’t mind”]

<p>Would you stay with a student from another country?<br />[checkbox* checkbox-451 exclusive “Yes” “No” “I don’t mind”]

<p>Do you smoke?<br />[checkbox* checkbox-451 exclusive “Yes” “No”]

<p>Do you have health problems or allergies?<br />[checkbox* checkbox-451 exclusive “Yes” “No”]

<p>If “Yes”<br />
<p>Please specify<br />[text text-618]

<p>I have read the enrolment conditions<br />[checkbox* checkbox-808 “Yes”]

<p>[submit “Send”]</p>