[type="radio"] {
visibility: hidden; /* hide default radio button */
/* you may need to adjust margin here, too */
}
[type="radio"]::before { /* create pseudoelement */
border: 2px solid gray; /* thickness, style, color */
height: .9em; /* height adjusts with font */
width: .9em; /* width adjusts with font */
border-radius: 50%; /* make it round */
display: block; /* or flex or inline-block */
content: " "; /* won't display without this */
cursor: pointer; /* appears clickable to mouse users */
visibility: visible; /* reverse the 'hidden' above */
}
[type="radio"]:checked::before { /* selected */
/* add middle dot when selected */
/* slightly bigger second value makes it smooth */
/* even more (e.g., 20% 50%) would make it fuzzy */
background: radial-gradient(gray 36%, transparent 38%);
}