No, websites do not need to look exactly the same in every browser, but while styling a details/summary element recently, I thought I had found smart way to make the default "open/closed" markers behave visually a bit nicer without resorting to re-invent several wheels and hacking my way with "::before" contents:

.acc-trigger {
list-style-type: none;
}
.acc-trigger .section__heading {
color: #900;
cursor: pointer;
display: inherit;
list-style-type: disclosure-closed;
list-style-position: inside;
}
.acc-item[open] .section__heading {
list-style-type: disclosure-open;
}
.acc-item .content {
margin-left: 1.25em;
}

Problem is: even without looking at another platform, Firefox, Safari and Chrome on my Mac can't find a common ground on how this should be rendered.

Firefox is spot on to my intentions:
A ...