.o-back-to-top {
    position: fixed;
    right: max(16px, env(safe-area-inset-right));
    bottom: max(16px, env(safe-area-inset-bottom));
    z-index: 90;
    display: grid;
    place-items: center;
    width: 48px;
    height: 48px;
    padding: 0;
    border: 1px solid #cad8e8;
    border-radius: 50%;
    background: #06345d;
    color: #fff;
    box-shadow: 0 3px 12px #03182b33;
    cursor: pointer;
}
.o-back-to-top:hover { background: #03182b; }
.o-back-to-top:focus-visible {
    outline: 3px solid #06345d;
    outline-offset: 3px;
    box-shadow: 0 0 0 3px #fff;
}
.o-back-to-top[hidden],
.has-modal-open .o-back-to-top,
body:has(dialog[open]) .o-back-to-top { display: none; }
@media (min-width: 960px) {
    .o-back-to-top {
        right: max(24px, env(safe-area-inset-right));
        bottom: max(24px, env(safe-area-inset-bottom));
    }
}