uBlock/platform/mv3/extension/css/filtering-mode.css

.filteringModeSlider {
    align-items: center;
    display: flex;
    height: 60px;
    justify-content: center;
    position: relative;
    width: 240px;
    }

.filteringModeButton {
    background-color: var(--surface-1);
    box-sizing: border-box;
    border-radius: 30% 15% / 15% 30%;
    height: 100%;
    position: absolute;
    width: 25%;
    z-index: 10;
    }

.filteringModeButton > div {
    background-color: var(--accent-surface-1);
    border: 4px solid var(--accent-surface-1);
    border-radius: inherit;
    box-sizing: border-box;
    height: calc(100% - 2px);
    margin: 1px;
    width: calc(100% - 2px);
    }

.filteringModeSlider.moving .filteringModeButton > div,
.filteringModeButton > div:hover {
    filter: brightness(0.9);
    }

.filteringModeSlider[data-level="0"] .filteringModeButton > div {
    background-color: var(--surface-2);
    border-color: var(--surface-2);
    }

.filteringModeSlider span[data-level] {
    background-color: var(--accent-surface-1);
    display: inline-flex;
    height: 30%;
    margin-left: 1px;
    width: 25%;
    }

.filteringModeSlider.moving span[data-level] {
    pointer-events: none;
    }

.filteringModeSlider[data-level="0"] .filteringModeButton {
    left: 0;
    }
.filteringModeSlider[data-level="1"] .filteringModeButton {
    left: 25%;
    }
.filteringModeSlider[data-level="2"] .filteringModeButton {
    left: 50%;
    }
.filteringModeSlider[data-level="3"] .filteringModeButton {
    left: 75%;
    }
[dir="rtl"] .filteringModeSlider[data-level="0"] .filteringModeButton {
    left: 75%;
    }
[dir="rtl"] .filteringModeSlider[data-level="1"] .filteringModeButton {
    left: 50%;
    }
[dir="rtl"] .filteringModeSlider[data-level="2"] .filteringModeButton {
    left: 25%;
    }
[dir="rtl"] .filteringModeSlider[data-level="3"] .filteringModeButton {
    left: 0;
    }


.filteringModeSlider[data-level="0"] span[data-level] {
    background-color: var(--surface-2);
    }

.filteringModeSlider[data-level="1"] span[data-level]:nth-of-type(1) ~ span[data-level] {
    background-color: var(--surface-2);
    }

.filteringModeSlider[data-level="2"] span[data-level]:nth-of-type(2) ~ span[data-level] {
    background-color: var(--surface-2);
    }

.filteringModeSlider[data-level]:not(.moving) span[data-level]:hover {
    filter: brightness(0.9);
    }