theme-store/themes/cb5efa80-f1e1-43ce-8c0b-fece8462d225/chrome.css

.tabbrowser-tab[usercontextid]:is([selected],
[visuallyselected],
[multiselected]):has(.tab-context-line)
  .tab-background {
  background-color: color-mix(
    in srgb,
    var(--identity-tab-color, var(--tab-group-color-gray-invert)) 10%,
    transparent
  ) !important;
  border: 2.5px solid
    color-mix(
      in srgb,
      var(--identity-tab-color, var(--tab-group-color-gray-invert)) 90%,
      transparent
    ) !important;
  opacity: 1 !important;
  border-left: 2px solid
    color-mix(
      in srgb,
      var(--identity-tab-color, var(--tab-group-color-gray-invert)) 90%,
      transparent
    ) !important;
}

.tabbrowser-tab[usercontextid]:not([selected]):not([visuallyselected]):not([multiselected]):has(.tab-context-line)
.tab-background {
  background-color: color-mix(
    in srgb,
    var(--identity-tab-color, var(--tab-group-color-gray-invert)) 5%,
    transparent
  ) !important;
  border: 2.5px solid
    color-mix(
      in srgb,
      var(--identity-tab-color, var(--tab-group-color-gray-invert)) 45%,
      transparent
    ) !important;
  opacity: 0.8 !important;
  border-left: 2px solid
    color-mix(
      in srgb,
      var(--identity-tab-color, var(--tab-group-color-gray-invert)) 45%,
      transparent
    ) !important;
}

.tabbrowser-tab .tab-context-line {
    display: none !important;
    visibility: hidden !important;
    width: 0 !important;
    min-width: 0 !important;
    margin-inline-start: 0 !important;
    padding: 0 !important;
}