userContent.css
/* :root {
   --console-error-color: #fff !important;
   --console-error-border: #e3b2b245 !important;
   --console-error-background: #e78cbf3d !important;
   --theme-icon-error-color: #fff !important;

   --console-warning-color: #fff !important;
   --console-warning-border: #f7eacc85 !important;
   --console-warning-background: #f7bb5d52 !important;
   --theme-icon-warning-color: #fff !important;

   .message {
      padding: 4px;
      border-top-color: #ffffff6b !important;
   }

   .message-repeats {
      background-color: white !important;
      color: black !important;
   }

   .frame-link-filename {
      color: #bcbcbc !important;
   }

   .frame-link .frame-link-source {
      color: #bcbcbc !important;
   }

   .ruleview-rule-source-label {
      color: #c6c6c6bd !important;
   }

   .panel-container {
      background: #6c6c6c4f !important;
      border-radius: 0 0 5px 5px !important
   }

   .CodeMirror-line {
      padding: 4px !important;
   }

   .network-monitor {
      outline: 1px solid rgba(255, 255, 255, 0.5) !important;
      border-radius: 0 0 5px 5px !important;
   }

   .network.message .network-info #response-panel {
      height: 350px !important;
   }

} */

:root.theme-dark {
   --theme-tab-toolbar-background: #2a2a2c !important;
   --theme-toolbar-background: #323234 !important;
   --theme-selection-color: #ffffff !important;
   --theme-splitter-color: rgba(0, 0, 0, 0.25) !important;
   --theme-comment: #7f8c98 !important;

   --test-theme-body-background: #1e1e20 !important;
   --theme-sidebar-background: #252527 !important;
   /* --panel-background: #303033 !important; */

   --theme-body-color: #cdcdcd !important;
   --theme-body-color-alt: #e0e0e0 !important;
   --theme-content-color1: #f0f0f0 !important;
   --theme-content-color2: #cdcdcd !important;
   --theme-content-color3: #969696 !important;

   --theme-border-radius: 6px !important;
   --theme-box-shadow: 0 2px 12px rgba(0, 0, 0, 0.3) !important;
   --theme-transition-duration: 0.2s !important;
   --theme-transition-timing: cubic-bezier(0.4, 0, 0.2, 1) !important;

   --theme-selection-background: rgba(255, 255, 255, 0.07) !important;
   --theme-focus-outline-color: rgba(255, 255, 255, 0.07) !important;
   --theme-toolbar-hover: rgba(255, 255, 255, 0.07) !important;
   --theme-toolbar-active: rgba(255, 255, 255, 0.12) !important;

   --theme-highlight-blue: #82aaff !important;
   --theme-highlight-purple: #c792ea !important;
   --theme-highlight-pink: #ff5370 !important;
   --theme-highlight-red: #f07178 !important;
   --theme-highlight-orange: #f78c6c !important;
   --theme-highlight-lightorange: #ffcb6b !important;
   --theme-highlight-green: #c3e88d !important;
   --theme-highlight-bluegrey: #89ddff !important;
   --theme-highlight-yellow: #ffcb6b !important;

   --console-error-color: #fff;
   --console-error-border: #e3b2b245;
   --console-error-background: #e78cbf3d;
   --theme-icon-error-color: #fff;

   --console-warning-color: #fff;
   --console-warning-border: #f7eacc85;
   --console-warning-background: #f7bb5d52;
   --theme-icon-warning-color: #fff;

   .message {
      padding: 4px;
      border-top-color: #ffffff6b !important;
   }

   .message-repeats {
      background-color: white !important;
      color: black !important;
   }

   .frame-link-filename {
      color: #bcbcbc !important;
   }

   .frame-link .frame-link-source {
      color: #bcbcbc !important;
   }

   .ruleview-rule-source-label {
      color: #c6c6c6bd !important;
   }

   .panel-container {
      background: #6c6c6c4f !important;
      border-radius: 0 0 5px 5px !important;
   }

   .CodeMirror-line {
      padding: 4px !important;
   }

   .network-monitor {
      outline: 1px solid rgba(255, 255, 255, 0.5) !important;
      border-radius: 0 0 5px 5px !important;
   }

   .network.message .network-info #response-panel {
      height: 350px !important;
   }

   .theme-body {
      background: #18181a !important;
   }

   .devtools-tab,
   .devtools-sidebar-tabs tab {
      border-radius: var(--theme-border-radius) var(--theme-border-radius) 0 0 !important;
      transition: background-color var(--theme-transition-duration) var(--theme-transition-timing),
         box-shadow var(--theme-transition-duration) var(--theme-transition-timing),
         padding var(--theme-transition-duration) var(--theme-transition-timing) !important;
      font-family: var(--theme-font-family);
      letter-spacing: 0.2px;
   }

   .devtools-tab.selected {
      position: relative !important;
      background-color: rgba(255, 255, 255, 0.07) !important;
   }

   .devtools-tab.selected::after {
      position: absolute !important;
      bottom: 0 !important;
      left: 0 !important;
      right: 0 !important;
      height: 2px !important;
      background-color: var(--theme-highlight-blue) !important;
      border-top: 0 solid transparent !important;
      border-radius: 1px !important;
   }

   .devtools-tab:hover {
      padding: 3px !important;
   }

   .devtools-button,
   .devtools-toolbarbutton {
      border-radius: 4px !important;
      transition: all var(--theme-transition-duration) var(--theme-transition-timing) !important;
      font-family: var(--theme-font-family);
   }

   .devtools-tabbar-button:hover {
      background-color: var(--theme-toolbar-hover) !important;
      transform: translateY(-1px) !important;
   }

   .devtools-tabbar-button:active {
      background-color: var(--theme-toolbar-active) !important;
      transform: translateY(0) !important;
   }

   .devtools-button:hover,
   .devtools-toolbarbutton:hover {
      background-color: var(--theme-toolbar-hover) !important;
      transform: translateY(-1px) !important;
   }

   .devtools-button:active,
   .devtools-toolbarbutton:active {
      background-color: var(--theme-toolbar-active) !important;
      transform: translateY(0) !important;
   }

   .devtools-container,
   .devtools-sidebar,
   /* .theme-panel, */
   .devtools-main-content {
      border-radius: var(--theme-border-radius) !important;
      overflow: hidden !important;
      box-shadow: var(--theme-box-shadow) !important;
   }

   .CodeMirror,
   .inspector-tabpanel {
      border-radius: var(--theme-border-radius) !important;
      transition: opacity var(--theme-transition-duration) var(--theme-transition-timing) !important;
      font-family: "SF Mono", Menlo, monospace !important;
   }

   .tree-rows,
   .devtools-list {
      border-radius: var(--theme-border-radius) !important;
   }

   .tree-row:hover,
   .devtools-list-item:hover {
      transition: background-color var(--theme-transition-duration) var(--theme-transition-timing) !important;
      background-color: var(--theme-toolbar-hover) !important;
   }

   .devtools-separator {
      opacity: 0;
   }

   .devtools-togglebutton {
      border-block: none !important;
      padding: 4px 8px !important;
      border-radius: 4px !important;
      border: none !important;
   }

   .devtools-togglebutton[aria-pressed="true"] {
      background-color: #80808024 !important;
      color: #fff !important;
   }

   .split-box.vert>.splitter {
      min-width: 10px !important;
   }

   .split-box.horz>.splitter {
      min-height: 10px !important;
   }

   .devtools-side-splitter {
      min-width: 10px !important;
   }

   .devtools-tab-line {
      display: none;
   }

   .ruleview-enableproperty {
      appearance: auto !important;
      margin-bottom: 2px !important;
   }

   .tabs .tabs-menu-item {
      transition: background-color var(--theme-transition-duration) var(--theme-transition-timing), box-shadow var(--theme-transition-duration) var(--theme-transition-timing), padding var(--theme-transition-duration) var(--theme-transition-timing) !important;
   }

   .tabs .tabs-menu-item.is-active {
      background-color: rgba(255, 255, 255, 0.07) !important;
   }

   .tag-line {
      padding-block: 3px;
   }

   .theme-twisty {
      opacity: 0.5 !important;
      transition: opacity var(--theme-transition-duration) var(--theme-transition-timing) !important;
   }

   .theme-twisty:hover {
      opacity: 1 !important;
   }

   .theme-selected {
      background-color: #39393b !important;
   }

   .ruleview-highlight {
      background-color: rgb(0, 0, 0) !important;
   }

   .stylesheet-system.splitview-nav>li.splitview-active {
      background-color: var(--theme-toolbar-active) !important;
   }

   .devtools-tabbar-button.checked {
      color: white !important;
   }

   .tree-node.focused {
      background-color: var(--theme-toolbar-active) !important;
   }

   .tree .tree-node:not(.focused):hover {
      background-color: var(--theme-toolbar-active) !important;
      color: white !important;
   }

   .source-tab::before {
      background-color: unset !important;
   }

   .source-tab.active {
      background-color: var(--theme-toolbar-active) !important;
   }

   .checkbox-container.menu-standard-padding {
      background: #303033 !important;
      border-radius: 12px !important;
   }

   /* .tooltip-panel {
      background: transparent !important;
   }

   .tooltip-container.tooltip-bottom {
      background: transparent !important;
   }

   .tooltip-arrow {
      display: none !important;
   } */
}

:root.theme-light {
   --theme-tab-toolbar-background: #f0f0f2 !important;
   --theme-toolbar-background: #e8e8ea !important;
   --theme-selection-color: #000000 !important;
   --theme-splitter-color: rgba(0, 0, 0, 0.15) !important;
   --theme-comment: #5c6773 !important;

   --test-theme-body-background: #ffffff !important;
   --theme-sidebar-background: #f5f5f7 !important;
   /* --panel-background: #5c6773 !important; */

   --theme-body-color: #333333 !important;
   --theme-body-color-alt: #202020 !important;
   --theme-content-color1: #0f0f0f !important;
   --theme-content-color2: #333333 !important;
   --theme-content-color3: #696969 !important;

   --theme-border-radius: 6px !important;
   --theme-box-shadow: 0 2px 12px rgba(0, 0, 0, 0.15) !important;
   --theme-transition-duration: 0.2s !important;
   --theme-transition-timing: cubic-bezier(0.4, 0, 0.2, 1) !important;

   --theme-selection-background: rgba(0, 0, 0, 0.07) !important;
   --theme-focus-outline-color: rgba(0, 0, 0, 0.07) !important;
   --theme-toolbar-selected-color: black !important;
   --theme-toolbar-hover: rgba(0, 0, 0, 0.07) !important;
   --theme-toolbar-active: rgba(0, 0, 0, 0.12) !important;

   --theme-highlight-blue: #1565c0 !important;
   --theme-highlight-purple: #6a1b9a !important;
   --theme-highlight-pink: #d81b60 !important;
   --theme-highlight-red: #c62828 !important;
   --theme-highlight-orange: #ef6c00 !important;
   --theme-highlight-lightorange: #f57f17 !important;
   --theme-highlight-green: #2e7d32 !important;
   --theme-highlight-bluegrey: #0277bd !important;
   --theme-highlight-yellow: #f9a825 !important;

   --console-error-color: #000;
   --console-error-border: #e3b2b245;
   --console-error-background: #e78cbf3d;
   --theme-icon-error-color: #000;

   --console-warning-color: #000;
   --console-warning-border: #f7eacc85;
   --console-warning-background: #f7bb5d52;
   --theme-icon-warning-color: #000;

   .message {
      padding: 4px;
      border-top-color: #0000006b !important;
   }

   .message-repeats {
      background-color: black !important;
      color: white !important;
   }

   .frame-link-filename {
      color: #4c4c4c !important;
   }

   .frame-link .frame-link-source {
      color: #4c4c4c !important;
   }

   .ruleview-rule-source-label {
      color: #3c3c3cbd !important;
   }

   .panel-container {
      background: #dcdcdc4f !important;
      border-radius: 0 0 5px 5px !important;
   }

   .CodeMirror-line {
      padding: 4px !important;
   }

   .network-monitor {
      outline: 1px solid rgba(0, 0, 0, 0.5) !important;
      border-radius: 0 0 5px 5px !important;
   }

   .network.message .network-info #response-panel {
      height: 350px !important;
   }

   .theme-body {
      background: #ffffff !important;
   }

   .devtools-tab,
   .devtools-sidebar-tabs tab {
      border-radius: var(--theme-border-radius) var(--theme-border-radius) 0 0 !important;
      transition: background-color var(--theme-transition-duration) var(--theme-transition-timing),
         box-shadow var(--theme-transition-duration) var(--theme-transition-timing),
         padding var(--theme-transition-duration) var(--theme-transition-timing) !important;
      font-family: var(--theme-font-family);
      letter-spacing: 0.2px;
   }

   .devtools-tab.selected {
      position: relative !important;
      background-color: rgba(0, 0, 0, 0.07) !important;
   }

   .devtools-tab.selected::after {
      position: absolute !important;
      bottom: 0 !important;
      left: 0 !important;
      right: 0 !important;
      height: 2px !important;
      background-color: var(--theme-highlight-blue) !important;
      border-top: 0 solid transparent !important;
      border-radius: 1px !important;
   }

   .devtools-tab:hover {
      padding: 3px !important;
   }

   .devtools-button,
   .devtools-toolbarbutton {
      border-radius: 4px !important;
      transition: all var(--theme-transition-duration) var(--theme-transition-timing) !important;
      font-family: var(--theme-font-family);
   }

   .devtools-tabbar-button:hover {
      background-color: var(--theme-toolbar-hover) !important;
      transform: translateY(-1px) !important;
   }

   .devtools-tabbar-button:active {
      background-color: var(--theme-toolbar-active) !important;
      transform: translateY(0) !important;
   }

   .devtools-button:hover,
   .devtools-toolbarbutton:hover {
      background-color: var(--theme-toolbar-hover) !important;
      transform: translateY(-1px) !important;
   }

   .devtools-button:active,
   .devtools-toolbarbutton:active {
      background-color: var(--theme-toolbar-active) !important;
      transform: translateY(0) !important;
   }

   .devtools-container,
   .devtools-sidebar,
   /* .theme-panel, */
   .devtools-main-content {
      border-radius: var(--theme-border-radius) !important;
      overflow: hidden !important;
      box-shadow: var(--theme-box-shadow) !important;
   }

   .CodeMirror,
   .inspector-tabpanel {
      border-radius: var(--theme-border-radius) !important;
      transition: opacity var(--theme-transition-duration) var(--theme-transition-timing) !important;
      font-family: var(--theme-firefox_devtools-font_family) !important;
   }

   .tree-rows,
   .devtools-list {
      border-radius: var(--theme-border-radius) !important;
   }

   .tree-row:hover,
   .devtools-list-item:hover {
      transition: background-color var(--theme-transition-duration) var(--theme-transition-timing) !important;
      background-color: var(--theme-toolbar-hover) !important;
   }

   .devtools-separator {
      opacity: 0;
   }

   .devtools-togglebutton {
      border-block: none !important;
      padding: 4px 8px !important;
      border-radius: 4px !important;
      border: none !important;
   }

   .devtools-togglebutton[aria-pressed="true"] {
      background-color: rgba(0, 0, 0, 0.14) !important;
      color: #000 !important;
   }

   .split-box.vert>.splitter {
      min-width: 10px !important;
   }

   .split-box.horz>.splitter {
      min-height: 10px !important;
   }

   .devtools-side-splitter {
      min-width: 10px !important;
   }

   .devtools-tab-line {
      display: none;
   }

   .ruleview-enableproperty {
      appearance: auto !important;
      margin-bottom: 2px !important;
   }

   .tabs .tabs-menu-item {
      transition: background-color var(--theme-transition-duration) var(--theme-transition-timing), box-shadow var(--theme-transition-duration) var(--theme-transition-timing), padding var(--theme-transition-duration) var(--theme-transition-timing) !important;
   }

   .tabs .tabs-menu-item.is-active {
      background-color: rgba(0, 0, 0, 0.07) !important;
   }

   .tag-line {
      padding-block: 3px;
   }

   .theme-twisty {
      opacity: 0.5 !important;
      transition: opacity var(--theme-transition-duration) var(--theme-transition-timing) !important;
   }

   .theme-twisty:hover {
      opacity: 1 !important;
   }

   .theme-selected {
      background-color: #e0e0e2 !important;
   }

   .ruleview-highlight {
      background-color: rgba(255, 217, 15, 0.59) !important;
   }

   .stylesheet-system.splitview-nav>li.splitview-active {
      background-color: var(--theme-toolbar-active) !important;
   }

   .devtools-tabbar-button.checked {
      color: black !important;
   }

   .tree-node.focused {
      background-color: var(--theme-toolbar-active) !important;
   }

   .tree .tree-node:not(.focused):hover {
      background-color: var(--theme-toolbar-active) !important;
      color: black !important;
   }

   .source-tab::before {
      background-color: unset !important;
   }

   .source-tab.active {
      background-color: var(--theme-toolbar-active) !important;
   }

   .checkbox-container.menu-standard-padding {
      background: #f0f0f2 !important;
      border-radius: 12px !important;
   }

   /* .tooltip-panel {
      background: transparent !important;
   }

   .tooltip-container.tooltip-bottom {
      background: transparent !important;
   }

   .tooltip-arrow {
      display: none !important;
   } */
}

.tooltip-container,
.devtools-tooltip {
   box-shadow: var(--theme-box-shadow) !important;
   animation: tooltipFade 0.2s var(--theme-transition-timing) !important;
   font-family: var(--theme-font-family);
}

@keyframes tooltipFade {
   from {
      opacity: 0;
      transform: translateY(5px);
   }

   to {
      opacity: 1;
      transform: translateY(0);
   }
}

#toolbox-close {
   position: relative;
}

#toolbox-close::before {
   content: "";
   background-image: url("chrome://devtools/skin/images/close.svg");
   background-size: contain;
   background-repeat: no-repeat;
   display: inline-block;
   width: 24px;
   height: 24px;
   opacity: 1;
   transition: transform 0.3s cubic-bezier(0.4, 0, 0.2, 1), opacity 0.3s cubic-bezier(0.4, 0, 0.2, 1);
   position: absolute;
   top: 50%;
   left: 50%;
   transform: translate(-50%, -50%) scale(1);
}

#toolbox-close::after {
   content: "👋";
   font-family: 24px !important;
   display: inline-block;
   opacity: 0;
   transition: transform 0.3s cubic-bezier(0.4, 0, 0.2, 1), opacity 0.3s cubic-bezier(0.4, 0, 0.2, 1);
   position: absolute;
   top: 50%;
   left: 50%;
   transform: translate(-50%, -50%) scale(0);
   font-size: 20px;
}

#toolbox-close:hover::before {
   transform: translate(-50%, -50%) scale(0);
   opacity: 0;
}

#toolbox-close:hover::after {
   transform: translate(-50%, -50%) scale(1);
   opacity: 1;
}