diff --git a/devtools/client/inspector/inspector.xhtml b/devtools/client/inspector/inspector.xhtml
index d3e13fb7b781..b2e084d9fd74 100644
--- a/devtools/client/inspector/inspector.xhtml
+++ b/devtools/client/inspector/inspector.xhtml
@@ -14,7 +14,6 @@
-
diff --git a/devtools/client/jar.mn b/devtools/client/jar.mn
index 628a336e45c0..b68d20740c14 100644
--- a/devtools/client/jar.mn
+++ b/devtools/client/jar.mn
@@ -177,7 +177,6 @@ devtools.jar:
skin/images/noise.png (themes/images/noise.png)
skin/images/dropmarker.svg (themes/images/dropmarker.svg)
skin/boxmodel.css (themes/boxmodel.css)
- skin/deprecated-boxmodel.css (themes/deprecated-boxmodel.css)
skin/images/geometry-editor.svg (themes/images/geometry-editor.svg)
skin/images/pause.svg (themes/images/pause.svg)
skin/images/play.svg (themes/images/play.svg)
diff --git a/devtools/client/themes/deprecated-boxmodel.css b/devtools/client/themes/deprecated-boxmodel.css
deleted file mode 100644
index e1f6d1432e20..000000000000
--- a/devtools/client/themes/deprecated-boxmodel.css
+++ /dev/null
@@ -1,259 +0,0 @@
-/* This Source Code Form is subject to the terms of the Mozilla Public
- * License, v. 2.0. If a copy of the MPL was not distributed with this
- * file, You can obtain one at http://mozilla.org/MPL/2.0/ */
-
-/**
- * THIS STYLESHEET IS FOR THE DEPRECATED BOX MODEL MODULE (deprecated-box-model.js) AND
- * SHOULD NO LONGER BE MODIFIED.
- */
-
-#old-boxmodel-wrapper {
- border-bottom-style: solid;
- border-bottom-width: 1px;
- border-color: var(--theme-splitter-color);
- -moz-user-select: none;
-}
-
-#old-boxmodel-container {
- /* The view will grow bigger as the window gets resized, until 400px */
- max-width: 400px;
- margin: 0px auto;
- padding: 0;
-}
-
-/* Header */
-
-#old-boxmodel-header,
-#old-boxmodel-info {
- display: flex;
- align-items: center;
- padding: 4px 17px;
-}
-
-#old-layout-geometry-editor {
- visibility: hidden;
-}
-
-#old-layout-geometry-editor::before {
- background: url(images/geometry-editor.svg) no-repeat center center / 16px 16px;
-}
-
-/* Main: contains the box-model regions */
-
-#old-boxmodel-main {
- position: relative;
- box-sizing: border-box;
- /* The regions are semi-transparent, so the white background is partly
- visible */
- background-color: white;
- color: var(--theme-selection-color);
- /* Make sure there is some space between the window's edges and the regions */
- margin: 0 14px 4px 14px;
- width: calc(100% - 2 * 14px);
-}
-
-.old-boxmodel-margin,
-.old-boxmodel-size {
- color: var(--theme-highlight-blue);
-}
-
-/* Regions are 3 nested elements with wide borders and outlines */
-
-#old-boxmodel-content {
- height: 18px;
-}
-
-#old-boxmodel-margins,
-#old-boxmodel-borders,
-#old-boxmodel-padding {
- border-color: hsla(210,100%,85%,0.2);
- border-width: 18px;
- border-style: solid;
- outline: dotted 1px hsl(210,100%,85%);
-}
-
-#old-boxmodel-margins {
- /* This opacity applies to all of the regions, since they are nested */
- opacity: .8;
-}
-
-/* Regions colors */
-
-#old-boxmodel-margins {
- border-color: #edff64;
-}
-
-#old-boxmodel-borders {
- border-color: #444444;
-}
-
-#old-boxmodel-padding {
- border-color: #6a5acd;
-}
-
-#old-boxmodel-content {
- background-color: #87ceeb;
-}
-
-.theme-firebug #old-boxmodel-main,
-.theme-firebug #old-boxmodel-borders,
-.theme-firebug #old-boxmodel-content {
- border-style: solid;
-}
-
-.theme-firebug #old-boxmodel-main,
-.theme-firebug #old-boxmodel-header {
- font-family: var(--proportional-font-family);
-}
-
-.theme-firebug #old-boxmodel-main {
- color: var(--theme-body-color);
- font-size: var(--theme-toolbar-font-size);
-}
-
-.theme-firebug #old-boxmodel-header {
- font-size: var(--theme-toolbar-font-size);
-}
-
-/* Editable region sizes are contained in absolutely positioned */
-
-#old-boxmodel-main > p {
- position: absolute;
- pointer-events: none;
- margin: 0;
- text-align: center;
-}
-
-#old-boxmodel-main > p > span,
-#old-boxmodel-main > p > input {
- vertical-align: middle;
- pointer-events: auto;
-}
-
-/* Coordinates for the region sizes */
-
-.old-boxmodel-top,
-.old-boxmodel-bottom {
- width: calc(100% - 2px);
- text-align: center;
-}
-
-.old-boxmodel-padding.old-boxmodel-top {
- top: 37px;
-}
-
-.old-boxmodel-padding.old-boxmodel-bottom {
- bottom: 38px;
-}
-
-.old-boxmodel-border.old-boxmodel-top {
- top: 19px;
-}
-
-.old-boxmodel-border.old-boxmodel-bottom {
- bottom: 20px;
-}
-
-.old-boxmodel-margin.old-boxmodel-top {
- top: 1px;
-}
-
-.old-boxmodel-margin.old-boxmodel-bottom {
- bottom: 2px;
-}
-
-.old-boxmodel-size,
-.old-boxmodel-margin.old-boxmodel-left,
-.old-boxmodel-margin.old-boxmodel-right,
-.old-boxmodel-border.old-boxmodel-left,
-.old-boxmodel-border.old-boxmodel-right,
-.old-boxmodel-padding.old-boxmodel-left,
-.old-boxmodel-padding.old-boxmodel-right {
- top: 22px;
- line-height: 80px;
-}
-
-.old-boxmodel-size {
- width: calc(100% - 2px);
-}
-
-.old-boxmodel-margin.old-boxmodel-right,
-.old-boxmodel-margin.old-boxmodel-left,
-.old-boxmodel-border.old-boxmodel-left,
-.old-boxmodel-border.old-boxmodel-right,
-.old-boxmodel-padding.old-boxmodel-right,
-.old-boxmodel-padding.old-boxmodel-left {
- width: 21px;
-}
-
-.old-boxmodel-padding.old-boxmodel-left {
- left: 35px;
-}
-
-.old-boxmodel-padding.old-boxmodel-right {
- right: 35px;
-}
-
-.old-boxmodel-border.old-boxmodel-left {
- left: 16px;
-}
-
-.old-boxmodel-border.old-boxmodel-right {
- right: 17px;
-}
-
-.old-boxmodel-margin.old-boxmodel-right {
- right: 0;
-}
-
-.old-boxmodel-margin.old-boxmodel-left {
- left: 0;
-}
-
-.old-boxmodel-rotate.old-boxmodel-left:not(.old-boxmodel-editing) {
- transform: rotate(-90deg);
-}
-
-.old-boxmodel-rotate.old-boxmodel-right:not(.old-boxmodel-editing) {
- transform: rotate(90deg);
-}
-
-/* Legend: displayed inside regions */
-
-.old-boxmodel-legend {
- position: absolute;
- margin: 2px 6px;
- z-index: 1;
-}
-
-.old-boxmodel-legend[data-box="margin"] {
- color: var(--theme-highlight-blue);
-}
-
-/* Editable fields */
-
-.old-boxmodel-editable {
- border: 1px dashed transparent;
- -moz-user-select: none;
-}
-
-.old-boxmodel-editable:hover {
- border-bottom-color: hsl(0, 0%, 50%);
-}
-
-/* Make sure the content size doesn't appear as editable like the other sizes */
-
-.old-boxmodel-size > span {
- cursor: default;
-}
-
-/* Box Model Info: contains the position and size of the element */
-
-#old-boxmodel-element-size {
- flex: 1;
-}
-
-#old-boxmodel-position-group {
- display: flex;
- align-items: center;
-}