--- a/browser/extensions/pocket/skin/shared/pocket.css
+++ b/browser/extensions/pocket/skin/shared/pocket.css
@@ -39,24 +39,18 @@
 #pocket-button-box[animate="true"] > #pocket-animatable-box,
 #pocket-button > .toolbarbutton-animatable-box {
   position: absolute;
   overflow: hidden;
   top: calc(50% - 8px); /* 8px is half the height of the sprite */
   /* Since .toolbarbutton-icon uses a different width than the animatable box,
      we need to set a padding relative to the difference in widths. */
   margin-inline-start: calc((16px + 2 * var(--toolbarbutton-inner-padding) - 20px) / 2);
-  /* Set the min- and max- width and height of the box equal to that
-     of each frame of the SVG sprite. Setting the width and height via
-     the `width` and `height` CSS properties causes an assertion for
-     `inline-size less than zero: 'aContainingBlockISize >= 0'` (bug 1379332). */
-  min-width: 20px;
-  max-width: 20px;
-  min-height: 16px;
-  max-height: 16px;
+  width: 20px; /* Width of each frame within the SVG sprite */
+  height: 16px; /* Height of each frame within the SVG sprite */
 }
 
 #pocket-button-box[animate="true"] > #pocket-animatable-box {
   /* .urlbar-icon has width 28px. Each frame is 20px wide. Set margin-inline-start
      to be half the difference, 4px. */
   margin-inline-start: 4px;
 }
 

--- a/browser/themes/shared/downloads/indicator.inc.css
+++ b/browser/themes/shared/downloads/indicator.inc.css
@@ -163,22 +163,18 @@
   position: relative;
   /* The selected tab may overlap #downloads-indicator-notification */
   z-index: 5;
 }
 
 /* download start animation */
 
 #downloads-notification-anchor {
-  width: 42px;
-  /* Height is equal to height of each frame in the SVG animation
-     Use of min/max-height instead of height is to avoid an
-     assertion for `inline-size less than zero..` (bug 1379332). */
-  min-height: 98px;
-  max-height: 98px;
+  width: 42px; /* Width of each frame within the SVG sprite */
+  height: 98px; /* Height of each frame within the SVG sprite */
   overflow: hidden;
   /* animation is not directional and shouldn't be reversed in RTL */
   direction: ltr;
 }
 
 #downloads-indicator-notification {
   opacity: 0;
   min-width: 1344px;

--- a/browser/themes/shared/toolbarbutton-icons.inc.css
+++ b/browser/themes/shared/toolbarbutton-icons.inc.css
@@ -100,24 +100,18 @@ toolbar[brighttext] {
 #reload-button > .toolbarbutton-animatable-box,
 #stop-button > .toolbarbutton-animatable-box {
   position: absolute;
   overflow: hidden;
   top: calc(50% - 10px); /* Vertically center the 20px tall animatable image */
   /* Since .toolbarbutton-icon uses a different width than the animatable-box,
      we need to set a padding relative to the difference in widths. */
   margin-inline-start: calc((16px + 2 * var(--toolbarbutton-inner-padding) - 18px) / 2);
-  /* Set the min- and max- width and height of the box equal to that
-     of each frame of the SVG sprite. Setting the width and height via
-     the `width` and `height` CSS properties causes an assertion for
-     `inline-size less than zero: 'aContainingBlockISize >= 0'` (bug 1379332). */
-  min-width: 18px;
-  max-width: 18px;
-  min-height: 20px;
-  max-height: 20px;
+  width: 18px; /* Width of each frame within the SVG sprite */
+  height: 20px; /* Height of each frame within the SVG sprite */
 }
 
 #reload-button > .toolbarbutton-animatable-box > .toolbarbutton-animatable-image,
 #stop-button > .toolbarbutton-animatable-box > .toolbarbutton-animatable-image {
   height: var(--toolbarbutton-height); /* Height must be equal to height of toolbarbutton padding-box */
 }
 
 #stop-reload-button[animate] > #reload-button > .toolbarbutton-animatable-box > .toolbarbutton-animatable-image {
@@ -475,22 +469,18 @@ toolbar[brighttext] {
      based on the size difference between half of the button height and half
      of the sprite height. The titlebar may have padding from -moz-appearance
      that needs to be accounted for. */
   top: calc(var(--library-button-y) + var(--library-button-height) / 2 - 27px - var(--toolbox-y));
   /* Set a margin relative to the difference in widths of the .toolbarbutton-icon
      and the .toolbar-animatable-box. This is correct even in RTL because the item
      is positioned using `left`. */
   left: calc(var(--library-icon-x) + (16px + 2 * var(--toolbarbutton-inner-padding) - 22px) / 2);
-  /* Set the min- and max- width and height of the box equal to that
-     of each frame of the SVG sprite (must use min- and max- due to bug 1379332). */
-  min-width: 22px;
-  max-width: 22px;
-  min-height: 54px;
-  max-height: 54px;
+  width: 22px; /* Width of each frame within the SVG sprite */
+  height: 54px; /* Height of each frame within the SVG sprite */
   z-index: 2;
 }
 
 .toolbarbutton-animatable-box[animate] > .toolbarbutton-animatable-image {
   height: var(--toolbarbutton-height);
   min-height: 54px; /* Minimum height must be equal to the height of the SVG sprite */
 }
 

--- a/browser/themes/shared/urlbar-searchbar.inc.css
+++ b/browser/themes/shared/urlbar-searchbar.inc.css
@@ -289,22 +289,18 @@
 
 #star-button-box[animationsenabled] > #star-button[starred][animate] + #star-button-animatable-box {
   position: absolute;
   overflow: hidden;
   top: calc(50% - 16.5px); /* 16.5px is half the height of the sprite */
   /* .urlbar-icon has width 28px. Each frame is 33px wide. Set margin-inline-start
      to be half the difference, -2.5px. */
   margin-inline-start: -2.5px;
-  /* Set the height to equal the height of each frame of the SVG. Must use
-     min- and max- width and height due to bug 1379332. */
-  min-width: 33px;
-  max-width: 33px;
-  min-height: 33px;
-  max-height: 33px;
+  width: 33px; /* Width of each frame within the SVG sprite */
+  height: 33px; /* Height of each frame within the SVG sprite */
 }
 
 :root[uidensity=compact] #star-button-box[animationsenabled] > #star-button[starred][animate] + #star-button-animatable-box {
   /* .urlbar-icon has width 24px in this case */
   margin-inline-start: -4.5px;
 }
 
 :root[uidensity=touch] #star-button-box[animationsenabled] > #star-button[starred][animate] + #star-button-animatable-box {