--- a/devtools/client/netmonitor/src/assets/styles/RequestList.css
+++ b/devtools/client/netmonitor/src/assets/styles/RequestList.css
@@ -70,24 +70,29 @@
   left: 0;
   right: 0;
   overflow-x: hidden;
   overflow-y: auto;
   --timings-scale: 1;
   --timings-rev-scale: 1;
 }
 
+.requests-list-headers > .requests-list-column {
+  padding: 0;
+}
+
 .requests-list-column {
   display: table-cell;
   cursor: default;
-  text-align: center;
   white-space: nowrap;
   overflow: hidden;
   text-overflow: ellipsis;
   vertical-align: middle;
+  padding-inline-start: 4px;
+  border-inline-end: var(--theme-splitter-color) 1px solid;
   max-width: 50px;
   min-width: 50px;
 }
 
 .requests-list-column > * {
   display: inline-block;
 }
 
@@ -112,27 +117,21 @@
   width: 100%;
 }
 
 .requests-list-headers .requests-list-column:first-child .requests-list-header-button {
   border-width: 0;
 }
 
 .requests-list-header-button {
+  display: block;
   background-color: transparent;
-  border-image: linear-gradient(transparent 15%,
-                                var(--theme-splitter-color) 15%,
-                                var(--theme-splitter-color) 85%,
-                                transparent 85%) 1 1;
   border-width: 0;
-  border-inline-start-width: 1px;
-  padding-inline-start: 16px;
   width: 100%;
-  min-height: 23px;
-  text-align: center;
+  height: 24px;
   color: inherit;
 }
 
 .requests-list-header-button::-moz-focus-inner {
   border: 0;
   padding: 0;
 }
 
@@ -219,17 +218,16 @@
 }
 
 .theme-firebug .requests-list-status {
   font-weight: bold;
 }
 
 .requests-list-status-code {
   margin-inline-start: 3px;
-  width: 3em;
 }
 
 .requests-list-status-icon {
   background: #fff;
   height: 10px;
   width: 10px;
   margin-inline-start: 5px;
   margin-inline-end: 5px;