--- a/devtools/client/themes/common.css
+++ b/devtools/client/themes/common.css
@@ -224,16 +224,25 @@ textbox :-moz-focusring {
 /* Form fields should already have box-shadow hightlight */
 select:-moz-focusring,
 input[type="radio"]:-moz-focusring,
 input[type="checkbox"]:-moz-focusring,
 checkbox:-moz-focusring {
   outline: none;
 }
 
+/* Tab and button of toolbox does not need to display outline */
+
+.devtools-button:-moz-focusring,
+.devtools-tab:-moz-focusring {
+  outline:none;
+  padding-inline-end: 0;
+  padding-inline-start: 0;
+}
+
 /* Toolbar buttons */
 .devtools-menulist,
 .devtools-toolbarbutton,
 .devtools-button {
   -moz-appearance: none;
   background: transparent;
   border: 1px solid var(--toolbarbutton-border-color);
   border-radius: 2px;
@@ -243,16 +252,21 @@ checkbox:-moz-focusring {
   text-shadow: none;
   padding: 1px;
   margin: 1px;
 
   /* Button text should not wrap on multiple lines */
   white-space: nowrap;
 }
 
+/* Remove system form border from devtools-button. */
+.devtools-button::-moz-focus-inner {
+  border: 0;
+}
+
 .devtools-toolbarbutton:not([label]) > .toolbarbutton-icon,
 .devtools-button:empty::before {
   width: 16px;
   height: 16px;
   margin: 0 3px;
   transition: opacity 0.05s ease-in-out;
 
   color: var(--theme-toolbar-color);
@@ -318,16 +332,20 @@ checkbox:-moz-focusring {
   padding: 0 5px;
 }
 
 .devtools-toolbarbutton:not([label]):hover,
 .devtools-button:empty:not(:disabled):hover {
   background: var(--toolbarbutton-background);
 }
 
+.devtools-button:focus {
+  background-color: var(--theme-toolbar-hover);
+}
+
 .devtools-button:not(:empty):not(:disabled):not(.checked):hover,
 .devtools-toolbarbutton[label]:not(:-moz-any([checked=true],[disabled])):hover,
 .devtools-button:empty:not(:disabled):-moz-any(:hover:active,.checked),
 .devtools-toolbarbutton:not([label]):-moz-any([checked],[open],:hover:active) {
   background: var(--toolbarbutton-hover-background);
   border-color: var(--toolbarbutton-hover-border-color);
 }
 
@@ -709,16 +727,22 @@ checkbox:-moz-focusring {
 
 .devtools-tab.selected .devtools-tab-line,
 .tabs-menu-item.is-active .devtools-tab-line {
   background: var(--tab-line-selected-color);
   opacity: 1;
   transform: scaleX(1);
 }
 
+.devtools-tab:not(.selected):focus .devtools-tab-line {
+  background: var(--tab-line-hover-color);
+  opacity: 1;
+  transform: scaleX(1);
+}
+
 /* No result message styles */
 
 .devtools-sidepanel-no-result {
   font-style: italic;
   text-align: center;
   padding: 0.5em;
   -moz-user-select: none;
   font-size: 12px;

--- a/devtools/client/themes/toolbox.css
+++ b/devtools/client/themes/toolbox.css
@@ -94,20 +94,26 @@
 .devtools-tab-icon-only {
   min-width: 24px;
 }
 
 .devtools-tab {
   color: var(--theme-toolbar-color);
 }
 
-.devtools-tab:hover {
+.devtools-tab:hover,
+.devtools-tab:focus {
   background-color: var(--theme-toolbar-hover);
 }
 
+/* Remove system control border from devtools-tab. */
+.devtools-tab::-moz-focus-inner {
+  border: 0;
+}
+
 .devtools-tab:hover:active {
   background-color: var(--theme-toolbar-hover-active);
 }
 
 .devtools-tab.selected {
   color: var(--theme-toolbar-selected-color);
 }