improve hc theme (part of #16869)

src/vs/workbench/browser/parts/activitybar/media/activityaction.css

@@ -156,10 +156,15 @@
 	opacity: 1;
 }
 
-.hc-black .monaco-workbench > .activitybar > .content .monaco-action-bar .action-item .action-label.active:before {
+.hc-black .monaco-workbench > .activitybar > .content .monaco-action-bar .action-item .action-label.active:before,
+.hc-black .monaco-workbench > .activitybar > .content .monaco-action-bar .action-item .action-label.active:hover:before {
 	outline: 1px solid #f38518;
 }
 
+.hc-black .monaco-workbench > .activitybar > .content .monaco-action-bar .action-item .action-label:hover:before {
+	outline: 1px dashed #f38518;
+}
+
 .hc-black .monaco-workbench > .activitybar > .content .monaco-action-bar.global .action-item .action-label.active:before {
 	border: none;
 }

src/vs/workbench/browser/parts/activitybar/media/activitybarpart.css

@@ -25,11 +25,12 @@
 }
 
 /* High Contrast Theming */
-.hc-black .monaco-workbench > .part.activitybar.left {
+
+.hc-black .monaco-workbench > .part.activitybar.left .content {
 	border-right: 1px solid #6FC3DF;
 }
 
-.hc-black .monaco-workbench > .part.activitybar.right {
+.hc-black .monaco-workbench > .part.activitybar.right .content {
 	border-left: 1px solid #6FC3DF;
 }
 

src/vs/workbench/browser/parts/editor/media/tabstitle.css

@@ -13,6 +13,10 @@
 	background: #252526;
 }
 
+.hc-black .monaco-workbench > .part.editor > .content > .one-editor-silo > .container > .title.tabs {
+	border-bottom: 1px solid #6FC3DF;
+}
+
 .monaco-workbench > .part.editor > .content > .one-editor-silo > .container > .title.tabs > .monaco-scrollable-element {
 	flex: 1;
 }
@@ -80,13 +84,23 @@
 	border-left-color: transparent;
 }
 
-.hc-black .monaco-workbench > .part.editor > .content > .one-editor-silo > .container > .title .tabs-container > .tab  {
+.hc-black .monaco-workbench > .part.editor > .content > .one-editor-silo > .container > .title .tabs-container > .tab:not(:first-child) {
 	border-left-color: #6FC3DF;
 }
 
-.hc-black .monaco-workbench > .part.editor > .content > .one-editor-silo > .container > .title .tabs-container > .tab.active  {
-	outline: 2px solid #f38518;
-	outline-offset: -1px;
+.hc-black .monaco-workbench > .part.editor > .content > .one-editor-silo > .container > .title .tabs-container > .tab:last-child {
+	border-right-color: #6FC3DF;
+}
+
+.hc-black .monaco-workbench > .part.editor > .content > .one-editor-silo > .container > .title .tabs-container > .tab.active,
+.hc-black .monaco-workbench > .part.editor > .content > .one-editor-silo > .container > .title .tabs-container > .tab.active:hover  {
+	outline: 1px solid #f38518;
+	outline-offset: -5px;
+}
+
+.hc-black .monaco-workbench > .part.editor > .content > .one-editor-silo > .container > .title .tabs-container > .tab:hover  {
+	outline: 1px dashed #f38518;
+	outline-offset: -5px;
 }
 
 .vs .monaco-workbench > .part.editor > .content > .one-editor-silo > .container > .title .tabs-container.dropfeedback,
@@ -103,7 +117,7 @@
 .hc-black .monaco-workbench > .part.editor > .content > .one-editor-silo > .container > .title .tabs-container > .tab.dropfeedback {
 	background: none !important;
 	outline: 2px dashed #f38518;
-	outline-offset: -2px;
+	outline-offset: -5px;
 }
 
 /* Tab Label */
@@ -190,6 +204,13 @@
 	background: url('close-inverse.svg') center center no-repeat;
 }
 
+.hc-black .monaco-workbench > .part.editor > .content > .one-editor-silo > .container > .title .tabs-container > .tab.active > .tab-close .action-label,
+.hc-black .monaco-workbench > .part.editor > .content > .one-editor-silo > .container > .title .tabs-container > .tab.active:hover > .tab-close .action-label,
+.hc-black .monaco-workbench > .part.editor > .content > .one-editor-silo > .container > .title .tabs-container > .tab.dirty > .tab-close .action-label,
+.hc-black .monaco-workbench > .part.editor > .content > .one-editor-silo > .container > .title .tabs-container > .tab:hover > .tab-close .action-label {
+	opacity: 1 !important;
+}
+
 /* No Tab Close Button */
 
 .monaco-workbench > .part.editor > .content > .one-editor-silo > .container > .title .tabs-container > .tab.no-close-button {