update

src/assets/gtk/scalable/close-symbolic@2.svg

@@ -0,0 +1,3 @@
+<svg width="32" height="32" version="1.1" viewBox="0 0 32 32" xmlns="http://www.w3.org/2000/svg">
+ <path d="m8.9295 7.9298c-0.2555 0-0.511 0.0972-0.70678 0.29298-0.39156 0.39172-0.39156 1.0223 0 1.4141l6.3632 6.3632-6.3632 6.3632c-0.39156 0.39172-0.39156 1.0223 0 1.4141 0.39156 0.39172 1.0224 0.39172 1.4141 0l6.3632-6.3632 6.3632 6.3632c0.39156 0.39172 1.0223 0.39172 1.4141 0 0.39156-0.39172 0.39156-1.0223 0-1.4141l-6.3632-6.3632 6.3632-6.3632c0.39156-0.39172 0.39156-1.0223 0-1.4141-0.39156-0.39172-1.0223-0.39172-1.4141 0l-6.3632 6.3632-6.3632-6.3632c-0.1958-0.1958-0.45128-0.29298-0.70678-0.29298z" fill="#ffffff" stroke-width="2"/>
+</svg>

src/assets/gtk/scalable/maximize-symbolic@2.svg

@@ -0,0 +1,3 @@
+<svg width="32" height="32" version="1.1" viewBox="0 0 32 32" xmlns="http://www.w3.org/2000/svg">
+ <path d="m12 8c-2.216 0-4 1.784-4 4v8c0 2.216 1.784 4 4 4h8c2.216 0 4-1.784 4-4v-8c0-2.216-1.784-4-4-4zm0 2h8c1.108 0 2 0.89204 2 2v8c0 1.108-0.89204 2-2 2h-8c-1.1079 0-2-0.89204-2-2v-8c0-1.108 0.89206-2 2-2z" fill="#ffffff" stroke-width="2"/>
+</svg>

src/assets/gtk/scalable/minimize-symbolic@2.svg

@@ -0,0 +1,3 @@
+<svg width="32" height="32" version="1.1" viewBox="0 0 32 32" xmlns="http://www.w3.org/2000/svg">
+ <rect x="8" y="15" width="16" height="2" rx="1" ry="1" fill="#ffffff" stroke-width="2"/>
+</svg>

src/assets/gtk/scalable/unmaximize-symbolic@2.svg

@@ -0,0 +1,4 @@
+<svg width="32" height="32" version="1.1" viewBox="0 0 32 32" xmlns="http://www.w3.org/2000/svg">
+ <path d="m12 12c-2.216 0-4 1.784-4 4v4c0 2.216 1.784 4 4 4h4c2.216 0 4-1.784 4-4v-4c0-2.216-1.784-4-4-4zm0 2h4c1.108 0 2 0.892 2 2v4c0 1.108-0.892 2-2 2h-4c-1.108 0-2-0.892-2-2v-4c0-1.108 0.892-2 2-2z" fill="#ffffff" stroke-width="2"/>
+ <path d="m16 8c-2.216 0-4 1.784-4 4h2c0-1.108 0.892-2 2-2h4c1.108 0 2 0.892 2 2v4c0 1.108-0.892 2-2 2v2c2.216 0 4-1.784 4-4v-4c0-2.216-1.784-4-4-4z" fill="#ffffff" opacity=".35" stroke-width="2"/>
+</svg>

src/sass/gtk/_common-3.0.scss

@@ -137,8 +137,6 @@
 
   &:disabled { color: $text-disabled; }
 
-  // &:hover, &:selected { border-radius: $corner-radius; }
-
   &:selected {
     @extend %selected_items_primary;
 
@@ -1514,8 +1512,6 @@ treeview.view {
 
   rubberband { @extend rubberband; } // to avoid borders being overridden by the previously set props
 
-  &:hover, &:selected { border-radius: 0; }
-
   &.separator {
     min-height: $space-size;
     color: $divider;
@@ -3857,19 +3853,22 @@ decoration {
 
   &.minimize { // Window minimize button
     &:hover, &:active {
-      background-image: url("assets/scalable/minimize.svg");
+      background-image: -gtk-scaled(url("assets/scalable/minimize-symbolic.svg"),
+                                    url("assets/scalable/minimize-symbolic@2.svg"));
     }
   }
 
   &.maximize { // Window maximize button
     &:hover, &:active {
-      background-image: url("assets/scalable/maximize.svg");
+      background-image: -gtk-scaled(url("assets/scalable/maximize-symbolic.svg"),
+                                    url("assets/scalable/maximize-symbolic@2.svg"));
     }
   }
 
   &.close { // Window close button
     &:hover, &:active {
-      background-image: url("assets/scalable/close.svg");
+      background-image: -gtk-scaled(url("assets/scalable/close-symbolic.svg"),
+                                    url("assets/scalable/close-symbolic@2.svg"));
     }
   }
 }
@@ -3884,11 +3883,10 @@ button.titlebutton:not(.suggested-action):not(.destructive-action) {
     @extend %normal_window_button;
   }
 
-  .background.csd.maximized headerbar.titlebar.default-decoration &.maximize,
-  .background.csd.fullscreen headerbar.titlebar.default-decoration &.maximize,
-  .background.csd.tiled headerbar.titlebar.default-decoration &.maximize {
+  .background.csd.maximized headerbar.titlebar.default-decoration &.maximize {
     &:hover, &:active {
-      background-image: url("assets/scalable/unmaximize.svg");
+      background-image: -gtk-scaled(url("assets/scalable/unmaximize-symbolic.svg"),
+                                    url("assets/scalable/unmaximize-symbolic@2.svg"))
     }
   }
 }

src/sass/gtk/_common-4.0.scss

@@ -3578,8 +3578,9 @@ row {
 
     &:focus {
       color: $text;
-      background-color: $overlay-normal;
+      background-color: transparent;
       box-shadow: none;
+      outline: none;
     }
 
     &:hover, &.has-open-popup {