diff --git a/phpBB/styles/prosilver/theme/buttons.css b/phpBB/styles/prosilver/theme/buttons.css
index 3bbcc51ef5..77325f3d32 100644
--- a/phpBB/styles/prosilver/theme/buttons.css
+++ b/phpBB/styles/prosilver/theme/buttons.css
@@ -16,9 +16,9 @@
 	padding: 2px 8px;
 	cursor: pointer;
 	touch-action: manipulation;
+	-webkit-user-select: none;
 	-moz-user-select: none;
 	-ms-user-select: none;
-	-webkit-user-select: none;
 	user-select: none;
 }
 
diff --git a/phpBB/styles/prosilver/theme/colours.css b/phpBB/styles/prosilver/theme/colours.css
index 11090c0e77..2788295b68 100644
--- a/phpBB/styles/prosilver/theme/colours.css
+++ b/phpBB/styles/prosilver/theme/colours.css
@@ -97,15 +97,15 @@ th a:hover {
 .headerbar,
 .forumbg {
 	background-color: #13a4ec;
-	background-image: -webkit-linear-gradient(top, #80d5ff 0%, #0077b3 2px, #13a4ec 92px, #13a4ec 100%);
-	background-image: linear-gradient(to bottom, #80d5ff 0%, #0077b3 2px, #13a4ec 92px, #13a4ec 100%);
+	background-image: -webkit-gradient(linear, left top, left bottom, from(#80d5ff), color-stop(0.1%, #0077b3), color-stop(30%, #13a4ec), to(#13a4ec));
+	background-image: linear-gradient(to bottom, #80d5ff 0%, #0077b3 0.1%, #13a4ec 30%, #13a4ec 100%);
 	background-repeat: repeat-x;
 }
 
 .forabg {
 	background-color: #0077b3;
-	background-image: -webkit-linear-gradient(top, #80d5ff 0%, #13a4ec 2px, #0077b3 92px, #0077b3 100%);
-	background-image: linear-gradient(to bottom, #80d5ff 0%, #13a4ec 2px, #0077b3 92px, #0077b3 100%);
+	background-image: -webkit-gradient(linear, left top, left bottom, from(#80d5ff), color-stop(0.1%, #13a4ec), color-stop(30%, #0077b3), to(#0077b3));
+	background-image: linear-gradient(to bottom, #80d5ff 0%, #13a4ec 0.1%, #0077b3 30%, #0077b3 100%);
 	background-repeat: repeat-x;
 }
 
@@ -317,7 +317,7 @@ p.post-notice {
 /*	colours and backgrounds for content.css */
 ul.forums {
 	background-color: #edf4f7;
-	background-image: -webkit-linear-gradient(top, #b8d3e0 0%, #edf4f7 100%);
+	background-image: -webkit-gradient(linear, left top, left bottom, from(#b8d3e0), to(#edf4f7));
 	background-image: linear-gradient(to bottom, #b8d3e0 0%, #edf4f7 100%);
 }
 
@@ -591,16 +591,17 @@ dd.profile-warnings {
 /*	colours and backgrounds for buttons.css */
 .button {
 	background-color: #e0e0e0;
-	background-image: -webkit-linear-gradient(top, #ffffff 0%, #e0e0e0 100%);
+	background-image: -webkit-gradient(linear, left top, left bottom, from(#ffffff), to(#e0e0e0));
 	background-image: linear-gradient(to bottom, #ffffff 0%, #e0e0e0 100%);
 	border-color: #bdbdbd;
+	-webkit-box-shadow: 0 0 0 1px #ffffff inset;
 	box-shadow: 0 0 0 1px #ffffff inset;
 	color: #d41142;
 }
 
 .button:hover,
 .button:focus {
-	background-image: -webkit-linear-gradient(top, #e0e0e0 0%, #ffffff 100%);
+	background-image: -webkit-gradient(linear, left top, left bottom, from(#e0e0e0), to(#ffffff));
 	background-image: linear-gradient(to bottom, #e0e0e0 0%, #ffffff 100%);
 	border-color: #0077b3;
 	text-shadow: 1px 1px 0 #ffffff, -1px -1px 0 #ffffff, -1px -1px 0 rgba(189, 40, 77, 0.2);
@@ -615,6 +616,7 @@ dd.profile-warnings {
 .button-form,
 .button-form-bold {
 	border-color: #757575;
+	-webkit-box-shadow: none;
 	box-shadow: none;
 	color: #212121;
 }
@@ -663,6 +665,7 @@ dd.profile-warnings {
 	-webkit-filter: none;
 	filter: none;
 	border-color: #bdbdbd;
+	-webkit-box-shadow: none;
 	box-shadow: none;
 	color: #9e9e9e;
 }
@@ -696,6 +699,7 @@ dd.profile-warnings {
 }
 
 .search-header {
+	-webkit-box-shadow: 0 0 10px #0077b3;
 	box-shadow: 0 0 10px #0077b3;
 }
 
@@ -822,9 +826,10 @@ ul.cplist {
 .tabs .activetab > a,
 .tabs .activetab > a:hover {
 	background-color: #c9dee8;
-	background-image: -webkit-linear-gradient(top, #e6f7ff 0%, #c9dee8 100%);
+	background-image: -webkit-gradient(linear, left top, left bottom, from(#e6f7ff), to(#c9dee8));
 	background-image: linear-gradient(to bottom, #e6f7ff 0%, #c9dee8 100%);
 	border-color: #c9dee8;
+	-webkit-box-shadow: 0 1px 1px #e6f7ff inset;
 	box-shadow: 0 1px 1px #e6f7ff inset;
 	color: #212121;
 }
@@ -845,14 +850,14 @@ ul.cplist {
 /* link styles for the sub-section links */
 .navigation a {
 	background: #c0d3dd;
-	background-image: -webkit-linear-gradient(left, #aab9c0 50%, #c0d3dd 100%);
+	background-image: -webkit-gradient(linear, left top, right top, color-stop(50%, #aab9c0), to(#c0d3dd));
 	background-image: linear-gradient(to right, #aab9c0 50%, #c0d3dd 100%);
 	color: #212121;
 }
 
 .rtl .navigation a {
 	background: #afc5cf;
-	background-image: -webkit-linear-gradient(left, #c0d3dd 50%, #aab9c0 100%);
+	background-image: -webkit-gradient(linear, left top, right top, color-stop(50%, #c0d3dd), to(#aab9c0));
 	background-image: linear-gradient(to right, #c0d3dd 50%, #aab9c0 100%);
 }
 
@@ -1020,6 +1025,33 @@ input.disabled {
 	background-color: #000000;
 }
 
+/* stylelint-disable at-rule-no-vendor-prefix */
+
+@-webkit-keyframes colors {
+	0% {
+		stroke: #4285f4;
+	}
+
+	25% {
+		stroke: #de3e35;
+	}
+
+	50% {
+		stroke: #f7c223;
+	}
+
+	75% {
+		stroke: #1b9a59;
+	}
+
+	100% {
+		stroke: #4285f4;
+	}
+}
+
+/* stylelint-enable at-rule-no-vendor-prefix */
+
+
 @keyframes colors {
 	0% {
 		stroke: #4285f4;
@@ -1068,7 +1100,7 @@ input.disabled {
 
 .dropdown-extended .header {
 	background-color: #e6f7ff;
-	background-image: -webkit-linear-gradient(top, #e6f7ff 0%, #c9dee8 100%);
+	background-image: -webkit-gradient(linear, left top, left bottom, from(#e6f7ff), to(#c9dee8));
 	background-image: linear-gradient(to bottom, #e6f7ff 0%, #c9dee8 100%);
 }
 
@@ -1087,10 +1119,12 @@ input.disabled {
 .dropdown .dropdown-contents {
 	background: #ffffff;
 	border-color: #bdbdbd;
+	-webkit-box-shadow: 1px 3px 5px rgba(0, 0, 0, 0.2);
 	box-shadow: 1px 3px 5px rgba(0, 0, 0, 0.2);
 }
 
 .dropdown-up .dropdown-contents {
+	-webkit-box-shadow: 1px 0 5px rgba(0, 0, 0, 0.2);
 	box-shadow: 1px 0 5px rgba(0, 0, 0, 0.2);
 }
 
diff --git a/phpBB/styles/prosilver/theme/common.css b/phpBB/styles/prosilver/theme/common.css
index 0df80d1c9d..f5c6f84809 100644
--- a/phpBB/styles/prosilver/theme/common.css
+++ b/phpBB/styles/prosilver/theme/common.css
@@ -450,6 +450,7 @@ a.header-avatar span:after {
 	width: 0;
 	height: 0;
 	-webkit-transform: rotate(360deg); /* better anti-aliasing in webkit */
+	transform: rotate(360deg);
 }
 
 .dropdown-up .pointer,
@@ -1046,43 +1047,82 @@ fieldset.fields1 dl.pmlist dd.recipients {
 }
 
 .spinner {
+	-webkit-animation: rotator 1s linear infinite;
 	animation: rotator 1s linear infinite;
 }
 
 /* stylelint-disable no-unknown-animations */
 .spinner-path {
+	-webkit-transform-origin: center;
 	transform-origin: center;
+	-webkit-animation: dash 1s ease-in-out infinite, colors 4s ease-in-out infinite;
 	animation: dash 1s ease-in-out infinite, colors 4s ease-in-out infinite;
 	stroke-dasharray: 187;
 	stroke-dashoffset: 0;
 }
 /* stylelint-enable no-unknown-animations */
 
-@keyframes rotator {
+/* stylelint-disable at-rule-no-vendor-prefix */
+@-webkit-keyframes rotator {
 	0% {
+		-webkit-transform: rotate(0deg);
 		transform: rotate(0deg);
 	}
 
 	100% {
+		-webkit-transform: rotate(270deg);
 		transform: rotate(270deg);
 	}
 }
 
+@keyframes rotator {
+	0% {
+		-webkit-transform: rotate(0deg);
+		transform: rotate(0deg);
+	}
+
+	100% {
+		-webkit-transform: rotate(270deg);
+		transform: rotate(270deg);
+	}
+}
+
+@-webkit-keyframes dash {
+	0% {
+		stroke-dashoffset: 187;
+	}
+
+	50% {
+		-webkit-transform: rotate(135deg);
+		transform: rotate(135deg);
+		stroke-dashoffset: 46.75;
+	}
+
+	100% {
+		-webkit-transform: rotate(450deg);
+		transform: rotate(450deg);
+		stroke-dashoffset: 187;
+	}
+}
+
 @keyframes dash {
 	0% {
 		stroke-dashoffset: 187;
 	}
 
 	50% {
+		-webkit-transform: rotate(135deg);
 		transform: rotate(135deg);
 		stroke-dashoffset: 46.75;
 	}
 
 	100% {
+		-webkit-transform: rotate(450deg);
 		transform: rotate(450deg);
 		stroke-dashoffset: 187;
 	}
 }
+/* stylelint-enable at-rule-no-vendor-prefix */
 
 
 /* Miscellaneous styles
diff --git a/phpBB/styles/prosilver/theme/content.css b/phpBB/styles/prosilver/theme/content.css
index f9d80c6f85..89b503eae0 100644
--- a/phpBB/styles/prosilver/theme/content.css
+++ b/phpBB/styles/prosilver/theme/content.css
@@ -69,6 +69,7 @@ ul.topiclist.two-columns dt .list-inner {
 
 ul.topiclist dd {
 	border-left: 1px solid transparent;
+	-webkit-box-sizing: border-box;
 	box-sizing: border-box;
 	padding: 4px 0;
 }
@@ -135,6 +136,7 @@ li.header dt .list-inner {
 }
 
 li.header dd {
+	-webkit-box-sizing: border-box;
 	box-sizing: border-box;
 	padding-left: 1px;
 }
@@ -308,6 +310,7 @@ dd.option {
 }
 
 .postbody img.postimage {
+	-webkit-box-sizing: border-box;
 	box-sizing: border-box;
 	max-width: 100%;
 }
@@ -567,6 +570,7 @@ blockquote .codebox {
 	border: 1px dashed transparent;
 	float: left;
 	clear: left;
+	-webkit-box-sizing: border-box;
 	box-sizing: border-box;
 	width: auto;
 	max-width: 100%;
@@ -646,6 +650,7 @@ dl.file dd {
 
 dl.thumbnail img {
 	border: 1px solid transparent;
+	-webkit-box-sizing: border-box;
 	box-sizing: border-box;
 	padding: 3px;
 }
diff --git a/phpBB/styles/prosilver/theme/forms.css b/phpBB/styles/prosilver/theme/forms.css
index 6598f7955c..1257c2c56d 100644
--- a/phpBB/styles/prosilver/theme/forms.css
+++ b/phpBB/styles/prosilver/theme/forms.css
@@ -84,7 +84,6 @@ fieldset dd {
 	margin-left: 41%;
 }
 
-
 fieldset.fields1 div {
 	margin-bottom: 3px;
 }
@@ -270,6 +269,7 @@ fieldset.submit-buttons input {
 	max-width: 100%;
 	height: 270px;
 	resize: vertical;
+	-webkit-transition: all 0.5s ease, height 1ms linear;
 	transition: all 0.5s ease, height 1ms linear;
 }
 
@@ -326,6 +326,7 @@ input[type="number"] {
 
 input[type="search"] {
 	-webkit-box-sizing: content-box;
+	box-sizing: content-box;
 	-webkit-appearance: textfield;
 }
 
@@ -361,6 +362,7 @@ input.disabled {
 	border-right-width: 0;
 	border-radius: 4px 0 0 4px;
 	float: left;
+	-webkit-box-sizing: border-box;
 	box-sizing: border-box;
 	height: 24px;
 	padding: 3px;
diff --git a/phpBB/styles/prosilver/theme/links.css b/phpBB/styles/prosilver/theme/links.css
index b83f49b0a2..3a8407e2a6 100644
--- a/phpBB/styles/prosilver/theme/links.css
+++ b/phpBB/styles/prosilver/theme/links.css
@@ -45,6 +45,7 @@ th a:hover {
 	top: 50%;
 	right: 0;
 	display: none;
+	-webkit-box-sizing: border-box;
 	box-sizing: border-box;
 	margin-top: -20px;
 }
diff --git a/phpBB/styles/prosilver/theme/responsive.css b/phpBB/styles/prosilver/theme/responsive.css
index a619b7ebb1..07cdd1cff9 100644
--- a/phpBB/styles/prosilver/theme/responsive.css
+++ b/phpBB/styles/prosilver/theme/responsive.css
@@ -420,6 +420,7 @@
 	textarea,
 	dd textarea,
 	.message-box textarea {
+		-webkit-box-sizing: border-box;
 		box-sizing: border-box;
 		width: 100%;
 	}