diff --git a/code/__defines/_compile_options.dm b/code/__defines/_compile_options.dm
index d395c4019a..37fca65861 100644
--- a/code/__defines/_compile_options.dm
+++ b/code/__defines/_compile_options.dm
@@ -54,3 +54,6 @@
 //CHOMPEdit end
 
 #endif //ifdef REFERENCE_TRACKING
+
+// Standard flags to use for browser-options
+#define DEFAULT_CLIENT_BROWSER_OPTIONS "byondstorage,find"
diff --git a/code/controllers/hooks.dm b/code/controllers/hooks.dm
index e7888304e5..293a90aff0 100644
--- a/code/controllers/hooks.dm
+++ b/code/controllers/hooks.dm
@@ -29,10 +29,10 @@
 		error("Invalid hook '/hook/[hook]' called.")
 		return 0
 
-	var/caller = new hook_path
+	var/requester = new hook_path
 	var/status = 1
 	for(var/P in typesof("[hook_path]/proc"))
-		if(!call(caller, P)(arglist(args)))
+		if(!call(requester, P)(arglist(args)))
 			error("Hook '[P]' failed or runtimed.")
 			status = 0
 
diff --git a/code/game/antagonist/antagonist_panel.dm b/code/game/antagonist/antagonist_panel.dm
index 0f42ad5893..8fa2d060f0 100644
--- a/code/game/antagonist/antagonist_panel.dm
+++ b/code/game/antagonist/antagonist_panel.dm
@@ -17,7 +17,7 @@
 /datum/antagonist/proc/get_extra_panel_options()
 	return
 
-/datum/antagonist/proc/get_check_antag_output(var/datum/admins/caller)
+/datum/antagonist/proc/get_check_antag_output(var/datum/admins/requester)
 
 	if(!current_antagonists || !current_antagonists.len)
 		return ""
@@ -31,7 +31,7 @@
 			if(!M.client)      dat += " <i>(logged out)</i>"
 			if(M.stat == DEAD) dat += " <b><font color=red>(DEAD)</font></b>"
 			dat += "</td>"
-			dat += "<td>\[<A HREF='?src=\ref[caller];[HrefToken()];adminplayeropts=\ref[M]'>PP</A>]\[<A href='?src=\ref[caller];[HrefToken()];priv_msg=\ref[M]'>PM</A>\]\[<A href='?src=\ref[caller];[HrefToken()];traitor=\ref[M]'>TP</A>\]</td>"
+			dat += "<td>\[<A HREF='?src=\ref[requester];[HrefToken()];adminplayeropts=\ref[M]'>PP</A>]\[<A href='?src=\ref[requester];[HrefToken()];priv_msg=\ref[M]'>PM</A>\]\[<A href='?src=\ref[requester];[HrefToken()];traitor=\ref[M]'>TP</A>\]</td>"
 		else
 			dat += "<td>[player.key] <i>Mob not found!</i></td>"
 		dat += "</tr>"
@@ -45,17 +45,17 @@
 			while(!istype(disk_loc, /turf))
 				if(istype(disk_loc, /mob))
 					var/mob/M = disk_loc
-					dat += "carried by <a href='?src=\ref[caller];[HrefToken()];adminplayeropts=\ref[M]'>[M.real_name]</a> "
+					dat += "carried by <a href='?src=\ref[requester];[HrefToken()];adminplayeropts=\ref[M]'>[M.real_name]</a> "
 				if(istype(disk_loc, /obj))
 					var/obj/O = disk_loc
 					dat += "in \a [O.name] "
 				disk_loc = disk_loc.loc
 			dat += "in [disk_loc.loc] at ([disk_loc.x], [disk_loc.y], [disk_loc.z])</td></tr>"
 		dat += "</table>"
-	dat += get_additional_check_antag_output(caller)
+	dat += get_additional_check_antag_output(requester)
 	dat += "<hr>"
 	return dat
 
 //Overridden elsewhere.
-/datum/antagonist/proc/get_additional_check_antag_output(var/datum/admins/caller)
+/datum/antagonist/proc/get_additional_check_antag_output(var/datum/admins/requester)
 	return ""
diff --git a/code/modules/client/client procs.dm b/code/modules/client/client procs.dm
index 72c6f5a171..2bcaee9c41 100644
--- a/code/modules/client/client procs.dm	
+++ b/code/modules/client/client procs.dm	
@@ -185,6 +185,10 @@
 	//CONNECT//
 	///////////
 /client/New(TopicData)
+	// TODO: Remove version check with 516
+	if(byond_version >= 516) // Enable 516 compat browser storage mechanisms
+		winset(src, null, "browser-options=[DEFAULT_CLIENT_BROWSER_OPTIONS]")
+
 	TopicData = null							//Prevent calls to client.Topic from connect
 
 	if(!(connection in list("seeker", "web")))					//Invalid connection type.
@@ -314,6 +318,12 @@
 	fully_created = TRUE
 	attempt_auto_fit_viewport()
 
+	// TODO: Remove version check with 516
+	if(byond_version >= 516)
+		// Now that we're fully initialized, use our prefs
+		if(prefs?.read_preference(/datum/preference/toggle/browser_dev_tools))
+			winset(src, null, "browser-options=[DEFAULT_CLIENT_BROWSER_OPTIONS],devtools")
+
 	//////////////
 	//DISCONNECT//
 	//////////////
diff --git a/code/modules/client/preferences/types/misc.dm b/code/modules/client/preferences/types/misc.dm
index 54a85477e3..3efea58893 100644
--- a/code/modules/client/preferences/types/misc.dm
+++ b/code/modules/client/preferences/types/misc.dm
@@ -81,3 +81,15 @@
 	savefile_key = "AutoPunctuation"
 	default_value = FALSE
 	savefile_identifier = PREFERENCE_PLAYER
+
+/datum/preference/toggle/browser_dev_tools
+	category = PREFERENCE_CATEGORY_GAME_PREFERENCES
+	savefile_key = "BrowserDevTools"
+	default_value = FALSE
+	savefile_identifier = PREFERENCE_PLAYER
+
+/datum/preference/toggle/browser_dev_tools/apply_to_client(client/client, value)
+	if(value)
+		winset(client, null, "browser-options=[DEFAULT_CLIENT_BROWSER_OPTIONS],devtools")
+	else
+		winset(client, null, "browser-options=[DEFAULT_CLIENT_BROWSER_OPTIONS]")
diff --git a/code/modules/tgui_panel/external.dm b/code/modules/tgui_panel/external.dm
index d7545ac6b1..e64660977f 100644
--- a/code/modules/tgui_panel/external.dm
+++ b/code/modules/tgui_panel/external.dm
@@ -35,6 +35,12 @@
 	// Force show the panel to see if there are any errors
 	winset(src, "output", "is-disabled=1&is-visible=0")
 	winset(src, "browseroutput", "is-disabled=0;is-visible=1")
+	// TODO: Remove version check with 516
+	if(byond_version >= 516)
+		if(prefs?.read_preference(/datum/preference/toggle/browser_dev_tools))
+			winset(src, null, "browser-options=[DEFAULT_CLIENT_BROWSER_OPTIONS],devtools")
+		else
+			winset(src, null, "browser-options=[DEFAULT_CLIENT_BROWSER_OPTIONS]")
 
 /client/verb/refresh_tgui()
 	set name = "Refresh TGUI"
diff --git a/code/modules/vore/trycatch_vr.dm b/code/modules/vore/trycatch_vr.dm
index 396352aadc..fa1b556280 100644
--- a/code/modules/vore/trycatch_vr.dm
+++ b/code/modules/vore/trycatch_vr.dm
@@ -49,10 +49,10 @@ The hooks you're calling should return nonzero values on success.
 			error("hook_vr: Invalid hook '/hook/[hook]' called.")
 			return 0
 
-		var/caller = new hook_path
+		var/hook_instance = new hook_path
 		var/status = 1
 		for(var/P in typesof("[hook_path]/proc"))
-			if(!call(caller, P)(arglist(args)))
+			if(!call(hook_instance, P)(arglist(args)))
 				error("hook_vr: Hook '[P]' failed or runtimed.")
 				status = 0
 
diff --git a/tgui/packages/common/storage.js b/tgui/packages/common/storage.js
index 8bc35b0b59..2235199075 100644
--- a/tgui/packages/common/storage.js
+++ b/tgui/packages/common/storage.js
@@ -7,7 +7,7 @@
  */
 
 export const IMPL_MEMORY = 0;
-export const IMPL_LOCAL_STORAGE = 1;
+export const IMPL_HUB_STORAGE = 1;
 export const IMPL_INDEXED_DB = 2;
 
 const INDEXED_DB_VERSION = 1;
@@ -25,14 +25,11 @@ const testGeneric = (testFn) => () => {
   }
 };
 
-// Localstorage can sometimes throw an error, even if DOM storage is not
-// disabled in IE11 settings.
-// See: https://superuser.com/questions/1080011
-// prettier-ignore
-const testLocalStorage = testGeneric(() => (
-  window.localStorage && window.localStorage.getItem
-));
+const testHubStorage = testGeneric(
+  () => window.hubStorage && window.hubStorage.getItem,
+);
 
+// TODO: Remove with 516
 // prettier-ignore
 const testIndexedDb = testGeneric(() => (
   (window.indexedDB || window.msIndexedDB)
@@ -45,49 +42,50 @@ class MemoryBackend {
     this.store = {};
   }
 
-  get(key) {
+  async get(key) {
     return this.store[key];
   }
 
-  set(key, value) {
+  async set(key, value) {
     this.store[key] = value;
   }
 
-  remove(key) {
+  async remove(key) {
     this.store[key] = undefined;
   }
 
-  clear() {
+  async clear() {
     this.store = {};
   }
 }
 
-class LocalStorageBackend {
+class HubStorageBackend {
   constructor() {
-    this.impl = IMPL_LOCAL_STORAGE;
+    this.impl = IMPL_HUB_STORAGE;
   }
 
-  get(key) {
-    const value = localStorage.getItem(key);
+  async get(key) {
+    const value = await window.hubStorage.getItem('chomp-' + key); // CHOMPEdit
     if (typeof value === 'string') {
       return JSON.parse(value);
     }
   }
 
   set(key, value) {
-    localStorage.setItem(key, JSON.stringify(value));
+    window.hubStorage.setItem('chomp-' + key, JSON.stringify(value)); // CHOMPEdit
   }
 
   remove(key) {
-    localStorage.removeItem(key);
+    window.hubStorage.removeItem('chomp-' + key); // CHOMPEdit
   }
 
   clear() {
-    localStorage.clear();
+    window.hubStorage.clear();
   }
 }
 
 class IndexedDbBackend {
+  // TODO: Remove with 516
   constructor() {
     this.impl = IMPL_INDEXED_DB;
     /** @type {Promise<IDBDatabase>} */
@@ -108,7 +106,7 @@ class IndexedDbBackend {
     });
   }
 
-  getStore(mode) {
+  async getStore(mode) {
     // prettier-ignore
     return this.dbPromise.then((db) => db
       .transaction(INDEXED_DB_STORE_NAME, mode)
@@ -125,13 +123,6 @@ class IndexedDbBackend {
   }
 
   async set(key, value) {
-    // The reason we don't _save_ null is because IE 10 does
-    // not support saving the `null` type in IndexedDB. How
-    // ironic, given the bug below!
-    // See: https://github.com/mozilla/localForage/issues/161
-    if (value === null) {
-      value = undefined;
-    }
     // NOTE: We deliberately make this operation transactionless
     const store = await this.getStore(READ_WRITE);
     store.put(value, key);
@@ -157,6 +148,10 @@ class IndexedDbBackend {
 class StorageProxy {
   constructor() {
     this.backendPromise = (async () => {
+      if (!Byond.TRIDENT && testHubStorage()) {
+        return new HubStorageBackend();
+      }
+      // TODO: Remove with 516
       if (testIndexedDb()) {
         try {
           const backend = new IndexedDbBackend();
@@ -164,9 +159,9 @@ class StorageProxy {
           return backend;
         } catch {}
       }
-      if (testLocalStorage()) {
-        return new LocalStorageBackend();
-      }
+      console.warn(
+        'No supported storage backend found. Using in-memory storage.',
+      );
       return new MemoryBackend();
     })();
   }
diff --git a/tgui/packages/tgui-panel/chat/middleware.js b/tgui/packages/tgui-panel/chat/middleware.js
index f1745b353b..d2b55898b7 100644
--- a/tgui/packages/tgui-panel/chat/middleware.js
+++ b/tgui/packages/tgui-panel/chat/middleware.js
@@ -35,7 +35,7 @@ import { chatRenderer } from './renderer';
 import { selectChat, selectCurrentChatPage } from './selectors';
 
 // List of blacklisted tags
-const FORBID_TAGS = ['a', 'iframe', 'link', 'video'];
+const blacklisted_tags = ['a', 'iframe', 'link', 'video'];
 let storedRounds = [];
 let storedLines = [];
 
@@ -72,7 +72,7 @@ const loadChatFromStorage = async (store) => {
     for (let message of messages) {
       if (message.html) {
         message.html = DOMPurify.sanitize(message.html, {
-          FORBID_TAGS,
+          FORBID_TAGS: blacklisted_tags,
         });
       }
     }
@@ -90,7 +90,7 @@ const loadChatFromStorage = async (store) => {
     for (let archivedMessage of archivedMessages) {
       if (archivedMessage.html) {
         archivedMessage.html = DOMPurify.sanitize(archivedMessage.html, {
-          FORBID_TAGS,
+          FORBID_TAGS: blacklisted_tags,
         });
       }
     }
diff --git a/tgui/packages/tgui-panel/styles/tgchat/chat-dark.scss b/tgui/packages/tgui-panel/styles/tgchat/chat-dark.scss
index cb27c044ad..a23afafa9c 100644
--- a/tgui/packages/tgui-panel/styles/tgchat/chat-dark.scss
+++ b/tgui/packages/tgui-panel/styles/tgchat/chat-dark.scss
@@ -15,7 +15,7 @@ img {
   margin: 0;
   padding: 0;
   line-height: 1;
-  -ms-interpolation-mode: nearest-neighbor;
+  -ms-interpolation-mode: nearest-neighbor; // TODO: Remove with 516
   image-rendering: pixelated;
 }
 
@@ -176,12 +176,6 @@ a.popt {
   padding: 2px 0;
 }
 
-.filterMessages input {
-}
-
-.filterMessages label {
-}
-
 .icon-stack {
   height: 1em;
   line-height: 1em;
@@ -375,19 +369,6 @@ img.icon.bigicon {
   font-weight: bold;
 }
 
-.say,
-.emote,
-.emotesubtle,
-.multizsay,
-.npcemote,
-.npcsay,
-.infoplain,
-.oocplain,
-.warningplain,
-.chatexport,
-.body {
-}
-
 .warningplain {
   font-style: italic;
 }
@@ -396,9 +377,6 @@ img.icon.bigicon {
   font-style: italic;
 }
 
-.nif {
-}
-
 .psay {
   color: #e300e4;
   font-style: italic;
diff --git a/tgui/packages/tgui-panel/styles/tgchat/chat-light.scss b/tgui/packages/tgui-panel/styles/tgchat/chat-light.scss
index e7b4e47ba7..3d6385f904 100644
--- a/tgui/packages/tgui-panel/styles/tgchat/chat-light.scss
+++ b/tgui/packages/tgui-panel/styles/tgchat/chat-light.scss
@@ -33,7 +33,7 @@ img {
   margin: 0;
   padding: 0;
   line-height: 1;
-  -ms-interpolation-mode: nearest-neighbor;
+  -ms-interpolation-mode: nearest-neighbor; // TODO: Remove with 516
   image-rendering: pixelated;
 }
 
@@ -194,12 +194,6 @@ a.popt {
   padding: 2px 0;
 }
 
-.filterMessages input {
-}
-
-.filterMessages label {
-}
-
 .icon-stack {
   height: 1em;
   line-height: 1em;
@@ -393,19 +387,6 @@ img.icon.bigicon {
   font-weight: bold;
 }
 
-.say,
-.emote,
-.emotesubtle,
-.multizsay,
-.npcemote,
-.npcsay,
-.infoplain,
-.oocplain,
-.warningplain,
-.chatexport,
-.body {
-}
-
 .warningplain {
   font-style: italic;
 }
@@ -414,9 +395,6 @@ img.icon.bigicon {
   font-style: italic;
 }
 
-.nif {
-}
-
 .psay {
   color: #800080;
   font-style: italic;
diff --git a/tgui/packages/tgui-panel/styles/tgchat/chat-vchatdark.scss b/tgui/packages/tgui-panel/styles/tgchat/chat-vchatdark.scss
index 32ab6331d5..5797bc3243 100644
--- a/tgui/packages/tgui-panel/styles/tgchat/chat-vchatdark.scss
+++ b/tgui/packages/tgui-panel/styles/tgchat/chat-vchatdark.scss
@@ -15,7 +15,7 @@ img {
   margin: 0;
   padding: 0;
   line-height: 1;
-  -ms-interpolation-mode: nearest-neighbor;
+  -ms-interpolation-mode: nearest-neighbor; // TODO: Remove with 516
   image-rendering: pixelated;
 }
 
@@ -176,12 +176,6 @@ a.popt {
   padding: 2px 0;
 }
 
-.filterMessages input {
-}
-
-.filterMessages label {
-}
-
 .icon-stack {
   height: 1em;
   line-height: 1em;
@@ -375,18 +369,6 @@ img.icon.bigicon {
   font-weight: bold;
 }
 
-.say,
-.emote,
-.emotesubtle,
-.multizsay,
-.npcemote,
-.npcsay,
-.infoplain,
-.oocplain,
-.chatexport,
-.body {
-}
-
 .warningplain {
   font-style: italic;
 }
@@ -396,9 +378,6 @@ img.icon.bigicon {
   color: #ffffff;
 }
 
-.nif {
-}
-
 .psay {
   color: #e300e4;
   font-style: italic;
diff --git a/tgui/packages/tgui-panel/styles/tgchat/chat-vchatlight.scss b/tgui/packages/tgui-panel/styles/tgchat/chat-vchatlight.scss
index fd4c060a7f..eef022ff5b 100644
--- a/tgui/packages/tgui-panel/styles/tgchat/chat-vchatlight.scss
+++ b/tgui/packages/tgui-panel/styles/tgchat/chat-vchatlight.scss
@@ -33,7 +33,7 @@ img {
   margin: 0;
   padding: 0;
   line-height: 1;
-  -ms-interpolation-mode: nearest-neighbor;
+  -ms-interpolation-mode: nearest-neighbor; // TODO: Remove with 516
   image-rendering: pixelated;
 }
 
@@ -194,12 +194,6 @@ a.popt {
   padding: 2px 0;
 }
 
-.filterMessages input {
-}
-
-.filterMessages label {
-}
-
 .icon-stack {
   height: 1em;
   line-height: 1em;
@@ -393,19 +387,6 @@ img.icon.bigicon {
   font-weight: bold;
 }
 
-.say,
-.emote,
-.emotesubtle,
-.multizsay,
-.npcemote,
-.npcsay,
-.infoplain,
-.oocplain,
-.warningplain,
-.chatexport,
-.body {
-}
-
 .warningplain {
   font-style: italic;
 }
@@ -414,9 +395,6 @@ img.icon.bigicon {
   font-style: italic;
 }
 
-.nif {
-}
-
 .psay {
   color: #800080;
   font-style: italic;
diff --git a/tgui/packages/tgui-say/TguiSay.tsx b/tgui/packages/tgui-say/TguiSay.tsx
index cb11f78e89..9c558c3411 100644
--- a/tgui/packages/tgui-say/TguiSay.tsx
+++ b/tgui/packages/tgui-say/TguiSay.tsx
@@ -1,4 +1,4 @@
-import { KEY } from 'common/keys';
+import { isEscape, KEY } from 'common/keys';
 import { clamp } from 'common/math';
 import { BooleanLike } from 'common/react';
 import { Component, createRef, RefObject } from 'react';
@@ -31,6 +31,14 @@ type State = {
 
 const CHANNEL_REGEX = /^:\w\s|^,b\s/;
 
+const ROWS: Record<keyof typeof WINDOW_SIZES, number> = {
+  small: 1,
+  medium: 2,
+  large: 3,
+  max: 6,
+  width: 1, // not used
+} as const;
+
 export class TguiSay extends Component<{}, State> {
   private channelIterator: ChannelIterator;
   private chatHistory: ChatHistory;
@@ -281,9 +289,10 @@ export class TguiSay extends Component<{}, State> {
         }
         break;
 
-      case KEY.Escape:
-        this.handleClose();
-        break;
+      default:
+        if (isEscape(event.key)) {
+          this.handleClose();
+        }
     }
   }
 
@@ -369,11 +378,14 @@ export class TguiSay extends Component<{}, State> {
               {this.state.buttonContent}
             </button>
             <textarea
+              autoCorrect="off"
               className={`textarea textarea-${theme}`}
               maxLength={this.maxLength}
               onInput={this.handleInput}
               onKeyDown={this.handleKeyDown}
               ref={this.innerRef}
+              spellCheck={false} // TODO: make preference
+              rows={ROWS[this.state.size] || 1}
             />
           </div>
           <Dragzone position="right" theme={theme} />
diff --git a/tgui/packages/tgui-say/styles/button.scss b/tgui/packages/tgui-say/styles/button.scss
index 2ec90f75fa..7d546a6b73 100644
--- a/tgui/packages/tgui-say/styles/button.scss
+++ b/tgui/packages/tgui-say/styles/button.scss
@@ -19,6 +19,13 @@
   }
 }
 
+// Remove conditionals with 516
+@supports (not (-webkit-hyphens: none)) and (not (-moz-appearance: none)) {
+  .button {
+    outline: none;
+  }
+}
+
 .button-lightMode {
   background-color: colors.$lightBorder;
   border: none;
diff --git a/tgui/packages/tgui-say/styles/colors.scss b/tgui/packages/tgui-say/styles/colors.scss
index 543f4ddd6c..b16da489bd 100644
--- a/tgui/packages/tgui-say/styles/colors.scss
+++ b/tgui/packages/tgui-say/styles/colors.scss
@@ -5,6 +5,7 @@ $button: #1f1f1f;
 $lightMode: #ffffff;
 $lightBorder: #bbbbbb;
 $lightHover: #eaeaea;
+$scrollbar-color-multiplier: 1 !default;
 
 $_channel_map: (
   // Radio (EVA, Cas, Int use default color)
diff --git a/tgui/packages/tgui-say/styles/content.scss b/tgui/packages/tgui-say/styles/content.scss
index 83cb4dc8f1..25170935c8 100644
--- a/tgui/packages/tgui-say/styles/content.scss
+++ b/tgui/packages/tgui-say/styles/content.scss
@@ -1,14 +1,41 @@
 .center {
   display: flex;
-  flex: 1 1;
-  height: 100%;
-  width: 100%;
+}
+
+// Remove conditionals with 516
+@supports (not (-webkit-hyphens: none)) and (not (-moz-appearance: none)) {
+  .center {
+    flex-grow: 1;
+  }
+}
+
+// Remove with 516
+@media screen and (-ms-high-contrast: active), (-ms-high-contrast: none) {
+  .center {
+    height: 100%;
+    width: 100%;
+    flex: 1 1 0;
+  }
 }
 
 .input {
   display: flex;
-  flex: 1 1;
-  height: 100%;
-  width: 100%;
   font-family: 'Consolas', monospace;
 }
+
+// Remove conditionals with 516
+@supports (not (-webkit-hyphens: none)) and (not (-moz-appearance: none)) {
+  .input {
+    flex-grow: 1;
+    gap: 0.2rem;
+  }
+}
+
+// Remove with 516
+@media screen and (-ms-high-contrast: active), (-ms-high-contrast: none) {
+  .input {
+    height: 100%;
+    width: 100%;
+    flex: 1 1 0;
+  }
+}
diff --git a/tgui/packages/tgui-say/styles/dragzone.scss b/tgui/packages/tgui-say/styles/dragzone.scss
index 314b57c4e4..8b035477d0 100644
--- a/tgui/packages/tgui-say/styles/dragzone.scss
+++ b/tgui/packages/tgui-say/styles/dragzone.scss
@@ -1,7 +1,17 @@
 @use 'sass:color';
 @use './colors.scss';
 
-$dragSize: 0.6rem;
+// Remove conditionals with 516
+@supports (not (-webkit-hyphens: none)) and (not (-moz-appearance: none)) {
+  $dragSize: 0.3rem;
+}
+
+// Remove with 516
+@media screen and (-ms-high-contrast: active), (-ms-high-contrast: none) {
+  $dragSize: 0.6rem;
+}
+
+$dragSize: 0.3rem;
 $borderSize: 0.2rem;
 
 .dragzone-horizontal {
diff --git a/tgui/packages/tgui-say/styles/textarea.scss b/tgui/packages/tgui-say/styles/textarea.scss
index a5bfbe6695..135da37e01 100644
--- a/tgui/packages/tgui-say/styles/textarea.scss
+++ b/tgui/packages/tgui-say/styles/textarea.scss
@@ -1,11 +1,51 @@
+@use 'sass:color';
+@use './colors.scss';
+
+@supports (not (-webkit-hyphens: none)) and (not (-moz-appearance: none)) {
+  * {
+    &::-webkit-scrollbar {
+      width: 0.8rem;
+    }
+
+    &::-webkit-scrollbar-track {
+      background: color.scale(
+        colors.$button,
+        $lightness: -25% * colors.$scrollbar-color-multiplier
+      );
+    }
+
+    &::-webkit-scrollbar-thumb {
+      background: color.scale(
+        colors.$button,
+        $lightness: 10% * colors.$scrollbar-color-multiplier
+      );
+    }
+  }
+}
+
 .textarea {
-  align-items: center;
   background: transparent;
   border: none;
-  display: flex;
-  flex-grow: 5;
   font-family: inherit;
   font-size: 1.1rem;
-  overflow: hidden;
-  margin: 0 0 0 0.4rem;
+}
+
+// Remove conditionals with 516
+@supports (not (-webkit-hyphens: none)) and (not (-moz-appearance: none)) {
+  .textarea {
+    flex-grow: 8;
+    outline: none;
+    resize: none;
+  }
+}
+
+// Remove with 516
+@media screen and (-ms-high-contrast: active), (-ms-high-contrast: none) {
+  .textarea {
+    align-items: center;
+    display: flex;
+    flex-grow: 4;
+    overflow: hidden;
+    margin: 0.1rem 0 0 0.4rem;
+  }
 }
diff --git a/tgui/packages/tgui-say/styles/window.scss b/tgui/packages/tgui-say/styles/window.scss
index acbe1b34d2..5d5bc7dc71 100644
--- a/tgui/packages/tgui-say/styles/window.scss
+++ b/tgui/packages/tgui-say/styles/window.scss
@@ -6,11 +6,17 @@
   display: flex;
   flex-direction: column;
   max-width: 360px;
-  height: 100%;
-  width: 100%;
   overflow: hidden;
 }
 
+// Remove with 516
+@media screen and (-ms-high-contrast: active), (-ms-high-contrast: none) {
+  .window {
+    height: 100%;
+    width: 100%;
+  }
+}
+
 .window-lightMode {
   background-color: colors.$lightMode;
 }
diff --git a/tgui/packages/tgui/components/Image.tsx b/tgui/packages/tgui/components/Image.tsx
index 5d3a943feb..cf510b154e 100644
--- a/tgui/packages/tgui/components/Image.tsx
+++ b/tgui/packages/tgui/components/Image.tsx
@@ -41,6 +41,7 @@ export function Image(props: Props) {
   computedProps['style'] = {
     ...computedProps.style,
     '-ms-interpolation-mode': fixBlur ? 'nearest-neighbor' : 'auto',
+    'image-rendering': fixBlur ? '-webkit-optimize-contrast' : 'auto',
     objectFit,
   };
 
diff --git a/tgui/packages/tgui/interfaces/PreferencesMenu/preferences/features/game_preferences/misc.tsx b/tgui/packages/tgui/interfaces/PreferencesMenu/preferences/features/game_preferences/misc.tsx
index 8361e5cca2..b3e062348c 100644
--- a/tgui/packages/tgui/interfaces/PreferencesMenu/preferences/features/game_preferences/misc.tsx
+++ b/tgui/packages/tgui/interfaces/PreferencesMenu/preferences/features/game_preferences/misc.tsx
@@ -88,3 +88,11 @@ export const AutoPunctuation: FeatureToggle = {
     'When enabled, if your message ends in a letter with no punctuation, a period will be added.',
   component: CheckboxInput,
 };
+
+export const BrowserDevTools: FeatureToggle = {
+  name: 'Browser Dev Tools',
+  category: 'UI',
+  description:
+    'When enabled, you can right click -> inspect to open Microsoft Edge dev tools. BYOND 516+ Only.',
+  component: CheckboxInput,
+};
diff --git a/tgui/packages/tgui/layouts/Layout.tsx b/tgui/packages/tgui/layouts/Layout.tsx
index 173ed1cbb4..f3f395e540 100644
--- a/tgui/packages/tgui/layouts/Layout.tsx
+++ b/tgui/packages/tgui/layouts/Layout.tsx
@@ -21,6 +21,7 @@ type Props = Partial<{
 
 export function Layout(props: Props) {
   const { className, theme = 'nanotrasen', children, ...rest } = props;
+  document.documentElement.className = `theme-${theme}`;
 
   return (
     <div className={'theme-' + theme}>
diff --git a/tgui/packages/tgui/styles/components/Button.scss b/tgui/packages/tgui/styles/components/Button.scss
index a11c5c1e8c..7664470134 100644
--- a/tgui/packages/tgui/styles/components/Button.scss
+++ b/tgui/packages/tgui/styles/components/Button.scss
@@ -58,7 +58,7 @@ $bg-map: colors.$bg-map !default;
   margin-bottom: base.em(2px);
   // Disable selection in buttons
   user-select: none;
-  -ms-user-select: none;
+  -ms-user-select: none; // TODO: Remove with 516
 
   &:last-child {
     margin-right: 0;
diff --git a/tgui/packages/tgui/styles/components/Dialog.scss b/tgui/packages/tgui/styles/components/Dialog.scss
index c7b7fd1326..09adcd8f89 100644
--- a/tgui/packages/tgui/styles/components/Dialog.scss
+++ b/tgui/packages/tgui/styles/components/Dialog.scss
@@ -28,7 +28,7 @@ $background-color: base.$color-bg !default;
   line-height: 1.928em;
   background-color: rgba(0, 0, 0, 0.5);
   user-select: none;
-  -ms-user-select: none;
+  -ms-user-select: none; // TODO: Remove with 516
 }
 
 .Dialog__title {
diff --git a/tgui/packages/tgui/styles/components/Flex.scss b/tgui/packages/tgui/styles/components/Flex.scss
index d4b6b8ec38..8c0c2a3be2 100644
--- a/tgui/packages/tgui/styles/components/Flex.scss
+++ b/tgui/packages/tgui/styles/components/Flex.scss
@@ -4,7 +4,7 @@
  */
 
 .Flex {
-  display: -ms-flexbox;
+  display: -ms-flexbox; // TODO: Remove with 516
   display: flex;
 }
 
diff --git a/tgui/packages/tgui/styles/components/Input.scss b/tgui/packages/tgui/styles/components/Input.scss
index c2e779529f..bd76fe71f4 100644
--- a/tgui/packages/tgui/styles/components/Input.scss
+++ b/tgui/packages/tgui/styles/components/Input.scss
@@ -56,6 +56,13 @@ $border-radius: base.$border-radius !default;
   color: $text-color;
   color: inherit;
 
+  &::placeholder {
+    font-style: italic;
+    color: #777;
+    color: rgba(255, 255, 255, 0.45);
+  }
+
+  // TODO: Remove with 516
   &:-ms-input-placeholder {
     font-style: italic;
     color: #777;
diff --git a/tgui/packages/tgui/styles/components/TextArea.scss b/tgui/packages/tgui/styles/components/TextArea.scss
index fa45857ed9..bef0f227ab 100644
--- a/tgui/packages/tgui/styles/components/TextArea.scss
+++ b/tgui/packages/tgui/styles/components/TextArea.scss
@@ -65,6 +65,13 @@ $border-radius: Input.$border-radius !default;
   word-wrap: break-word;
   overflow: hidden;
 
+  &::placeholder {
+    font-style: italic;
+    color: #777;
+    color: rgba(255, 255, 255, 0.45);
+  }
+
+  // TODO: Remove with 516
   &:-ms-input-placeholder {
     font-style: italic;
     color: #777;
diff --git a/tgui/packages/tgui/styles/interfaces/IntegratedCircuit.scss b/tgui/packages/tgui/styles/interfaces/IntegratedCircuit.scss
index 7cfecb250a..fdb7d45f76 100644
--- a/tgui/packages/tgui/styles/interfaces/IntegratedCircuit.scss
+++ b/tgui/packages/tgui/styles/interfaces/IntegratedCircuit.scss
@@ -18,7 +18,7 @@ $fg-map: colors.$fg-map !default;
 
   white-space: nowrap;
 
-  -ms-user-select: none;
+  -ms-user-select: none; // TODO: Remove with 516
   user-select: none;
 }
 
@@ -26,7 +26,7 @@ $fg-map: colors.$fg-map !default;
   white-space: nowrap;
   background-color: rgba(0, 0, 0, 0.5);
 
-  -ms-user-select: none;
+  -ms-user-select: none; // TODO: Remove with 516
   user-select: none;
 }
 
diff --git a/tgui/packages/tgui/styles/layouts/Layout.scss b/tgui/packages/tgui/styles/layouts/Layout.scss
index fdf6435e31..2a43402c71 100644
--- a/tgui/packages/tgui/styles/layouts/Layout.scss
+++ b/tgui/packages/tgui/styles/layouts/Layout.scss
@@ -5,12 +5,29 @@
 
 @use 'sass:color';
 @use '../base.scss';
+@use '../functions.scss' as *;
 
 $scrollbar-color-multiplier: 1 !default;
+$luminance: luminance(base.$color-bg);
+$scrollbar-base: color.scale(
+  base.$color-bg,
+  $lightness: -25% * $scrollbar-color-multiplier
+);
+$scrollbar-face: color.scale(
+  base.$color-bg,
+  $lightness: if($luminance > 0.05, 30%, 10%) * $scrollbar-color-multiplier
+);
 
+// Fancy scrollbar
+html,
+body {
+  scrollbar-color: $scrollbar-face $scrollbar-base;
+}
+
+// Remove with 516, IE legacy code
 .Layout,
 .Layout * {
-  // Fancy scrollbar
+  // Remove with 516, IE legacy code
   scrollbar-base-color: color.scale(
     base.$color-bg,
     $lightness: -25% * $scrollbar-color-multiplier
diff --git a/tgui/packages/tgui/styles/layouts/NtosWindow.scss b/tgui/packages/tgui/styles/layouts/NtosWindow.scss
index bed4abab53..7b8f9d452b 100644
--- a/tgui/packages/tgui/styles/layouts/NtosWindow.scss
+++ b/tgui/packages/tgui/styles/layouts/NtosWindow.scss
@@ -16,7 +16,7 @@
   font-family: Consolas, monospace;
   font-size: base.em(14px);
   user-select: none;
-  -ms-user-select: none;
+  -ms-user-select: none; // TODO: Remove with 516
 }
 
 .NtosWindow__content .Layout__content {
diff --git a/tgui/packages/tgui/styles/layouts/TitleBar.scss b/tgui/packages/tgui/styles/layouts/TitleBar.scss
index 1a26dd9e29..79a2d3fd4d 100644
--- a/tgui/packages/tgui/styles/layouts/TitleBar.scss
+++ b/tgui/packages/tgui/styles/layouts/TitleBar.scss
@@ -18,7 +18,7 @@ $shadow-color: rgba(0, 0, 0, 0.1) !default;
   box-shadow: 0 2px 2px $shadow-color;
   box-shadow: 0 base.rem(2px) base.rem(2px) $shadow-color;
   user-select: none;
-  -ms-user-select: none;
+  -ms-user-select: none; // TODO: Remove with 516
 }
 
 .TitleBar__clickable {
diff --git a/tgui/packages/tgui/styles/main.scss b/tgui/packages/tgui/styles/main.scss
index a79f94f9a2..ee8bde3bfa 100644
--- a/tgui/packages/tgui/styles/main.scss
+++ b/tgui/packages/tgui/styles/main.scss
@@ -80,7 +80,7 @@
 // NT Theme
 .Layout__content {
   background-image: url('../assets/bg-nanotrasen.svg');
-  background-size: 70%;
+  background-size: 70% 70%;
   background-position: center;
   background-repeat: no-repeat;
 }
diff --git a/tgui/packages/tgui/styles/themes/paper.scss b/tgui/packages/tgui/styles/themes/paper.scss
index ea9da08ffb..c61a4eca8c 100644
--- a/tgui/packages/tgui/styles/themes/paper.scss
+++ b/tgui/packages/tgui/styles/themes/paper.scss
@@ -99,6 +99,13 @@ $font-size: 24px;
     color: #fff;
     color: inherit;
 
+    &::placeholder {
+      font-style: italic;
+      color: #777;
+      color: rgba(255, 255, 255, 0.45);
+    }
+
+    // TODO: Remove with 516
     &:-ms-input-placeholder {
       font-style: italic;
       color: #777;