diff --git a/crates/treehouse/src/html/markdown.rs b/crates/treehouse/src/html/markdown.rs
index 7b20875..e29a5b5 100644
--- a/crates/treehouse/src/html/markdown.rs
+++ b/crates/treehouse/src/html/markdown.rs
@@ -527,7 +527,8 @@ where
                                 escape_html(&mut self.writer, &branch.attributes.id)?;
                                 self.writer.write_str("\">")?;
                             }
-                            self.writer.write_str("<img is=\"th-emoji\" title=\":")?;
+                            self.writer
+                                .write_str("<img data-cast=\"emoji\" title=\":")?;
                             escape_html(&mut self.writer, name)?;
                             self.writer.write_str(":\" src=\"")?;
                             escape_html(&mut self.writer, &self.config.site)?;
diff --git a/crates/treehouse/src/html/tree.rs b/crates/treehouse/src/html/tree.rs
index 9e26416..988b642 100644
--- a/crates/treehouse/src/html/tree.rs
+++ b/crates/treehouse/src/html/tree.rs
@@ -45,9 +45,9 @@ pub fn branch_to_html(
     }
 
     let component = if let Content::Link(_) = branch.attributes.content {
-        "th-b-linked"
+        "b-linked"
     } else {
-        "th-b"
+        "b"
     };
 
     let linked_branch = if let Content::Link(link) = &branch.attributes.content {
@@ -64,7 +64,7 @@ pub fn branch_to_html(
 
     write!(
         s,
-        "<li is=\"{component}\" class=\"{class}\" id=\"{}\"{linked_branch}{do_not_persist}>",
+        "<li data-cast=\"{component}\" class=\"{class}\" id=\"{}\"{linked_branch}{do_not_persist}>",
         EscapeAttribute(&branch.html_id)
     )
     .unwrap();
diff --git a/crates/treehouse/src/tree/attributes.rs b/crates/treehouse/src/tree/attributes.rs
index 1415ad5..6a317ca 100644
--- a/crates/treehouse/src/tree/attributes.rs
+++ b/crates/treehouse/src/tree/attributes.rs
@@ -107,7 +107,7 @@ pub enum Content {
 
 #[derive(Debug, Default, Clone, PartialEq, Eq, Deserialize)]
 pub struct Classes {
-    /// Classes to append to the branch itself (<li is="th-b">).
+    /// Classes to append to the branch itself (<li data-cast="b">).
     #[serde(default)]
     pub branch: String,
 
diff --git a/jsconfig.json b/jsconfig.json
index 5eb03be..b6fa674 100644
--- a/jsconfig.json
+++ b/jsconfig.json
@@ -8,6 +8,7 @@
             "tairu/*": [
                 "./components/tairu/*"
             ]
-        }
+        },
+        "target": "ES2020",
     },
 }
diff --git a/static/css/main.css b/static/css/main.css
index fae54f8..46047ff 100644
--- a/static/css/main.css
+++ b/static/css/main.css
@@ -447,7 +447,7 @@ h1.page-title {
 }
 
 /* Style the `new` link on the homepage */
-a[is="th-new"] {
+a[data-cast~="new"] {
     flex-shrink: 0;
     color: var(--text-color);
     opacity: 50%;
@@ -509,7 +509,7 @@ footer {
 
 /* Style emojis to be readable */
 
-img[is="th-emoji"] {
+img[data-cast~="emoji"] {
     max-width: 1.5em;
     max-height: 1.5em;
     vertical-align: bottom;
@@ -777,7 +777,7 @@ th-literate-program[data-mode="output"] {
 
 /* Style settings sections */
 
-section[is="th-settings"] {
+section[data-cast~="settings"] {
     /* Don't display settings when JavaScript is disabled.
        JS overrides this value on the element itself. */
     display: none;
diff --git a/static/css/new.css b/static/css/new.css
index 5ff71ea..1df466c 100644
--- a/static/css/new.css
+++ b/static/css/new.css
@@ -64,7 +64,7 @@ section {
     }
 }
 
-section[is="th-settings"] {
+section.settings {
     & h3 {
         display: inline;
     }
@@ -131,4 +131,4 @@ section[is="th-settings"] {
             border-color: white;
         }
     }
-}
\ No newline at end of file
+}
diff --git a/static/js/emoji.js b/static/js/emoji.js
index 3e689ce..d82fb89 100644
--- a/static/js/emoji.js
+++ b/static/js/emoji.js
@@ -1,10 +1,13 @@
 // Emoji zoom-in functionality.
 
+import { addSpell } from "treehouse/spells.js";
+
 class EmojiTooltip extends HTMLElement {
-    constructor(emoji, { onClosed }) {
+    constructor(emoji, element, { onClosed }) {
         super();
 
         this.emoji = emoji;
+        this.emojiElement = element;
         this.onClosed = onClosed;
     }
 
@@ -12,12 +15,12 @@ class EmojiTooltip extends HTMLElement {
         this.role = "tooltip";
 
         this.image = new Image();
-        this.image.src = this.emoji.src;
+        this.image.src = this.emojiElement.src;
 
         this.description = document.createElement("p");
         this.description.textContent = `${this.emoji.emojiName}`;
 
-        let emojiBoundingBox = this.emoji.getBoundingClientRect();
+        let emojiBoundingBox = this.emojiElement.getBoundingClientRect();
         this.style.left = `${emojiBoundingBox.left + emojiBoundingBox.width / 2}px`;
         this.style.top = `calc(${emojiBoundingBox.top}px + 1.5em)`;
 
@@ -68,8 +71,8 @@ class EmojiTooltips extends HTMLElement {
         this.abortController.abort();
     }
 
-    openTooltip(emoji) {
-        let tooltip = new EmojiTooltip(emoji, {
+    openTooltip(emoji, element) {
+        let tooltip = new EmojiTooltip(emoji, element, {
             onClosed: () => {
                 this.removeChild(tooltip);
                 this.tooltips.delete(tooltip);
@@ -95,21 +98,21 @@ class EmojiTooltips extends HTMLElement {
 
 customElements.define("th-emoji-tooltips", EmojiTooltips);
 
-class Emoji extends HTMLImageElement {
-    connectedCallback() {
-        this.emojiName = this.title;
+class Emoji {
+    constructor(element) {
+        this.emojiName = element.title;
 
         // title makes the browser add a tooltip. We replace browser tooltips with our own,
         // so remove the title.
-        this.title = "";
+        element.title = "";
 
-        this.addEventListener("mouseenter", () => this.openTooltip());
-        this.addEventListener("mouseleave", () => this.closeTooltip());
-        this.addEventListener("scroll", () => this.closeTooltip());
+        element.addEventListener("mouseenter", () => this.openTooltip(element));
+        element.addEventListener("mouseleave", () => this.closeTooltip());
+        element.addEventListener("scroll", () => this.closeTooltip());
     }
 
-    openTooltip() {
-        this.tooltip = emojiTooltips.openTooltip(this);
+    openTooltip(element) {
+        this.tooltip = emojiTooltips.openTooltip(this, element);
     }
 
     closeTooltip() {
@@ -118,4 +121,4 @@ class Emoji extends HTMLImageElement {
     }
 }
 
-customElements.define("th-emoji", Emoji, { extends: "img" });
+addSpell("emoji", Emoji);
diff --git a/static/js/news.js b/static/js/news.js
index 8cbcd52..d7763a8 100644
--- a/static/js/news.js
+++ b/static/js/news.js
@@ -1,6 +1,7 @@
 // news.js because new.js makes the TypeScript language server flip out.
 // Likely because `new` is a keyword, but also, what the fuck.
 
+import { addSpell, spell } from "treehouse/spells.js";
 import { getSettingValue } from "treehouse/settings.js";
 import { Branch } from "treehouse/tree.js";
 
@@ -15,15 +16,17 @@ function saveSeenStates() {
 }
 
 function markAsRead(branch) {
-    if (!seenStates.has(branch.namedID) && seenCount > 0) {
+    let branchData = spell(branch, Branch);
+
+    if (!seenStates.has(branchData.namedID) && seenCount > 0) {
         let badge = document.createElement("span");
         badge.classList.add("badge", "red", "before-content");
         badge.textContent = "new";
 
-        branch.branchContent.firstChild.insertBefore(badge, branch.branchContent.firstChild.firstChild);
+        branchData.branchContent.firstChild.insertBefore(badge, branchData.branchContent.firstChild.firstChild);
     }
 
-    seenStates.add(branch.namedID);
+    seenStates.add(branchData.namedID);
 }
 
 export function initNewsPage() {
@@ -43,8 +46,8 @@ export function markAllAsUnread() {
     localStorage.removeItem(seenStatesKey);
 }
 
-class New extends HTMLAnchorElement {
-    connectedCallback() {
+addSpell("new", class New {
+    constructor(element) {
         // Do not show the badge to people who have never seen any news.
         // It's just annoying in that case.
         // In case you do not wish to see the badge anymore, go to the news page and uncheck the
@@ -54,17 +57,15 @@ class New extends HTMLAnchorElement {
         if (userSawNews && userWantsToSeeNews && unseenCount > 0) {
             this.newText = document.createElement("span");
             this.newText.classList.add("new-text");
-            this.newText.textContent = this.textContent;
-            this.textContent = "";
-            this.appendChild(this.newText);
+            this.newText.textContent = element.textContent;
+            element.textContent = "";
+            element.appendChild(this.newText);
 
             this.badge = document.createElement("span");
             this.badge.classList.add("badge", "red");
             this.badge.textContent = unseenCount.toString();
-            this.appendChild(this.badge);
-            this.classList.add("has-news");
+            element.appendChild(this.badge);
+            element.classList.add("has-news");
         }
     }
-}
-
-customElements.define("th-new", New, { extends: "a" });
+});
diff --git a/static/js/settings.js b/static/js/settings.js
index 6b18a2a..64e432d 100644
--- a/static/js/settings.js
+++ b/static/js/settings.js
@@ -1,3 +1,5 @@
+import { addSpell } from "treehouse/spells.js";
+
 const settingsKey = "treehouse.settings";
 const settings = JSON.parse(localStorage.getItem(settingsKey)) || {};
 
@@ -13,23 +15,15 @@ export function getSettingValue(setting) {
     return settings[setting] ?? defaultSettingValues[setting];
 }
 
-class SettingCheckbox extends HTMLInputElement {
-    connectedCallback() {
-        this.checked = getSettingValue(this.id);
+class SettingCheckbox {
+    constructor(element) {
+        element.checked = getSettingValue(element.id);
 
-        this.addEventListener("change", () => {
-            settings[this.id] = this.checked;
+        element.addEventListener("change", () => {
+            settings[element.id] = element.checked;
             saveSettings();
         });
     }
 }
 
-customElements.define("th-setting-checkbox", SettingCheckbox, { extends: "input" });
-
-class Settings extends HTMLElement {
-    connectedCallback() {
-        this.style.display = "block";
-    }
-}
-
-customElements.define("th-settings", Settings, { extends: "section" });
+addSpell("setting-checkbox", SettingCheckbox);
diff --git a/static/js/spells.js b/static/js/spells.js
new file mode 100644
index 0000000..1699a5c
--- /dev/null
+++ b/static/js/spells.js
@@ -0,0 +1,85 @@
+// Spells are a simplistic, composition-based replacement for the is="" attribute, which is not
+// supported on Webkit due to Apple's engineering being a bunch of obstinate idiots who explicitly
+// choose not to follow web standards.
+
+// Limitations:
+//   - The data-cast attribute cannot be added dynamically.
+//   - There is no disconnectedCallback. Only a constructor which initializes a spell.
+
+let spells = new Map();
+let elementsWithUnknownSpells = new Map();
+
+const sSpells = Symbol("spells");
+
+function castSpellOnElement(spellName, element) {
+    element[sSpells] ??= new Map();
+    if (!elementsWithUnknownSpells.has(spellName)) {
+        elementsWithUnknownSpells.set(spellName, new Set());
+    }
+
+    let Spell = spells.get(spellName);
+    if (Spell != null && !element[sSpells].has(Spell)) {
+        element[sSpells].set(Spell, new Spell(element));
+        elementsWithUnknownSpells.get(spellName).delete(element);
+    } else {
+        elementsWithUnknownSpells.get(spellName).add(element);
+    }
+}
+
+function applySpells(elements) {
+    for (let element of elements) {
+        if (element instanceof Element) {
+            let spellListString = element.getAttribute("data-cast");
+            if (spellListString != null) {
+                let spellList = spellListString.split(' ');
+                for (let spellName of spellList) {
+                    castSpellOnElement(spellName, element);
+                }
+            }
+        }
+    }
+}
+
+export function addSpell(name, spell) {
+    spells.set(name, spell);
+    let elementsWithThisSpell = elementsWithUnknownSpells.get(name);
+    if (elementsWithThisSpell != null) {
+        for (let element of elementsWithThisSpell) {
+            castSpellOnElement(name, element);
+        }
+    }
+}
+
+// Returns a spell's data. Gotchas: the spell needs to already be on the element.
+// Therefore, if this is used from within a spell, the requested spell must have already been
+// applied by this point.
+// Someday I may change this to an async function that resumes whenever the spell is available to
+// iron over this limitation. But today is not that day.
+export function spell(element, spell) {
+    return element[sSpells].get(spell);
+}
+
+// Apply spells to elements which have them and have been loaded so far.
+let loadedSoFar = document.querySelectorAll("[data-cast]");
+applySpells(loadedSoFar);
+
+// For all other elements, add a mutation observer that will handle them.
+let mutationObserver = new MutationObserver(records => {
+    for (let record of records) {
+        let mutatedNodes = new Set();
+        // NOTE: Added nodes may contain children which also need to be processed.
+        // Collect those that have [data-cast] on them and apply spells to them.
+        for (let addedNode of record.addedNodes) {
+            addedNode.querySelectorAll("[data-cast]").forEach(element => mutatedNodes.add(element));
+        }
+        applySpells(mutatedNodes);
+    }
+});
+mutationObserver.observe(document, { subtree: true, childList: true });
+
+// ------------ Common spells ------------
+
+// js makes things visible only when JavaScript is enabled.
+addSpell("js", function (element) {
+    element.style.display = "block";
+});
diff --git a/static/js/thanks-webkit.js b/static/js/thanks-webkit.js
deleted file mode 100644
index efcfcf5..0000000
--- a/static/js/thanks-webkit.js
+++ /dev/null
@@ -1,21 +0,0 @@
-// Detect if we can have crucial functionality (ie. custom elements call constructors).
-// This doesn't seem to happen in Epiphany, and also other Webkit-based browsers.
-let works = false;
-class WebkitMoment extends HTMLLIElement {
-    constructor() {
-        super();
-        works = true;
-    }
-}
-
-customElements.define("th-webkit-moment", WebkitMoment, { extends: "li" });
-
-let willItWorkOrWillItNot = document.createElement("div");
-willItWorkOrWillItNot.innerHTML = `<li is="th-webkit-moment"></li>`;
-
-// If my takeoff fails
-// tell my mother I'm sorry
-let box = document.getElementById("webkit-makes-me-go-insane");
-if (!works) {
-    box.style = "display: block";
-}
diff --git a/static/js/tree.js b/static/js/tree.js
index 3dd9d2f..414f973 100644
--- a/static/js/tree.js
+++ b/static/js/tree.js
@@ -1,5 +1,6 @@
 // This is definitely not a three.js ripoff.
 
+import { addSpell } from "treehouse/spells.js";
 import { navigationMap } from "/navmap.js";
 import * as ulid from "treehouse/ulid.js";
 
@@ -17,18 +18,20 @@ function branchIsOpen(branchID) {
     return branchState[branchID];
 }
 
-export class Branch extends HTMLLIElement {
+export class Branch {
     static branchesByNamedID = new Map();
     static onAdded = [];
 
-    connectedCallback() {
-        this.isLeaf = this.classList.contains("leaf");
+    constructor(element) {
+        this.element = element;
 
-        this.details = this.childNodes[0];
+        this.isLeaf = element.classList.contains("leaf");
+
+        this.details = element.childNodes[0];
         this.innerUL = this.details.childNodes[1];
 
         if (this.isLeaf) {
-            this.contentContainer = this.childNodes[0];
+            this.contentContainer = element.childNodes[0];
         } else {
             this.contentContainer = this.details.childNodes[0];
         }
@@ -36,19 +39,19 @@ export class Branch extends HTMLLIElement {
         this.branchContent = this.contentContainer.childNodes[1];
         this.buttonBar = this.contentContainer.childNodes[2];
 
-        let doPersist = !this.hasAttribute("data-th-do-not-persist");
-        let isOpen = branchIsOpen(this.id);
+        let doPersist = !element.hasAttribute("data-th-do-not-persist");
+        let isOpen = branchIsOpen(element.id);
         if (doPersist && isOpen !== undefined) {
             this.details.open = isOpen;
         }
         if (!this.isLeaf) {
             this.details.addEventListener("toggle", _ => {
-                saveBranchIsOpen(this.id, this.details.open);
+                saveBranchIsOpen(element.id, this.details.open);
             });
         }
 
-        this.namedID = this.id.split(':')[1];
-        Branch.branchesByNamedID.set(this.namedID, this);
+        this.namedID = element.id.split(':')[1];
+        Branch.branchesByNamedID.set(this.namedID, element);
 
         if (ulid.isCanonicalUlid(this.namedID)) {
             let timestamp = ulid.getTimestamp(this.namedID);
@@ -59,22 +62,22 @@ export class Branch extends HTMLLIElement {
         }
 
         for (let callback of Branch.onAdded) {
-            callback(this);
+            callback(element, this);
         }
     }
 }
 
-customElements.define("th-b", Branch, { extends: "li" });
+addSpell("b", Branch);
 
 /* Linked branches */
 
 class LinkedBranch extends Branch {
     static byLink = new Map();
 
-    connectedCallback() {
-        super.connectedCallback();
+    constructor(element) {
+        super(element);
 
-        this.linkedTree = this.getAttribute("data-th-link");
+        this.linkedTree = element.getAttribute("data-th-link");
         LinkedBranch.byLink.set(this.linkedTree, this);
 
         this.loadingText = document.createElement("p");
@@ -115,11 +118,10 @@ class LinkedBranch extends Branch {
             let styles = main.getElementsByTagName("link");
             let scripts = main.getElementsByTagName("script");
 
-
             this.loadingText.remove();
             this.innerUL.innerHTML = ul.innerHTML;
 
-            this.append(...styles);
+            this.element.append(...styles);
             for (let script of scripts) {
                 // No need to await for the import because we don't use the resulting module.
                 // Just fire and forger 💀
@@ -139,7 +141,7 @@ class LinkedBranch extends Branch {
     }
 }
 
-customElements.define("th-b-linked", LinkedBranch, { extends: "li" });
+addSpell("b-linked", LinkedBranch);
 
 /* Fragment navigation */
 
diff --git a/static/js/usability.js b/static/js/usability.js
index ffa84b8..46318e4 100644
--- a/static/js/usability.js
+++ b/static/js/usability.js
@@ -7,12 +7,3 @@ document.addEventListener("click", event => {
         event.preventDefault();
     }
 })
-
-// Certain words don't make sense if scripts are disabled.
-class YesScript extends HTMLElement {
-    connectedCallback() {
-        this.classList.add("yes-indeed");
-    }
-}
-
-customElements.define("th-yesscript", YesScript);
diff --git a/template/_new.hbs b/template/_new.hbs
index dfc40fd..d2efad8 100644
--- a/template/_new.hbs
+++ b/template/_new.hbs
@@ -11,13 +11,12 @@
 
     {{!-- For /index, include a "new" link that goes to the curated news feed page. --}}
     {{#if (eq page.tree_path "index")}}
-    <a href="{{ config.site }}/treehouse/new.html" is="th-new">new</a>
+    <a href="{{ config.site }}/treehouse/new.html" data-cast="new">new</a>
     {{/if}}
 
     {{/ components/_nav.hbs }}
 
     {{> components/_noscript.hbs }}
-    {{> components/_webkit.hbs }}
 
     <section>
         <p>welcome!</p>
@@ -33,7 +32,7 @@
         </p>
     </section>
 
-    <section is="th-settings">
+    <section class="settings" data-cast="js">
         <details>
             <summary>
                 settings
@@ -41,7 +40,7 @@
             <section>
                 <p>if you find the newsfeed annoying, you can customize some aspects of it.</p>
                 <p>
-                    <input type="checkbox" is="th-setting-checkbox" id="showNewPostIndicator">
+                    <input type="checkbox" data-cast="setting-checkbox" id="showNewPostIndicator">
                     <label for="showNewPostIndicator">show the <span class="badge red">1</span> badge on the homepage
                         for
                         new posts you haven't read yet</label>
@@ -70,4 +69,4 @@
     </script>
 </body>
 
-</html>
\ No newline at end of file
+</html>
diff --git a/template/_tree.hbs b/template/_tree.hbs
index 3f1c4ce..9dfa2e9 100644
--- a/template/_tree.hbs
+++ b/template/_tree.hbs
@@ -11,13 +11,12 @@
 
     {{!-- For /index, include a "new" link that goes to the curated news feed page. --}}
     {{#if (eq page.tree_path "index")}}
-    <a href="{{ config.site }}/treehouse/new.html" is="th-new">new</a>
+    <a href="{{ config.site }}/treehouse/new.html" data-cast="new">new</a>
     {{/if}}
 
     {{/ components/_nav.hbs }}
 
     {{> components/_noscript.hbs }}
-    {{> components/_webkit.hbs }}
 
     {{!--
     NOTE: ~ because components/_tree.hbss must not include any extra indentation, because it may
diff --git a/template/components/_head.hbs b/template/components/_head.hbs
index d1f00d1..eb257f3 100644
--- a/template/components/_head.hbs
+++ b/template/components/_head.hbs
@@ -20,12 +20,12 @@
     const TREEHOUSE_NEWS_COUNT = {{ len feeds.news.branches }};
 </script>
 <script type="module" src="{{ config.site }}/navmap.js"></script>
+<script type="module" src="{{ config.site }}/static/js/spells.js"></script>
 <script type="module" src="{{ config.site }}/static/js/ulid.js"></script>
 <script type="module" src="{{ config.site }}/static/js/usability.js"></script>
 <script type="module" src="{{ config.site }}/static/js/settings.js"></script>
 <script type="module" src="{{ config.site }}/static/js/tree.js"></script>
 <script type="module" src="{{ config.site }}/static/js/emoji.js"></script>
-<script type="module" src="{{ config.site }}/static/js/thanks-webkit.js"></script>
 <script type="module" src="{{ config.site }}/static/js/news.js"></script>
 
 <meta property="og:site_name" content="{{ config.user.title }}">
diff --git a/template/components/_webkit.hbs b/template/components/_webkit.hbs
deleted file mode 100644
index 1de9824..0000000
--- a/template/components/_webkit.hbs
+++ /dev/null
@@ -1,7 +0,0 @@
-<div id="webkit-makes-me-go-insane" class="noscript" role="note">
-    <p>hey! looks like you're using a weird or otherwise quirky web browser. this basically means, the website will
-        not work for you correctly. I might fix it in the future but I have very limited time to work on this
-        website and so don't have an estimate on when that might happen.</p>
-    <p>in the meantime I suggest switching to <a href="https://firefox.com">something more modern.</a></p>
-    <p>sorry for the inconvenience!</p>
-</div>