diff --git a/src/generators/dom/index.ts b/src/generators/dom/index.ts
index bd39842f6e..831e4ebd5f 100644
--- a/src/generators/dom/index.ts
+++ b/src/generators/dom/index.ts
@@ -4,7 +4,7 @@ import annotateWithScopes from '../../utils/annotateWithScopes';
 import isReference from '../../utils/isReference';
 import { walk } from 'estree-walker';
 import deindent from '../../utils/deindent';
-import { stringify } from '../../utils/stringify';
+import { stringify, escape } from '../../utils/stringify';
 import CodeBuilder from '../../utils/CodeBuilder';
 import visit from './visit';
 import shared from './shared';
@@ -184,7 +184,7 @@ export default function dom(
 		${generator.customElement ?
 			deindent`
 				this.attachShadow({ mode: 'open' });
-				${css && `this.shadowRoot.innerHTML = \`<style>${options.dev ? `${css}\n/*# sourceMappingURL=${cssMap.toUrl()} */` : css}</style>\`;`}
+				${css && `this.shadowRoot.innerHTML = \`<style>${options.dev ? `${escape(css, { onlyEscapeAtSymbol: true })}\n/*# sourceMappingURL=${cssMap.toUrl()} */` : escape(css, { onlyEscapeAtSymbol: true })}</style>\`;`}
 			` :
 			(generator.stylesheet.hasStyles && options.css !== false &&
 			`if (!document.getElementById("${generator.stylesheet.id}-style")) @add_css();`)
@@ -236,8 +236,6 @@ export default function dom(
 				`}
 			}
 		`}
-
-
 	`;
 
 	if (generator.customElement) {
diff --git a/test/js/samples/css-shadow-dom-keyframes/_config.js b/test/js/samples/css-shadow-dom-keyframes/_config.js
new file mode 100644
index 0000000000..735dd07e62
--- /dev/null
+++ b/test/js/samples/css-shadow-dom-keyframes/_config.js
@@ -0,0 +1,5 @@
+export default {
+	options: {
+		customElement: true
+	}
+};
\ No newline at end of file
diff --git a/test/js/samples/css-shadow-dom-keyframes/expected-bundle.js b/test/js/samples/css-shadow-dom-keyframes/expected-bundle.js
new file mode 100644
index 0000000000..d960061391
--- /dev/null
+++ b/test/js/samples/css-shadow-dom-keyframes/expected-bundle.js
@@ -0,0 +1,246 @@
+function noop() {}
+
+function assign(target) {
+	var k,
+		source,
+		i = 1,
+		len = arguments.length;
+	for (; i < len; i++) {
+		source = arguments[i];
+		for (k in source) target[k] = source[k];
+	}
+
+	return target;
+}
+
+function appendNode(node, target) {
+	target.appendChild(node);
+}
+
+function insertNode(node, target, anchor) {
+	target.insertBefore(node, anchor);
+}
+
+function detachNode(node) {
+	node.parentNode.removeChild(node);
+}
+
+function createElement(name) {
+	return document.createElement(name);
+}
+
+function createText(data) {
+	return document.createTextNode(data);
+}
+
+function destroy(detach) {
+	this.destroy = noop;
+	this.fire('destroy');
+	this.set = this.get = noop;
+
+	if (detach !== false) this._fragment.unmount();
+	this._fragment.destroy();
+	this._fragment = this._state = null;
+}
+
+function differs(a, b) {
+	return a !== b || ((a && typeof a === 'object') || typeof a === 'function');
+}
+
+function dispatchObservers(component, group, changed, newState, oldState) {
+	for (var key in group) {
+		if (!changed[key]) continue;
+
+		var newValue = newState[key];
+		var oldValue = oldState[key];
+
+		var callbacks = group[key];
+		if (!callbacks) continue;
+
+		for (var i = 0; i < callbacks.length; i += 1) {
+			var callback = callbacks[i];
+			if (callback.__calling) continue;
+
+			callback.__calling = true;
+			callback.call(component, newValue, oldValue);
+			callback.__calling = false;
+		}
+	}
+}
+
+function get(key) {
+	return key ? this._state[key] : this._state;
+}
+
+function fire(eventName, data) {
+	var handlers =
+		eventName in this._handlers && this._handlers[eventName].slice();
+	if (!handlers) return;
+
+	for (var i = 0; i < handlers.length; i += 1) {
+		handlers[i].call(this, data);
+	}
+}
+
+function observe(key, callback, options) {
+	var group = options && options.defer
+		? this._observers.post
+		: this._observers.pre;
+
+	(group[key] || (group[key] = [])).push(callback);
+
+	if (!options || options.init !== false) {
+		callback.__calling = true;
+		callback.call(this, this._state[key]);
+		callback.__calling = false;
+	}
+
+	return {
+		cancel: function() {
+			var index = group[key].indexOf(callback);
+			if (~index) group[key].splice(index, 1);
+		}
+	};
+}
+
+function on(eventName, handler) {
+	if (eventName === 'teardown') return this.on('destroy', handler);
+
+	var handlers = this._handlers[eventName] || (this._handlers[eventName] = []);
+	handlers.push(handler);
+
+	return {
+		cancel: function() {
+			var index = handlers.indexOf(handler);
+			if (~index) handlers.splice(index, 1);
+		}
+	};
+}
+
+function set(newState) {
+	this._set(assign({}, newState));
+	if (this._root._lock) return;
+	this._root._lock = true;
+	callAll(this._root._beforecreate);
+	callAll(this._root._oncreate);
+	callAll(this._root._aftercreate);
+	this._root._lock = false;
+}
+
+function _set(newState) {
+	var oldState = this._state,
+		changed = {},
+		dirty = false;
+
+	for (var key in newState) {
+		if (differs(newState[key], oldState[key])) changed[key] = dirty = true;
+	}
+	if (!dirty) return;
+
+	this._state = assign({}, oldState, newState);
+	this._recompute(changed, this._state, oldState, false);
+	if (this._bind) this._bind(changed, this._state);
+	dispatchObservers(this, this._observers.pre, changed, this._state, oldState);
+	this._fragment.update(changed, this._state);
+	dispatchObservers(this, this._observers.post, changed, this._state, oldState);
+}
+
+function callAll(fns) {
+	while (fns && fns.length) fns.pop()();
+}
+
+function _mount(target, anchor) {
+	this._fragment.mount(target, anchor);
+}
+
+function _unmount() {
+	this._fragment.unmount();
+}
+
+var proto = {
+	destroy: destroy,
+	get: get,
+	fire: fire,
+	observe: observe,
+	on: on,
+	set: set,
+	teardown: destroy,
+	_recompute: noop,
+	_set: _set,
+	_mount: _mount,
+	_unmount: _unmount
+};
+
+function create_main_fragment(state, component) {
+	var div, text;
+
+	return {
+		create: function() {
+			div = createElement("div");
+			text = createText("fades in");
+		},
+
+		mount: function(target, anchor) {
+			insertNode(div, target, anchor);
+			appendNode(text, div);
+		},
+
+		update: noop,
+
+		unmount: function() {
+			detachNode(div);
+		},
+
+		destroy: noop
+	};
+}
+
+class SvelteComponent extends HTMLElement {
+	constructor(options = {}) {
+		super();
+		this.options = options;
+		this._state = options.data || {};
+
+		this._observers = {
+			pre: Object.create(null),
+			post: Object.create(null)
+		};
+
+		this._handlers = Object.create(null);
+
+		this._root = options._root || this;
+		this._yield = options._yield;
+		this._bind = options._bind;
+
+		this.attachShadow({ mode: 'open' });
+		this.shadowRoot.innerHTML = `<style>div{animation:foo 1s}@keyframes foo{0%{opacity:0}100%{opacity:1}}</style>`;
+
+		this._fragment = create_main_fragment(this._state, this);
+
+		this._fragment.create();
+		this._fragment.mount(this.shadowRoot, null);
+
+		if (options.target) this._mount(options.target, options.anchor || null);
+	}
+
+	static get observedAttributes() {
+		return [];
+	}
+
+	attributeChangedCallback(attr, oldValue, newValue) {
+		this.set({ [attr]: newValue });
+	}
+}
+
+customElements.define("custom-element", SvelteComponent);
+assign(SvelteComponent.prototype, proto , {
+	_mount(target, anchor) {
+		target.insertBefore(this, anchor);
+	},
+
+	_unmount() {
+		this.parentNode.removeChild(this);
+	}
+});
+
+export default SvelteComponent;
diff --git a/test/js/samples/css-shadow-dom-keyframes/expected.js b/test/js/samples/css-shadow-dom-keyframes/expected.js
new file mode 100644
index 0000000000..c8bc7e187e
--- /dev/null
+++ b/test/js/samples/css-shadow-dom-keyframes/expected.js
@@ -0,0 +1,75 @@
+import { appendNode, assign, createElement, createText, detachNode, insertNode, noop, proto } from "svelte/shared.js";
+
+function create_main_fragment(state, component) {
+	var div, text;
+
+	return {
+		create: function() {
+			div = createElement("div");
+			text = createText("fades in");
+		},
+
+		mount: function(target, anchor) {
+			insertNode(div, target, anchor);
+			appendNode(text, div);
+		},
+
+		update: noop,
+
+		unmount: function() {
+			detachNode(div);
+		},
+
+		destroy: noop
+	};
+}
+
+class SvelteComponent extends HTMLElement {
+	constructor(options = {}) {
+		super();
+		this.options = options;
+		this._state = options.data || {};
+
+		this._observers = {
+			pre: Object.create(null),
+			post: Object.create(null)
+		};
+
+		this._handlers = Object.create(null);
+
+		this._root = options._root || this;
+		this._yield = options._yield;
+		this._bind = options._bind;
+
+		this.attachShadow({ mode: 'open' });
+		this.shadowRoot.innerHTML = `<style>div{animation:foo 1s}@keyframes foo{0%{opacity:0}100%{opacity:1}}</style>`;
+
+		this._fragment = create_main_fragment(this._state, this);
+
+		this._fragment.create();
+		this._fragment.mount(this.shadowRoot, null);
+
+		if (options.target) this._mount(options.target, options.anchor || null);
+	}
+
+	static get observedAttributes() {
+		return [];
+	}
+
+	attributeChangedCallback(attr, oldValue, newValue) {
+		this.set({ [attr]: newValue });
+	}
+}
+
+customElements.define("custom-element", SvelteComponent);
+assign(SvelteComponent.prototype, proto , {
+	_mount(target, anchor) {
+		target.insertBefore(this, anchor);
+	},
+
+	_unmount() {
+		this.parentNode.removeChild(this);
+	}
+});
+
+export default SvelteComponent;
\ No newline at end of file
diff --git a/test/js/samples/css-shadow-dom-keyframes/input.html b/test/js/samples/css-shadow-dom-keyframes/input.html
new file mode 100644
index 0000000000..fcdc7a9f0e
--- /dev/null
+++ b/test/js/samples/css-shadow-dom-keyframes/input.html
@@ -0,0 +1,18 @@
+<div>fades in</div>
+
+<style>
+	div {
+		animation: foo 1s;
+	}
+
+	@keyframes foo {
+		0% { opacity: 0; }
+		100% { opacity: 1; }
+	}
+</style>
+
+<script>
+	export default {
+		tag: 'custom-element'
+	};
+</script>
\ No newline at end of file