diff --git a/src/compiler/compile/css/Stylesheet.ts b/src/compiler/compile/css/Stylesheet.ts
index d448cda58e8e..eb284d05a5f9 100644
--- a/src/compiler/compile/css/Stylesheet.ts
+++ b/src/compiler/compile/css/Stylesheet.ts
@@ -9,7 +9,32 @@ function remove_css_prefix(name: string): string {
 	return name.replace(/^-((webkit)|(moz)|(o)|(ms))-/, '');
 }
 
-const is_keyframes_node = (node: Node) => remove_css_prefix(node.name) === 'keyframes';
+const is_keyframes_node = (node: Node) =>
+	remove_css_prefix(node.name) === 'keyframes';
+
+const at_rule_has_declaration = ({ block }: Node): true =>
+	block &&
+	block.children &&
+	block.children.find((node: Node) => node.type === 'Declaration');
+
+function minify_declarations(
+	code: MagicString,
+	start: number,
+	declarations: Array<Declaration>
+): number {
+	let c = start;
+
+	declarations.forEach((declaration, i) => {
+		const separator = i > 0 ? ';' : '';
+		if ((declaration.node.start - c) > separator.length) {
+			code.overwrite(c, declaration.node.start, separator);
+		}
+		declaration.minify(code);
+		c = declaration.node.end;
+	});
+
+	return c;
+}
 
 // https://github.com/darkskyapp/string-hash/blob/master/index.js
 function hash(str: string): string {
@@ -64,16 +89,7 @@ class Rule {
 		code.remove(c, this.node.block.start);
 
 		c = this.node.block.start + 1;
-		this.declarations.forEach((declaration, i) => {
-			const separator = i > 0 ? ';' : '';
-			if ((declaration.node.start - c) > separator.length) {
-				code.overwrite(c, declaration.node.start, separator);
-			}
-
-			declaration.minify(code);
-
-			c = declaration.node.end;
-		});
+		c = minify_declarations(code, c, this.declarations)
 
 		code.remove(c, this.node.block.end - 1);
 	}
@@ -141,10 +157,12 @@ class Declaration {
 class Atrule {
 	node: Node;
 	children: Array<Atrule|Rule>;
+	declarations: Array<Declaration>;
 
 	constructor(node: Node) {
 		this.node = node;
 		this.children = [];
+		this.declarations = [];
 	}
 
 	apply(node: Element, stack: Element[]) {
@@ -179,11 +197,6 @@ class Atrule {
 			});
 
 			code.remove(c, this.node.block.start);
-		} else if (is_keyframes_node(this.node)) {
-			let c = this.node.start + this.node.name.length + 1;
-			if (this.node.expression.start - c > 1) code.overwrite(c, this.node.expression.start, ' ');
-			c = this.node.expression.end;
-			if (this.node.block.start - c > 0) code.remove(c, this.node.block.start);
 		} else if (this.node.name === 'supports') {
 			let c = this.node.start + 9;
 			if (this.node.expression.start - c > 1) code.overwrite(c, this.node.expression.start, ' ');
@@ -192,12 +205,26 @@ class Atrule {
 				c = query.end;
 			});
 			code.remove(c, this.node.block.start);
+		} else {
+			let c = this.node.start + this.node.name.length + 1;
+			if(this.node.expression) {
+				if (this.node.expression.start - c > 1) code.overwrite(c, this.node.expression.start, ' ');
+				c = this.node.expression.end;
+			}
+			if (this.node.block && this.node.block.start - c > 0) {
+				code.remove(c, this.node.block.start);
+			}
 		}
 
 		// TODO other atrules
 
 		if (this.node.block) {
 			let c = this.node.block.start + 1;
+			if (this.declarations.length) {
+				c = minify_declarations(code, c, this.declarations);
+				// if the atrule has children, leave the last declaration semicolon alone
+				if (this.children.length) c++;
+			}
 
 			this.children.forEach(child => {
 				if (child.is_used(dev)) {
@@ -296,6 +323,11 @@ export default class Stylesheet {
 									this.keyframes.set(expression.name, `${this.id}-${expression.name}`);
 								}
 							});
+						} else if (at_rule_has_declaration(node)) {
+							const at_rule_declarations = node.block.children
+								.filter(node => node.type === 'Declaration')
+								.map(node => new Declaration(node));
+							atrule.declarations.push(...at_rule_declarations);
 						}
 
 						current_atrule = atrule;
diff --git a/test/css/samples/supports-charset/expected.css b/test/css/samples/supports-charset/expected.css
new file mode 100644
index 000000000000..55cfd4ea2dd9
--- /dev/null
+++ b/test/css/samples/supports-charset/expected.css
@@ -0,0 +1 @@
+@charset "utf-8";
\ No newline at end of file
diff --git a/test/css/samples/supports-charset/input.svelte b/test/css/samples/supports-charset/input.svelte
new file mode 100644
index 000000000000..25704d3eb454
--- /dev/null
+++ b/test/css/samples/supports-charset/input.svelte
@@ -0,0 +1,3 @@
+<style>
+	@charset "utf-8";
+</style>
diff --git a/test/css/samples/supports-font-face/expected.css b/test/css/samples/supports-font-face/expected.css
new file mode 100644
index 000000000000..652ecb1dc2af
--- /dev/null
+++ b/test/css/samples/supports-font-face/expected.css
@@ -0,0 +1 @@
+@font-face{font-family:MyHelvetica;src:local('Helvetica Neue Bold'), local('HelveticaNeue-Bold'), url(MgOpenModernaBold.ttf);font-weight:bold}
\ No newline at end of file
diff --git a/test/css/samples/supports-font-face/input.svelte b/test/css/samples/supports-font-face/input.svelte
new file mode 100644
index 000000000000..3ed82008bf7f
--- /dev/null
+++ b/test/css/samples/supports-font-face/input.svelte
@@ -0,0 +1,7 @@
+<style>
+	@font-face {
+		font-family: MyHelvetica;
+		src: local('Helvetica Neue Bold'), local('HelveticaNeue-Bold'), url(MgOpenModernaBold.ttf);
+		font-weight: bold;
+	}
+</style>
diff --git a/test/css/samples/supports-import/expected.css b/test/css/samples/supports-import/expected.css
new file mode 100644
index 000000000000..485d9d272f09
--- /dev/null
+++ b/test/css/samples/supports-import/expected.css
@@ -0,0 +1 @@
+@import 'custom.css';@import "common.css" screen;@import url(chrome://communicator/skin/);@import url(fineprint.css) print;@import url(landscape.css) screen and (orientation:landscape);@import url(red.css) (min-width:400px);
\ No newline at end of file
diff --git a/test/css/samples/supports-import/input.svelte b/test/css/samples/supports-import/input.svelte
new file mode 100644
index 000000000000..dccfc4cb9582
--- /dev/null
+++ b/test/css/samples/supports-import/input.svelte
@@ -0,0 +1,8 @@
+<style>
+	@import 'custom.css';
+	@import "common.css" screen;
+	@import url(chrome://communicator/skin/);
+	@import url(fineprint.css) print;
+	@import url(landscape.css) screen and (orientation:landscape);
+	@import url(red.css) (min-width:400px);
+</style>
diff --git a/test/css/samples/supports-namespace/expected.css b/test/css/samples/supports-namespace/expected.css
new file mode 100644
index 000000000000..7ca9f4f23d13
--- /dev/null
+++ b/test/css/samples/supports-namespace/expected.css
@@ -0,0 +1 @@
+@namespace url(http://www.w3.org/1999/xhtml);@namespace svg url(http://www.w3.org/2000/svg);a{color:blue}svg|a{color:green}*|a{color:red}
\ No newline at end of file
diff --git a/test/css/samples/supports-namespace/input.svelte b/test/css/samples/supports-namespace/input.svelte
new file mode 100644
index 000000000000..6322ac631011
--- /dev/null
+++ b/test/css/samples/supports-namespace/input.svelte
@@ -0,0 +1,19 @@
+<style>
+	@namespace url(http://www.w3.org/1999/xhtml);
+	@namespace svg url(http://www.w3.org/2000/svg);
+
+	/* This matches all XHTML <a> elements, as XHTML is the default unprefixed namespace */
+	:global(a) {
+		color: blue;
+	}
+
+	/* This matches all SVG <a> elements */
+	:global(svg|a) {
+		color: green;
+	}
+
+	/* This matches both XHTML and SVG <a> elements */
+	:global(*|a) {
+		color: red;
+	}
+</style>
diff --git a/test/css/samples/supports-nested-page/expected.css b/test/css/samples/supports-nested-page/expected.css
new file mode 100644
index 000000000000..d526b5798952
--- /dev/null
+++ b/test/css/samples/supports-nested-page/expected.css
@@ -0,0 +1 @@
+@page vertical{size:A4 portrait;@top-center{content:"Vertical"}}@page :right{@top-center{content:"Preliminary edition"}@bottom-center{content:counter(page)}}@page :first{color:green;font-size:20pt;@top-left{content:"foo";color:blue}@top-right{content:"bar"}}
\ No newline at end of file
diff --git a/test/css/samples/supports-nested-page/input.svelte b/test/css/samples/supports-nested-page/input.svelte
new file mode 100644
index 000000000000..a36c8263ceb7
--- /dev/null
+++ b/test/css/samples/supports-nested-page/input.svelte
@@ -0,0 +1,32 @@
+<style>
+	@page vertical {
+		size: A4 portrait;
+		@top-center {
+			content: "Vertical";
+		}
+	}
+
+	@page :right {
+		@top-center {
+			content: "Preliminary edition";
+		}
+
+		@bottom-center {
+			content: counter(page);
+		}
+	}
+
+	@page :first {
+		color: green;
+		font-size: 20pt;
+
+		@top-left {
+			content: "foo";
+			color: blue;
+		}
+
+		@top-right {
+			content: "bar";
+		}
+	}
+</style>
diff --git a/test/css/samples/supports-page/expected.css b/test/css/samples/supports-page/expected.css
new file mode 100644
index 000000000000..6978c3ecec05
--- /dev/null
+++ b/test/css/samples/supports-page/expected.css
@@ -0,0 +1 @@
+@page{margin:1cm;size:A4;bleed:7pt}
\ No newline at end of file
diff --git a/test/css/samples/supports-page/input.svelte b/test/css/samples/supports-page/input.svelte
new file mode 100644
index 000000000000..70c089c35687
--- /dev/null
+++ b/test/css/samples/supports-page/input.svelte
@@ -0,0 +1,7 @@
+<style>
+	@page{
+		margin: 1cm;
+		size: A4;
+		bleed: 7pt;
+	}
+</style>