diff --git a/web/core/src/jsMain/kotlin/org/jetbrains/compose/web/elements/Style.kt b/web/core/src/jsMain/kotlin/org/jetbrains/compose/web/elements/Style.kt
index 017debfac2..5e82a54d4b 100644
--- a/web/core/src/jsMain/kotlin/org/jetbrains/compose/web/elements/Style.kt
+++ b/web/core/src/jsMain/kotlin/org/jetbrains/compose/web/elements/Style.kt
@@ -81,6 +81,38 @@ private fun fillRule(
     }
 }
 
+fun CSSRuleDeclaration.stringPresentation(
+    baseIndent: String = "",
+    indent: String = "    ",
+    delimiter: String = "\n"
+): String {
+    val cssRuleDeclaration = this
+    val strings = mutableListOf<String>()
+    strings.add("$baseIndent${cssRuleDeclaration.header} {")
+    when (cssRuleDeclaration) {
+        is CSSStyledRuleDeclaration -> {
+            cssRuleDeclaration.style.properties.forEach { (name, value) ->
+                strings.add("$baseIndent$indent$name: $value;")
+            }
+            cssRuleDeclaration.style.variables.forEach { (name, value) ->
+                strings.add("$baseIndent$indent--$name: $value;")
+            }
+        }
+        is CSSGroupingRuleDeclaration -> {
+            cssRuleDeclaration.rules.forEach { childRuleDeclaration ->
+                strings.add(childRuleDeclaration.stringPresentation(baseIndent + indent, indent, delimiter))
+            }
+        }
+        is CSSKeyframesRuleDeclaration -> {
+            cssRuleDeclaration.keys.forEach { childRuleDeclaration ->
+                strings.add(childRuleDeclaration.stringPresentation(baseIndent + indent, indent, delimiter))
+            }
+        }
+    }
+    strings.add("$baseIndent}")
+    return strings.joinToString(delimiter)
+}
+
 internal fun setProperty(
     style: CSSStyleDeclaration,
     name: String,
diff --git a/web/core/src/jsTest/kotlin/css/AnimationTests.kt b/web/core/src/jsTest/kotlin/css/AnimationTests.kt
new file mode 100644
index 0000000000..bb93e992e8
--- /dev/null
+++ b/web/core/src/jsTest/kotlin/css/AnimationTests.kt
@@ -0,0 +1,99 @@
+/*
+ * Copyright 2020-2021 JetBrains s.r.o. and respective authors and developers.
+ * Use of this source code is governed by the Apache 2.0 license that can be found in the LICENSE.txt file.
+ */
+package org.jetbrains.compose.web.core.tests.css
+
+import org.jetbrains.compose.web.ExperimentalComposeWebApi
+import org.jetbrains.compose.web.testutils.*
+import org.jetbrains.compose.web.css.*
+import org.jetbrains.compose.web.dom.stringPresentation
+import org.w3c.dom.HTMLElement
+import org.w3c.dom.HTMLStyleElement
+import org.w3c.dom.css.CSSStyleSheet
+import org.w3c.dom.get
+import kotlin.test.Test
+import kotlin.test.assertContains
+
+object AnimationsStyleSheet : StyleSheet() {
+    val bounce by keyframes {
+        from {
+            property("transform", "translateX(50%)")
+        }
+
+        to {
+            property("transform", "translateX(-50%)")
+        }
+    }
+
+    val animationClass by style {
+        animation(bounce) {
+            duration(2.s)
+            timingFunction(AnimationTimingFunction.EaseIn)
+            direction(AnimationDirection.Alternate)
+        }
+    }
+}
+
+@ExperimentalComposeWebApi
+class AnimationTests {
+    @Test
+    fun animationClassGenerated() = runTest {
+        val generatedRules = AnimationsStyleSheet.cssRules.map { it.stringPresentation() }
+
+        assertContains(
+            generatedRules,
+            """
+                @keyframes AnimationsStyleSheet-bounce {
+                    from {
+                        transform: translateX(50%);
+                    }
+                    to {
+                        transform: translateX(-50%);
+                    }
+                }
+            """.trimIndent(),
+            "Animation keyframes wasn't generated correctly"
+        )
+        assertContains(
+            generatedRules,
+            """
+                .AnimationsStyleSheet-animationClass {
+                    animation: AnimationsStyleSheet-bounce 2s ease-in alternate;
+                }
+            """.trimIndent(),
+            "Animation class wasn't generated correctly"
+        )
+    }
+
+    @Test
+    fun animationClassInjected() = runTest {
+        composition {
+            Style(AnimationsStyleSheet)
+        }
+
+        val el = root.children[0] as HTMLStyleElement
+        val cssRules = (el.sheet as? CSSStyleSheet)?.cssRules
+        val rules = (0 until (cssRules?.length ?: 0)).map {
+            cssRules?.item(it)?.cssText ?: ""
+        }
+
+        assertContains(
+            rules,
+            """
+                @keyframes AnimationsStyleSheet-bounce { 
+                  0% { transform: translateX(50%); }
+                  100% { transform: translateX(-50%); }
+                }
+            """.trimIndent(),
+            "Animation keyframes wasn't injected correctly"
+        )
+        assertContains(
+            rules,
+            """
+                .AnimationsStyleSheet-animationClass { animation: 2s ease-in 0s 1 alternate none running AnimationsStyleSheet-bounce; }
+            """.trimIndent(),
+            "Animation class wasn't injected correctly"
+        )
+    }
+}