diff --git a/src/index.tsx b/src/index.tsx
index d1ea08a..dbb3490 100644
--- a/src/index.tsx
+++ b/src/index.tsx
@@ -101,7 +101,7 @@ export function stylesToCSS(): string {
   for (const [selector, style] of Object.entries(styles)) {
     if (Object.keys(style).length === 0) continue
 
-    out.push(`${expandSelector(selector)} { `)
+    out.push(`${selector} { `)
     for (const [name, value] of Object.entries(style).sort(([a], [b]) => a.localeCompare(b)))
       out.push(`  ${name}: ${value};`)
     out.push(`}\n`)
@@ -110,10 +110,6 @@ export function stylesToCSS(): string {
   return out.join('\n')
 }
 
-function expandSelector(selector: string): string {
-  return selector.startsWith('.') ? selector : `.${selector}`
-}
-
 // creates a CSS class name
 function makeClassName(baseName: string, partName?: string, variantName?: string, variantKey?: string): string {
   const cls = partName ? `${baseName}_${partName}` : baseName
@@ -211,7 +207,7 @@ function stateName(state: string): string {
 
 // Register base styles, selectors, and states for a class
 function registerClassStyles(name: string, className: string, def: TagDef) {
-  styles[className] ??= makeStyle(def)
+  styles[`.${className}`] ??= makeStyle(def)
 
   for (let [selector, selectorDef] of Object.entries(def.selectors ?? {})) {
     selector = selector.replace(/@(\w+)/g, (_, partName) => `.${makeClassName(name, partName)}`)
@@ -221,7 +217,7 @@ function registerClassStyles(name: string, className: string, def: TagDef) {
   }
 
   for (const [state, style] of Object.entries(def.states ?? {}))
-    styles[`${className}${stateName(state)}`] = makeStyle(style)
+    styles[`.${className}${stateName(state)}`] = makeStyle(style)
 }
 
 // adds CSS styles for tag definition
@@ -287,7 +283,7 @@ export function define(nameOrDef: string | TagDef, defIfNamed?: TagDef) {
   const def = defIfNamed ?? nameOrDef as TagDef
   const name = defIfNamed ? (nameOrDef as string) : anonName(def)
 
-  if (styles[name]) throw `${name} is already defined! Must use unique names.`
+  if (styles[`.${name}`]) throw `${name} is already defined! Must use unique names.`
   registerStyles(name, def)
 
   return (props: Record<string, any>) => {