diff --git a/theme/src/client/components/Home/VPHomeHero.vue b/theme/src/client/components/Home/VPHomeHero.vue
index d3435e25..192864c9 100644
--- a/theme/src/client/components/Home/VPHomeHero.vue
+++ b/theme/src/client/components/Home/VPHomeHero.vue
@@ -46,7 +46,9 @@ function noTransition() {
 
 let defaultTheme: string | undefined
 watch(() => props.forceDark, () => {
-  if (inBrowser && props.forceDark) {
+  if (!inBrowser || __VUEPRESS_SSR__)
+    return
+  if (props.forceDark) {
     defaultTheme ??= document.documentElement.dataset.theme
     document.documentElement.dataset.theme = 'dark'
     document.documentElement.classList.add('force-dark')
diff --git a/theme/src/client/composables/css-var.ts b/theme/src/client/composables/css-var.ts
index a47e356e..e24dfac8 100644
--- a/theme/src/client/composables/css-var.ts
+++ b/theme/src/client/composables/css-var.ts
@@ -15,7 +15,7 @@ export function useCssVar(
 
   function updateCssVar() {
     const _window = typeof window ? window : null
-    const target = _window?.document.documentElement
+    const target = _window?.document?.documentElement
     const key = toValue(prop)
     if (target && key) {
       const value = _window.getComputedStyle(target).getPropertyValue(key)?.trim()