diff --git a/htmgo-site/internal/markdown/render.go b/htmgo-site/internal/markdown/render.go
index edfa40e..97168af 100644
--- a/htmgo-site/internal/markdown/render.go
+++ b/htmgo-site/internal/markdown/render.go
@@ -11,10 +11,12 @@ import (
 	"github.com/yuin/goldmark/renderer/html"
 	"io"
 	"io/fs"
+	"sync"
 )
 
 type Renderer struct {
 	cache map[string]string
+	lock  sync.Mutex
 }
 
 func NewRenderer() *Renderer {
@@ -22,6 +24,8 @@ func NewRenderer() *Renderer {
 }
 
 func (r *Renderer) RenderFile(source string, system fs.FS) string {
+	r.lock.Lock()
+	defer r.lock.Unlock()
 	if val, ok := r.cache[source]; ok {
 		return val
 	}
diff --git a/htmgo-site/pages/markdown.go b/htmgo-site/pages/markdown.go
index 7005c6d..26d4779 100644
--- a/htmgo-site/pages/markdown.go
+++ b/htmgo-site/pages/markdown.go
@@ -25,7 +25,7 @@ func MarkdownContent(ctx *h.RequestContext, path string, id string) *h.Element {
 			h.Id(id),
 		),
 		h.Div(
-			h.Class("w-full flex flex-col prose max-w-[90vw] md:max-w-3xl lg:max-w-4xl prose-code:text-black prose-p:my-1 prose:p-0 prose-li:m-0 prose-ul:m-0 prose-ol:m-0"),
+			h.Class("w-full flex flex-col prose max-w-[90vw] md:max-w-xl md:px-4 lg:max-w-4xl xl:max-w-5xl prose-code:text-black prose-p:my-1 prose:p-0 prose-li:m-0 prose-ul:m-0 prose-ol:m-0"),
 			h.UnsafeRaw(renderer.RenderFile(path, embeddedMd)),
 		),
 	)