fix: enforce viewport-based mobile certificate scale

Compute certificate preview scale from actual viewport width in the component so phone rendering cannot fall back to desktop zoom, ensuring the full certificate is visible.

Author: dotsystemsdevs

src/components/CertificateCard.tsx

@@ -11,6 +11,19 @@ interface Props {
   onReset: () => void
 }
 
+const DESKTOP_CERT_UI_SCALE = 0.604
+const CERT_RENDER_WIDTH = 794
+const CERT_RENDER_HEIGHT = 1123
+
+function clamp(value: number, min: number, max: number) {
+  return Math.min(max, Math.max(min, value))
+}
+
+function getCertificateUiScale(viewportWidth: number) {
+  if (viewportWidth > 900) return DESKTOP_CERT_UI_SCALE
+  return clamp((viewportWidth - 170) / CERT_RENDER_WIDTH, 0.18, 0.32)
+}
+
 const SOCIAL_BG = '#E8E8E8'
 const SOCIAL_EXPORT_FORMATS = {
   instagramPortrait: { width: 1080, height: 1350, padding: 64, filename: 'instagram-portrait' },
@@ -66,6 +79,7 @@ export default function CertificateCard({ cert, onReset }: Props) {
   const visibleStampRef = useRef<HTMLDivElement>(null)
   const exportStampRef = useRef<HTMLDivElement>(null)
   const [visible, setVisible] = useState(false)
+  const [uiScale, setUiScale] = useState(DESKTOP_CERT_UI_SCALE)
   const [isGeneratingShare, setIsGeneratingShare] = useState(false)
   const [showInlineShare, setShowInlineShare] = useState(false)
   const [copied, setCopied] = useState(false)
@@ -75,6 +89,14 @@ export default function CertificateCard({ cert, onReset }: Props) {
     return () => clearTimeout(t)
   }, [])
 
+  useEffect(() => {
+    if (typeof window === 'undefined') return
+    const applyScale = () => setUiScale(getCertificateUiScale(window.innerWidth))
+    applyScale()
+    window.addEventListener('resize', applyScale)
+    return () => window.removeEventListener('resize', applyScale)
+  }, [])
+
   async function exportBlob(pixelRatio: number, watermark = false): Promise<Blob | null> {
     if (!exportCardRef.current) return null
     const wrapper = wrapperRef.current
@@ -84,8 +106,8 @@ export default function CertificateCard({ cert, onReset }: Props) {
       cacheBust: true,
       pixelRatio,
       backgroundColor: '#FAF6EF',
-      width: 794,
-      height: 1123,
+      width: CERT_RENDER_WIDTH,
+      height: CERT_RENDER_HEIGHT,
     })
     if (!watermark && exportStampRef.current) exportStampRef.current.style.visibility = ''
     if (wrapper) wrapper.style.zoom = ''
@@ -280,11 +302,11 @@ export default function CertificateCard({ cert, onReset }: Props) {
         <div
           ref={wrapperRef}
           style={{
-            width: '794px',
+            width: `${CERT_RENDER_WIDTH}px`,
             flexShrink: 0,
             transformOrigin: 'top center',
-            transform: 'scale(var(--cert-ui-scale, 0.604))',
-            marginBottom: 'calc((1123px * var(--cert-ui-scale, 0.604)) - 1123px)',
+            transform: `scale(${uiScale})`,
+            marginBottom: `calc((${CERT_RENDER_HEIGHT}px * ${uiScale}) - ${CERT_RENDER_HEIGHT}px)`,
           }}
         >
           <CertificateFixed
@@ -305,8 +327,8 @@ export default function CertificateCard({ cert, onReset }: Props) {
           position: 'fixed',
           left: '-10000px',
           top: 0,
-          width: '794px',
-          height: '1123px',
+          width: `${CERT_RENDER_WIDTH}px`,
+          height: `${CERT_RENDER_HEIGHT}px`,
           opacity: 0,
           pointerEvents: 'none',
           overflow: 'hidden',