diff --git a/src/lib/emailRenderer.ts b/src/lib/emailRenderer.ts
index 47a1732..1d33415 100644
--- a/src/lib/emailRenderer.ts
+++ b/src/lib/emailRenderer.ts
@@ -233,6 +233,15 @@ export function renderSingleModuleHtml(m: any, campaign: NewsletterCampaign): st
   return renderModule(m, campaign, 'preview');
 }
 
+// Žiara (tieň) tlačidla vo farbe tlačidla: #rrggbb / #rgb → rgba(r, g, b, alpha)
+function glowColor(hex: string, alpha: number): string {
+  const m = /^#?([0-9a-f]{3}|[0-9a-f]{6})$/i.exec((hex || '').trim());
+  if (!m) return `rgba(0, 0, 0, ${alpha})`;
+  const h = m[1].length === 3 ? m[1].split('').map((c) => c + c).join('') : m[1];
+  const [r, g, b] = [0, 2, 4].map((i) => parseInt(h.slice(i, i + 2), 16));
+  return `rgba(${r}, ${g}, ${b}, ${alpha})`;
+}
+
 // Globálna platnosť akcie kampane (zdieľaná všetkými produktovými sekciami)
 export function getCampaignValidity(campaign: NewsletterCampaign): string {
   const mod = (campaign.modules || []).find(
@@ -364,7 +373,7 @@ function renderModule(m: any, campaign: NewsletterCampaign, mode: RenderMode = '
                   <table align="center" role="presentation" cellspacing="0" cellpadding="0" border="0" style="margin: auto;" class="btn-table">
                       <tr>
                           <td style="text-align: center;">
-                              <a href="${escapeHtml(m.data.buttonUrl || '#')}" class="btn force-text-white" style="background-color: ${m.data.buttonBgColor || '#e2001a'}; color: #fefefe; font-family: 'Poppins', sans-serif; font-size: 13px; font-weight: 800; text-decoration: none; padding: 12px 30px; border-radius: 25px; display: inline-block; text-transform: uppercase; letter-spacing: 0.5px; box-shadow: 0 4px 12px rgba(226, 0, 26, 0.35);">${escapeHtml(m.data.buttonText)}</a>
+                              <a href="${escapeHtml(m.data.buttonUrl || '#')}" class="btn force-text-white" style="background-color: ${m.data.buttonBgColor || '#e2001a'}; color: #fefefe; font-family: 'Poppins', sans-serif; font-size: 13px; font-weight: 800; text-decoration: none; padding: 12px 30px; border-radius: 25px; display: inline-block; text-transform: uppercase; letter-spacing: 0.5px; box-shadow: 0 4px 12px ${glowColor(m.data.buttonBgColor || '#e2001a', 0.35)};">${escapeHtml(m.data.buttonText)}</a>
                           </td>
                       </tr>
                   </table>` : ''}
@@ -451,7 +460,7 @@ function renderModule(m: any, campaign: NewsletterCampaign, mode: RenderMode = '
                                             <table align="center" role="presentation" cellspacing="0" cellpadding="0" border="0" style="margin: auto;" class="btn-table">
                                                 <tr>
                                                     <td style="text-align: center;">
-                                                        <a href="${escapeHtml(it1.linkUrl || '#')}" class="btn force-text-white" style="background-color: ${it1.btnBgColor || '#e2001a'}; color: #fefefe; font-family: 'Poppins', sans-serif; font-size: 12px; font-weight: 800; text-decoration: none; padding: 10px 24px; border-radius: 25px; display: inline-block; text-transform: uppercase; letter-spacing: 0.5px; box-shadow: 0 4px 12px rgba(226, 0, 26, 0.35);">${escapeHtml(it1.btnText)}</a>
+                                                        <a href="${escapeHtml(it1.linkUrl || '#')}" class="btn force-text-white" style="background-color: ${it1.btnBgColor || '#e2001a'}; color: #fefefe; font-family: 'Poppins', sans-serif; font-size: 12px; font-weight: 800; text-decoration: none; padding: 10px 24px; border-radius: 25px; display: inline-block; text-transform: uppercase; letter-spacing: 0.5px; box-shadow: 0 4px 12px ${glowColor(it1.btnBgColor || '#e2001a', 0.35)};">${escapeHtml(it1.btnText)}</a>
                                                     </td>
                                                 </tr>
                                             </table>
@@ -485,7 +494,7 @@ function renderModule(m: any, campaign: NewsletterCampaign, mode: RenderMode = '
                                             <table align="center" role="presentation" cellspacing="0" cellpadding="0" border="0" style="margin: auto;" class="btn-table">
                                                 <tr>
                                                     <td style="text-align: center;">
-                                                        <a href="${escapeHtml(it2.linkUrl || '#')}" class="btn force-text-white" style="background-color: ${it2.btnBgColor || '#29446f'}; color: #fefefe; font-family: 'Poppins', sans-serif; font-size: 12px; font-weight: 800; text-decoration: none; padding: 10px 24px; border-radius: 25px; display: inline-block; text-transform: uppercase; letter-spacing: 0.5px; box-shadow: 0 4px 12px rgba(41, 68, 111, 0.3);">${escapeHtml(it2.btnText)}</a>
+                                                        <a href="${escapeHtml(it2.linkUrl || '#')}" class="btn force-text-white" style="background-color: ${it2.btnBgColor || '#29446f'}; color: #fefefe; font-family: 'Poppins', sans-serif; font-size: 12px; font-weight: 800; text-decoration: none; padding: 10px 24px; border-radius: 25px; display: inline-block; text-transform: uppercase; letter-spacing: 0.5px; box-shadow: 0 4px 12px ${glowColor(it2.btnBgColor || '#29446f', 0.3)};">${escapeHtml(it2.btnText)}</a>
                                                     </td>
                                                 </tr>
                                             </table>