Fixed bg image opacity overlay

ref #36

src/templates/runner_certificate.html

@@ -5,23 +5,6 @@
   <title>Sponsoring contract</title>
   <link rel="stylesheet" href="https://cdn.jsdelivr.net/npm/bulma@0.9.1/css/bulma.min.css">
   <style>
-    /* Sheet:before is used to provide a background image with opacity */
-    .sheet:before {
-      content: ' ';
-      display: block;
-      position: absolute;
-      left: 0;
-      top: 0;
-      width: 100%;
-      height: 100%;
-      opacity: 0.4;
-      background-image: url("./certficate_background.png");
-      background-repeat: no-repeat;
-      background-size: 11cm;
-      background-position: 5cm 5cm;
-      background-blend-mode: darken;
-    }
-
     .sheet {
       margin: 0;
       overflow: hidden;
@@ -29,6 +12,12 @@
       box-sizing: border-box;
       page-break-after: always;
       padding: 1.2cm 2cm 1.2cm 2cm;
+      background-image: url("./certficate_background.png");
+      background-repeat: no-repeat;
+      background-size: 11cm;
+      background-position: 5cm 5cm;
+      background-color: rgba(255, 255, 255, 0.7);
+      background-blend-mode: lighten;
       /* border-style: solid; */
     }
 
@@ -76,7 +65,6 @@
       <h1 style="font-size: 2.5cm;">Sponsorings</h1>
     </header>
     <main>
-      asd
       <table style="border: solid; width: 17cm;">
         <thead>
           <td>Sponsor:in</td>