[IMP] survey: fixes certification layout, adding dpi and removing width and height in css

addons/survey/static/src/scss/survey_reports.scss

@@ -28,13 +28,11 @@
 }
 
 #o_survey_certification.certification-wrapper {
-    width: 297mm;
-    height: 210mm;
     background-color: #875A7B;
     position: relative;
     display: flex;
-    margin-left: -15px;
-    margin-right: -15px;
+    margin-left: -4mm;
+    margin-right: -4mm;
 
     &.blue {
         background-color: #263e86;

addons/survey/views/survey_reports.xml

@@ -14,6 +14,7 @@
             <field name="header_line" eval="False"/>
             <field name="header_spacing">0</field>
             <field name="disable_shrinking" eval="True"/>
+            <field name="dpi">96</field>
         </record>
         <!-- QWeb Reports -->
         <record id="certification_report" model="ir.actions.report">