[FIX] survey: fix trophy background certif in safari

Fix weird behavior between linear-gradient and background-size
with safari, if we don't set the value for linear-gradient.

task-2334731

closes odoo/odoo#58673

X-original-commit: c2747c60161c66f9c77feae884fd101edb693d80
Signed-off-by: Thibault Delavallee (tde) <tde@openerp.com>

addons/survey/static/src/scss/survey_views.scss

@@ -11,7 +11,7 @@
         url(/survey/static/src/img/trophy-solid.svg);
     background-repeat: no-repeat;
     background-position: bottom 6px left -45px;
-    background-size: 100px;
+    background-size: 100%, 100px;
 }
 
 table.o_section_list_view tr.o_data_row.o_is_section {