diff --git a/sppa/calc/index.html b/sppa/calc/index.html
index 79d44ea5..79324b09 100644
--- a/sppa/calc/index.html
+++ b/sppa/calc/index.html
@@ -12,6 +12,13 @@
height: 50px;
font-size: 20px;
}
+ center {
+ display: block !important;
+ margin-left: auto !important;
+ margin-right: auto !important;
+ text-align: center !important;
+}
+