diff -r 5635abeac42d -r bcd694fda81d src/pyams_skin/resources/less/forms.less
--- a/src/pyams_skin/resources/less/forms.less	Wed Oct 17 11:30:37 2018 +0200
+++ b/src/pyams_skin/resources/less/forms.less	Wed Oct 17 14:38:55 2018 +0200
@@ -1810,6 +1810,22 @@
 	.icon-prepend-2 {
 		left: 31px;
 	}
+	.field-with-prefix {
+		display: flex;
+		border: 1px solid #ccc;
+
+		.prefix {
+			padding: 4px 0 4px 6px;
+		}
+		.prefix + input {
+			border-width: 0;
+			padding-left: 3px;
+
+			&:focus {
+				border-width: 1px 1px 1px 0;
+			}
+		}
+	}
 	.checkbox i,
 	.icon-append,
 	.icon-prepend,