fix styling issues in PDF invoice (#2097)

assets/sass/invoice-pdf.scss

@@ -17,12 +17,14 @@ table, tr, td, p {
 }
 th {
     border: none;
-    font-weight: bold;
     text-align: left;
 }
 td {
     vertical-align: top;
 }
+p {
+    margin-bottom: 12px;
+}
 .text-right {
     text-align: right;
 }
@@ -74,7 +76,7 @@ table.items {
     width: 100%;
     border-collapse: collapse;
     margin-top: 50px;
-    margin-bottom: 50px;
+    margin-bottom: 60px;
 }
 table.items thead th,
 table.items tbody td {
@@ -99,6 +101,9 @@ table.items tfoot th {
     padding: 20px 0 0 0;
     line-height: 1px;
 }
+table.items tfoot td.last {
+    padding-left: 10px;
+}
 table.items tr.odd {
     background-color: #f5f5f5;
 }