correct / Modifications mini graph style Update device/ports.inc.php

about mini graph style (add css class -> custom/css)
request librenms https://github.com/librenms/librenms/pull/10313

Add styles.css standard css class for modificaition of device/ports.inc.php
https://github.com/librenms/librenms/pull/10314

html/css/custom/styles.css

@@ -675,6 +675,37 @@ legend {
     box-shadow: 0 5px 15px rgba(0,0,0,.5);
 }
 
+.overlib-text {
+  font-weight: bold;
+  font-size: 16px;
+  color:cyan ;
+}
+
+.overlib-title {
+  color:cyan ;
+}
+
+/* Mini graph */
+
+.minigraph-image {
+  margin: 2px;
+}
+
+.minigraph-div {
+ display: block; 
+ padding: 3px; 
+ margin: 3px; 
+ min-width: 183px; 
+ max-width:183px; 
+ min-height:90px; 
+ max-height:90px; 
+ text-align: center;
+ float: left; 
+ background-color: #333;
+ border:solid 1px;
+ border-color:#777;
+}
+
 /* FOOTER */
 
 .panel-footer {