fix button css

IPython/frontend/html/notebook/static/css/celltoolbar.css

@@ -1,111 +1,109
 /* Css for the metadata edit area */
 
 
 .celltoolbar {
     border: thin solid #CFCFCF;
     border-bottom: none;
     background : #EEE;
     border-top-right-radius: 3px;
     border-top-left-radius: 3px;
     width:100%;
     -webkit-box-pack: end;
     height:20px;
 }
 
 
 .no_input_radius {
     border-top-right-radius: 0px;
     border-top-left-radius: 0px;
 }
 
 .text_cell .ctb_prompt {
     display: none;
 }
 
 .code_cell .ctb_prompt {
     display: block;
 }
 
 .ctb_hideshow {
     display:none;
     vertical-align:bottom;
     padding-right: 2px;
 }
 
 .celltoolbar > div {
    padding-top: 0px;
 }
 
 .ctb_area {
     margin:0;
     padding:0;
     width:100%;
 
 }
 
 
 /*ctb_show is added to either body or the ctb_hideshow div to show
 all or one cell's toolbars.
 */
 .ctb_show.ctb_hideshow, .ctb_show .ctb_hideshow {
     display:block;
 }
 
 .ctb_show .input_area,
 .ctb_show .ctb_hideshow + div.text_cell_input {
     border-top-right-radius: 0px;
     border-top-left-radius: 0px;
 }
 
 .ctb_show > .celltoolbar {
     border-bottom-right-radius: 0px;
     border-bottom-left-radius: 0px;
 }
 
 .button_container {
     margin-top:0;
     margin-bottom:0;
 }
 
-.button_container .ui-state-default, .button_container .ui-state-hover, .button_container .ui-state-hover span{
-    border-radius : 0 0 0 0;
-    border : none;
-    margin:0;
-}
 
+.ui-button {
+    min-width:30px;
+}
 .celltoolbar .button_container select {
     margin: 10px;
     margin-top: 1px;
     margin-bottom: 0px;
     padding:0;
     font-size: 87%;
     width:auto;
     display:inline-block;
     height:18px;
     line-height:18px;
     vertical-align:top;
 }
 
 .celltoolbar label{
     display:inline-block;
     height:15px;
     line-height:15px;
     vertical-align:top;
 }
 
 .celltoolbar label span {
     font-size: 85%;
 }
 
 .celltoolbar input[type=checkbox] {
     margin: 0px;
     margin-left: 4px;
     margin-right: 4px;
 }
 
 
 .celltoolbar .ui-button {
     border: none;
     vertical-align:top;
     height:20px;
 }