docs/_static/css/ribbon.css

.ribbon {
   z-index: 1000;
   background-color: #a00;
   overflow: hidden;
   white-space: nowrap;
   position: fixed;
   top: 25px;
   right: -50px;
   -webkit-transform: rotate(45deg);
      -moz-transform: rotate(45deg);
       -ms-transform: rotate(45deg);
        -o-transform: rotate(45deg);
           transform: rotate(45deg);
   -webkit-box-shadow: 0 0 10px #888;
      -moz-box-shadow: 0 0 10px #888;
           box-shadow: 0 0 10px #888;
 
 }
 
 .ribbon a {
   border: 1px solid #faa;
   color: #fff;
   display: block;
   font: bold 81.25% 'Helvetica Neue', Helvetica, Arial, sans-serif;
   margin: 1px 0;
   padding: 10px 50px;
   text-align: center;
   text-decoration: none;
   text-shadow: 0 0 5px #444;
   transition: 0.5s;
 }
 
 .ribbon a:hover {
   background: #c11;
   color: #fff;
 }
 
 
 /* override table width restrictions */
 @media screen and (min-width: 767px) {
 
    .wy-table-responsive table td, .wy-table-responsive table th {
       /* !important prevents the common CSS stylesheets from overriding
          this as on RTD they are loaded after this stylesheet */
       white-space: normal !important;
    }
 
    .wy-table-responsive {
       overflow: visible !important;
    }
 }
 
 @media screen and (max-width: 767px) {
     .wy-table-responsive table td {
         white-space: nowrap;
     }
 }
 
 /* fix width of the screen */
 
 .wy-nav-content {
     max-width: 800px;
 }