flask-boilerplate/app/static/css/custom.css

/* Layout */

html,
body {
   margin:0;
   padding:0;
   height:100%;
   overflow-x: hidden;
}

#container {
   height: 100%;
   min-height: 100%;
   position: relative;
}

#body {
   margin: 20px;
   min-height: 100%;
}

#footer {
   bottom: 0;
   width: 100%;
   height: 50px;   /* Height of the footer */
   text-align: center;
}

/* Forms */

.form-user {
   width: 33% !important;
   margin: 0 auto !important;
   margin-top: 10% !important;
}

.form-error {
   color: #E50000 !important;
}

/* Flask flashes */

.flash {
   margin-right: 20px !important;
}

/* Errors */

.error-box {
   margin-top: 8%;
}