odoo/addons/auth_signup/static/src/css/auth_signup.css

.openerp .oe_login .oe_login_pane ul.oe_signup a {
  color: #eeeeee;
  margin: 0 8px;
}
.openerp .oe_login .oe_login_pane ul.oe_signup a:hover {
  text-decoration: underline;
}