Checkbox style : demo 12

                        .checkbox{ display: inline-block; }
                        .checkbox input[type=checkbox]{
                            margin: 0;
                            visibility: hidden;
                            left: 1px;
                            top: 1px;
                        }
                        .checkbox label{
                            background:linear-gradient(#ccc,#ddd);
                            width: 25px;
                            height: 25px;
                            padding: 0;
                            cursor: pointer;
                            border: 4px solid #fff;
                            box-shadow: 0 0 1px #808080, 0 0 10px -3px rgba(0,0,0,0.2);
                            overflow: hidden;
                            transform: rotate(45deg);
                            transition: all 0.4s ease 0s;
                        }
                        .checkbox label:before{
                            content: "";
                            background: linear-gradient(#36D1DC, #5B86E5);
                            width: 100%;
                            height: 100%;
                            position: absolute;
                            top: 30px;
                            left: -20px;
                            transition: all 0.25s ease-in-out;
                        }
                        .checkbox input[type=checkbox]:checked+label:before{
                            transform: translateX(-50%) translateY(-50%);
                            top: 50%;
                            left: 50%;
                        }
                        @media only screen and (max-width:767px){
                            .checkbox{ margin: 0 0 20px; }
                        }