buttons style : demo 30

CSS

                        .btn{
                            color: #333;
                            border-radius: 0;
                            background: #fff;
                            overflow: hidden;
                            text-transform: uppercase;
                            position: relative;
                            z-index: 1;
                            transition: all 0.40s ease 0s;
                        }
                        .btn:hover{
                            color: #fff;
                        }
                        .btn:after{
                            content: "";
                            width: 100%;
                            height: 100%;
                            position: absolute;
                            top: 0;
                            right: -100%;
                            z-index: -1;
                            transition: right 0.40s ease 0s;
                        }
                        .btn:hover:after{
                            right: 0;
                        }
                        .btn.red{
                            border-right: 3px solid #ff3939;
                        }
                        .btn.red:after{
                            background: #fc7171;
                        }
                        .btn.blue{
                            border-right: 3px solid #3fb7c8;
                        }
                        .btn.blue:after{
                            background: #52d6e7;
                        }
                        .btn.orange{
                            border-right: 3px solid #f88030;
                        }
                        .btn.orange:after{
                            background: #f49c63;
                        }
                        .btn.green{
                            border-right: 3px solid #35c568;
                        }
                        .btn.green:after{
                            background: #85d7a2;
                        }
                        @media only screen and (max-width: 767px) {
                            .btn{  margin-bottom: 15px; }
                        }
                    
License Terms