<button class="animated-border-button">Submit</button>

.animated-border-button {
                                                                    background-color: #141414;
                                                                    border: none;
                                                                    color: #ffffff;
                                                                    outline: none;
                                                                    padding: 12px 40px 10px;
                                                                    position: relative;
                                                                  }
                                                                  
                                                                  .animated-border-button:before,
                                                                  .animated-border-button:after {
                                                                    border: 0 solid transparent;
                                                                    transition: all 0.3s;
                                                                    content: '';
                                                                    height: 0;
                                                                    position: absolute;
                                                                    width: 24px;
                                                                  }
                                                                  
                                                                  .animated-border-button:before {
                                                                    border-top: 2px solid #141414;
                                                                    right: 0;
                                                                    top: -4px;
                                                                  }
                                                                  
                                                                  .animated-border-button:after {
                                                                    border-bottom: 2px solid #141414;
                                                                    bottom: -4px;
                                                                    left: 0;
                                                                  }
                                                                  
                                                                  .animated-border-button:hover:before,
                                                                  .animated-border-button:hover:after {
                                                                    width: 100%;
                                                                  }