Code: 👇

                            <!-- HTML -->
                            
                            <div class="buttons">
                                  <button class="btn-hover color-1">BUTTON</button>
                                  <button class="btn-hover color-2">BUTTON</button>
                                  <button class="btn-hover color-3">BUTTON</button>
                                  <button class="btn-hover color-4">BUTTON</button>
                                  <button class="btn-hover color-5">BUTTON</button>
                                  <button class="btn-hover color-6">BUTTON</button>
                                  <button class="btn-hover color-7">BUTTON</button>
                                  <button class="btn-hover color-8">BUTTON</button>
                                  <button class="btn-hover color-9">BUTTON</button>
                                  <button class="btn-hover color-10">BUTTON</button>
                                  <button class="btn-hover color-11">BUTTON</button>
                              </div>

                            
                            
                            
                            <!-- CSS -->
                            
                           * {
                                  -webkit-box-sizing: border-box;
                                  -moz-box-sizing: border-box;
                                  box-sizing: border-box;
                              }

                              .buttons {
                                  margin: 10%;
                                  text-align: center;
                              }

                              .btn-hover {
                                  width: 200px;
                                  font-size: 16px;
                                  font-weight: 600;
                                  color: #fff;
                                  cursor: pointer;
                                  margin: 20px;
                                  height: 55px;
                                  text-align:center;
                                  border: none;
                                  background-size: 300% 100%;

                                  border-radius: 50px;
                                  moz-transition: all .4s ease-in-out;
                                  -o-transition: all .4s ease-in-out;
                                  -webkit-transition: all .4s ease-in-out;
                                  transition: all .4s ease-in-out;
                              }

                              .btn-hover:hover {
                                  background-position: 100% 0;
                                  moz-transition: all .4s ease-in-out;
                                  -o-transition: all .4s ease-in-out;
                                  -webkit-transition: all .4s ease-in-out;
                                  transition: all .4s ease-in-out;
                              }

                              .btn-hover:focus {
                                  outline: none;
                              }

                              .btn-hover.color-1 {
                                  background-image: linear-gradient(to right, #25aae1, #40e495, #30dd8a, #2bb673);
                                  box-shadow: 0 4px 15px 0 rgba(49, 196, 190, 0.75);
                              }
                              .btn-hover.color-2 {
                                  background-image: linear-gradient(to right, #f5ce62, #e43603, #fa7199, #e85a19);
                                  box-shadow: 0 4px 15px 0 rgba(229, 66, 10, 0.75);
                              }
                              .btn-hover.color-3 {
                                  background-image: linear-gradient(to right, #667eea, #764ba2, #6B8DD6, #8E37D7);
                                  box-shadow: 0 4px 15px 0 rgba(116, 79, 168, 0.75);
                              }
                              .btn-hover.color-4 {
                                  background-image: linear-gradient(to right, #fc6076, #ff9a44, #ef9d43, #e75516);
                                  box-shadow: 0 4px 15px 0 rgba(252, 104, 110, 0.75);
                              }
                              .btn-hover.color-5 {
                                  background-image: linear-gradient(to right, #0ba360, #3cba92, #30dd8a, #2bb673);
                                  box-shadow: 0 4px 15px 0 rgba(23, 168, 108, 0.75);
                              }
                              .btn-hover.color-6 {
                                  background-image: linear-gradient(to right, #009245, #FCEE21, #00A8C5, #D9E021);
                                  box-shadow: 0 4px 15px 0 rgba(83, 176, 57, 0.75);
                              }
                              .btn-hover.color-7 {
                                  background-image: linear-gradient(to right, #6253e1, #852D91, #A3A1FF, #F24645);
                                  box-shadow: 0 4px 15px 0 rgba(126, 52, 161, 0.75);
                              }
                              .btn-hover.color-8 {
                                  background-image: linear-gradient(to right, #29323c, #485563, #2b5876, #4e4376);
                                  box-shadow: 0 4px 15px 0 rgba(45, 54, 65, 0.75);
                              }
                              .btn-hover.color-9 {
                                  background-image: linear-gradient(to right, #25aae1, #4481eb, #04befe, #3f86ed);
                                  box-shadow: 0 4px 15px 0 rgba(65, 132, 234, 0.75);
                              }
                              .btn-hover.color-10 {
                                      background-image: linear-gradient(to right, #ed6ea0, #ec8c69, #f7186a , #FBB03B);
                                  box-shadow: 0 4px 15px 0 rgba(236, 116, 149, 0.75);
                              }
                              .btn-hover.color-11 {
                                    background-image: linear-gradient(to right, #eb3941, #f15e64, #e14e53, #e2373f);  box-shadow: 0 5px 15px rgba(242, 97, 103, .4);
                              }