Resolve "Change buttons colors"

Closes #82 (closed)

src/css/custom.css

 @import url("variables.css");
+@import url("buttons.css");
 @import url("fonts.css");
 @import url("footer.css");
 @import url("dark-theme.css");
@@ -126,48 +127,6 @@ ul {
   padding-bottom: 20px;
 }
 
-.btn-little-txt {
-  font-size: small;
-}
-
-/***** BUTTON *****/
-.button {
-  margin: 10px;
-  border-color: var(--ifm-color-success);
-  color: var(--ifm-color-frame);
-  border-style: none;
-  white-space : initial;
-  font-family: var(--ifm-font-family-base);
-}
-
-.button--beta {
-  border-color: var(--ifm-color-success);
-  border-style: none;
-  background-color: var(--ifm-color-frame);
-  color: var(--ifm-color-black);
-}
-
-.button--beta:hover {
-  color: var(--ifm-color-secondary);
-  background-color: var(--ifm-color-success);
-  border-style: none;
-}
-
-.button--warning {
-  color: var(--ifm-color-success);
-  border-style: none;
-}
-
-.button--warning:hover, .button--warning:not(.button--outline):hover {
-  color: var(--ifm-color-secondary);
-  background-color: var(--ifm-color-info);
-  border-style: none;
-}
-
-.button--warning:not(.button--outline) {
-  background-color: var(--ifm-color-frame);
-}
-
 /******* MAIN ELEM *******/
 .section-promises {
   padding: 4rem 0;
@@ -239,12 +198,6 @@ ul {
   color: var(--ifm-color-warning);
 }
 
-/* button "La doc de Froggit" */
-.breadcrumbs__item--active .breadcrumbs__link {
-  background: var(--ifm-breadcrumb-item-background-active);
-  color: var(--ifm-color-warning);
-}
-
 /****** MEDIA SCREEN *******/
 @media screen and (max-width:330px) {
   .navbar {