/*Эффект для кнопки*/
.t-btn, [data-elem-type=button], .t-submit {
    background-image: linear-gradient(to bottom, #3f6f8d, #284e65 52%, #1b3647); /*сначала темный потом светлый*/
    background-position: 100% 0 !important;
    background-size: 200% 200%;
    color: #fff !important;
    transition: all 0.5s ease-in-out !important;
}
/*Эффект для кнопки*/
.t-submit:hover {
   box-shadow: 0 0 0 0 rgba(0,91,115,0); /*здесь темный*/
   background-position: 0 0 !important;
   background-image: linear-gradient(to top, #3f6f8d, #284e65 52%, #1b3647);
}

.t-btn:hover {
   box-shadow: 0 0 0 0 rgba(0,91,115,0);
   background-position: 0 0 !important;
   color: #fff !important;
   background-image: linear-gradient(to top, #3f6f8d, #284e65 52%, #1b3647);
}

[data-elem-type=button]:hover {
   box-shadow: 0 0 0 0 rgba(0,91,115,0);
   background-position: 0 0 !important;
   background-image: linear-gradient(to top, #3f6f8d, #284e65 52%, #1b3647);
}