Actualización de 2019 para Bootstrap 4
Ahora que Bootstrap 4 usa SASS, puede cambiar fácilmente el color del botón principal usando los button-variant
mixins:
$mynewcolor:#77cccc;
.btn-primary {
@include button-variant($mynewcolor, darken($mynewcolor, 7.5%), darken($mynewcolor, 10%), lighten($mynewcolor,5%), lighten($mynewcolor, 10%), darken($mynewcolor,30%));
}
.btn-outline-primary {
@include button-outline-variant($mynewcolor, #222222, lighten($mynewcolor,5%), $mynewcolor);
}
https://www.codeply.com/go/2bHYxYSC0n ( demostración de SASS )
Este SASS se compila en el siguiente CSS ...
.btn-primary {
color: #212529;
background-color: #7cc;
border-color: #5bc2c2
}
.btn-primary:hover {
color: #212529;
background-color: #52bebe;
border-color: #8ad3d3
}
.btn-primary:focus,
.btn-primary.focus {
box-shadow: 0 0 0 .2rem rgba(91, 194, 194, 0.5)
}
.btn-primary.disabled,
.btn-primary:disabled {
color: #212529;
background-color: #7cc;
border-color: #5bc2c2
}
.btn-primary:not(:disabled):not(.disabled):active,
.btn-primary:not(:disabled):not(.disabled).active,
.show>.btn-primary.dropdown-toggle {
color: #212529;
background-color: #9cdada;
border-color: #2e7c7c
}
.btn-primary:not(:disabled):not(.disabled):active:focus,
.btn-primary:not(:disabled):not(.disabled).active:focus,
.show>.btn-primary.dropdown-toggle:focus {
box-shadow: 0 0 0 .2rem rgba(91, 194, 194, 0.5)
}
.btn-outline-primary {
color: #7cc;
background-color: transparent;
background-image: none;
border-color: #7cc
}
.btn-outline-primary:hover {
color: #222;
background-color: #8ad3d3;
border-color: #7cc
}
.btn-outline-primary:focus,
.btn-outline-primary.focus {
box-shadow: 0 0 0 .2rem rgba(119, 204, 204, 0.5)
}
.btn-outline-primary.disabled,
.btn-outline-primary:disabled {
color: #7cc;
background-color: transparent
}
.btn-outline-primary:not(:disabled):not(.disabled):active,
.btn-outline-primary:not(:disabled):not(.disabled).active,
.show>.btn-outline-primary.dropdown-toggle {
color: #212529;
background-color: #8ad3d3;
border-color: #7cc
}
.btn-outline-primary:not(:disabled):not(.disabled):active:focus,
.btn-outline-primary:not(:disabled):not(.disabled).active:focus,
.show>.btn-outline-primary.dropdown-toggle:focus {
box-shadow: 0 0 0 .2rem rgba(119, 204, 204, 0.5)
}
https://www.codeply.com/go/lD3tUE01lo ( demostración de CSS )
Para cambiar el color primario de todas las clases, consulte: Personalización de la plantilla CSS de Bootstrap y ¿Cómo cambiar el color primario de Bootstrap ?