src/styles/mixins/button.less

.button-size(@padding; @font-size; @border-radius) {
    padding: @padding;
    font-size: @font-size;
    border-radius: @border-radius;
}
.button-color(@color; @background; @border) {
    color: @color;
    background-color: @background;
    border-color: @border;
    // a inside Button which only work in Chrome
    // http://stackoverflow.com/a/17253457
    > a:only-child {
        color: currentColor;
        &:after {
            content: '';
            position: absolute;
            top: 0;
            left: 0;
            bottom: 0;
            right: 0;
            background: transparent;
        }
    }
}
.button-variant(@color; @background; @border) {
    .button-color(@color; @background; @border);
    &:hover
    //&:focus
    {
        .button-color(tint(@color, 20%); tint(@background, 20%); tint(@border, 20%));
    }
    &:active,
    &.active {
        .button-color(shade(@color, 5%); shade(@background, 5%); shade(@background, 5%));
    }
    &.disabled,
    &[disabled],
    fieldset[disabled] & {
        &,
        &:hover,
        &:focus,
        &:active,
        &.active {
            .button-color(@btn-disable-color; @btn-disable-bg; @btn-disable-border);
        }
    }
}
.button-group-base(@btnClassName) {
    position: relative;
    display: inline-block;
    vertical-align: middle;
    > .@{btnClassName} {
        position: relative;
        float: left;
        &:hover,
        //&:focus,
        &:active,
        &.active {
            z-index: 2;
        }
    }
    &-circle .@{btnClassName} {
        border-radius: @btn-circle-size;
    }
    // size
    &-large&-circle .@{btnClassName} {
        border-radius: @btn-circle-size-large;
    }
    &-large {
        & > .@{btnClassName} {
            .button-size(@btn-padding-large; @btn-font-size-large; @btn-border-radius);
        }
    }
    &-small&-circle .@{btnClassName} {
        border-radius: @btn-circle-size-small;
    }
    &-small {
        & > .@{btnClassName}{
            .button-size(@btn-padding-small; @btn-font-size; @btn-border-radius-small);
            > .@{css-prefix-iconfont} {
                font-size: @btn-font-size;
            }
        }
    }
}
.btn() {
    display: inline-block;
    margin-bottom: 0;
    font-weight: @btn-font-weight;
    text-align: center;
    vertical-align: middle;
    touch-action: manipulation;
    cursor: pointer;
    background-image: none;
    border: 1px solid transparent;
    white-space: nowrap;
    line-height: @line-height-base;
    user-select: none;
    .button-size(@btn-padding-base; @btn-font-size; @btn-border-radius);
    .transform(translate3d(0, 0, 0));
    //.transition(all @transition-time linear);
    .transition3(color @transition-time linear, background-color @transition-time linear, border @transition-time linear);
    > .@{css-prefix-iconfont} {
        line-height: 1;
    }
    &,
    &:active,
    &:focus {
        outline: 0;
    }
    &:not([disabled]):hover {
        text-decoration: none;
    }
    &:not([disabled]):active {
        outline: 0;
        .transition(none)
    }
    &.disabled,
    &[disabled] {
        cursor: @cursor-disabled;
        > * {
            pointer-events: none;
        }
    }
    &-large {
        .button-size(@btn-padding-large; @btn-font-size-large; @btn-border-radius);
    }
    &-small {
        .button-size(@btn-padding-small; @btn-font-size; @btn-border-radius-small);
    }
}
// Default
.btn-default() {
    .button-variant(@btn-default-color; @btn-default-bg; @btn-default-border);
    &:hover
    //&:focus
    {
        .button-color(tint(@primary-color, 20%); white; tint(@primary-color, 20%));
    }
    &:active,
    &.active {
        .button-color(shade(@primary-color, 5%); white; shade(@primary-color, 5%));
    }
}
// Primary
.btn-primary() {
    .button-variant(@btn-primary-color; @btn-primary-bg; @primary-color);
    &:hover,
    //&:focus,
    &:active,
    &.active {
        color: @btn-primary-color;
    }
}
// Ghost
.btn-ghost() {
    .button-variant(@btn-ghost-color, @btn-ghost-bg, @btn-ghost-border);
    &:hover
    //&:focus
    {
        .button-color(tint(@primary-color, 20%); @btn-ghost-bg; tint(@primary-color, 20%));
    }
    &:active,
    &.active {
        .button-color(shade(@primary-color, 5%); @btn-ghost-bg; shade(@primary-color, 5%));
    }
}
// Dashed
.btn-dashed() {
    .button-variant(@btn-ghost-color, @btn-ghost-bg, @btn-ghost-border);
    border-style: dashed;
    &:hover
    //&:focus
    {
        .button-color(tint(@primary-color, 20%); @btn-ghost-bg; tint(@primary-color, 20%));
    }
    &:active,
    &.active {
        .button-color(shade(@primary-color, 5%); @btn-ghost-bg; shade(@primary-color, 5%));
    }
}
// Text
.btn-text() {
    .button-variant(@link-color, @btn-ghost-bg, transparent);
    // for disabled
    &.disabled,
    &[disabled],
    fieldset[disabled] & {
        &,
        &:hover,
        &:focus,
        &:active,
        &.active {
            .button-color(@btn-disable-color; @btn-ghost-bg; transparent);
        }
    }
    &:hover
        //&:focus
    {
        .button-color(tint(@primary-color, 20%); @btn-ghost-bg; transparent);
    }
    &:active,
    &.active {
        .button-color(shade(@primary-color, 5%); @btn-ghost-bg; transparent);
    }
}
// Circle for Icon
.btn-circle(@btnClassName: ivu-btn) {
    border-radius: @btn-circle-size;
    &.@{btnClassName}-large{
        border-radius: @btn-circle-size-large;
    }
    &.@{btnClassName}-size{
        border-radius: @btn-circle-size-small;
    }
    &.@{btnClassName}-icon-only{
        .square(@btn-circle-size);
        .button-size(0; @font-size-base + 2; 50%);
        &.@{btnClassName}-large{
            .square(@btn-circle-size-large);
            .button-size(0; @btn-font-size-large + 2; 50%);
        }
        &.@{btnClassName}-small{
            .square(@btn-circle-size-small);
            .button-size(0; @font-size-base; 50%);
        }
    }
}
// Group
.btn-group(@btnClassName: ivu-btn) {
    .button-group-base(@btnClassName);
    .@{btnClassName} + .@{btnClassName},
    .@{btnClassName} + &,
    & + .@{btnClassName},
    & + & {
        margin-left: -1px;
    }
    .@{btnClassName}:not(:first-child):not(:last-child) {
        border-radius: 0;
    }
    > .@{btnClassName}:first-child {
        margin-left: 0;
        &:not(:last-child) {
            border-bottom-right-radius: 0;
            border-top-right-radius: 0;
        }
    }
    > .@{btnClassName}:last-child:not(:first-child) {
        border-bottom-left-radius: 0;
        border-top-left-radius: 0;
    }
    & > & {
        float: left;
    }
    & > &:not(:first-child):not(:last-child) > .@{btnClassName} {
        border-radius: 0;
    }
    & > &:first-child:not(:last-child) {
        > .@{btnClassName}:last-child {
            border-bottom-right-radius: 0;
            border-top-right-radius: 0;
            padding-right: 8px;
        }
    }
    & > &:last-child:not(:first-child) > .@{btnClassName}:first-child {
        border-bottom-left-radius: 0;
        border-top-left-radius: 0;
        padding-left: 8px;
    }
}