with pobem

button_theme_islands.styl

block(button).mod(theme islands) {
    font-family: Arial, Helvetica, sans-serif;

    position: relative;

    display: inline-block;

    margin: 0;
    padding: 0;

    user-select: none;

    color: #000;
    border: 0;
    border-radius: 3px;
    outline: 0;
    background: rgba(0, 0, 0, 0.2);

    text-align: center;
    white-space: nowrap;

    -webkit-tap-highlight-color: rgba(0, 0, 0, 0);

    &::-moz-focus-inner
    {
        padding: 0;

        border: 0;
    }

    elem(text)
    {
        position: relative;

        display: inline-block;
        overflow: hidden;

        text-overflow: ellipsis;
        vertical-align: top;
    }

    block(icon)
    {
        position: relative;
    }

    mod(type link)
    {
        text-decoration: none;
    }

    // Decorative element (inner background)
    &:before
    {
        position: absolute;
        top: 1px;
        right: 1px;
        bottom: 1px;
        left: 1px;

        content: '';

        border-radius: 2px;
        background: #fff;
    }

    mod(hovered)
    {
        cursor: pointer;

        background: rgba(0, 0, 0, 0.3);
    }

    mod(focused-hard)
    {
        z-index: 1;

        background: rgba(178, 142, 0, 0.6);
        box-shadow: 0 0 0 1px #ffcc00, inset 0 0 0 1px #ffcc00;
    }

    mod(pressed):before
    {
        background: #f6f5f3;
    }

    mod(checked)
    {
        background: rgba(153, 122, 0, 0.5);

        &:before
        {
            background: #ffeba0;
        }

        mod(pressed)
        {
            background: rgba(129, 103, 0, 0.6);

            &:before
            {
                background: #fee481;
            }
        }

        mod(hovered)
        {
            background: rgba(129, 103, 0, 0.6);
        }
    }

    mod(view plain)
    {
        background: none;

        &:before
        {
            display: none;
        }

        mod(pressed)
        {
            background: #f6f5f3;
        }

        mod(checked)
        {
            background: #ffeba0;

            mod(pressed)
            {
                background: #fee481;
            }
        }

        mod(disabled)
        {
            background: none;
        }
    }

    mod(view action)
    {
        background: rgba(191, 153, 0, 0.8);

        &:before
        {
            background: #ffdb4d;
        }

        mod(pressed):before
        {
            background: #fc0;
        }

        mod(hovered)
        {
            background: rgba(159, 127, 0, 0.8);
        }
    }

    mod(view pseudo)
    {
        overflow: hidden;

        background: none;

        &:before
        {
            background: none;
            box-shadow: 0 0 0 1px rgba(0, 0, 0, 0.2);
        }

        mod(hovered):before
        {
            box-shadow: 0 0 0 1px rgba(0, 0, 0, 0.3);
        }

        mod(focused-hard):before
        {
            box-shadow: none;
        }

        mod(pressed):before
        {
            background: rgba(0, 0, 0, 0.05);
        }

        mod(checked)
        {
            &:before
            {
                background: #ffeba0;
                box-shadow: 0 0 0 1px rgba(153, 122, 0, 0.5);
            }

            mod(hovered):before
            {
                box-shadow: 0 0 0 1px rgba(129, 103, 0, 0.6);
            }

            mod(pressed):before
            {
                background: #fee481;
                box-shadow: 0 0 0 1px rgba(129, 103, 0, 0.6);
            }
        }
    }

    mod(disabled)
    {
        background: rgba(0, 0, 0, 0.08);

        &:before
        {
            display: none;
        }

        mod(checked):before
        {
            display: block;

            background: #ffeba0;
        }

        elem(text)
        {
            color: #aaa;
        }

        block(icon)
        {
            opacity: 0.3;
        }
    }

    mod(size s)
    {
        font-size: 13px;
        line-height: 24px;

        block(icon)
        {
            width: 24px;
        }

        elem(text)
        {
            margin: 0 10px;
        }
    }

    mod(size m)
    {
        font-size: 13px;
        line-height: 28px;

        block(icon)
        {
            width: 28px;
        }

        elem(text)
        {
            margin: 0 13px;
        }
    }

    mod(size l)
    {
        font-size: 15px;
        line-height: 32px;

        block(icon)
        {
            width: 32px;
        }

        elem(text)
        {
            margin: 0 15px;
        }
    }

    mod(size xl)
    {
        font-size: 18px;
        line-height: 38px;

        block(icon)
        {
            width: 38px;
        }

        elem(text)
        {
            margin: 0 18px;
        }
    }

    block(icon) + block(button).elem(text)
    {
        margin-left: 0;
    }

    elem(text):not(:last-child)
    {
        margin-right: 0;
    }
}

block(control-group)
{
    block(button).mod(checked) + block(button).mod(theme islands):before,
    block(radio).mod(checked) + block(radio) block(button).mod(theme islands):before,
    block(checkbox).mod(checked) + block(checkbox) block(button).mod(theme islands):before
    {
        left: 0;
    }

    block(button).mod(theme islands) {
        border-radius: 0;

        &:before
        {
            right: 0;

            border-radius: 0;
        }

        mod(checked),
        mod(focused-hard).button // Weight of selector should be greater for focused button (#1170)
        {
            &:before
            {
                right: 1px;
            }
        }

        mod(focused-hard).button:before
        {
            left: 1px;
        }
    }

    > block(button).mod(theme islands):first-child,
    > :first-child block(button).mod(theme islands)
    {
        border-radius: 3px 0 0 3px;

        &:before
        {
            border-radius: 2px 0 0 2px;
        }
    }

    > block(button).mod(theme islands):last-child,
    > :last-child block(button).mod(theme islands)
    {
        border-radius: 0 3px 3px 0;

        &:before
        {
            border-radius: 0 2px 2px 0;
            right: 1px;
        }
    }

    > :only-child block(button).mod(theme islands)
    {
        border-radius: 3px;

        &:before
        {
            border-radius: 2px;
        }
    }
}