Hikashop Cart Notification Plugin

-- HikaShop version -- : 4.4.1
-- Joomla version -- : 3.9.26
-- PHP version -- : 7.4.15

Hello,
I have attempted to make div.vex-content larger and to change the color of the buttons, using the following code within Hikashop / CSS Options / Front-end CSS File, and also within my template's CSS. Yet, the vex-content does not increase in size nor does the button color change.
What is the correct css, and where should I place the css code?

Thanks

CODE:
.vex.vex-theme-default .vex-content {
width: 550px;
}

.vex.vex-theme-default .vex-dialog-button.vex-dialog-button-primary {
background: #30506e;
}

Also attempted