_theme.scss

/*=============== THEME ===============*/
/*========== Variables Dark theme ==========*/
body.dark-theme{
    --first-color-dark: hsl(var(--hue), 8%, 20%);
    --title-color: hsl(var(--hue), 4%, 95%);
    --text-color: hsl(var(--hue), 4%, 75%);
    --body-color: hsl(var(--hue), 8%, 12%);
    --container-color: hsl(var(--hue), 8%, 16%);
}

/*========== Button Dark/Light ==========*/
.change-theme {
    color: var(--title-color);
    font-size: 1.15rem;
    cursor: pointer;
}

.nav__btns{
    display: inline-flex;
    align-items: center;
    column-gap: 1rem;
}

/*========== 
Color changes in some parts of 
the website, in dark theme 
==========*/
.dark-theme .steps__bg,
.dark-theme .questions{
    background-color: var(--first-color-dark);
}

.dark-theme .product__circle,
.dark-theme .footer__subscribe{
    background-color: var(--container-color);
}

.dark-theme .scroll-header{
    box-shadow: 0 1px 4px hsla(var(--hue), 4%, 4%, .3);
}