1. Override Colors

For any change in colors : scss/variable.scss

                  
// colors
$white: #fff !default;
$gray-100: #f6f8fb !default;
$gray-200: #ecf0f2 !default;
$gray-300: #f1f9ff !default;  
$gray-400: #ced4da !default;
$gray-500: #546269 !default;
$gray-600: #6c757d !default;
$gray-700: #4f5467 !default;
$gray-800: #11142d !default;
$gray-900: #223640 !default;
$black: #000 !default;

// Color
$blue: #1a9bfc !default;
$indigo: #6610f2 !default;
$purple: #7460ee !default;
$pink: #e83e8c !default;
$red: #fc4b6c !default;
$orange: #fb8c00 !default;
$yellow: #fdc90f !default;
$green: #39cb7f !default;
$teal: #20c997 !default;
$cyan: #0bb2fb !default;

// Main Colors
$primary: $blue !default;
$secondary: #6c757d !default;
$success: $green !default;
$info: $cyan !default;
$warning: $yellow !default;
$danger: $red !default;
$light: $gray-100 !default;
$muted: #777e89 !default;
$dark: $gray-800 !default;
$dark-light: $gray-800 !default;
$light-gray: $gray-100 !default;
$light-indigo: #ebf3fe;

// light colors
$primary-bg-subtle: #ddebff !default;
$secondary-bg-subtle: #e7e9f0 !default;
$success-bg-subtle: #ebfaf2 !default;
$info-bg-subtle: #e6f4ff !default;
$warning-bg-subtle: #fff4e5 !default;
$danger-bg-subtle: #fdf3f5 !default;
$light-bg-subtle: $gray-100 !default;
$dark-bg-subtle: $gray-800 !default;