.card
  h1 3D Button with Shading (Experiment)
  div
    button.btn Default
    button.btn.btn-info Information
    button.btn.btn-success Success
    button.btn.btn-warning Warning
    button.btn.btn-error Error
    button.btn.btn-dark Dark
    //- Custom style by setting the prepared variables
    button.btn(style="--color: #ffffff; --background-color: #ff4081; --border-color: #ec407a;") Jelly beans

////////////////////////////////////////////////////////////////////////////////
// IF YOU WANT TO USE THIS STYLE, PLEASE READ THIS                            //
////////////////////////////////////////////////////////////////////////////////
// This is written in SCSS. If you would like to use the CSS, you may compile //
// the code, then use the CSS style on your own project.                      //
// Please take note that the code above the block of comment:                 //
// STYLES RELATED TO EXPERIMENT BUTTONS                                       //
// Is just for the styling of the page. These are not related to the styles   //
// of the buttons. So after compiling to CSS, you may just take the part      //
// on or below the said block of comments.                                    //
// You may also customize the colors of the buttons, or actually add a new    //
// class for the buttons, by editing the $btn-type map before compiling the   //
// source code into CSS.                                                      //
////////////////////////////////////////////////////////////////////////////////

@import url("https://fonts.googleapis.com/css?family=Open+Sans:400,400i,700");

body {
  font-family: "Open Sans", sans-serif;
  font-size: 16px;
  background-color: #e2e2e2;
  width: 100vw;
  height: 100vh;
  display: flex;
}

.card {
  background-color: #ffffff;
  width: calc(100% - 4rem);
  padding: 4rem 2rem;
  border: solid 1px #eaeaea;
  margin: auto;
  border-radius: 2.5rem;
  box-sizing: border-box;
  box-shadow: 0 1rem 2rem rgba(#000000, 0.3);
  h1 {
    text-align: center;
    padding: 0;
    margin: 0;
    margin-bottom: 2rem;
  }
  div {
    display: flex;
    align-items: center;
    justify-content: center;
    flex-wrap: wrap;
  }
}

.btn {
  margin-bottom: 0.5rem;
  margin-right: 0.5rem;
  &:last-child {
    margin-right: 0;
  }
}

@media screen and (min-width: 960px) {
  .card {
    width: calc(960px - 4rem);
  }
}

/******************************************************************************/
/* STYLES RELATED TO EXPERIMENT BUTTONS                                       */
/******************************************************************************/

$btn-padding: 0.6rem 0.9rem;
$btn-border-radius: 0.5rem;
$btn-transition-time: 64ms;

// The Map for the CSS class of the buttons
$btn-type: (
  "info": (
    "color": #ffffff,
    "background-color": #0091ea,
  ),
  "success": (
    "color": #ffffff,
    "background-color": #00c853,
  ),
  "warning": (
    "color": #3e2723,
    "background-color": #ffc400,
  ),
  "error": (
    "color": #ffffff,
    "background-color": #d50000,
  ),
  "dark": (
    "color": #ffffff,
    "background-color": #303030,
  ),
);

.btn {
  --color: #000000;
  --background-color: #d8d8d8;
  --border-color: darken(#d8d8d8, 7.5%);
  color: var(--color);
  font-family: inherit;
  background-color: var(--background-color);
  padding: $btn-padding;
  border: solid 1px var(--border-color);
  outline: none;
  position: relative;
  border-radius: $btn-border-radius;
  user-select: none;
  box-shadow:
    0 0.2rem 0.4rem rgba(0, 0, 0, 0.4),
    0 -0.3rem 0.6rem rgba(0, 0, 0, 0.2) inset;
  transition: box-shadow $btn-transition-time ease-out;
  &:after {
    content: "";
    background-color: #ffffff;
    width: 75%;
    height: 12.5%;
    position: absolute;
    top: 0.15rem;
    left: 12.5%;
    border-radius: 50%;
    filter: blur(0.15rem);
    transition: opacity $btn-transition-time ease-out;
  }
  &:active {
    box-shadow:
      0 0 0 rgba(0, 0, 0, 0.4),
      0 0.4rem 1rem rgba(0, 0, 0, 0.3) inset;
    &:after {
      opacity: 0;
    }
  }
}

@each $type, $styles in $btn-type {
  .btn-#{$type} {
    @each $style, $value in $styles {
      --#{$style}: #{$value};
      @if ($style == "background-color") {
        --border-color: #{darken($value, 7.5%)};
      }
      &:active {
        @if ($style == "color") {
          --#{$style}: #{darken($value, 7.5%)};
        }
      }
    }
  }
}