edx-platform/lms/static/sass/shared-v2/_modal.scss

#lean_overlay {
  @include background-image(radial-gradient(circle at 50% 30%, $shadow-d1, $shadow-d2));

  display: none;
  height:100%;
  left: 0;
  position: fixed;
  top: 0;
  width:100%;
  z-index: 100;
}

.modal {
  @include span(5);

  z-index: z-index(mid-front);
  display: none;
  position: absolute;
  left: 50%;
  padding: 8px;
  border-radius: 3px;
  box-shadow: 0 0 5px 0 $shadow-d1;
  background: $gray-d2;
  color: $body-color;

  .inner-wrapper {
    z-index: z-index(mid-front);
    background: $modal-bg-color;
    border-radius: 0;
    border: 1px solid $border-color;
    box-shadow: inset 0 1px 0 0 $white-opacity-70;
    overflow: hidden;
    padding-left: ($baseline/2);
    padding-right: ($baseline/2);
    padding-bottom: ($baseline/2);
    position: relative;

    p {
      font-size: font-size(small);
      line-height: 1.4;
    }

    a {
      &:hover,
      &:focus {
        text-decoration: underline;
      }
    }

    header {
      z-index: z-index(mid-front);
      margin-bottom: ($baseline*1.5);
      overflow: hidden;
      padding: 28px $baseline 0;
      position: relative;

      &::before {
        @include background-image(
          radial-gradient(
            50% 50%, circle closest-side,
            $white-opacity-80 0%,
                        $white-transparent 100%
                   )
               );

        content: '';
        display: block;
        height: 400px;
        left: 0;
        margin: 0 auto;
        position: absolute;
        top: -140px;
        width: 100%;
        z-index: z-index(base);
      }

      hr {
        @include background-image(
          linear-gradient(
            180deg,
            $white-transparent 0%,
                        $white-opacity-80 50%,
                        $white-transparent
                   )
               );

        height: 1px;
        width: 100%;
        border: none;
        margin: 0;
        position: relative;
        z-index: z-index(base);

        &::after {
          @include background-image(
            linear-gradient(
              180deg,
              $light-grey-transparent 0%,
                            $light-grey-solid 50%,
                            $light-grey-transparent
                       )
                   );

          height: 1px;
          width: 100%;
          bottom: 0;
          content: '';
          display: block;
          position: absolute;
          top: -1px;
        }
      }

      h2 {
        @extend .hd-4;

        position: relative;
        text-align: center;
        text-shadow: 0 1px $white-opacity-40;
        z-index: z-index(base);
        font-family: $font-family-serif;

        .edx {
          text-transform: none;
        }
      }
    }

    .modal-form-error {
      background: palette(error, back);
      border: 1px solid palette(error, accent);
      color: palette(error, text);
      display: none;
      margin-bottom: $baseline;
      padding: 12px;
    }

    .notice {
      background: $yellow;
      border: 1px solid darken($yellow, 60%);
      color: darken($yellow, 60%);
      display: none;
      margin-bottom: $baseline;
      padding: 12px;
    }

    .activation-message, .message {
      padding: 0 ($baseline*2) ($baseline/2);

      p {
        margin-bottom: ($baseline/2);
      }
    }

    form {
      margin-bottom: 12px;
      padding: 0 ($baseline*2) $baseline;
      position: relative;
      z-index: 2;

      .input-group {
        @include clearfix();

        border-bottom: 1px solid palette(grayscale, back);
        box-shadow: 0 1px 0 0 $white-opacity-60;
        margin-bottom: ($baseline*1.5);
        padding-bottom: ($baseline/2);
      }

      label {
        color: $text-color;
        font: {
          family: $font-family-serif;
          style: italic;
        }

        line-height: 1.6;

        &.field-error {
          display: block;
          color: palette(error, text);

          + input,
          + textarea {
            border: 1px solid palette(error, accent);
            color: palette(error, text);
          }
        }
      }

      input[type="checkbox"] {
        @include margin-right($baseline/4);
      }

      textarea {
        background: $white;
        display: block;
        height: 45px;
        margin-bottom: $baseline;
        width: 100%;
      }

      input[type="email"],
      input[type="text"],
      input[type="password"] {
        background: $white;
        display: block;
        height: 45px;
        margin-bottom: $baseline;
        width: 100%;
      }

      .submit {
        padding-top: ($baseline/2);

        input[type="submit"] {
          @extend .btn-brand;

          display: block;
          height: auto;
          margin: 0 auto;
          width: 100%;
          white-space: normal;
        }
      }
    }

    .close-modal {
      @include transition(all 0.15s ease-out 0s);

      border-radius: 2px;
      cursor: pointer;
      display: inline-block;
      padding: 10px;
      position: absolute;
      right: 2px;
      top: 0;
      z-index: z-index(front);
      color: $lighter-base-font-color;
      font: {
        size: font-size(large);
        family: $font-family-sans-serif;
      }

      line-height: 1;
      text-align: center;
      border: none;
      background: transparent;
      text-shadow: none;
      letter-spacing: 0;
      text-transform: none;

      &:hover,
      &:focus {
        color: $body-color;
        text-decoration: none;
        opacity: 0.8;
      }

      &:focus {
        border: none !important;
      }
    }
  }

  #help_wrapper,
  #feedback_form_wrapper,
  .discussion-alert-wrapper {
    padding: 0 ($baseline*1.5) ($baseline*1.5);

    header {
      @include padding-left(0);
      @include padding-right(0);

      margin-bottom: $baseline;
    }

    .note {
      font: {
        size: font-size(x-small);
        family: $font-family-sans-serif;
      }

      line-height: 1.475;
      margin-top: ($baseline/2);
      color: $lighter-base-font-color;
    }
  }

  .tip {
    font-size: font-size(x-small);
    display: block;
    color: $dark-gray;
  }
}

.leanModal_box {
  @extend .modal;
}