discourse/app/assets/stylesheets/common/components/date-input.scss

$calendar-icon: '<svg xmlns="http://www.w3.org/2000/svg" width="14px" height="16px" viewBox="0 0 448 512"><path d="M400 64h-48V12c0-6.6-5.4-12-12-12h-40c-6.6 0-12 5.4-12 12v52H160V12c0-6.6-5.4-12-12-12h-40c-6.6 0-12 5.4-12 12v52H48C21.5 64 0 85.5 0 112v352c0 26.5 21.5 48 48 48h352c26.5 0 48-21.5 48-48V112c0-26.5-21.5-48-48-48zm-6 400H54c-3.3 0-6-2.7-6-6V160h352v298c0 3.3-2.7 6-6 6z"></path></svg>';

.d-date-input {
  display: inline-flex;
  cursor: pointer;
  flex-direction: column;
  min-width: 140px;
  flex: 1 0 auto;

  .date-picker {
    cursor: pointer;
    margin: 0;
    text-align: left;
    width: 100%;
    box-shadow: none;
    position: relative;

    &::-webkit-input-placeholder,
    &::-ms-input-placeholder,
    &::placeholder {
      font-size: var(--font-0);
      color: var(--primary-medium);
    }

    &:focus {
      @include default-focus;
    }

    // iOS doesn't display the placeholder attribute for date inputs
    html.ios-device &:after {
      font-size: var(--font-0);
      color: var(--primary-medium);
      content: attr(placeholder);
    }

    // use custom icon and fix issues across browsers
    // - Safari does not use an icon
    // - default Chrome/IE icon too tall, makes input height inconsistent
    // - default Chrome/IE icon are black on dark themes
    // - allows themes to style as needed
    // Note that this does nothing in Firefox
    html:not(.ios-device) & {
      &::after {
        content: "";
        -webkit-mask: svg-uri($calendar-icon) no-repeat 50% 50%;
        mask: svg-uri($calendar-icon) no-repeat 50% 50%;
        position: absolute;
        right: 4px;
        top: 0px;
        box-sizing: border-box;
        background-color: var(--primary);
        height: 100%;
        width: 20px;
        z-index: 1;
      }
      &::-webkit-calendar-picker-indicator {
        background: transparent;
        position: absolute;
        cursor: pointer;
        right: 0px;
        z-index: 2;
      }
    }
  }

  .pika-single {
    margin-left: -1px;
    margin-top: 1px;

    .pika-row td {
      .pika-button.pika-day {
        box-shadow: none;
        border-radius: 0;
      }
    }
  }
}

.d-date-input + .d-time-input {
  margin-left: 1px;
}

.d-time-input + .d-date-input {
  margin-left: 1px;
}

.d-date-input + .clear-date-time {
  margin-left: 1px;
}