Mardown card not working with template

Hi all,

I’m having an issue with the markdown card:

custom_fields:
  blur: |
    <div></div> 
  close: >
    <ha-icon icon="ios:xmark" style="width: 25px; color:
    rgb(255, 255, 255, 0.5);"></ha-icon>
  templates:
    card:
      type: markdown
      card_mod:
        style: |
          ha-card {
            --ha-card-background: transparent;
            color: var(--secondary-text-color) ;
            text-align: left; }
      content: >
        <font size="3px">  De temperatuur buiten bedraagt {{
        states.weather.huis.attributes.temperature }}C.
        De luchtvochtigheid is {{
        states.weather.huis.attributes.humidity }}% En het blaast
        {{ states.weather.huis.attributes.wind_speed
        }}km/h. 

It’s stating:
“custom element doesn’t exist: markdown.”

When leaving the “templates:” out it and fixing indentation passes without error, but doesn’t display the card though.

Any help?