Remove (border) space of cards

If someone is interested in my result:

elements:
  - entities:
      - entity: sensor.processor_use
        max: 100
        min: 0
        name: CPU
        severity:
          - color: '#40bf40'
            from: 0
            to: 40
          - color: '#ffde00'
            from: 41
            to: 80
          - color: '#fd0000'
            from: 81
            to: 100
      - entity: sensor.cpu_temperature
        max: 100
        min: 0
        name: Temperatur
        decimal: 0
        severity:
          - color: '#40bf40'
            from: 0
            to: 40
          - color: '#ffde00'
            from: 41
            to: 80
          - color: '#fd0000'
            from: 81
            to: 100
      - entity: sensor.memory_use
        max: 1024
        min: 0
        name: Memory
        decimal: 0
        severity:
          - color: '#40bf40'
            from: 0
            to: 640
          - color: '#ffde00'
            from: 640
            to: 768
          - color: '#fd0000'
            from: 768
            to: 1024
      - entity: sensor.disk_use
        max: 30
        min: 0
        name: Disk
        decimal: 0
        severity:
          - color: '#40bf40'
            from: 0
            to: 15
          - color: '#ffde00'
            from: 15
            to: '22,5'
          - color: '#fd0000'
            from: '22,5'
      - entity: sensor.swap_use
        max: 1024
        min: 0
        name: Swap
        decimal: 0
        severity:
          - color: '#40bf40'
            from: 0
            to: 640
          - color: '#ffde00'
            from: 640
            to: 768
          - color: '#fd0000'
            from: 768
    columns: 5
    direction: up
    width: 10px
    height: 90px
    positions:
      icon: 'off'
      indicator: 'off'
      minmax: 'off'
      title: outside
      value: outside
      name: outside
    style:
      left: 50%
      top: 68%
      width: 100%
      scale: 100%
    type: 'custom:bar-card'
  - entity: sensor.uptime
    prefix: 'UpTime: '
    style:
      color: white
      font-size: 125%
      left: 70%
      top: 24%
    title: text
    type: state-label
image: /local/images/RPi-card.png
style:
  '#root > bar-card':
    $: |
      ha-card {
        background: none;
        box-shadow: none;
      }
      bar-card-name {
        color: white;
        font-size: 100%;
        font-weight: normal;
        margin: 4px;     
      } 
      bar-card-backgroundbar {
        border-shadow: 2pt;
        margin-top: -2pt;
        margin-left: -2pt;
        border-radius: 5pt;
        border-style: solid;
        #background: rgba(255, 0, 0, 0.8);
        background: black;
      }
      bar-card-value {
        font-size: 125%;
        color: white;
        font-weight: bold;
        margin: 4px;
      }
      bar-card-currentbar {
        border-radius: 5pt;
      }
type: picture-elements