Applying CSS Styles to Lovelace Entities

In creating new dashboards for my HA installation some of the entity sensor values appear in text that is too large. I created a test card and have had some success in controlling the color and font-size but while I can change the text-size of the card name, I cannot seem to change font-size of the displayed entity value. The color changes okay but not the size.

card_mod: null
style: |
  ha-card
    { color: blue; font-size: 50px}
    .header .name
    {font-size: 20px; color:green}
type: entity
entity: sensor.sonoff_1000bdxxxx_temperature
name: H2O Temp
attribute: temperature. 

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