Card_Mod and Font-Size - Not reliable?

Configuration
1

Hi,
I have an Entities Card (with a Card_Mod addition) that I wish to show on an Android phone. This is the yaml:

type: entities
entities:
  - entity: sensor.motorhome_ds18b20_ds18b20_temperature
    name: Temperature
  - type: divider
    style:
      height: 5px
  - entity: sensor.motorhome_hlsr10_bat_veh_voltage
    name: Veh. Volts
    icon: mdi:gauge
  - entity: sensor.motorhome_hlsr10_bat_veh_current
    name: Veh. Current
    icon: mdi:current-dc
  - type: divider
    style:
      height: 5px
  - entity: sensor.motorhome_hlsr10_bat_lei_voltage
    name: Lei. Volts
    icon: mdi:gauge
  - entity: sensor.motorhome_hlsr10_bat_lei_current
    name: Lei. Current
    icon: mdi:current-dc
show_header_toggle: false
card_mod:
  style: |
    ha-card {
      font-size: 28px;
      line-height: 30px;
    }

However, when the card is loaded on the phone, the font-size is ignored. This is what it looks like:

small-font
small-font1080×1920 127 KB

Only if I switch the Dashboard away to another and back again is the font shown as I would wish it to be. Like so:
Correct-font
Correct-font1080×1920 140 KB

I guess that this is a “feature” of Chrome on the phone that is giving me grief? But if anyone has any thoughts on how to get the card to display reliably in the large font, I’d love to hear from you.
Regards, Martin