Make subtitle full width when within block
Make subtitle full width when within block

gds-attic/transactions-explorer,alphagov/transactions-explorer,gds-attic/transactions-explorer,alphagov/transactions-explorer,gds-attic/transactions-explorer,alphagov/transactions-explorer,gds-attic/transactions-explorer,alphagov/transactions-explorer,gds-attic/transactions-explorer,alphagov/transactions-explorer