fix highlight in dark mode

README.md

@@ -7,7 +7,7 @@ language:
 
 This model card aims to simplify the use of the [portuguese Bert, a.k.a, Bertimbau](https://github.com/neuralmind-ai/portuguese-bert) for the Named Entity Recognition task. 
 
-For this model card the we used the <mark style="background-color: #d3d3d3"> **BERT-CRF (selective scenario, 5 classes)** </mark> model available in the [ner_evaluation](https://github.com/neuralmind-ai/portuguese-bert/tree/master/ner_evaluation) folder of the original Bertimbau repo.
+For this model card the we used the <mark style="background-color: grey"> **BERT-CRF (selective scenario, 5 classes)** </mark> model available in the [ner_evaluation](https://github.com/neuralmind-ai/portuguese-bert/tree/master/ner_evaluation) folder of the original Bertimbau repo.
 
 Available classes are: