@eherman24 I thank you for the answer. I was able to implement what I want by adding the code below to the css panel.
.post__thumbnail {
margin: 0;
max-height: 10em;
overflow: hidden;
padding-bottom: 52.5%;
padding-bottom: calc(var(–theme-featured-img–height, 35%)*1.5);
position: relative;
z-index: -1;
}
.post__thumbnail:after {
background-image: -webkit-gradient(linear, left top, left bottom, color-stop(0, rgba(0, 0, 0, .2)), color-stop(40%, transparent));
background-image: linear-gradient(180deg, rgba(0, 0, 0, .2), transparent 40%);
content: “”;
height: 100%;
}
.post__thumbnail:after, .post__thumbnail img {
bottom: 0;
left: 0;
position: absolute;
right: 0;
top: 0;
width: 100%;
background: #000;
transition: opacity 1200ms ease-in-out;
opacity: 0.6;
z-index: 5;
}
I adjusted the display size of the featured images in the posts as well as inserting transparency and opacity in them.
Links with example:
https://baudosamba.com.br/albuns/caymmi-e-seu-violao/
https://baudosamba.com.br/albuns/cartola-verde-que-te-quero-rosa/
https://baudosamba.com.br/albuns/aracy-de-almeida-apresenta-sambas-de-noel-rosa/