How to create responsive covers for flipbooks

Settings(Pro Version):

From version 2.1 covers are automatically responsive.

The settings are available under dFlipBooks -> Settings as Book Thumb Type. Available options are Image and Div and respective HTML elements will be used to display the thumb image. We recommend using Image option for advanced users.

Note: The value can be overridden from shortcode using thumbtype attribute.

Case: Image background (Recommended):

[dflip books="all" limit="8" thumbtype="img"][/dflip]

Case: Stretch background.:

[dflip books="all" limit="8" thumbtype="div"][/dflip]

Responsive CSS:

.dflip-books {
}

.dflip-books ._df_thumb {
    margin-left: 0;
    margin-right: 0;
    padding-left: 10px;
    padding-right: 10px;
    box-shadow: none;
}

.dflip-books ._df_thumb:before {
    content: " ";
    box-shadow: 0 1px 2px rgba(0,0,0,0.22);
    height: 100%;
    position: absolute;
    top: 0;
    left: 10px;
    right: 10px;
}

.dflip-books ._df_thumb[thumbtype="img"] img {
    max-height: 100%;
}

.dflip-books ._df_thumb[thumbtype="img"] {
    width: 25%;
}

.dflip-books ._df_thumb[thumbtype="div"] {
    width: 25%;
}

@media only screen and (max-width: 900px) {
    .dflip-books ._df_thumb[thumbtype="img"] {
        width: 33.33%;
    }

    .dflip-books ._df_thumb[thumbtype="div"] {
        width: 33.33%;
    }
}

@media only screen and (max-width: 700px) {
    .dflip-books ._df_thumb[thumbtype="img"] {
        width: 50%;
    }

    .dflip-books ._df_thumb[thumbtype="div"] {
        width: 50%;
    }
}

@media (max-width: 400px) {
    .dflip-books ._df_thumb[thumbtype="img"] {
        width: 100%;
    }

    .dflip-books ._df_thumb[thumbtype="div"] {
        width: 100%;
    }
}