threema-web/src/sass/components/_dialogs.scss

md-dialog {
    min-width: 470px;
    max-width: 600px;
    p {
        margin-bottom: 16px;
        line-height: 1.3em;
        &:last-of-type {
            margin-bottom: 0;
        }
    }
    h2 {
        font-size: 1.4em;
        margin-top: 24px;
        margin-bottom: 16px;
    }
    ul {
        margin-left: 1.3em;
        li {
            line-height: 1.5em;
        }
    }
    md-dialog-content {
        line-height: 1.3em;
    }
}

md-dialog.send-file-dialog {
    md-input-container.input-caption {
        margin-bottom: 0;
    }
    md-input-container.input-send-as-file {
        margin-top: 0;
    }
}