Rambox-CE/ext/packages/ext-theme-base/sass/src/form/FieldSet.scss

.#{$prefix}fieldset {
    display: block; /* preserve margins in IE */
    position: relative;
    overflow: hidden;
}

.#{$prefix}fieldset-header {
    overflow: hidden; // fixes a webkit bug where legend elements that have floated children are not displayed

    .#{$prefix}form-item,
    .#{$prefix}tool {
        float: left;
    }
    
    .#{$prefix}fieldset-header-text {
        float: left;
    }

    .#{$prefix}form-cb-wrap {
        font-size: 0;
        line-height: 0;
        height: auto; // override form-cb-wrap's height from neutral theme
    }

    .#{$prefix}form-cb {
        margin: 0; // override the default checkbox margin
        position: static; // Checkboxes are now absolutely positioned so reset the positioning (see EXTJSIV-10302).
    }
}

.#{$prefix}fieldset-body {
    overflow: hidden;
}

.#{$prefix}fieldset-collapsed {
    padding-bottom: 0 !important;

    > .#{$prefix}fieldset-body {
        display: none;
    }
}

.#{$prefix}fieldset-header-text-collapsible {
    cursor: pointer;
}

@if $include-rtl {
    .#{$prefix}rtl.#{$prefix}fieldset-header {
        .#{$prefix}form-item,
        .#{$prefix}tool {
            float: right;
        }
        
        .#{$prefix}fieldset-header-text {
            float: right;
        }
    }
}