JezK
Edit File: editor.min.css
.block-editor-freeform-modal .block-editor-freeform-modal__content .mce-edit-area iframe{height:50vh!important}@media (min-width:960px){.block-editor-freeform-modal .block-editor-freeform-modal__content:not(.is-full-screen){height:9999rem}.block-editor-freeform-modal .block-editor-freeform-modal__content .components-modal__header+div{height:100%}.block-editor-freeform-modal .block-editor-freeform-modal__content .mce-tinymce{height:calc(100% - 52px)}.block-editor-freeform-modal .block-editor-freeform-modal__content .mce-container-body{display:flex;flex-direction:column;height:100%;min-width:50vw}.block-editor-freeform-modal .block-editor-freeform-modal__content .mce-edit-area{display:flex;flex-direction:column;flex-grow:1}.block-editor-freeform-modal .block-editor-freeform-modal__content .mce-edit-area iframe{flex-grow:1;height:10px!important}}.block-editor-freeform-modal__actions{margin-top:16px}