tinymce upload image with custom css

I want to add max-width:’100%’ style to uploaded image. How can I do this?

 file_picker_callback(cb, value, meta) {
                const input = document.createElement('input');
                input.setAttribute('type', 'file');
                input.setAttribute('accept', 'image/*');

                input.onchange = () => {
                    const file = input.files[0];
                    const reader = new FileReader();
                    reader.onload = () => {
                        const id = 'blobid' + new Date().getTime();
                        const blobCache = tinymce.activeEditor.editorUpload.blobCache;
                        const base64 = (<string>reader.result).split(',')[1];
                        const blobInfo = blobCache.create(id, file, base64);
                        blobCache.add(blobInfo);
                        cb(blobInfo.blobUri(), { title: file.name });
                    };
                    reader.readAsDataURL(file);
                };

                input.click();
            },

I use this code to upload image on tinyMce.init.