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Accessible Spreadsheet Checklist

    Creator: Accessible Libraries

    Date of Update: November 9, 2023

    Overview

    This outline discusses and provides guidelines for creating accessible spreadsheets – in Microsoft Excel, Google Sheets, and Apple Numbers. Accessible spreadsheets create an inclusive experience and ensure the information is understandable for all library staff and patrons.

    Checklist

    1. Add a descriptive title to your spreadsheet workbook.
    2. Consider your font choices.
    3. Consider your use of colour.
    4. Give each worksheet a unique and descriptive name.
    5. Delete blank worksheets.
    6. Add a summary of the worksheet/workbook to the A1 cell.
    7. Add white space around the text.
    8. Define the language of your workbook.
    9. Ensure that the hyperlinks are informative.
    10. Create accessible tables.
    11. Create accessible charts.
    12. Freeze columns and/or rows when you must scroll the page to read the content.
    13. Hide unused rows and columns.
    14. Add alt text to images, graphics, and charts.
    15. Let readers know that they have reached the end of a document in Excel.
    16. Use the accessibility checker in Excel.

    You can download a simple form of the checklist here:

    Simple Accessible Spreadsheet ChecklistDownload

    Accessible spreadsheet examples:

    Download the Google Sheets Accessible Spreadsheet

    Download the Apple Numbers Accessible Spreadsheet

    Excel Accessible SpreadsheetDownload

    Add a descriptive title to your spreadsheet workbook.

    Write a descriptive and informative title for your spreadsheet workbook. Your title will be all one-word (without spaces) and should use the Pascal Case (camel case) naming convention. This capitalizes the first letter of each word. This will cause screen readers to read the separate words of the title rather than mistakenly trying to pronounce the title as one word. For example, “LibraryCollectionFormats.”

    How to write a descriptive title in spreadsheet programs.

    How to add or change a title in Microsoft Excel, Google Sheets, and Apple Numbers.

    In Microsoft Excel:

    After saving the spreadsheet and creating a file name, you can add a title to the spreadsheet properties.

    • In Windows: Select “File” > “Info” > “Add Title.”
    • On a Mac: Select “File” > “Properties” > “Summary” > add a “Title.”

    In Google Sheets:

    • Add a workbook title in the top left textbook. To rename the workbook, you can click on the textbox again or select “File” > “Rename.”

    In Apple Numbers:

    • Save the workbook and input the file name. You can rename your spreadsheet by selecting “File” > “Rename.”

    Consider your font and font attribute choices.

    Consider your spreadsheet’s font and font attributes so that persons with low vision and those with learning disabilities can read and understand your content.

    Use accessible font formats and colours:

    • A sans serif font like Arial, Helvetica, and Veranda.
    • Use a larger font size, such as 12 points.
    • Avoid elaborate font attributes (italics, all caps, etc.)
    • Do not align text to the center.
    • Ensure the font has a good colour contrast with the spreadsheet background (below).

    Consider your use of colour.

    When using colour in spreadsheets, choose how, where, and when you use colour wisely.

    Colour contrast

    Ensure that foreground worksheet text has sufficient colour contrast with its background. There should be sufficient colour contrast between the text and background.

    Your spreadsheet should have a high colour contrast in the presentation’s design and the contrast between the font and the slide background. The Web Content Accessibility Guidelines (WCAG) state that the contrast ratio should be at least 4.5:1.

    The colour contrast ratio is calculated by comparing two colours’ brightness (or luminance). The higher the contrast, the better; for example, black text on a white background is accessible (and has a ratio of 21:1), but the light grey text on a white background has low contrast (e.g., 1.3:1), which is difficult to read.

    You can check your colour contrast using sites like ContrastChecker.com with the font, background, design elements, etc., and hexadecimal (hex) colour code.

    How to find the hex code of your colours

    In Microsoft Excel:

    • Click on the font (for example) dropdown menu and select “more colours.”
    • In Windows, click on the “Custom” tab.
    • In Mac, click “Colour Sliders” and select “RGB Sliders” from the drop-down menu.

    In Google Sheets:

    • Click on a colour toolbar icon like font and select the “Custom” option, which gives you the hex code.

    In Apple Numbers:

    • Click on the colour wheel labelled “Click to show more colours or create your own.” Select “Colour Sliders” and choose “RGB Sliders” from the drop-down menu. At the bottom of this popup is the colour hex code.

    Do not use colour alone to convey meaning.

    If you must use colour, make sure you do one of the following techniques to make it more accessible:

    • Screen readers do not announce that a cell has a different background or foreground text colour.
    • When a table uses colour and conditional formatting, use the text summary in A1 to state which cells have additional meaning.

    Consider this if you create charts and graphs as well.

    Give each worksheet a unique and descriptive name.

    Give all worksheets unique names and remove blank names, informing readers about what the worksheet contains. For example, rename the default, e.g., “Sheet1,” to something representing the information on those sheets. (e.g., “PopularLibraryBooks” or “LibraryFees”).

    Please make sure that the titles are descriptive and human-readable. For example, avoid using a string of numbers as the title or sheet name (e.g., 3986749-D).

    If you don’t want to add spaces in the sheet names, ensure that you format the titles in Pascal case (also known as camel case), capitalizing the first letter of the adjoined words.

    How to give worksheets a unique title.

    In Microsoft Excel:

    • Right-click on the worksheet title that you want to change > select “Rename” from the menu > and type the new worksheet title > press enter.

    In Google Sheets:

    • Right-click or click on the arrow beside the worksheet title > select “Rename” from the menu > and type the new worksheet title > press enter.

    In Apple Numbers:

    • Right-click or click on the arrow beside the worksheet title > select “Rename” from the menu > and type the new worksheet title > press enter.

    Delete blank worksheets.

    Delete any blank worksheets in your workbook. Readers, including those who use screen readers, will expect them to have content.

    Note: When opening a new workbook, only one spreadsheet is open. You only need to delete blank worksheets if you have created more and they are empty.

    How to delete blank worksheets

    In Microsoft Excel:

    • Right-click on the worksheet > select “Delete” from the menu.

    In Google Sheets:

    • Right-click on the worksheet > select “Delete” from the menu > click “Okay” in the confirmation popup.

    In Apple Numbers:

    • Click on the worksheet > the drop-down menu and select “Delete.”

    Add a summary of the worksheet/workbook to the A1 cell.

    The A1 cell (at the uppermost left corner of the spreadsheet) is the first cell selected by screen readers. Use this cell to provide information about your worksheet by adding the title or a summary. 

    If you provide a summary of the worksheet in the A1 cell, the information you may want to include is:

    • Describe the workbook or worksheet’s structure, noting if there is more than one table in the worksheet.
    • Describe any accessibility techniques used.
    • Note any tables, graphs, and irregular items in the worksheet.
    • Note the start cell for the items in the summary.

    Note: This is not possible to do in Apple Numbers, as this program requires the first row to be a header row.

    Add white space around the text.

    Provide visual or white space around the text of your spreadsheet by increasing the width of the columns and rows. This will help readers with low vision to read the text easier.

    Note: Do not create whitespace in your tables or worksheets by leaving empty columns and rows between the text.

    How to increase the column row width in your worksheets.

    Note: the width and height of the columns and rows will depend on your workbook’s content.

    In Microsoft Excel:

    • Column width: select the column by clicking on the label (e.g., A, B, C…) > right-click on the selected column > choose “Column Width…” > increase the number > click “Okay.”
    • Row width: select the whole sheet by using the keyboard shortcut (control + A or Command + A) or the top-left corner/triangle button > right-click and select “Row Height…” > increase the number > click “Okay.”

    In Google Sheets:

    • Column width: Select the columns you would like to widen > right-click and select “Resize columns X-X” (e.g., A-G) > enter a new width (in pixels) or “Fit to data” > click “Okay.”
    • Row Width: Select the rows you would like to make higher > right-click and select “Resize rows #-#” (e.g., 1-19) > enter a new height (in pixels) or “Fit to data” > click “Okay.”

    You can choose more than one row or column to resize, but the size of those selected will all be the same unless you select “Fit to data.”

    In Apple Numbers:

    • Column width: Select the column or columns you would like to widen > in the right “Table” toolbar, increase the “Width” by using the up arrow, changing the points number, or by clicking on “Fit” to adjust the width to the content. 
    • Row width: Select the row or rows you would like to widen > in the right “Table” toolbar, increase the “Height” by using the up arrow, changing the points number, or by clicking on “Fit” to adjust the height to the content. 

    If you want to increase the size of all the rows or columns in your table, do not select anything (row or column) and then increase the height and/or width in the right “Table” toolbar.

    Define the language of your workbook.

    Defining the language of your workbook is especially important so that screen readers pronounce the text correctly. You can only define the language of the full spreadsheet in all programs.

    Note: Defining the language also affects details like currency, dates, etc.

    How to define the language in workbooks.

    In Microsoft Excel:

    • Click on “Tools” > “Language” > select the language > click on “Okay.”

    In Google Sheets:

    • Click on “File” > “Settings” > select the language for the spreadsheet.

    In Apple Numbers:

    • Click on “File” > “Advanced” > “Language & Region” > choose a language from the drop-down menu > select “Okay.”

    Hyperlinks need to be informative for users of assistive technologies who navigate using links.

    • For digital documents, use informative text. For example, to learn more, visit the Accessible Libraries website.
    • Use the shortest URL possible in a Pascal case (also known as camel case) format for presentations and physical handouts. For example, AccessibleLibraries.ca

    In spreadsheets, you can use links to jump to different worksheet areas using links (or create anchors). For example, you can link to the worksheet table from the A1 cell summary.

    How to create hyperlinks in your worksheet.

    In Microsoft Excel:

    • Click on the cell you would like to add a hyperlink to > press Control + K (Windows) or Command + K (Mac) > Add the URL to the popup.

    In Google Sheets:

    • Click on the cell with or highlight the text you would like to add a hyperlink to > press Control + K (Windows) or Command + K (Mac) > Add the URL to the popup.
    • You can link to a table or different sheet in the A1 cell summary by highlighting the text and pressing Control + K (Windows) or Command + K (Mac). Select the option “Sheets and named ranges” > Select the sheet to link to, or if linking to a table in the page, choose “Select a range of cells to link” > highlight the cells to link to or enter in the data range (e.g., A2:E16).

    In Apple Numbers:

    • Highlight the text you would like to add a hyperlink to > press Command + K (Mac) > choose a “Link to” option (webpage, email, phone number, or sheet) > Add the URL to the popup.

    How to link to different cells in your worksheet.

    In Microsoft Excel:

    • Click on the cell you would like to add a hyperlink to > press Control + K (Windows) or Command + K > in the popup, select the option “This Document” > enter a cell (e.g., A2) or the name of the worksheet.

    In Google Sheets:

    • Click on the cell with or highlight the text you would like to add a hyperlink to > select “Sheets and Named Ranges” from the popup > choose to link to another worksheet or a range of cells (e.g.,

    In Apple Numbers:

    • Highlight the text you would like to add a hyperlink to > Select “Sheet” in the drop-down “Link to menu” > Choose the worksheet you would like to link to > press okay.

    Create accessible tables.

    When creating tables within your workbooks, they need to be accessible. A big part of this is avoiding tables that are too long and overly complex. If you must have more than one table in a worksheet, leave one blank row between the tables.

    Try to limit the number of tables on each page (just one is ideal). If you have more than one table in a spreadsheet, note this in the summary at the beginning of the page and identify (by cell) where the table starts.

    Tips and Guidelines for Creating Accessible Tables

    • Use a simple table structure and avoid overly complex tables.
    • Tables need to have headers to identify rows and columns.
    • Do not merge table cells. It disrupts screen reader users’ navigation and understanding of where they are located within the spreadsheet.
    • Do not split cells.
    • Do not nest tables.
    • Do not have blank cells or rows.
    • Separate data so each piece has its own column/cell (e.g., don’t list a book’s title and author in the same cell – divide them into separate columns)

    For more complex tables, you should break them up into multiple tables. If you absolutely must create a complex table (e.g., multi-tiered column headers), properly describe them (in the A1 cell summary).

    How to Create Basic Accessible Tables

    Creating accessible tables depends on your program and may require more than one step.

    In Microsoft Excel:

    First, you must create the table:

    • Select the table cells (rows and columns) that you would like to be in the table.
    • Select “Insert” > “Table” (or Ctrl + C)

    For the table to be accessible, the header needs to be defined.

    • When creating the table, select “My table has headers.” This will ensure that the “header row” checkbox is selected (located under the “Table” toolbar).
    • If you did not select the “My table has headers,” you can manually select the “header row” checkbox under the “Table” toolbar.

    In Google Sheets:

    • Select the table cells (rows and columns) and choose “Format” > “Alternating Colours.” Ensure the “Header” option is selected.
    • To create filters for your table headers, select the headings and choose “Data” > “Create filters.”

    In Apple Numbers:

    Apple Numbers creates tables for you automatically when you open a new blank document. To ensure that they are as accessible as possible, you need to define the header rows.

    • Under the “Format” option > select “Table” in the right formatting column. There, you can choose what row/column contains the headings of your table.
    • In the “Format” pane, you can also enlarge the font, make the gridlines bolder, alternate the colour of the table, etc.

    If your Apple Numbers sheet is not preformatted as a table, you can specify that the first row and column contain headers.

    • Control or right-click the number or letter next to your table’s first row or column, then choose “Convert to Header Row” or “Convert to Header Column.”

    Create accessible charts and graphs.

    Graphs in spreadsheets float above the spreadsheet and must be noted that they exist for assistive technology users. This is a great thing to specify in the A1 cell.

    We recommend avoiding graphs in your spreadsheet when possible. Navigating to and within the charts and graphs can be difficult for assistive technology users. If you do use them, you must provide alt text.

    Accessible Considerations for Charts and Graphs

    • Your charts and graphs should have high colour contrast between design elements and the background.
    • Ensure the text labels of your charts and graphs are clear and descriptive (including the title of the chart/graph)
    • Use the largest readable font size possible for your text labels.
    • Use a sans-serif font.
    • Add alt text to describe your graphs and tables.

    How to create and format charts and graphs.

    In Microsoft Excel

    • How to create a chart: Highlight the column with the data you would like displayed in your chart > select “Chart” > type of chart you want to insert.
      • OR, to insert a pivot table, select “Home” > “Analyze Data.” If you choose this option, a new table will be created in a separate sheet.
    • How to format chart: Select the chart > choose the “Format” tab > select what area of the chart you would like to format from the drop-down menu on the left (e.g., “Chart Area” or “Horizontal (Value) Axis”).

    In Google Sheets

    • How to create a chart: Highlight the column with the data you would like displayed in your chart > select “Insert” from the top menu > choose the “Chart” option.
    • How to format chart: Click on the three dots in the top right corner > select “Edit chart.” Here, you can choose the chart type, styles, colours, font, etc.

    In Apple Numbers

    • How to create a chart: Select the columns/rows with the data you would like in the chart > select “Insert” > “Chart” > choose the type of chart you would like to insert (e.g., pie, bar, etc.).
    • How to format chart: Click on the chart you would like to format > choose the “Format” option in the top toolbar, opening a right-sidebar > From here, you can edit the colours used, the font size, the chart labels, etc.

    Note: Data used to create charts in Apple Numbers should be numerical for best results.

    How to add alt text/long descriptions to your graphs and charts.

    If you use graphs and charts, they need to be described. This section includes how to add alt text and/or long descriptions (suggested for charts) to describe them so everyone can access the information.

    Long descriptions are detailed descriptions of complex images, like charts, graphs, infographics, etc. You can add them in the surrounding text or on a separate page (not the location of the long description in the A1 cell summary).

    For more information about how to craft alt text/long descriptions, check out Accessible Publishing’s Guide to Image Descriptions.

    In Microsoft Excel:

    • Select the chart > Right-click on the chart > select “View Alt Text” from the popup menu. You can then edit the auto-generated alt text (highly recommended).

    In Google Sheets:

    • Click on the three-dot menu in the chart pane (top-right) > Select “Alt text” > add your chart description.

    Note: When writing this checklist, you cannot add alt text to charts in Apple Numbers. You can add a chart long description to your worksheet in a text box.  

    Apple Numbers audio graphs

    Apple Numbers provides an audio graph description for charts, representing chart data as sound. Typically, the audio graph represents the x-axis as time and the y-axis as pitch, playing a series of tones or a continuous tone, depending on the chart type, from left to right. The higher the value of the data, the higher the pitch and vice versa (a low value has a low pitch). Apple Numbers also provides an auto-generated chart description (with a summary of the chart features and statistics), which is helpful. However, we still recommend that you provide a chart long description. 

    Apple Numbers automatically generates the audio graph in your spreadsheet. For the best results, use a graph/chart with an x and y axis (e.g., not a pie chart).

    Caption. A demonstration of an audio graph in Apple Numbers.

    Freeze the heading columns and/or rows when you must scroll the page to read the content.

    Freezing the heading rows and columns in tables with large amounts of data that extend beyond the edges of the spreadsheet is helpful for persons with low vision. Frozen rows/columns will scroll with the reader as they move within the table/spreadsheet.

    How to freeze the heading rows and columns.

    In Microsoft Excel:

    • To freeze the header column/row:
      • Select the cell immediately below and to the right of the sheet headers.
        • This is dependent on what headers your table has. If you have headers both in a column and row, then select the topmost corner below them. (e.g., B1 is the row header, and the first column header is B2, then select the cell B3).
        • Select “View” > choose the option “Freeze Panes.”

    In Google Sheets:

    • To freeze the header row:
      • Select the row (by clicking on the row number on the left side of the sheet) > right-click on the row and select “View more row actions” > choose “Freeze up to row #” (the option depends on the number of cells above the header row).
    • To freeze the column headers:
      • Select the column by clicking on the column letter at the top of the sheet > right-click on the column and select “View more column actions” > choose “Freeze up to column X.”

    In Apple Numbers:

    • To freeze the header row:
      • Select the row (by clicking on the row number on the left side of the sheet) > right-click on the row (or click on the green down arrow that appears to the right of the row number) > and select “Freeze Header Rows.”
    • To freeze the column headers:
      • Select the column by clicking on the column letter at the top of the sheet > right-click on the column (or click on the green down arrow that appears to the right of the column letter) > select “Freeze Header Columns.”

    Hide unused rows and columns.

    Hiding unused cells and rows will hide the extra content from persons who use assistive technologies and minimize possible distractions for persons with a learning disability.

    How to hide unused rows and columns.

    In Microsoft Excel:

    • To hide columns:
      • Select/highlight the column immediately to the right of the spreadsheet content.
      • Select all columns by pressing “Shift + Ctrl/control + Right-Arrow” (on PC/Mac).
      • Right-click on the highlighted columns and select “Hide.”
    • To hide rows:
      • Select/highlight the row immediately below the spreadsheet content.
      • Select all the rows by pressing “Shift + Ctrl/control + Down-Arrow” (on PC/Mac).
      • Right-click on the highlighted columns and select “Hide.”
    • To unhide the columns and rows, click on the top-left corner of the worksheet > Right-click > select “Unhide.”

    In Google Sheets:

    • To hide columns:
      • Select/highlight the column immediately to the right of the spreadsheet content.
      • Select all columns by pressing “Shift + Ctrl/control + Right-Arrow” (on PC/Mac).
      • Right-click on the highlighted columns and select “Hide Columns X-X.”
    • To hide rows:
      • Select/highlight the row immediately below the spreadsheet content.
      • Select all the rows by pressing “Shift + Ctrl/control + Down-Arrow” (on PC/Mac).
      • Right-click the highlighted columns and select “Hide Rows #-#.”
    • Click the small arrows on the last unhidden column/row to unhide the columns and rows.

    In Apple Numbers:

    • To hide columns:
      • Select/highlight the column immediately to the right of the spreadsheet content.
      • Select all columns by pressing “Shift + Control + Right-Arrow.”
      • Right-click on the highlighted columns and select “Hide Selected Columns.”
    • To hide rows:
      • Select/highlight the row immediately below the spreadsheet content.
      • Select all the rows by pressing “Shift + Control + Down-Arrow.”
      • Right-click on the highlighted columns and select “Hide Selected Rows.”
    • To unhide the columns and rows:
      • For columns: Select a column > right-click or select the small arrow to the right of the column > choose “Unhide all Columns.”
        • If you select the last column shown, you can also choose to “Unhide columns X-X” (the next two columns in the sheet).
      • For rows: Select a row > right-click or select the small arrow that appears to the right of the column > choose “Unhide all Rows.”
        • If you select the last row shown, you can also choose “Unhide rows #-#” (the next two rows in the sheet).

    Add Alt-Text to Images

    If your spreadsheets have visual items (images, shapes, etc.), they must be described, just like for charts. For more information about how to craft image descriptions, check out Accessible Publishing’s Guide to Image Descriptions.

    How to add alt text to images.

    In Microsoft Excel:

    • Right-click on the visual item > select “Edit Alt-text” or select the image > choose “Format” from the top menu > Select “Alt-text.”
    • A popup on the right side of the spreadsheet comes up, where you can write out the alt text for your image.

    In the alt-text editing popup, you can also mark an image as “decorative” so screen readers will ignore it.

    In Google Sheets:

    • There are two ways to add alt text to images, depending on how the visual media has been inserted into the spreadsheet.
    • If the visual media is inserted into the cell:
      • Right-click on the cell > select “Image > choose “Add alt text to cell.”
      • A popup on the right side of the spreadsheet appears, where you can write out the alt text for your image.
    • If the visual media overlays the spreadsheet cells:
      • Click on the three-dot menu at the top-right of the image > Select “Alt text.”
      • A popup on the right side of the spreadsheet appears, where you can write out the alt text for your image.

    In Apple Numbers:

    • Click on the image/visual media and choose “Format” from the top toolbar (if not already selected).
    • In the “Image” tab of the right sidebar, add the visual media alt text to the “Description” textbox.

    For more information, check out the AccesssiblePublishing.ca guidelines for creating image descriptions (alt text).

    Let readers know that they have reached the end of a document in Excel.

    By writing “End of Worksheet” or something similar. You can do this just before any hidden rows/columns in your worksheet.

    You only need to add this in Microsoft Excel. Apple Numbers and Google Sheets inform screen reader users about the end of the spreadsheet.

    Use the accessibility checker in Excel.

    Excel provides an accessibility checker, letting you know if your spreadsheet has accessibility barriers like missing alt text or poor colour contrast.

    How to use the Accessibility Checker in Excel.

    • Click on the “Accessibility” tab > select “Check Accessibility.
    • Or click on the “Accessibility” option at the very bottom left side of the spreadsheet window (e.g., “Accessibility: Good to go” or “Accessibility: Investigate”).
    • This opens a popup on the right side of the spreadsheet window with the “Inspection Results.” If there are identified barriers, click on them to go to the issue in your spreadsheet and correct them.

    An example of an accessibility issue is missing alt-text or poor colour contrast.

    Note: The Accessibility Checker is a great starting point but will not catch everything. Following this checklist and testing the spreadsheet with assistive technologies, such as a screen reader, is always recommended.

    References

    Apple Developer Documentation. (2023). Audio graphs. Accessed November 7, 2023. https://developer.apple.com/documentation/accessibility/audio_graphs  

    Apple Support. (2023, October 12). Create accessible documents, spreadsheets, or presentations with pages, numbers, or keynote. Accessed November 7, 2023. https://support.apple.com/en-ca/102031

    Apple Support. (2023b). Use voiceover to create a numbers spreadsheet on iPhone. Accessed November 7, 2023. https://support.apple.com/en-ca/guide/numbers-iphone/tan70326493e/ios

    Government of British Columbia (2022, October 26). Creating accessible Microsoft Excel documents. Province of British Columbia. Accessed February 7, 2023. Retrieved from: https://www2.gov.bc.ca/gov/content/home/accessible-government/toolkit/documents/microsoft-excel 

    Microsoft (January 24, 2022). Make your Excel documents accessible to people with disabilities. Accessed February 7, 2023. Retrieved from: https://support.microsoft.com/en-us/office/make-your-excel-documents-accessible-to-people-with-disabilities-6cc05fc5-1314-48b5-8eb3-683e49b3e593 – PickTab=Windows

    Toronto Metropolitan University. (n.d.). Microsoft Excel Accessibility Tipsheet. Accessed February 7, 2023. Retrieved from: https://www.torontomu.ca/content/dam/accessibility/guides-resources/tipsheets/Microsoft-Excel-Accessibility-Tipsheet.pdf

    TPGi (October 19, 2021). On-Demand Webinar: How to Make an Accessible Excel Workbook. Accessed February 7, 2023. Retrieved from: https://www.tpgi.com/webinar-october-19-how-to-make-an-accessible-excel-workbook/

    W3C (n.d.). Table Tutorials. Accessed July 10, 2023. Retrieved from: https://www.w3.org/WAI/tutorials/tables/

    WebAIM (November, 29, 2022). WebAIM: Microsoft Excel Optimizing Spreadsheet Accessibility. Accessed February 22, 2022. Retrieved from: https://webaim.org/techniques/excel/