One place for hosting & domains

      Manipulate

      How To Use the Display Property to Manipulate the Box Model in CSS


      The author selected the Diversity in Tech Fund to receive a donation as part of the Write for DOnations program.

      Introduction

      HTML and CSS work together to render visual elements of a web page in the browser. HTML elements carry computational and hierarchical meaning and have default styles the browsers apply to these elements. Among these default styles is the display property. The value of this property affects the box model, the mechanism that determines how elements interact with one another on a page. Using the display property, you can efficiently control how an element interacts with the layout of your web page, allowing you to create more flexible solutions for situations like responsive mobile web design.

      In this tutorial, you will work through multiple demos using the display property and learn how it determines flow interactions with other elements. You will begin with the foundational values of display: block and inline. You will then use the combination value of inline-block to learn about the possibilities of the inline- prefixed values. Next, you will learn about the power and danger of using the none value. Lastly, you will use a max-width media query to transform a table into a display: block view on a small screen.

      Prerequisites

      Setting Up the Initial HTML and CSS files

      To begin, you will set up the HTML and CSS files that you will use throughout the tutorial. You will also explore the default display values of text-containing elements.

      Start by opening index.html in your text editor and adding the following code to your file:

      index.html

      <!doctype html>
      <html>
        <head>
          <meta charset="utf-8" />
          <meta name="viewport" content="width=device-width, initial-scale=1" />
          <title>The Terrestrial Planets</title>
          <link href="https://www.digitalocean.com/community/tutorials/styles.css" rel="stylesheet" />
        </head>
        <body>
        </body>
      </html>
      

      This code sets up the framework necessary for every HTML document. The information contained in the <head> element defines the page’s name in the <title> element and where to load the stylesheet, which is determined in the <link> element. The <meta> tags define the character encoding and small screen device handling, respectively. The main content of the page will be added inside the <body> tags throughout the tutorial.

      Next, inside the <body> element, create a <main> element with a class attribute set to content-width. You will use this element to handle the layout of the content within the page. Inside the <main> element, create an <h1> tag pair followed by a <p>. Within the <h1> and <p> elements, add the content shown in the following code block:

      index.html

      <!doctype html>
      <html>
        <head>
          ...
        </head>
        <body>
          <main class="content-width">
            <h1>The Terrestrial Planets of the Solar System</h1>
      
            <p>
              The four inner planets of the Solar System consist of Mercury, Venus, Earth, and Mars. These planets are known as terrestrial due to their hard, rocky surface. Compared to the gaseous planets of the outer solar system, the inner terrestrial planets are significantly smaller in size. Depending on tectonic activity and presence of liquids these planets will have features such as canyons, mountains, and volcanoes on their surface.
            </p>
          </main>
        </body>
      </html>
      

      Highlighted code, like that in the previous code block, is used throughout this tutorial to emphasize changes to the code.

      Save your changes to index.html, then create a new file called styles.css and open it in your editor as well.

      In your styles.css file, you will add selectors for the elements you created in index.html. Create a selector for body and .content-width, then add the styling properties as demonstrated in the following code block:

      styles.css

      body {
        margin: 0;
        font-family: sans-serif;
        line-height: 1.5;
        color: hsl(215, 5%, 20%);
        background-color: hsl(215, 5%, 98%);
      }
      
      .content-width {
        margin: 2rem auto;
        width: 90%;
        max-width: 40rem;
      }
      

      The styles for the body element reset some default layout and text styling with the margin, font-family, and line-height properties. The color and background color add a dark-gray blue and a light-gray blue to the page. The .content-width properties will keep it centered to the page, taking up 90% of the screen width until it reaches a maximum size of 40rem, or 640px.

      Next, add some font styling to make the text more legible:

      styles.css

      ...
      .content-width {
        margin: 2rem auto;
        width: 90%;
        max-width: 40rem;
      }
      
      h1 {
        font-size: 2rem;
        font-weight: 400;
        line-height: 1.2;
      }
      
      p {
        font-size: 1.125rem;
      }
      

      The h1 properties define the size and weight of the text and bring the line-height property down to a better spacing for headings. Lastly, the p element selector bumps up the font-size to 1.125rem, or 18px.

      Save your changes to styles.css, then open your web browser. Open index.html in the browser by dragging the file into the browser window or using the browser’s Open File option. The browser will render the HTML and CSS code to produce a page like the following image:

      Large header text and smaller paragraph text in a dark blue-gray color on a light gray background.

      So far, the HTML elements that you have worked with are known as block elements. These are elements that create defined areas of content that take up the full width of the parent container. Additionally, block elements are usually rendered by themselves on a new line. This means that added block elements stack toward the end of the page. For a top-to-bottom, left-to-right language like English, block elements stack toward the bottom of the browser window.

      Next, you will add inline elements, which are elements that exist within the flow of text content. Since inline elements do not take up the entire width of their parent, and since they are not rendered on their own lines, they are added in the direction of the text flow. For English, this is a left-to-right direction.

      Where block elements define the meaning and group of content, like a paragraph, inline elements provide context about a word or group of words, such as an emphasis.

      Return to index.html in your text editor. In the second sentence, wrap the word terrestrial in the emphasis tag, <em>. Then, in the third sentence, wrap the phrase gaseous planets in an anchor tag, <a>. In the opening <a> tag add an href attribute with a value of https://en.wikipedia.org/wiki/Giant_planet. This will link to the Wikipedia page on the topic. The highlighted HTML in the following code block demonstrates how this is set up:

      index.html

      ...
      <p>
        The four inner planets of the Solar System consist of Mercury, Venus, Earth, and Mars. These planets are known as <em>terrestrial</em> due to their hard, rocky surface. Compared to the <a href="https://en.wikipedia.org/wiki/Giant_planet">gaseous planets</a> of the outer solar system, the inner terrestrial planets are significantly smaller in size. Depending on tectonic activity and presence of liquids these planets will have features such as canyons, mountains, and volcanoes on their surface.
      </p>
      ...
      

      Save these additions to index.html then, return to styles.css in your text editor. To demonstrate the difference between block and inline elements, create an a element selector. Inside the selector add the display property set to block, as demonstrated in the following code block:

      styles.css

      ...
      p {
        font-size: 1.125rem;
      }
      
      a {
        display: block;
      }
      

      Save your change to styles.css, then return to the page in your web browser. Refresh the page to load the latest version of your code. The page demonstrates the key difference between a block and an inline element, as the link set to display: block now occupies its own line. This is demonstrated in the following image:

      Large header text and smaller paragraph text in a dark blue-gray color on a light gray background with a blue underlined text breaking up the paragraph into two sections.

      The primary difference between a block and an inline value is that a block breaks the current content flow while inline maintains it. Additionally, if a width property were applied to the a selector, it would not change the layout. When the content flow is disrupted by a block element, it remains broken, and the width always takes up the entire parent container width.

      inline and block are the most common browser default values. While the display property has many values, with a few exceptions, all remaining elements use one of these two values.

      Now that you have explored the differences between block and inline, return to styles.css in your text editor. In the a selector, remove the display: block and replace it with a color property with a value of hsl(215, 80%, 50%), which is a richer version of the blue used on the body. Then create an a:hover selector with a text-decoration property set to none. This will remove the underline when the link is hovered. The highlighted CSS in the following code block shows how this is written:

      styles.css

      ...
      a {
        color: hsl(215, 80%, 50%);
      }
      
      a:hover {
        text-decoration: none;
      }
      

      Save your changes to styles.css and refresh index.html in your web browser. The link will once again be inline with the text and will now be a lighter blue color, as shown in the following image:

      Large header text and smaller paragraph text in a dark blue-gray color on a light gray background with a blue underlined link.

      In this section, you set up the HTML and CSS files you will use throughout the tutorial. These files will be amended and modified regularly, so keep both files open in your text editor and remember to save regularly. You also learned about the default display values, inline and block, and changed the value of an inline element to block. In the next section, you will use the inline-block value, which combines the capabilities of inline and block.

      Using the inline-block Value

      Next, you will create a button element with a customizable width, rather than a button that takes up the whole width of the parent container. To do this, you will use the inline-block value, which maintains box model properties of the block value like margin and padding while also having the content flow properties of the inline value.

      The inline- prefix is available on several display values, including inline-flex, inline-grid, and inline-table. The inline-block value defines the box model of the element as a block, but it does not disrupt the content flow. Additionally, inline-block does not take up the full parent width, as block does. Instead, the inline-block element condenses down to only the width of its content. For shorter content, such as a button, this makes for a useful resizing of the element with block box model properties, such as margin.

      To begin working with inline-block, open index.html in your text editor. After the closing <p> tag, add an <a> tag with a class attribute set to button and an href attribute set to https://en.wikipedia.org/wiki/Terrestrial_planet. Inside that tag, add the text Learn more on Wikipedia. The highlighted HTML in the following code block demonstrates how this is written:

      index.html

      <div class="content-width">
        <h1>The Terrestrial Planets of the Solar System</h1>
      
        <p>
          ...
        </p>
      
        <a href="https://en.wikipedia.org/wiki/Terrestrial_planet" class="button">Learn more on Wikipedia</a>
      </div>
      

      Save your changes to index.html, then open styles.css in your text editor.

      In your styles.css file, add a class selector for .button. This will style the link you created in your index.html file. By default, an <a> has a display value of inline. For this step, change the display value to block for the button class, then add the additional highlighted styles from the following code block:

      styles.css

      ...
      a:hover {
        text-decoration: none;
      }
      
      .button {
        display:block;
        padding: 0.5rem 1.25rem;
        text-align: center;
        text-decoration: none;
        color: hsl(215, 20%, 95%);
        background: linear-gradient(to bottom, hsl(215, 80%, 60%), hsl(215, 80%, 40%));
      }
      

      The additional styles added to the .button element add padding, center the text, and remove the link underline. Additionally, the styles add a blue gradient of the same hue as the earlier versions of this blue with a near white text color.

      Save these changes to the styles.css, then return to your browser and refresh index.html. The button will fill the full width of the content area with a blue gradient. The following image shows how this will render in the browser:

      Large header text and smaller paragraph text in a dark blue-gray color on a light gray background with a blue button below the paragraph with white text. The button is as wide as the paragraph.

      Next, you will change the block value for the display property to inline-block. Return to styles.css in your text editor and change the display property value from block to inline-block, as highlighted in the following code block:

      styles.css

      ...
      .button {
        display: inline-block;
        padding: 0.5rem 1.25rem;
        text-align: center;
        text-decoration: none;
        color: hsl(215, 20%, 95%);
        background: linear-gradient(to bottom, hsl(215, 80%, 60%), hsl(215, 80%, 40%));
      }
      

      Save these changes to styles.css and then refresh index.html in your web browser. The width of the button has condensed from extending the full width of its parent to being just as wide as its content, plus the padding value. The following image demonstrates how the inline-block element renders in the browser:

      Large header text and smaller paragraph text in a dark blue-gray color on a light gray background with a blue button below the paragraph with white text. The button is only as wide as the text inside the button.

      Finally, return to styles.css to add in some last styling for the button. You will add styles to apply a 3D effect to the button by adding a border-radius, border, text-shadow, and box-shadow. Also, create a .button:hover selector and add a box-shadow and linear-gradien() that make a darker hover state. The highlighted CSS in the following code block show how to write these styles:

      styles.css

      ...
      .button {
        display: inline-block;
        padding: 0.5rem 1.25rem;
        text-align: center;
        text-decoration: none;
        color: hsl(215, 20%, 95%);
        background: linear-gradient(to bottom, hsl(215, 80%, 60%), hsl(215, 80%, 40%));
        border-radius: 0.25rem;
        border: 1px solid hsl(215, 80%, 35%);
        text-shadow: 0 -1px hsl(215, 80%, 35%);
        box-shadow: 0 1px hsl(215, 80%, 70%) inset;
      }
      
      .button:hover {
        box-shadow: 0 1px hsl(215, 80%, 60%) inset;
        background: linear-gradient(to bottom, hsl(215, 80%, 50%), hsl(215, 80%, 30%));
      }
      

      Save your changes to styles.css and then refresh the page in your web browser. Visually, the button now has more definition and depth, as shown in the following image:

      Blue gradient button with white text and a dark border.

      In this section, you used the inline-block value on a link to create a button that is large and clickable, but only as wide as the link’s text. You also learned how there are other inline- prefixed display values that allow for various display types that do not disrupt the content flow. In the next section, you will continue changing display values by switching table elements to block.

      Changing a Table to Use display: block

      Next, you will convert a whole table to use the display: block property value. A table requires HTML specific to the table element, and each child element of the table has its own default display value. For example, the <table> element has a display value of table, and the table cell, <td>, has a display value of table-cell. There can be many reasons why a table might need to change its display value, but most often it is for a small-screen device solution where the table doesn’t fit well.

      To begin working with a table’s display property, open index.html in your text editor. After the button link, add the highlighted HTML from the following code block:

      index.html

      ...
      <a href="https://en.wikipedia.org/wiki/Terrestrial_planet" class="button">Learn more on Wikipedia</a>
      
      <table>
        <caption>
          Terrestrial Planets Statistics
        </caption>
        <thead>
          <tr>
            <th>Name</th>
            <th>Radius</th>
            <th>Moons</th>
            <th>Gravity</th>
            <th>Wikipedia</th>
          </tr>
        </thead>
        <tbody>
          <tr>
            <th>Mercury</th>
            <td>2,439.7 km</td>
            <td>0</td>
            <td>3.7 m/s<sup>2</sup></td>
            <td>
              <a href="https://en.wikipedia.org/wiki/Mercury_(planet)" class="button">
                Learn More
              </a>
            </td>
          </tr>
          <tr>
            <th>Venus</th>
            <td>6,051.8 km</td>
            <td>0</td>
            <td>8.87 m/s<sup>2</sup></td>
            <td>
              <a href="https://en.wikipedia.org/wiki/Venus_(planet)" class="button">
                Learn More
              </a>
            </td>
          </tr>
          <tr>
            <th>Earth</th>
            <td>6,371.0 km</td>
            <td>1</td>
            <td>9.80665 m/s<sup>2</sup></td>
            <td>
              <a href="https://en.wikipedia.org/wiki/Earth_(planet)" class="button">
                Learn More
              </a>
            </td>
          </tr>
          <tr>
            <th>Mars</th>
            <td>3,389.5 km</td>
            <td>2</td>
            <td>3.72076 m/s<sup>2</sup></td>
            <td>
              <a href="https://en.wikipedia.org/wiki/Mars_(planet)" class="button">
                Learn More
              </a>
            </td>
          </tr>
        </tbody>
      </table>
      ...
      

      This table HTML creates a table called “Terrestrial Planets Statistics” by putting that name in the <caption> element, a necessary component of screen-reader accessible tables. Then the HTML creates a five-column table consisting of a header row and four data rows.

      Next, to add some visual styles to the table, open styles.css in your text editor. You will create a visual style that makes the caption like a header for the table. The table header row will become more distinct with a dark background, and you will create a zebra stripe effect with alternating background colors on the data rows. The highlighted CSS in the following code block demonstrates how these styles are written:

      styles.css

      ...
      table {
        border-collapse: collapse;
        width: 100%;
        margin: 3rem 0;
      }
      
      caption {
        font-size: 1.5rem;
        font-weight: 700;
        color: hsl(215, 25%, 25%);
        text-align: left;
        margin-bottom: 0.5em;
      }
      
      tr {
        text-align: center;
      }
      
      thead > tr {
        color: hsl(215, 25%, 100%);
        background-color: hsl(215, 80%, 20%);
      }
      
      tbody > tr:nth-child(even) {
        background-color: hsl(215, 50%, 93%);
      }
      
      tbody th {
        font-size: 1.125rem;
      }
      
      td, th {
        padding: 0.5rem;
      }
      

      Save your changes to styles.css and open index.html in your web browser. The table is styled with clear data and alignment, as shown in the following image:

      Table grid of data containing information about the four terrestrial planets.

      Open your local version of index.html on a smart phone, or scale your browser’s window down to about the size of a smart phone. The table will eventually start going off screen and will only be viewable by scrolling horizontally, as demonstrated in the following image:

      A phone containing a table going off screen, cutting off informations.

      This is a situation where changing the display value of the table elements can help provide a better viewing experience for those on smaller screens.

      Return to styles.css in your text editor and create a media query set to a max-width of 60rem. Normally, you would use min-width instead of max-width in your media queries to follow a mobile first design flow. However, since you will only change the style on small screens and then return to the browser default at a given screen size, in this example situation max-width requires the least work. Inside the media query, create a group combinator consisting of table, caption, thead, tbody, tr, th, and td. Then set the display property to block, as highlighted in the following code block:

      styles.css

      @media (max-width: 60rem) {
        table,
        caption,
        thead,
        tbody,
        tr,
        th,
        td {
          display: block;
        }
      }
      

      Save your changes to styles.css and return to index.html on your smartphone or in a small-size browser window. All the contents of the table are now stacked in one large column, with each row’s contents grouped together. The following image shows how this is rendered on a mobile phone:

      Contents of a table in a vertical stack.

      This change to the table’s display value creates two issues. The first is that the browser no longer recognizes the table as a table, and therefore will not be read to a screen reader as a table. The second is that some of the contents and styles are now not providing useful information. For starters, the table headers no longer provide visual connection to the data types. Secondly, the zebra stripes don’t provide as much information in this scenario.

      Return to styles.css in your text editor. First, remove thead from the group combinator. Next, create a new selector for the thead element and give it a display property set to a value of none. The display: none value completely removes an element visually from rendering in the browser. It is important to know that the none value also removes the element from the screen reader DOM, so the element is hidden from all users. The highlighted CSS in the following code block shows how this is set up:

      styles.css

      @media (max-width: 60rem) {
        table,
        caption,
        tbody,
        tr,
        th,
        td {
          display: block;
        }
      
        thead {
          display: none;
        }
      }
      

      Next, to begin addressing the style changes, start by adding a text-align property to the large group combinator with a value of left. Next, duplicate the selector used for the zebra stripes, tbody> tr:nth-child(even), and set the background-color to transparent. This will remove the zebra stripe effect on screens and windows smaller than 60rem, or 960px, wide. Then, make the Learn More button work as a full-width button on small screens. Create a table .button descendant selector with the display property set to block, which will cause the button to fill the width of the container. The highlighted CSS in the following code block illustrates how this looks:

      styles.css

      @media (max-width: 60rem) {
        table,
        caption,
        tbody,
        tr,
        th,
        td {
          display: block;
          text-align: left;
        }
      
        thead {
          display: none;
        }
      
        tbody > tr:nth-child(even) {
          background-color: transparent;
        }
      
        table .button {
          display: block;
        }
      }
      

      Save your changes to styles.css in your text editor and then refresh index.html in your browser. On small-screen devices, the content of the tables are now all left-aligned with the button spanning the width of the content. The following image shows how this is rendered in Safari on a mobile phone:

      A series of bold heading text with data information and a button for each group.

      In this section, you converted a table to a block element to make it more visually usable when the screen or browser window small. In the last section, you will improve the accessibility of the table both for sighted users and those using screen readers.

      Adding Small-Screen Context Elements

      Now that you have changed the display values for the table elements on a small screen, you can add some enhancements to make this view as useful as the large screen version. You will add some HTML that will help make the information more understandable on small screens. Then you will provide styling specifically for the small screen experience of the table information.

      To begin, open index.html in your text editor. To provide the table’s contextual information lost by hiding the thead element, you will add that header value to each cell inside a <span> element. For example, you will add <span>Radius: </span> before the value in the column containing the Radius information for the planet in each <td> element. Additionally, each <span> element will have a class attribute set to a value of label, so these elements can be quickly styled. The highlighted HTML in the following code block shows how to write the markup:

      index.html

      ...
        <tbody>
          <tr>
            <th>Mercury</th>
            <td><span class="label">Radius: </span>2,439.7 km</td>
            <td><span class="label">Moons: </span>0</td>
            <td><span class="label">Gravity: </span>3.7 m/s<sup>2</sup></td>
            <td>
              <a href="https://en.wikipedia.org/wiki/Mercury_(planet)" class="button">
                Learn More
              </a>
            </td>
          </tr>
          <tr>
            <th>Venus</th>
            <td><span class="label">Radius: </span>6,051.8 km</td>
            <td><span class="label">Moons: </span>0</td>
            <td><span class="label">Gravity: </span>8.87 m/s<sup>2</sup></td>
            <td>
              <a href="https://en.wikipedia.org/wiki/Venus_(planet)" class="button">
                Learn More
              </a>
            </td>
          </tr>
          <tr>
            <th>Earth</th>
            <td><span class="label">Radius: </span>6,371.0 km</td>
            <td><span class="label">Moons: </span>1</td>
            <td><span class="label">Gravity: </span>9.80665 m/s<sup>2</sup></td>
            <td>
              <a href="https://en.wikipedia.org/wiki/Earth_(planet)" class="button">
                Learn More
              </a>
            </td>
          </tr>
          <tr>
            <th>Mars</th>
            <td><span class="label">Radius: </span>3,389.5 km</td>
            <td><span class="label">Moons: </span>2</td>
            <td><span class="label">Gravity: </span>3.72076 m/s<sup>2</sup></td>
            <td>
              <a href="https://en.wikipedia.org/wiki/Mars_(planet)" class="button">
                Learn More
              </a>
            </td>
          </tr>
        </tbody>
      ...
      

      Save your changes to index.html and return to your browser to examine the small-screen view. The contextual information around what each data point means is now visually recognizable. The following image shows how this will render in the browser:

      A series of bold heading text with contextual data information and a button for each group.

      Next, return to styles.css in your text editor. These labels will be present on larger screens when they are no longer necessary, so they will need some styling to fix this issue. Due to the max-width media query approach, this means that the default styles for .label outside the query need to be set to display: none in order to hide the content on large screens. Then inside the media query, create a .label selector with a display property set to inline, since it should be in the content flow containing the value. To create a visual separation between the label and data point, add a font-weight property set to 700. The highlighted CSS in the following code block demonstrates how and where to apply these additions:

      styles.css

      ...
      td, th {
        padding: 0.5rem;
      }
      
      .label {
        display: none;
      }
      
      @media (max-width: 60rem) {
        ...
        .label {
          display: inline;
          font-weight: 700;
        }
      }
      

      Save your changes to styles.css and once again return to your browser and refresh index.html. The browser will render the labels as inline content that is bold, as shown in the following image:

      A series of bold heading text with bold contextual labels and data information and a button for each group.

      While still in your web browser on a large screen, expand the window out until the table returns to the tabular style. The labels are now hidden providing distinctive visual and accessible information for each scenario. The following image shows how the large screen version of the table is now rendered:

      Table grid of data containing information about the four terrestrial planets.

      Finally, you will provide additional styling for each table row that will make them appear as their own little tables.

      Open styles.css in your text editor. Inside the media query, add a tbody th descendant selector and add the color properties and values from the thead > tr selector. This will give the same dark blue background and near-white text color for each planet name. Then, add a border-radius property set to 0.5rem 0.5rem 0 0 to create a rounded top to the heading. The highlighted CSS of the following code block shows how to style the planet name:

      stlyes.css

      ...
      @media (max-width: 60rem) {
        ...
        .label {
          display: inline;
          font-weight: 700;
        }
      
        tbody th {
          color: hsl(215, 25%, 100%);
          background-color: hsl(215, 80%, 20%);
          border-radius: 0.5rem 0.5rem 0 0;
        }
      }
      

      Next, you will add some definition to the datasets and give some spacing between each grouping. First, create a tbody > tr selector inside the media query with a border property set to 1px solid hsl(215, 80%, 20%). Then add a border-radius property with a value of 0.5rem, which will round the corner of all sides of the container. Lastly, create a tbody > tr + tr adjacent sibling combinator, with a margin-top property set to 1rem, which will give space between each group of data. The highlighted CSS in the following code block demonstrates how this is written:

      stlyes.css

      ...
      @media (max-width: 60rem) {
        ...
        tbody th {
          color: hsl(215, 25%, 100%);
          background-color: hsl(215, 80%, 20%);
          border-radius: 0.5rem 0.5rem 0 0;
        }
      
        tbody > tr {
          border: 1px solid hsl(215, 80%, 20%);
          border-radius: 0.5rem;
        }
      
        tbody > tr + tr {
          margin-top: 1rem;
        }
      }
      

      Finally, you will add in a zebra stripe effect specifically for each td element. This is done by creating a td:nth-child(even) pseudo-class selector. Then use the same background-color property and value from before, as highlighted in the following code block:

      stlyes.css

      ...
      @media (max-width: 60rem) {
        ...
        tbody > tr + tr {
          margin-top: 1rem;
        }
      
        td:nth-child(even) {
          background-color: hsl(215, 50%, 93%);
        }
      }
      

      Save your changes to styles.css and open index.html on a small-width browser or smartphone. Each row from the table will now appear as though it were a table with a header, data points, and a button to learn more. The following image shows how this is rendered in on a smartphone browser:

      Groups of data blocks, with the header in white on a dark background, and data points in alternating rows of light blue and white background.

      In this last section, you used the display property to show and hide pertinent information that was contextual to the viewing scenario of a small-screen device. You also provided styling to the small-screen table to make it more accessible and usable.

      Conclusion

      There are many possibilities when working with the display property. In this tutorial, you learned about the default values of block and inline. You changed an <a> element to inline-block, which gave it a special combination of both block and inline. You then changed all the elements of a <table> to be block on a small screen and set them to return to their default table display values on a large screen. Lastly, you used the none value to hide content when and where necessary to users of all abilities. The display property is a powerful feature and has even more values available to further manipulate how the box model functions and affects elements.

      If you would like to read more CSS tutorials, try out the other tutorials in the How To Style HTML with CSS series.



      Source link

      How To Use the pathlib Module to Manipulate Filesystem Paths in Python 3


      The author selected the COVID-19 Relief Fund to receive a donation as part of the Write for DOnations program.

      Introduction

      Python 3 includes the pathlib module for manipulating filesystem paths agnostically whatever the operating system. pathlib is similar to the os.path module, but pathlib offers a higher level—and often times more convenient—interface than os.path.

      We can identify files on a computer with hierarchical paths. For example, we might identify the file wave.txt on a computer with this path: /Users/sammy/ocean/wave.txt. Operating systems represent paths slightly differently. Windows might represent the path to the wave.txt file like C:Userssammyoceanwave.txt.

      You might find the pathlib module useful if in your Python program you are creating or moving files on the filesystem, listing files on the filesystem that all match a given extension or pattern, or creating operating system appropriate file paths based on collections of raw strings. While you might be able to use other tools (like the os.path module) to accomplish many of these tasks, the pathlib module allows you to perform these operations with a high degree of readability and minimal amount of code.

      In this tutorial, we’ll go over some of the ways to use the pathlib module to represent and manipulate filesystem paths.

      Prerequisites

      To get the most out of this tutorial, it is recommended to have some familiarity with programming in Python 3. You can review these tutorials for the necessary background information:

      Constructing Path Instances

      The pathlib module provides several classes, but one of the most important is the Path class. Instances of the Path class represent a path to a file or directory on our computer’s filesystem.

      For example, the following code instantiates a Path instance that represents part of the path to a wave.txt file:

      from pathlib import Path
      
      wave = Path("ocean", "wave.txt")
      print(wave)
      

      If we run this code, we’ll receive output like the following:

      Output

      ocean/wave.txt

      from pathlib import Path makes the Path class available to our program. Then Path("ocean", "wave.txt") instantiates a new Path instance. Printing the output shows that Python has added the appropriate operating system separator of / between the two path components we gave it: "ocean" and "wave.txt".

      Note: Depending on your operating system, your output may vary slightly from the example outputs shown in this tutorial. If you are running Windows, for example, your output for this first example might look like oceanwave.txt.

      Currently, the Path object assigned to the wave variable contains a relative path. In other words, ocean/wave.txt might exist in several places on our filesystem. As an example, it may exist in /Users/user_1/ocean/wave.txt or /Users/user_2/research/ocean/wave.txt, but we haven’t specified exactly which one we are referring to. An absolute path, by contrast, unambiguously refers to one location on the filesystem.

      You can use Path.home() to get the absolute path to the home directory of the current user:

      home = Path.home()
      wave_absolute = Path(home, "ocean", "wave.txt")
      print(home)
      print(wave_absolute)
      

      If we run this code, we’ll receive output roughly like the following:

      Output

      /Users/sammy /Users/sammy/ocean/wave.txt

      Note: As mentioned earlier, your output will vary depending on your operating system. Your home directory, of course, will also be different than /Users/sammy.

      Path.home() returns a Path instance with an absolute path to the current user’s home directory. We then pass in this Path instance and the strings "ocean" and "wave.txt" into another Path constructor to create an absolute path to the wave.txt file. The output shows the first line is the home directory, and the second line is the home directory plus ocean/wave.txt.

      This example also illustrates an important feature of the Path class: the Path constructor accepts both strings and preexisting Path objects.

      Let’s look at the support of both strings and Path objects in the Path constructor a little more closely:

      shark = Path(Path.home(), "ocean", "animals", Path("fish", "shark.txt"))
      print(shark)
      

      If we run this Python code, we’ll receive output similar to the following:

      Output

      /Users/sammy/ocean/animals/fish/shark.txt

      shark is a Path to a file that we constructed using both Path objects (Path.home() and Path("fish", "shark.txt")) and strings ("ocean" and "animals"). The Path constructor intelligently handles both types of objects and cleanly joins them using the appropriate operating system separator, in this case /.

      Accessing File Attributes

      Now that we’ve learned how to construct Path instances, let’s review how you can use those instances to access information about a file.

      We can use the name and suffix attributes to access file names and file suffixes:

      wave = Path("ocean", "wave.txt")
      print(wave)
      print(wave.name)
      print(wave.suffix)
      

      Running this code, we’ll receive output similar to the following:

      Output

      /Users/sammy/ocean/wave.txt wave.txt .txt

      This output shows that the name of the file at the end of our path is wave.txt and the suffix of that file is .txt.

      Path instances also offer the with_name function that allow you to seamlessly create a new Path object with a different name:

      wave = Path("ocean", "wave.txt")
      tides = wave.with_name("tides.txt")
      print(wave)
      print(tides)
      

      If we run this, we’ll receive output like the following:

      ocean/wave.txt
      ocean/tides.txt
      

      The code first constructs a Path instance that points to a file named wave.txt. Then, we call the with_name method on wave to return a second Path instance that points to a new file named tides.txt. The ocean/ directory portion of the path remains unchanged, leaving the final path as ocean/tides.txt

      Accessing Ancestors

      Sometimes it is useful to access directories that contain a given path. Let’s consider an example:

      shark = Path("ocean", "animals", "fish", "shark.txt")
      print(shark)
      print(shark.parent)
      

      If we run this code, we’ll receive output that looks like the following:

      Output

      ocean/animals/fish/shark.txt ocean/animals/fish

      The parent attribute on a Path instance returns the most immediate ancestor of a given file path. In this case, it returns the directory that contains the shark.txt file: ocean/animals/fish.

      We can access the parent attribute multiple times in a row to traverse up the ancestry tree of a given file:

      shark = Path("ocean", "animals", "fish", "shark.txt")
      print(shark)
      print(shark.parent.parent)
      

      If we run this code, we’ll receive the following output:

      Output

      ocean/animals/fish/shark.txt ocean/animals

      The output is similar to the earlier output, but now we’ve traversed yet another level higher by accessing .parent a second time. Two directories up from shark.txt is the ocean/animals directory.

      Using Glob to List Files

      It’s also possible to use the Path class to list files using the glob method.

      Let’s say we had a directory structure that looked like this:

      └── ocean
          ├── animals
          │   └── fish
          │       └── shark.txt
          ├── tides.txt
          └── wave.txt
      

      An ocean directory contains the files tides.txt and wave.txt. We have a file named shark.txt nested under the ocean directory, an animals directory, and a fish directory: ocean/animals/fish.

      To list all the .txt files in the ocean directory, we could say:

      for txt_path in Path("ocean").glob("*.txt"):
          print(txt_path)
      

      This code would yield output like:

      Output

      ocean/wave.txt ocean/tides.txt

      The "*.txt" glob pattern finds all files ending in .txt. Since the code sample executes that glob in the ocean directory, it returns the two .txt files in the ocean directory: wave.txt and tides.txt.

      Note: If you would like to duplicate the outputs shown in this example, you’ll need to mimic the directory structure illustrated here on your computer.

      We can also use the glob method recursively. To list all the .txt files in the ocean directory and all its subdirectories, we could say:

      for txt_path in Path("ocean").glob("**/*.txt"):
          print(txt_path)
      

      If we run this code, we’d receive output like the following:

      Output

      ocean/wave.txt ocean/tides.txt ocean/animals/fish/shark.txt

      The ** part of the glob pattern will match this directory and all directories beneath it, recursively. So, not only do we have the wave.txt and tides.txt files in the output, but we also receive the shark.txt file that was nested under ocean/animals/fish.

      Computing Relative Paths

      We can use the Path.relative_to method to compute paths relative to one another. The relative_to method is useful when, for example, you want to retrieve a portion of a long file path.

      Consider the following code:

      shark = Path("ocean", "animals", "fish", "shark.txt")
      below_ocean = shark.relative_to(Path("ocean"))
      below_animals = shark.relative_to(Path("ocean", "animals"))
      print(shark)
      print(below_ocean)
      print(below_animals)
      

      If we run this, we’ll receive output like the following:

      Output

      ocean/animals/fish/shark.txt animals/fish/shark.txt fish/shark.txt

      The relative_to method returns a new Path object relative to the given argument. In our example, we compute the Path to shark.txt relative to the ocean directory, and then relative to both the ocean and animals directories.

      If relative_to can’t compute an answer because we give it an unrelated path, it raises a ValueError:

      shark = Path("ocean", "animals", "fish", "shark.txt")
      shark.relative_to(Path("unrelated", "path"))
      

      We’ll receive a ValueError exception raised from this code that will be something like this:

      Output

      Traceback (most recent call last): File "<stdin>", line 1, in <module> File "/usr/local/lib/Python3.8/pathlib.py", line 899, in relative_to raise ValueError("{!r} does not start with {!r}" ValueError: 'ocean/animals/fish/shark.txt' does not start with 'unrelated/path'

      unrelated/path is not a part of ocean/animals/fish/shark.txt, so there’s no way for Python to compute a relative path for us.

      Conclusion

      The pathlib module is a powerful part of the Python Standard Library that lets us manipulate filesystem paths quickly on any operating system. In this tutorial, we have learned to use some of pathlib’s key utilities for accessing file attributes, listing files with glob patterns, and traversing parent files and directories.

      The pathlib module exposes additional classes and utilities that we did not cover in this tutorial. Now that you have a baseline, you can use the pathlib module’s documentation to learn more about other available classes and utilities.

      If you’re interested in using other Python libraries, check out the following tutorials:



      Source link