Use <mark> instead of <span> for highlighting words

It's an HTML5 standard. Or, to put it another way: there's a tag
for that ;)

src/index.htm

@@ -29,7 +29,7 @@
           <a name="backed-by-experience">
             <h1 class="text-2xl font-sans">Backed by Experience <i class="icon-paperclip"></i></h1>
           </a>
-          <p class="py-2 text-lg">With a combined <span class="bg-blue-200 text-black px-2">10+ years</span> of experience in science communication, we have the skills to mentor you through the process of <span class="bg-blue-200 text-black px-2">sharing your work</span> in an articulate and accessible way.</p>
+          <p class="py-2 text-lg">With a combined <mark class="bg-blue-200 text-black px-2">10+ years</mark> of experience in science communication, we have the skills to mentor you through the process of <mark class="bg-blue-200 text-black px-2">sharing your work</mark> in an articulate and accessible way.</p>
           <p class="py-2"> As editors of Snipette magazine and assistant physics professor at Georgia Gwinnett University, we’ve been involved in intensive editing projects with authors from both ends of the spectrum: professional researchers working to communicate their technical work, and high school and college students eager to further their learning process through writing.</p>
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@@ -41,7 +41,7 @@
           <a name="stories-before-statistics">
             <h1 class="text-2xl font-sans">Stories before Statistics <i class="icon-flask"></i></h1>
           </a>
-          <p class="py-2 text-lg">There’s no point in science writing if people aren’t <span class="bg-blue-100 text-black px-2">interested in reading it</span>, which is why we specialise in adding a humorous touch—infusing technical writing with a dash of <span class="bg-blue-100 text-black px-2">literary flair</span> to help explain complex issues.</p>
+          <p class="py-2 text-lg">There’s no point in science writing if people aren’t <mark class="bg-blue-100 text-black px-2">interested in reading it</mark>, which is why we specialise in adding a humorous touch—infusing technical writing with a dash of <mark class="bg-blue-100 text-black px-2">literary flair</mark> to help explain complex issues.</p>
           <p class="py-2">Anyone can describe their work to their peers—but reaching the general public is harder. Our program will help you draw parallels with familiar concepts to better explain complicated topics in a short space. You will also work on grounding your findings in everyday experience and answering the question: how is this relevant to the layperson?</p>
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@@ -53,7 +53,7 @@
           <a name="learning-through-teaching">
             <h1 class="text-2xl font-sans">Learning through Teaching <i class="icon-edit"></i></h1>
           </a>
-          <p class="py-2 text-lg">There’s no better way to <span class="bg-blue-200 text-black px-2">understand a field</span> than to explain it to someone who knows nothing—a fact observed by no less than the brilliant physicist <span class="bg-blue-200 text-black px-2">Richard Feynman</span> himself.</p>
+          <p class="py-2 text-lg">There’s no better way to <mark class="bg-blue-200 text-black px-2">understand a field</mark> than to explain it to someone who knows nothing—a fact observed by no less than the brilliant physicist <mark class="bg-blue-200 text-black px-2">Richard Feynman</mark> himself.</p>
           <p class="py-2">Articulating your process work and findings for a lay audience will help you understand your own process better and streamline how things get done. On top of that, making your work accessible will spread awareness beyond your niche and help make you and your work more known to a wider audience.</p>
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       </div>