Update index.html

Author: Gmac4247

index.html

@@ -1475,7 +1475,7 @@ <h3 itemprop="name" style="margin:7px">Trigonometry</h3>
 </div>
 </section>
 <br><br><br><br>
-<div itemscope itemtype="https://schema.org/LearningResource https://schema.org/MathSolver">
+<main itemscope itemtype="https://schema.org/LearningResource https://schema.org/MathSolver">
 <meta itemprop="name" content="Core Geometric System ™">
 <meta itemprop="url" content="https://basic-geometry.github.io">
 <meta itemprop="sameAs" content="https://basic-geometry.pages.dev">
@@ -1489,7 +1489,8 @@ <h3 itemprop="name" style="margin:7px">Trigonometry</h3>
 <meta itemprop="educationalLevel" content="from basic to advanced">
 <meta itemprop="typicalAgeRange" content="6-18">
 <section itemprop="mathExpression" itemscope itemtype="https://schema.org/SolveMathAction" id="triangle">
-<h3 style="margin:7px" itemprop="eduQuestionType">Area of a Triangle</h3>
+<dl>
+<dt style="margin:7px" itemprop="eduQuestionType">Area of a Triangle</dt>
 <meta itemprop="target" content="https://basic-geometry.github.io?q={triangle_side1=3_side2=4_side3=5_area=?}">
 <div itemprop="result" itemscope itemtype="https://schema.org/LearningResource">
 <meta itemprop="name" content="Triangle area formula">
@@ -1500,7 +1501,7 @@ <h3 style="margin:7px" itemprop="eduQuestionType">Area of a Triangle</h3>
 <br>
 The square root of half of the area of the rectangle is the side length of the theoretical square that has the same area as the triangle.</p>
 <br>
-<div itemprop="text">
+<dd itemprop="text">
 <math display="block" xmlns="http://www.w3.org/1998/Math/MathML">
  <mrow>
  <mi>A</mi>
@@ -1517,7 +1518,7 @@ <h3 style="margin:7px" itemprop="eduQuestionType">Area of a Triangle</h3>
 </mrow>
  </mrow>
 </math>
-</div>
+</dd>
 </div>
 <br><br>
 <div itemprop="result" itemscope itemtype="https://schema.org/LearningResource">
@@ -1558,7 +1559,7 @@ <h3 style="margin:7px" itemprop="eduQuestionType">Area of a Triangle</h3>
 </math>
 </div>
 <br><br><br>
-<div itemprop="text">
+<dd itemprop="text">
 <math display="block" xmlns="http://www.w3.org/1998/Math/MathML"> 
 <mrow>
  <mi>A</mi>
@@ -1599,8 +1600,9 @@ <h3 style="margin:7px" itemprop="eduQuestionType">Area of a Triangle</h3>
 </mrow>
 </mrow>
 </math>
+</dd>
 </div>
-</div>
+</dl>
 <br><br>
 <div itemprop="subjectOf" itemscope itemtype="https://schema.org/SoftwareApplication" style="margin:12px" id="triangle_area_calculator">
 <meta itemprop="name" content="Triangle Area Calculator">
@@ -4823,7 +4825,7 @@ <h3 itemprop="eduQuestionType" style="margin:7px">Volume of a Tetrahedron</h3>
   </div>
 	<p style="margin:12px" itemprop="copyrightNotice">® All rights reserved</p>
 	<p style="margin:12px" itemprop="copyrightYear">2025</p>
-</div>
+</main>
 <br>
 <footer>
 <a style="margin:9px" itemscope itemtype="http://schema.org/AboutPage" href="about">About</a>