Display a list of categories with links

How can I redo a piece of code so that it displays a list of categories with links that would display products from a specific category? And the active category would be highlighted by formatting.

Now displays a list of categories with a list of products from the first category, where $id_kategori=$list_kategori[0]['id_category']; If the digit is changed, then it outputs the goods from another one, i.e. what is needed, only the replacement of the digit needs to be executed correctly. I understand that there should be a cycle in which instead of a digit in $list_kategori[0] there must be a variable. I tried it like this

<?php
for ($i = 1; $i <= $cek; $i++) {
   $id_kategori=$list_kategori[$i]['id_category'];
   }```

products disappear, instead of the first category error  ```Notice
: Undefined offset:
?>```


<?php
          mysqli_query($koneksi,"SET NAMES utf8mb4");
          $data=mysqli_query($koneksi,"select * from bot_shop_category order by name_category ASC");
          $cek= mysqli_num_rows($data);
          if($cek>0){
            $list_kategori = array();
              while ($row = mysqli_fetch_assoc($data)) {
              $list_kategori[] = $row;
               }
               $id_kategori=$list_kategori[0]['id_category'];
               foreach ($list_kategori as $row) {
                 ?>
          <div class="col-md-12">
          <p><a href="<?= $list_kategori?>"><?=$row['name_category']?></p>
          <hr>
           </div>
                 <?php
               }
          }
          else{
            echo 'There are no categories yet';
           }
        ?>
        </div>
    </div>
    <div class="col-md-10">
      <div class="row">

        <?php
        
        if(isset($_GET['id_category']) && $_GET['id_category']!=''){
          $id_kategori=$_GET['id_category'];
        }
          $data=mysqli_query($koneksi,"select * from bot_shop_product join bot_shop_category on bot_shop_product.id_category=bot_shop_category.id_category where bot_shop_product.id_category='$id_kategori' order by bot_shop_product.id_category ASC ");
           $cek= mysqli_num_rows($data);
           if($cek>0){
            $list_produk = array();
              while ($row = mysqli_fetch_assoc($data)) {
              $list_produk[] = $row;
               }
               foreach ($list_produk as $row) {
                 ?>
        <div class="col-md-4">
          <div class="card" >
             <a href="produk-detail.php?id=<?=$row['id_product']?>"><img src="/o220123/assets/img/produk/<?=$row['image']?>" class="card-img-top" alt="..."></a>
                  <div class="card-body">
              <p class="card-text text-center">
              <span style="color: #333;font-size: 90%"><?=$row['name_category']?></span><br><?=$row['name_product']?><br><b>Rb <?=number_format($row['price'])?></b>
              </p>
                </div>
            </div>
        </div>
                 <?php
               }
           }
           else{
            echo 'There are no products available in this category';
           }
        ?>
      </div>
    </div>
  </div>
</div> 

In mysql standard Category tables bot_shop_category with columns:id_category, name_category and Goods bot_shop_product: id_product, id_category, name_product