JSFiddle - React, Tailwind, and code Playground

by Johan Muller

HTML

<ul class="flat__grid">
    <li>
        <div>16</div>
        <div>17</div>
        <div>18</div>
    </li>
    <li>
        <div>11</div>
        <div>12</div>
        <div>13</div>
        <div>14</div>
        <div>15</div>
    </li>
    <li>
        <div>6</div>
        <div>7</div>
        <div>8</div>
        <div>9</div>
        <div>10</div>
    </li>
    <li>
        <div>1</div>
        <div>2</div>
        <div>3</div>
        <div>4</div>
        <div>5</div>
    </li>
    
</ul>

CSS

* { margin: 0; padding: 0; }
body { margin: 20px; }
ul,li { list-style: none; }

.flat__grid li { font-size: 0px; }

.flat__grid div {
    display: inline-block;
    width: 25px; height: 25px;
    text-align: center;
    font-family: sans-serif;
    font-size: 12px;
    line-height: 25px;
    border-bottom: 1px solid #555;
    border-right: 1px solid #555;
}