要在HTML中水平对齐两个div，请使用带有左侧值的float CSS属性。您可以尝试运行以下代码以了解如何水平对齐div-
<!DOCTYPE html>
<html>
<head>
<style>
.demo div {
float: left;
clear: none;
}
</style>
</head>
<body>
<div class="demo">
<div>
<span>div1</span>
<select size="5">
<option value="c1">India</option>
<option value="c2">US</option>
<option value="c3">UK</option>
<option value="c4">Australia</option>
</select>
</div>
<div>
<span>div2</span>
<select size="5">
<option value="r1">1</option>
<option value="r2">2</option>
<option value="r3">3</option>
<option value="r4">4</option>
</select>
</div>
</div>
</body>
</html>