revision:
<div class="grid_A">
<div>
<h3>resize with HTML</h3>
<img src="../images/1.jpg" width="400" height="300" alt="evening" style="margin-left:5vw;">
</div>
<div>
<h3>resize with CSS</h3>
<img class="resize" src="../images/1.jpg" alt="evening" style="margin-left:1vw;">
<img class="resize_a" src="../images/1.jpg" alt="evening" style="margin-left:1vw;">
</div>
</div>
<style>
img.resize{width: 30vw; height: 20vw;}
img.resize_a{max-width: 30%; max-height: 30%;}
</style>



<div >
<div class="box">
<div class="img-container"><img src="../images/1.jpg" alt="evening"></div>
</div>
<div class="box">
<div class="img-container"><img src="../images/2.jpg" alt="beach"></div>
</div>
<div class="box-vw">
<div class="img-container"><img src="../images/3.jpg" alt="bath"></div>
</div>
</div>
<style>
.box, .box-vw {background-color: green;border-radius: 1vw; overflow: hidden;margin-bottom: 1.5vw;}
.box:nth-of-type(2) {width: 26vw; }
.box-vw .img-container {width: 100vw; height: 66.620879vw; padding-bottom: inherit;}
.img-container {width: 100%; height: 0;/* Aspect ratio of picture*/padding-bottom: 66.620879%;}
img {width: 100%;}
</style>