Answers for "css decrease picture size"

reduce image size css

.container {
    width: 200px;
    height: 120px;
}

/* Resize images */
.container img {
    width: 100%;
    height: auto;
}

make an image smaller css

css:
.example-class {
    width: 400px;
    height: auto;
}

html:
<img class="example-class" src="example.jpg"/>