/**************************
RESET to ensure user agent padding and 
margin on elements do not affect layout.

Note this reset is not appropriate for
production websites.
***************************/

* {
    margin: 0;
    padding: 0;
}
body {
    font-family: Arial;
    color: #333;
    background-color: #E2E2E2;
}
main {
    width: 1000px;
    padding: 20px;
    margin: auto;
    display: block;
    background-color: white;
}
header {
    padding: 40px;
    background-color: azure;
}
h1 {
    text-align: center;
}
#one {
    background-color: aqua;
    display: flex;
    justify-content: space-between;
}
#one article {
    background-color: bisque;
    width: 31.5%;
}
#one article:nth-child(2) {
    background-color: beige;
}
h2 {
    margin-bottom: 1em;
}
#two {
    display: flex;
    justify-content: space-between;
    flex-wrap: wrap;
    background-color: #D5D5D5;
    padding: 20px;
}
#two h2 {
    text-align: center;
    flex: 100%;
}
#two article {
    width: 48%;
}
p {
    font-size: 1.4em;
    line-height: 1.2em;
    margin-bottom: 1em;
}
footer {
    padding: 40px;
    text-align: center;
    background-color: azure;
}

@media only screen and (max-width: 1040px) {
main {
    width: 100%;
    box-sizing: border-box;
}
}

@media only screen and (max-width: 700px) {
section {
    flex-wrap: wrap;
}
#one article:first-of-type {
    flex: 100%;
}
#one article {
    width: 48%;
}
#two article {
    width: auto;
}
}

@media only screen and (max-width: 500px) {
section {
    flex-direction: column;
}
#one article, #two article {
    width: auto;
}
}