styles.css

/*flexbox grid layout start*/

.flex-container {
    display: flex;
    margin-bottom: 10px;
}
[class*="col"] {
    margin-left: 1%;
    margin-right: 1%;
}
.col-full {
    flex-basis: 98%;
}
.col-large {
    background: #ecf0f1;
    text-align: center;
    flex-basis: 73%;
}
.col-medium {
    background: #2980b9;
    flex-basis: 48%;
    text-align: center;
}
.col-small {
    background: #f1c40f;
    flex-basis: 23%;
}
.col-xsmall {
    background: #1abc9c;
    flex-basis: calc(100% / 10);
}
.first {
    order: 1;
}
.second {
    order: 2;
}
.third {
    order: 3;
}
.fourth {
    order: 4;
}
.fifth {
    order: 5;
}
.container {
    max-width: 1150px;
    margin: 0 auto;
}
.col-medium img {
    max-width: 500px;
    max-height: 500px;
}
.col-small img {
    max-width: calc(100% - 50px);
}
/* mondrian */

.wrapper {
    width: 640px;
    height: 460px;
    margin-bottom: 40px;
    display: grid;
    grid-gap: 10px;
    font-weight: bold;
    font-size: 40px;
    background-color: black;
    grid-template-rows: 70px 70px 60px 70px 150px;
    grid-template-columns: 300px 90px 140px 80px;
}
.wrapper * {
    padding: 10px;
}
.a {
    grid-row: 1/5;
    grid-column: 1;
    background-color: red;
    color: white;
}
.b {
    grid-row: 1;
    grid-column: 2;
    background-color: gold;
    color: white;
}
.c {
    grid-row: 1/3;
    grid-column: 3;
    background-color: white;
}
.d {
    grid-row: 1;
    grid-column: 4;
    background-color: red;
    color: white;
}
.e {
    grid-row: 2/5;
    grid-column: 2;
    background-color: white;
}
.f {
    grid-row: 3;
    grid-column: 3;
    background-color: blue;
    color: white;
}
.g {
    grid-row: 2/4;
    grid-column: 4;
    background-color: white;
}
.h {
    grid-row: 5/6;
    grid-column: 1;
    background-color: white;
}
.i {
    grid-column: 2;
    background-color: blue;
    color: white;
}
.j {
    grid-row: 4/6;
    grid-column: 3/5;
    background-color: gold;
    color: white;
}
/*grid layout*/

.gridWrapper {
    display: grid;
    grid-gap: 20px;
    max-width: 1150px;
    margin: 0 auto;
    grid-template-columns: repeat(10, 1fr);
}
.cols8 {
    grid-column: 1/11;
}
.cols6 {
    grid-column: 1/8;
    background: #ecf0f1;
}
.cols2 {
    grid-column: 8/11;
    background: #f1c40f;
    text-align: center;
}
.cols1 {
    background: #1abc9c;
    text-align: center;
    padding: 5px;
    max-height: 200px;
}
.left-half {
    grid-column: 1/6;
    background: #2980b9;
    text-align: center;
}
.right-half {
    grid-column: 6/11;
    background: #2980b9;
    text-align: center;
}
.firstCol {
    grid-column-start: 1;
    grid-column-end: 2;
    grid-row: 1;
}
.secondCol {
    grid-column-start: 2;
    grid-column-end: 3;
    grid-row: 1;
}
.thirdCol {
    grid-column-start: 3;
    grid-column-end: 4;
    grid-row: 1;
}
.fourthCol {
    grid-column-start: 4;
    grid-column-end: 5;
    grid-row: 1;
}
[class*="half"] img {
    max-width: 500px;
    max-height: 500px;
}
[class*="cols2"] img {
    max-width: 230px;
}
.nested {
    display: grid;
    grid-column: 1/6;
    grid-template-columns: repeat(4, 1fr);
    grid-gap: calc(50px * .4);
    background: #ecf0f1;
}
/*nav*/

nav ul {
    list-style-type: none;
    margin: 0;
    padding: 0;
    overflow: hidden;
    background: linear-gradient(70deg, black, gray);
}
nav li {
    float: left;
}
li a {
    display: block;
    padding: 15px;
    text-decoration: none;
    color: #fff;
    transition-property: color, background-color;
    transition-duration: 1s;
    transition-timing-function: ease-out;
}
a:hover,
a:focus {
    color: #333;
    background-color: #fff;
}
.navbar {
    margin-bottom: 20px;
}
/* various */

* {
    font-family: Arial, Helvetica, sans-serif;
}
ul,
li {
    margin: 0;
    padding: 0;
    list-style-type: none;
}
.rounded {
    border-radius: 25px;
}
.shadow {
    filter: drop-shadow(16px 16px 10px #888888);
}
article p,
article h3 {
    float: left;
    clear: both;
}
footer {
    padding: 1rem;
    background-color: #efefef;
    text-align: center;
}
article,
aside {
    text-align: center;
}
article li {
    clear: both;
}
.tall {
    min-height: 500px;
}