html {
    font-family: 'Poppins', sans-serif;
    background-color: hsl(183, 45%, 53%);
    box-sizing: content-box;  
}

h1,
h2 {
    color: hsl(63, 45%, 53%);
    background-color: hsla(183, 45%, 20%, 0.5);
    border: 2px solid hsla(183, 45%, 20%, 0.3);
    width: 75%;
    text-align: center;
    margin: 1% auto;
}

.sub-heading {
    border: 2px solid hsla(183, 45%, 20%, 0.3);
    width: 75%;
    text-align: center;
    margin: 1% auto;
    padding: 0;
    background-color: hsla(183, 45%, 20%, 0.5);
    color: hsl(63, 45%, 53%);
}

span.example,
span.highlight,
span.syntax {
    background-color: hsla(65, 19%, 88%, 0.829);
    border-radius: 5px;
    color:hsl(183, 45%, 18%)
}

.tables,
.selectors {
    width: 75%;
    margin: auto;
}

table {
    table-layout: fixed;
    width: 100%;
    margin: auto;
    text-align: center;
    border: 3px solid hsl(183, 45%, 18%);
    border-collapse: collapse;
    padding: 0;
    color:hsl(183, 45%, 18%);
    background-color: hsl(183, 45%, 53%);
}

td {
    border: 2px solid hsl(183, 45%, 20%);
    padding: 2%;
}

thead th {
    font-weight: bold;
    border: 3px solid hsl(183, 45%, 18%);
    padding: 2px;
    background-color: hsla(183, 45%, 20%, 0.5);
    color: hsl(63, 45%, 53%);
}

th {
    font-weight: bold;
    border: 3px solid hsl(183, 45%, 18%);
    padding: 2px;
    background-color: hsla(183, 45%, 20%, 0.5);
    font-weight: bold;
}

.tables thead th:nth-child(1) {
    width: 10%;
}

.tables thead th:nth-child(2) {
    width: 15%;
}

.tables thead th:nth-child(3) {
    width: 65%;
}

.selectors thead th:nth-child(1) {
    width: 15%;
}

.selectors thead th:nth-child(2) {
    width: 29%;
}

.selectors thead th:nth-child(3) {
    width: 18%;
}

selectors thead th:nth-child(4) {
    width: 29%;
}

tbody tr:nth-child(odd) :not(th, .example, .syntax, .highlight) {
    background-color: hsl(63, 45%, 60%);
}

tbody tr:nth-child(even) :not(th, .example, .syntax, .highlight) {
    background-color: hsl(183, 45%, 53%);
}