main.css

* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
    font-family: 'Roboto', sans-serif;
}

html {
    overflow-x: hidden;
}

.container {
    max-width: 1024px;
    width: 100%;
    margin: 0 auto;
}

header {
    position: sticky;
    top: 0;
    left: 0;
    z-index: 1;
}

header, footer{
    background-color: #192a56;
    padding-top: 16px;
    color: #fff;
}

header > .container,
footer > .container {
    justify-content: space-between;
    align-items: center;
    padding-bottom: 16px;
}

nav {
    background-color: #575fcf;
    padding: 16px 0;
    display: none;
}

nav li {
    list-style: none;
    display: inline;
    margin-right: 16px;
    font-size: 18px;
    font-weight: bold;
    text-transform: uppercase;
}

nav li a {
    color: #fff;
    text-decoration: none;
}

.menu-hamburguer{
    width: 32px;
    cursor: pointer;
}

.menu-hamburguer span{
    height: 2px;
    width: 100%;
    background-color: #fff;
    display: block;
    margin-bottom: 4px;
}

.container-flex {
    display: flex;
}

.store-about img {
    max-width: 400px;
    margin-right: 24px;
}

section {
    padding: 48px 0;
}

section h2 {
    margin-bottom: 16px;
}

    /*.vehicles-list {
        justify-content: space-between;
    }
    Se adicionasse mais 2 itens, teria um espaço vazio
    entre os dois na linha de baixo.     
    */

.vehicles-list{
    flex-wrap: wrap;
}

.vehicles-list li {
    list-style: none;
    max-width: 30%;
    margin-bottom: 24px;
}

.vehicles-list img {
    max-width: 100%;
}

.vehicles-list li h3 {
    margin: 16px 0;
}

.central-item{
    margin: 0 5%;
} 

/* 5% por que 3 x 30% da 90%, então temos 10% 
de espaço em branco sobrando, dividimos o espaço
em branco à direita e à esquerda do item central. 
*/

button {
    display: block;
    width: 100%;
    padding: 8px 0;
    border: none;
    background-color: #119759;
    color: #fff;
    font-size: 16px;
    font-weight: bold;
    font-style: italic;
    cursor: pointer;
    border-radius: 6px;
}

.price {
    margin: 16px 0;
    display: block;
} 

    /*
    .vehicles-list li strong {
        margin: 16px 0;
        display: block;
    } 

    strong é um elemento inline, por isso mudamos
    para display block
    */

.price del {
    color: #ccc;
    font-size: 14px;
}

.form-field{
    margin-bottom: 16px;
}

.form-field label {
    font-weight: bold;
    display: block;
}

.form-field input,
.form-field textarea {
    width: 100%;
    display: block;
    padding: 8px;
}

.form-field textarea {
    resize: none;
    height: 120px;
}

form {
    max-width: 360px;
}

form button {
    max-width: 120px;
}

footer li {
    list-style: none;
    margin-left: 16px;
}

footer li img {
    height: 32px;
}