* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
}

.header {
    display: flex;
    justify-content: space-between;
    flex-direction: column;
    align-items: center;
    padding: 10px 20px;
    background-color: #333;
    color: #fff;
    padding-bottom: 20px;


}

.header h1 {
    font-size: 40px;

}

a {
    text-decoration: none;
}

.nav {
    padding: 3px;
    margin: 2px;
    border-radius: 3px;
    font-size: 20px;
    display: flex;
}

a.nav {
    color: white;
    transition-duration: .6s;
}

a::after,
a::before {
    content: "|";
}

a.nav:hover {
    color: white;
    text-decoration: underline;
    background-color: #4CAF50;
    transition-duration: .6s;
    font-size: 25px;
}

.container {
    display: grid;
    grid-template-areas:
        "intro intro"
        "box1  box2"
        "box3 box3";
    grid-gap: 20px;
    border-radius: 10px;
}

.intro {
    grid-area: intro;
    background-image: url(image1.jpg);
    background-size: cover;
    height: 350px;
    font-family: "Segoe UI", sans-serif;
    font-weight: 100;
    font-style: normal;
}

.intro p {
    border: 2px solid #000;
    border-radius: 5px;
    padding: 20px;
    font-size: 20px;
    background-color: #333;
    color: #fff;
    width: 75%;
    text-align: center;
    position: relative;
    left: 150px;
    top: 100px;
    box-shadow: 15px 15px 10px 5px;
}

.box {
    border: 1px solid;
    box-shadow: 2px 2px 5px 2px;
    margin: 20px;
    font-family: "Segoe UI", sans-serif;
    font-style: normal;
    background-color: lightgray;
    border-radius: 5px;
    font-weight: 100px;
    padding: 10px;
    text-align: center;
    font-size: 20px;
}

#startButton {
    font-size: 20px;
    background-color: #333;
    color: white;
    border-radius: 5px;
    box-shadow: 5px 5px 5px 1px;
    transition-duration: .6s;

}

#startButton:hover {
    font-size: 20px;
    background-color: #787676;
    color: dark black;
    transition-duration: .6s;
    box-shadow: 5px 5px 5px 1px #333;
}

/* Scrollbar */
::-webkit-scrollbar {
    width: 10px;
}

::-webkit-scrollbar-track {
    box-shadow: inset 0 0 5px rgb(12, 10, 10);
    border-radius: 10px;
}

::-webkit-scrollbar-thumb {
    background: #333;
    border-radius: 10px;
}

footer {
    background-color: #333;
    color: #fff;
    text-align: center;
    padding: 10px 0;
    left: 0;
    bottom: 0;
    width: 100%;
}