* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

html {
    font-size: 10px;
}

body {
    font-family: 'Open Sans', sans-serif;
    font-size: 1.6rem;
    line-height: 1.5;
    text-align: center;
    background-color: #333;
    color: white;

}

a {
    text-decoration: none;
}

p {
    padding: 1.6rem0;

}

img {
    width: 100%;
    height: auto;
}

/*btn */
.btn {
    display: inline-block;
    background: #333;
    color: #fff;
    border: 1px solid #666;
    padding: 0.5rem 1.5rem;
    margin: 1rem 1;
    transition: all 0.3s;
    border-radius: 5px;
    width: 200px;
    height: auto;
}

#firstbtn {
    margin-top: 1rem;
}

.btn:hover {
    background-color: #eaeaea;
    color: black;
}

#btn2 {
    width: 40px;
    padding: 5px;
    height: auto;
    display: inline-block;
}

/* header kısmı */

header {
    height: 30rem;

}

header .bg-image {
    position: relative;
    height: 30rem;
    width: 100%;
    background-size: cover;
    background-position: center;
    opacity: 0.6;
    z-index: -1;

}

header h1 {
    position: relative;
    margin-top: -25rem;


}

/* section a */

#section-a {
    background-color: #eaeaea;
    color: #333;
    padding: 3.2rem 0;
}

/* section b */

#section-b {
    padding: 2rem;
    overflow: hidden;
}

#section-b ul {

    overflow: hidden;
    list-style: none;
    overflow: hidden;
}

#section-b li {
    overflow: hidden;
    background: #fff;
    color: #333;
    margin-bottom: 1.5rem;
    box-shadow: 10px 10px 20px 5px rgba(0, 0, 1, 1) overflow: hidden;
}

#section-b li:hover {
    -webkit-box-shadow: 10px 10px 20px 2px rgba(0, 0, 0, .3);
    -mox-box-shadow: 10px 10px 20px 2px rgba(0, 0, 0, .3);
    box-shadow: 10px 10px 20px 20px rgba(0, 0, 0, .5);
    background-color: azure;
}

.col-content {
    
    padding: 1.5rem;
}

/* section c */

#section-c {
    background-color: #eaeaea;
    color: #333;
    padding: 2rem;
}

#section-d {
    background-color: darkgray;
    color: #333;
    padding: 2rem;
    
}

#section-e {
    background-color: #333;
    color: #fff;
    padding-top: 5px;
    height: 100px;
}

footer {
    height: 6rem;
    padding: 2rem;
    background: #000;
}

#footerh3 {
    font-size: 12px;
    text-align: center;
    color: grey;
}

#footerh3:hover {
    background: #eaeaea;
    color: black;
    border-radius: 5px;
}

/* Boyut ayarları */

@media screen and (min-width:1100px) {

    #section-b li {
        width: 29%;
        margin: 1%;
        display: inline-block;
        overflow: hidden;
    }

    ul {
        overflow: hidden;
    }

    .btn {
        font-size: 12px;
        width: 150px;
    }

    p {
        font-size: 2rem;
    }

    header {
        height: 45rem;

    }

    header .bg-image {

        height: 45rem;

    }

    header h1 {
        margin-top: -40rem;


    }

}

@media screen and (min-width:1200px) {
    #section-b li {
        width: 30%;
        margin: 1%;
        display: inline-block;
        overflow: hidden;
    }

    ul {
        overflow: hidden;
    }

    .btn {
        font-size: 16px;
        width: 200px;
    }

    p {
        font-size: 2rem;
    }
}