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

body{
font-family:Arial, Helvetica, sans-serif;
line-height:1.6;
color:#222;
background:#ffffff;
}

.container{
width:90%;
max-width:1100px;
margin:auto;
}

/* HEADER */

.site-header{
border-bottom:1px solid #eee;
background:#fff;
}

.nav{
display:flex;
flex-wrap:wrap;
align-items:center;
justify-content:space-between;
padding:15px 0;
}

.logo{
font-weight:bold;
font-size:20px;
}

nav a{
margin-left:15px;
text-decoration:none;
color:#333;
font-size:15px;
}

/* HERO */

.hero{
padding:80px 0;
text-align:center;
background:#f7f7f7;
}

.hero h1{
font-size:32px;
margin-bottom:10px;
}

.hero p{
margin-bottom:20px;
}

.button{
display:inline-block;
padding:12px 20px;
background:#111;
color:white;
text-decoration:none;
border-radius:5px;
}

/* BOOK GRID */

.featured-books{
padding:60px 0;
}

.book-grid{
display:grid;
grid-template-columns:1fr;
gap:30px;
margin-top:30px;
}

.book-card img{
width:100%;
height:auto;
border-radius:6px;
}

.book-card h3{
margin-top:10px;
}

.book-card p{
margin:10px 0;
}

/* DISCUSSIONS */

.discussions{
background:#fafafa;
padding:60px 0;
}

.discussion-list{
margin-top:20px;
list-style:none;
}

.discussion-list li{
margin-bottom:10px;
}

/* FOOTER */

footer{
border-top:1px solid #eee;
padding:30px 0;
text-align:center;
font-size:14px;
}

/* TABLET */

@media (min-width:600px){

.book-grid{
grid-template-columns:1fr 1fr;
}

.hero h1{
font-size:40px;
}

}

/* DESKTOP */

@media (min-width:900px){

.book-grid{
grid-template-columns:1fr 1fr 1fr;
}

.hero{
padding:120px 0;
}

.hero h1{
font-size:48px;
}


.video-container{
position:relative;
width:100%;
padding-bottom:56.25%; /* 16:9 ratio */
height:0;
margin-top:20px;
}

.video-container iframe{
position:absolute;
top:0;
left:0;
width:100%;
height:100%;
border:0;
}


}