:root{
  --cyan:#4394AD;
  --deep:#487799;
  --white:#fff;
  --soft-bg:#F4FAFB;
  --border:#C8E8EF;
  --text-dark:#1A2E3B;
  --text-sec:#4F6E7A;
}

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

body{
  font-family:'Plus Jakarta Sans',sans-serif;
  background:var(--soft-bg);
  color:var(--text-dark);
}

/* NAVBAR */
#navbar{
  position:fixed;
  top:0;
  left:0;
  right:0;
  z-index:100;
  background:rgba(255,255,255,.9);
  backdrop-filter:blur(15px);
  border-bottom:1px solid var(--border);
}

.nav-inner{
  max-width:1200px;
  margin:auto;
  height:90px;
  display:flex;
  align-items:center;
  justify-content:space-between;
  padding:0 20px;
}

.logo{
  display:flex;
  align-items:center;
}

.logo a{
  display:flex;
  align-items:center;
  text-decoration:none;
}

.logo img{
  height:240px;
  width:auto;
  object-fit:contain;
  transition:.3s;
}

.logo img:hover{
  transform:scale(1.03);
}

.nav-links{
  display:flex;
  align-items:center;
  gap:35px;
}

.nav-links a{
  text-decoration:none;
  color:var(--text-sec);
  font-weight:600;
  transition:.2s;
}

.nav-links a:hover{
  color:var(--deep);
}

/* HEADER */
.catalog-header{
  padding-top:150px;
  text-align:center;
  max-width:900px;
  margin:auto;
  padding-left:20px;
  padding-right:20px;
}

.catalog-title{
  font-family:'DM Serif Display',serif;
  font-size:3rem;
  margin-bottom:10px;
}

.catalog-desc{
  color:var(--text-sec);
  line-height:1.8;
}

/* FILTER */
.filter-area{
  max-width:1200px;
  margin:40px auto 0;
  display:flex;
  gap:15px;
  flex-wrap:wrap;
  padding:0 20px;
}

.search-box{
  flex:1;
  min-width:250px;
}

.search-box input,
.category-select{
  width:100%;
  padding:15px 18px;
  border-radius:14px;
  border:1px solid var(--border);
  font-family:inherit;
  outline:none;
}

.category-wrap{
  min-width:220px;
}

.btn-filter{
  border:none;
  border-radius:14px;
  padding:15px 24px;
  background:linear-gradient(135deg,#4394AD,#487799);
  color:white;
  font-weight:700;
  cursor:pointer;
}

/* GRID */
.catalog-container{
  max-width:1200px;
  margin:40px auto 80px;
  padding:0 20px;
}

.catalog-grid{
  display:grid;
  grid-template-columns:repeat(auto-fill,minmax(250px,1fr));
  gap:25px;
}

.book-card{
  background:white;
  border-radius:22px;
  overflow:hidden;
  border:1px solid var(--border);
  transition:.3s;
}

.book-card:hover{
  transform:translateY(-8px);
  box-shadow:0 18px 45px rgba(67,148,173,.15);
}

.book-cover{
  height:340px;
  overflow:hidden;
  background:#fff;
}

.book-cover img{
  width:100%;
  height:100%;
  object-fit:cover;
  transition:.4s;
}

.book-card:hover img{
  transform:scale(1.05);
}

.book-content{
  padding:20px;
}

.book-category{
  display:inline-block;
  background:rgba(67,148,173,.08);
  color:var(--deep);
  font-size:.7rem;
  font-weight:700;
  padding:6px 12px;
  border-radius:30px;
  margin-bottom:10px;
}

.book-title{
  font-weight:700;
  font-size:1rem;
  margin-bottom:8px;
  line-height:1.5;
}

.book-author{
  color:var(--text-sec);
  font-size:.85rem;
  margin-bottom:15px;
}

.book-footer{
  display:flex;
  justify-content:space-between;
  align-items:center;
  gap:10px;
}

.book-price{
  color:var(--deep);
  font-weight:800;
}

.btn-detail{
  text-decoration:none;
  background:linear-gradient(135deg,#4394AD,#487799);
  color:white;
  padding:8px 15px;
  border-radius:30px;
  font-size:.8rem;
  font-weight:600;
  white-space:nowrap;
}

.empty-box{
  background:white;
  border:1px solid var(--border);
  border-radius:20px;
  padding:40px;
  text-align:center;
  color:var(--text-sec);
  grid-column:1 / -1;
}

/* FOOTER */
.footer{
  background:linear-gradient(160deg,#1E3A52,#487799);
  color:white;
  text-align:center;
  padding:40px 20px;
}

@media(max-width:768px){
  .catalog-title{
    font-size:2.2rem;
  }

  .nav-links{
    display:none;
  }

  .filter-area{
    flex-direction:column;
  }

  .category-wrap{
    width:100%;
  }

  .book-cover{
    height:360px;
  }

  .logo img{
    height:65px;
  }
}