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

body{
  background:#f4f9f9;
  color:#222;
}

/* NAVBAR */
nav{
  background:#0b6e4f;
  padding:15px 8%;
  display:flex;
  justify-content:space-between;
  align-items:center;
  color:white;
  position:sticky;
  top:0;
  z-index:1000;
}

nav h1{
  font-size:28px;
  letter-spacing:2px;
}

nav ul{
  display:flex;
  list-style:none;
  gap:25px;
}

nav ul li a{
  color:white;
  text-decoration:none;
  font-weight:bold;
  transition:0.3s;
}

nav ul li a:hover{
  color:#b7ffda;
}

.nav-auth {
  display: flex;
  align-items: center;
  gap: 15px;
}

.nav-auth .btn {
  padding: 10px 20px;
  font-size: 16px;
  transition: all 0.3s ease;
}

.nav-auth .btn:hover {
  transform: translateY(-2px);
  box-shadow: 0 4px 12px rgba(0, 0, 0, 0.2);
}

#dashboardBtn {
  background: linear-gradient(135deg, #00b074 0%, #00d685 100%);
}

#dashboardBtn:hover {
  background: linear-gradient(135deg, #008c5b 0%, #00a566 100%);
}

/* HERO */
.hero{
  height:90vh;
  background:linear-gradient(rgba(0,0,0,0.5), rgba(0,0,0,0.5)),
  url('https://images.unsplash.com/photo-1588776814546-1ffcf47267a5?q=80&w=1600&auto=format&fit=crop');
  background-size:cover;
  background-position:center;
  display:flex;
  justify-content:center;
  align-items:center;
  text-align:center;
  color:white;
  padding:20px;
}

.hero-content h2{
  font-size:60px;
  margin-bottom:20px;
}

.hero-content p{
  font-size:22px;
  margin-bottom:30px;
}

.btn{
  padding:14px 30px;
  border:none;
  background:#00b074;
  color:white;
  font-size:18px;
  border-radius:8px;
  cursor:pointer;
  transition:0.3s;
}

.btn:hover{
  background:#008c5b;
}

/* COURSES */
.section{
  padding:80px 8%;
}

.section-title{
  text-align:center;
  margin-bottom:50px;
  font-size:40px;
  color:#0b6e4f;
}

.courses{
  display:grid;
  grid-template-columns:repeat(auto-fit, minmax(250px,1fr));
  gap:30px;
}

.card{
  background:white;
  border-radius:12px;
  overflow:hidden;
  box-shadow:0 5px 15px rgba(0,0,0,0.1);
  transition:0.3s;
}

.card:hover{
  transform:translateY(-10px);
}

.card img{
  width:100%;
  height:220px;
  object-fit:cover;
}

.card-content{
  padding:20px;
}

.card-content h3{
  margin-bottom:15px;
  color:#0b6e4f;
}

.card-content p{
  line-height:1.6;
  margin-bottom:20px;
}

/* FEATURES */
.features{
  display:grid;
  grid-template-columns:repeat(auto-fit, minmax(220px,1fr));
  gap:25px;
}

.feature-box{
  background:white;
  padding:30px;
  border-radius:12px;
  text-align:center;
  box-shadow:0 4px 12px rgba(0,0,0,0.1);
}

.feature-box h3{
  margin:15px 0;
  color:#0b6e4f;
}

/* QUIZ */
.quiz-box{
  max-width:700px;
  margin:auto;
  background:white;
  padding:40px;
  border-radius:12px;
  box-shadow:0 4px 15px rgba(0,0,0,0.1);
  text-align:center;
}

.quiz-box h3{
  margin-bottom:20px;
}

.quiz-box button{
  margin-top:20px;
}

.option-btn{
  background:#f0f0f0 !important;
  color:#333 !important;
  border: 2px solid #ddd;
  transition: all 0.3s;
  margin: 8px auto !important;
  width: 100%;
  max-width: 600px;
}

.option-btn:hover:not(:disabled){
  background:#e0e0e0 !important;
  border-color: #0b6e4f;
  transform: translateX(5px);
}

.option-btn:disabled{
  cursor: not-allowed;
}

.login-modal{
  display:none;
  position:fixed;
  left:0;
  top:0;
  width:100%;
  height:100%;
  background:rgba(0,0,0,0.6);
  justify-content:center;
  align-items:center;
  z-index:9999;
}

.login-box{
  background:white;
  width:380px;
  max-width:92%;
  padding:30px;
  border-radius:18px;
  text-align:center;
  animation:fadeIn 0.4s ease;
  box-shadow:0 18px 40px rgba(0,0,0,0.18);
}

.modal-tabs{
  display:flex;
  gap:10px;
  margin-bottom:20px;
}

.tab{
  flex:1;
  padding:12px 0;
  border:none;
  border-radius:999px;
  background:#eef7f3;
  color:#0b6e4f;
  cursor:pointer;
  font-weight:700;
}

.tab.active{
  background:#0b6e4f;
  color:white;
}

.auth-form{
  display:block;
}

.hidden{
  display:none;
}

.login-box h2{
  margin-bottom:20px;
  color:#0b6e4f;
}

.login-box input{
  width:100%;
  padding:14px;
  margin:10px 0;
  border:1px solid #d2dfe9;
  border-radius:10px;
  outline:none;
  font-size:15px;
}

.login-box input:focus{
  border-color:#00b074;
  box-shadow:0 0 0 3px rgba(0,176,116,0.12);
}

.login-box button{
  width:100%;
  padding:14px;
  border:none;
  background:#00b074;
  color:white;
  border-radius:10px;
  font-size:16px;
  cursor:pointer;
  margin-top:10px;
  transition:0.25s;
}

.login-box button:hover{
  background:#008c5b;
  transform:translateY(-1px);
}

.close-btn{
  float:right;
  font-size:28px;
  cursor:pointer;
  color:#888;
}

@keyframes fadeIn{
  from{
    opacity:0;
    transform:translateY(-20px);
  }
  to{
    opacity:1;
    transform:translateY(0);
  }
}

/* LIBRARY */
.books-grid{
  display:grid;
  grid-template-columns:repeat(auto-fit, minmax(280px,1fr));
  gap:25px;
  margin-top:30px;
}

.book-card{
  background:white;
  border-radius:15px;
  padding:25px;
  box-shadow:0 8px 20px rgba(0,0,0,0.12);
  transition:all 0.3s ease;
  border-left:5px solid #00b074;
}

.book-card:hover{
  transform:translateY(-8px);
  box-shadow:0 12px 30px rgba(0,0,0,0.18);
}

.book-cover{
  width:100%;
  height:200px;
  background:#f0f0f0;
  border-radius:10px;
  display:flex;
  align-items:center;
  justify-content:center;
  margin-bottom:15px;
  overflow:hidden;
}

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

.book-icon{
  font-size:50px;
  margin-bottom:12px;
}

.book-card h3{
  color:#0b6e4f;
  margin-bottom:10px;
  font-size:18px;
}

.book-card p{
  color:#666;
  font-size:14px;
  line-height:1.6;
  margin-bottom:15px;
}

.book-meta{
  display:flex;
  gap:15px;
  margin-bottom:15px;
  font-size:13px;
  color:#999;
  padding-bottom:15px;
  border-bottom:1px solid #eee;
}

.book-meta span{
  display:flex;
  align-items:center;
  gap:5px;
}

.book-actions{
  display:flex;
  gap:10px;
}

.btn-download,
.btn-preview{
  flex:1;
  padding:10px 12px;
  border:none;
  border-radius:8px;
  font-size:13px;
  cursor:pointer;
  font-weight:600;
  transition:0.25s;
}

.btn-download{
  background:#00b074;
  color:white;
  text-decoration:none;
  display:flex;
  align-items:center;
  justify-content:center;
}

.btn-download:hover{
  background:#008c5b;
}

.btn-preview{
  background:#eef7f3;
  color:#0b6e4f;
  border:1px solid #00b074;
}

.btn-preview:hover{
  background:#00b074;
  color:white;
}

/* DEVELOPER SECTION */
#developer {
  background: linear-gradient(135deg, #f5f9f9 0%, #e8f5f2 100%);
}

.developer-container {
  max-width: 900px;
  margin: 0 auto;
}

.developer-card {
  background: white;
  border-radius: 15px;
  padding: 50px;
  box-shadow: 0 10px 30px rgba(0, 0, 0, 0.1);
  display: grid;
  grid-template-columns: 1fr 1.5fr;
  gap: 40px;
  align-items: center;
}

.developer-image {
  display: flex;
  justify-content: center;
  align-items: center;
}

.developer-image img {
  width: 280px;
  height: 350px;
  border-radius: 15px;
  object-fit: cover;
  box-shadow: 0 8px 20px rgba(0, 0, 0, 0.15);
  border: 5px solid #00b074;
}

.developer-info h3 {
  font-size: 32px;
  color: #0b6e4f;
  margin-bottom: 8px;
  font-weight: 700;
}

.title {
  font-size: 16px;
  color: #00b074;
  font-weight: 600;
  margin-bottom: 25px;
}

.developer-details {
  display: flex;
  flex-direction: column;
  gap: 20px;
  margin-bottom: 25px;
  padding: 25px;
  background: #f8fdfb;
  border-radius: 12px;
  border-left: 4px solid #00b074;
}

.detail-item {
  display: flex;
  gap: 15px;
  align-items: flex-start;
}

.detail-item .icon {
  font-size: 24px;
  min-width: 30px;
  text-align: center;
}

.detail-item .label {
  font-size: 12px;
  color: #999;
  text-transform: uppercase;
  letter-spacing: 1px;
  margin: 0;
  margin-bottom: 4px;
  font-weight: 600;
}

.detail-item p {
  margin: 0;
  font-size: 16px;
  color: #333;
}

.detail-item a {
  color: #00b074;
  text-decoration: none;
  font-weight: 600;
  transition: 0.3s;
}

.detail-item a:hover {
  color: #008c5b;
  text-decoration: underline;
}

.developer-description {
  font-size: 16px;
  line-height: 1.8;
  color: #555;
  margin-bottom: 25px;
}

.developer-actions {
  display: flex;
  gap: 15px;
}

.btn-secondary {
  flex: 1;
  padding: 14px 20px;
  border: 2px solid #00b074;
  background: white;
  color: #00b074;
  border-radius: 8px;
  font-weight: 600;
  cursor: pointer;
  text-decoration: none;
  text-align: center;
  transition: all 0.3s ease;
  display: inline-block;
}

.btn-secondary:hover {
  background: #00b074;
  color: white;
  transform: translateY(-2px);
  box-shadow: 0 5px 15px rgba(0, 176, 116, 0.3);
}

/* FOOTER */
footer{
  background:#0b6e4f;
  color:white;
  text-align:center;
  padding:20px;
  margin-top:50px;
}

@media(max-width:768px){
  .hero-content h2{
    font-size:40px;
  }

  nav{
    flex-direction:column;
    gap:15px;
  }

  nav ul{
    flex-wrap:wrap;
    justify-content:center;
  }

  .developer-card {
    grid-template-columns: 1fr;
    padding: 30px 20px;
    gap: 25px;
  }

  .developer-image img {
    width: 220px;
    height: 280px;
  }

  .developer-info h3 {
    font-size: 24px;
  }

  .developer-actions {
    flex-direction: column;
  }

  .btn-secondary {
    width: 100%;
  }
}