/* Professional DBMS Learning Platform CSS */

/* CSS Reset and Base Styles */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

html {
    font-size: 16px;
    scroll-behavior: smooth;
}

body {
    font-family: 'Inter', sans-serif;
    line-height: 1.6;
    color: #1e293b;
    background-color: #ffffff;
    overflow-x: hidden;
}

/* Container */
.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 2rem;
}

/* Back Button */
.btn-back {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    width: 42px;
    height: 42px;
    background: linear-gradient(135deg, #6366f1 0%, #8b5cf6 100%);
    color: white;
    border-radius: 12px;
    text-decoration: none;
    font-size: 1.1rem;
    transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
    box-shadow: 0 4px 15px rgba(99, 102, 241, 0.3);
    margin-right: 1rem;
}

.btn-back:hover {
    transform: translateX(-3px);
    box-shadow: 0 6px 20px rgba(99, 102, 241, 0.4);
}

/* Navigation */
.navbar {
    background: rgba(255, 255, 255, 0.95);
    backdrop-filter: blur(20px);
    box-shadow: 0 4px 30px rgba(0, 0, 0, 0.08);
    position: fixed;
    top: 0;
    width: 100%;
    z-index: 1000;
    border-bottom: 1px solid rgba(99, 102, 241, 0.1);
}

.nav-container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 2rem;
    display: flex;
    justify-content: space-between;
    align-items: center;
    height: 80px;
}

.nav-logo h2 {
    background: linear-gradient(135deg, #6366f1 0%, #8b5cf6 100%);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
    font-weight: 700;
    font-size: 1.5rem;
}

.nav-logo i {
    margin-right: 0.5rem;
    color: #6366f1;
}

.nav-menu {
    display: flex;
    list-style: none;
    gap: 2rem;
}

.nav-link {
    text-decoration: none;
    color: #475569;
    font-weight: 500;
    transition: all 0.3s ease;
    position: relative;
    padding: 0.5rem 0;
}

.nav-link:hover,
.nav-link.active {
    color: #6366f1;
}

.nav-link.active::after {
    content: '';
    position: absolute;
    bottom: -5px;
    left: 0;
    width: 100%;
    height: 3px;
    background: linear-gradient(135deg, #6366f1 0%, #8b5cf6 100%);
    border-radius: 2px;
}

.nav-toggle {
    display: none;
    flex-direction: column;
    cursor: pointer;
    padding: 5px;
}

.nav-toggle span {
    width: 25px;
    height: 3px;
    background: #6366f1;
    margin: 3px 0;
    transition: 0.3s;
    border-radius: 2px;
}

/* Hero Section */
.hero {
    background: linear-gradient(135deg, #6366f1 0%, #8b5cf6 50%, #a855f7 100%);
    padding: 140px 0 100px;
    color: white;
    min-height: 100vh;
    display: flex;
    align-items: center;
    position: relative;
    overflow: hidden;
}

.hero::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: url("data:image/svg+xml,%3Csvg width='60' height='60' viewBox='0 0 60 60' xmlns='http://www.w3.org/2000/svg'%3E%3Cg fill='none' fill-rule='evenodd'%3E%3Cg fill='%23ffffff' fill-opacity='0.05'%3E%3Cpath d='M36 34v-4h-2v4h-4v2h4v4h2v-4h4v-2h-4zm0-30V0h-2v4h-4v2h4v4h2V6h4V4h-4zM6 34v-4H4v4H0v2h4v4h2v-4h4v-2H6zM6 4V0H4v4H0v2h4v4h2V6h4V4H6z'/%3E%3C/g%3E%3C/g%3E%3C/svg%3E");
    opacity: 0.3;
}

.hero-container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 2rem;
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 4rem;
    align-items: center;
    position: relative;
    z-index: 1;
}

.hero-title {
    font-size: 3.5rem;
    font-weight: 700;
    margin-bottom: 1rem;
    line-height: 1.2;
    animation: fadeInUp 0.8s ease-out;
}

.hero-subtitle {
    font-size: 1.2rem;
    opacity: 0.95;
    margin-bottom: 2rem;
    line-height: 1.8;
    animation: fadeInUp 0.8s ease-out 0.2s both;
}

.hero-buttons {
    display: flex;
    gap: 1rem;
    animation: fadeInUp 0.8s ease-out 0.4s both;
}

@keyframes fadeInUp {
    from {
        opacity: 0;
        transform: translateY(30px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

.btn {
    display: inline-flex;
    align-items: center;
    gap: 0.5rem;
    padding: 1rem 2rem;
    text-decoration: none;
    border-radius: 12px;
    font-weight: 600;
    transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
    cursor: pointer;
    border: none;
    font-size: 1rem;
}

.btn-primary {
    background: #ffffff;
    color: #6366f1;
    box-shadow: 0 4px 15px rgba(0, 0, 0, 0.1);
}

.btn-primary:hover {
    transform: translateY(-3px);
    box-shadow: 0 12px 30px rgba(0, 0, 0, 0.15);
}

.btn-secondary {
    background: rgba(255, 255, 255, 0.15);
    color: white;
    border: 2px solid rgba(255, 255, 255, 0.4);
    backdrop-filter: blur(10px);
}

.btn-secondary:hover {
    background: white;
    color: #6366f1;
    border-color: white;
}

.hero-visual {
    display: grid;
    grid-template-columns: 1fr;
    gap: 1.5rem;
    animation: fadeInUp 0.8s ease-out 0.6s both;
}

.hero-card {
    background: rgba(255, 255, 255, 0.12);
    backdrop-filter: blur(20px);
    padding: 2rem;
    border-radius: 16px;
    text-align: center;
    border: 1px solid rgba(255, 255, 255, 0.2);
    transition: all 0.3s ease;
}

.hero-card:hover {
    transform: translateY(-5px);
    background: rgba(255, 255, 255, 0.18);
}

.hero-card .card-icon {
    font-size: 2.5rem;
    margin-bottom: 1rem;
}

.hero-card h3 {
    font-size: 1.3rem;
    margin-bottom: 0.5rem;
}

.hero-card p {
    opacity: 0.9;
}

/* Overview Section */
.overview {
    padding: 100px 0;
    background: linear-gradient(180deg, #f8fafc 0%, #ffffff 100%);
}

.section-header {
    text-align: center;
    margin-bottom: 4rem;
}

.section-header h2 {
    font-size: 2.5rem;
    font-weight: 700;
    margin-bottom: 1rem;
    background: linear-gradient(135deg, #6366f1 0%, #8b5cf6 100%);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.section-header p {
    font-size: 1.2rem;
    color: #64748b;
    max-width: 600px;
    margin: 0 auto;
}

.features-grid {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 2rem;
}

.feature-card {
    background: white;
    padding: 2.5rem;
    border-radius: 20px;
    text-align: center;
    box-shadow: 0 10px 40px rgba(99, 102, 241, 0.08);
    transition: all 0.4s cubic-bezier(0.4, 0, 0.2, 1);
    border: 1px solid rgba(99, 102, 241, 0.1);
}

.feature-card:hover {
    transform: translateY(-8px);
    box-shadow: 0 25px 60px rgba(99, 102, 241, 0.15);
}

.feature-icon {
    width: 80px;
    height: 80px;
    background: linear-gradient(135deg, #6366f1 0%, #8b5cf6 100%);
    border-radius: 20px;
    display: flex;
    align-items: center;
    justify-content: center;
    margin: 0 auto 1.5rem;
    color: white;
    font-size: 2rem;
    box-shadow: 0 8px 25px rgba(99, 102, 241, 0.25);
}

.feature-card h3 {
    font-size: 1.4rem;
    margin-bottom: 1rem;
    color: #1e293b;
    font-weight: 600;
}

.feature-card p {
    color: #64748b;
    line-height: 1.7;
}

/* Learning Path Section */
.learning-path {
    padding: 100px 0;
    background: white;
}

.path-timeline {
    max-width: 800px;
    margin: 0 auto;
}

.path-item {
    display: flex;
    align-items: flex-start;
    margin-bottom: 3rem;
    position: relative;
}

.path-item:not(:last-child)::after {
    content: '';
    position: absolute;
    left: 29px;
    top: 70px;
    width: 4px;
    height: calc(100% + 0.5rem);
    background: linear-gradient(180deg, #6366f1 0%, #8b5cf6 100%);
    border-radius: 2px;
    z-index: 0;
}

.path-number {
    width: 60px;
    height: 60px;
    background: linear-gradient(135deg, #6366f1 0%, #8b5cf6 100%);
    color: white;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 1.5rem;
    font-weight: 700;
    margin-right: 2rem;
    flex-shrink: 0;
    box-shadow: 0 8px 25px rgba(99, 102, 241, 0.3);
    position: relative;
    z-index: 1;
}

.path-content {
    flex: 1;
    background: #f8fafc;
    padding: 2rem;
    border-radius: 16px;
    border: 1px solid rgba(99, 102, 241, 0.1);
    transition: all 0.3s ease;
}

.path-content:hover {
    box-shadow: 0 10px 30px rgba(99, 102, 241, 0.1);
}

.path-content h3 {
    font-size: 1.5rem;
    margin-bottom: 0.5rem;
    color: #1e293b;
    font-weight: 600;
}

.path-content p {
    color: #64748b;
    margin-bottom: 1rem;
    line-height: 1.7;
}

.path-link {
    color: #6366f1;
    text-decoration: none;
    font-weight: 600;
    display: inline-flex;
    align-items: center;
    gap: 0.5rem;
    transition: all 0.3s ease;
}

.path-link:hover {
    color: #8b5cf6;
    gap: 0.75rem;
}

/* Statistics Section */
.stats {
    padding: 80px 0;
    background: linear-gradient(135deg, #6366f1 0%, #8b5cf6 50%, #a855f7 100%);
    color: white;
}

.stats-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
    gap: 2rem;
    text-align: center;
}

.stat-item {
    padding: 1.5rem;
}

.stat-number {
    font-size: 3.5rem;
    font-weight: 800;
    margin-bottom: 0.5rem;
    text-shadow: 0 4px 15px rgba(0, 0, 0, 0.1);
}

.stat-label {
    font-size: 1.1rem;
    opacity: 0.9;
    font-weight: 500;
}

/* Footer */
.footer {
    background: #0f172a;
    color: white;
    padding: 80px 0 30px;
}

.footer-content {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 3rem;
    margin-bottom: 3rem;
}

.footer-section h3,
.footer-section h4 {
    margin-bottom: 1.5rem;
    background: linear-gradient(135deg, #6366f1 0%, #8b5cf6 100%);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
    font-weight: 600;
}

.footer-section p {
    line-height: 1.8;
    color: #94a3b8;
}

.footer-section ul {
    list-style: none;
}

.footer-section ul li {
    margin-bottom: 0.75rem;
}

.footer-section ul li a {
    color: #94a3b8;
    text-decoration: none;
    transition: all 0.3s ease;
}

.footer-section ul li a:hover {
    color: #6366f1;
    padding-left: 5px;
}

.footer-bottom {
    text-align: center;
    padding-top: 2rem;
    border-top: 1px solid rgba(148, 163, 184, 0.2);
    color: #64748b;
}

/* Page Header for Sub Pages */
.page-header {
    background: linear-gradient(135deg, #6366f1 0%, #8b5cf6 100%);
    color: white;
    padding: 140px 0 80px;
    text-align: center;
}

.page-title {
    font-size: 3rem;
    font-weight: 700;
    margin-bottom: 1rem;
}

.page-subtitle {
    font-size: 1.2rem;
    opacity: 0.9;
    max-width: 600px;
    margin: 0 auto;
}

/* Breadcrumb */
.breadcrumb {
    background: #f8fafc;
    padding: 1rem 0;
    margin-top: 80px;
}

.breadcrumb-nav {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    font-size: 0.9rem;
}

.breadcrumb-nav a {
    color: #6366f1;
    text-decoration: none;
    transition: color 0.3s ease;
}

.breadcrumb-nav a:hover {
    color: #8b5cf6;
}

.breadcrumb-nav span {
    color: #64748b;
}

/* Content Section */
.content {
    padding: 80px 0;
    background: white;
}

.content-container {
    max-width: 1000px;
    margin: 0 auto;
    padding: 0 2rem;
}

/* Enhanced Responsive Design */

/* Large tablets and small desktops (992px - 1199px) */
@media (max-width: 1199px) and (min-width: 992px) {
    .container {
        padding: 0 1.5rem;
    }
    
    .hero-title {
        font-size: 3rem;
    }
    
    .features-grid {
        grid-template-columns: repeat(3, 1fr);
        gap: 2rem;
    }
}

/* Medium tablets (768px - 991px) */
@media (max-width: 991px) and (min-width: 768px) {
    .container {
        padding: 0 1.25rem;
    }
    
    .hero-container {
        gap: 2rem;
    }
    
    .hero-title {
        font-size: 2.75rem;
    }
    
    .features-grid {
        grid-template-columns: repeat(2, 1fr);
        gap: 1.75rem;
    }
    
    .stats-grid {
        grid-template-columns: repeat(2, 1fr);
        gap: 1.5rem;
    }
}

/* Small tablets and large phones (481px - 767px) */
@media (max-width: 768px) {
    .container {
        padding: 0 1rem;
    }
    
    .nav-menu {
        position: fixed;
        left: -100%;
        top: 80px;
        flex-direction: column;
        background-color: white;
        width: 100%;
        text-align: center;
        transition: 0.3s;
        box-shadow: 0 10px 27px rgba(0,0,0,0.05);
        padding: 2rem 0;
        z-index: 999;
    }

    .nav-menu.active {
        left: 0;
    }

    .nav-toggle {
        display: flex;
    }

    .hero-container {
        grid-template-columns: 1fr;
        text-align: center;
        gap: 2rem;
        padding: 2rem 0;
    }

    .hero-title {
        font-size: 2.25rem;
        margin-bottom: 1rem;
    }
    
    .hero-subtitle {
        font-size: 1rem;
        margin-bottom: 2rem;
    }
    
    .hero-buttons {
        flex-direction: column;
        gap: 1rem;
        align-items: center;
    }
    
    .btn {
        width: 100%;
        max-width: 280px;
        padding: 1rem 1.5rem;
    }

    .features-grid {
        grid-template-columns: repeat(2, 1fr);
        gap: 1.25rem;
    }
    
    .feature-card {
        padding: 1.75rem;
    }
    
    .feature-icon {
        font-size: 2.5rem;
    }

    .path-item {
        flex-direction: column;
        text-align: center;
        padding: 1.5rem;
    }

    .path-item:not(:last-child)::after {
        display: none;
    }

    .path-number {
        margin-right: 0;
        margin-bottom: 1rem;
    }

    .stats-grid {
        grid-template-columns: repeat(2, 1fr);
        gap: 1.25rem;
    }

    .footer-content {
        grid-template-columns: 1fr;
        text-align: center;
        gap: 2rem;
    }
}

/* Small mobile phones (320px - 480px) */
@media (max-width: 480px) {
    .container {
        padding: 0 0.75rem;
    }
    
    .nav-container {
        padding: 0 1rem;
        height: 70px;
    }
    
    .nav-logo h2 {
        font-size: 1.25rem;
    }
    
    .nav-menu {
        top: 70px;
        padding: 1.5rem 0;
    }
    
    .hero-title {
        font-size: 1.875rem;
        line-height: 1.2;
    }
    
    .hero-subtitle {
        font-size: 0.9rem;
    }
    
    .btn {
        padding: 0.875rem 1.25rem;
        font-size: 0.9rem;
    }

    .features-grid {
        grid-template-columns: 1fr;
        gap: 1rem;
    }
    
    .feature-card {
        padding: 1.5rem;
    }
    
    .feature-card h3 {
        font-size: 1.125rem;
    }
    
    .feature-icon {
        font-size: 2.25rem;
        margin-bottom: 0.75rem;
    }
    
    .section-title {
        font-size: 2rem;
    }
    
    .section-subtitle {
        font-size: 0.9rem;
    }
    
    .path-item {
        padding: 1.25rem;
    }
    
    .path-number {
        width: 40px;
        height: 40px;
        font-size: 1.125rem;
    }
    
    .stats-grid {
        grid-template-columns: 1fr;
        gap: 1rem;
    }
    
    .stat-card {
        padding: 1.5rem;
    }
    
    .stat-number {
        font-size: 2rem;
    }
}

/* Extra small phones (below 375px) */
@media (max-width: 374px) {
    .container {
        padding: 0 0.5rem;
    }
    
    .nav-container {
        padding: 0 0.75rem;
        height: 65px;
    }
    
    .nav-logo h2 {
        font-size: 1.125rem;
    }
    
    .hero-title {
        font-size: 1.625rem;
    }
    
    .btn {
        padding: 0.75rem 1rem;
        font-size: 0.85rem;
    }
    
    .feature-card {
        padding: 1.25rem;
    }
    
    .section-title {
        font-size: 1.75rem;
    }
}