:root {
    --primary-color: #38bdf8;
    --primary-dark: #0ea5e9;
    --primary-glow: rgba(56, 189, 248, 0.5);
    --secondary-color: #22c55e;
    --text-color: #e2e8f0;
    --text-light: #94a3b8;
    --text-muted: #64748b;
    --bg-color: #050510;
    --bg-gradient: linear-gradient(135deg, #0a0a1a 0%, #0d1526 50%, #0a1020 100%);
    --container-bg: rgba(15, 23, 42, 0.8);
    --container-border: rgba(56, 189, 248, 0.15);
    --border-color: rgba(148, 163, 184, 0.2);
    --shadow-color: rgba(0, 0, 0, 0.3);
    --glow-shadow: 0 0 20px rgba(56, 189, 248, 0.3);
    --gradient-hero: linear-gradient(135deg, #0c1929 0%, #0a1628 50%, #061220 100%);
}

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

body {
    font-family: 'Poppins', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, sans-serif;
    background: var(--bg-gradient);
    background-attachment: fixed;
    color: var(--text-color);
    line-height: 1.6;
    min-height: 100vh;
}

/* Construction Ribbon */
.construction-ribbon {
    position: fixed;
    top: 0;
    right: 0;
    z-index: 10000;
    overflow: hidden;
    width: 200px;
    height: 200px;
    pointer-events: none;
}

.construction-ribbon span {
    display: block;
    position: absolute;
    top: 42px;
    right: -35px;
    width: 280px;
    padding: 8px 0;
    background: repeating-linear-gradient(
        -45deg,
        #f59e0b,
        #f59e0b 10px,
        #1a1a2e 10px,
        #1a1a2e 20px
    );
    color: #fff;
    text-align: center;
    font-family: 'Poppins', sans-serif;
    font-weight: 700;
    font-size: 13px;
    letter-spacing: 1px;
    text-transform: uppercase;
    transform: rotate(45deg);
    box-shadow: 0 2px 8px rgba(0,0,0,0.4);
    text-shadow: 0 1px 2px rgba(0,0,0,0.5);
    pointer-events: auto;
}

/* Navigation */
.navbar {
    background: rgba(10, 15, 30, 0.9);
    backdrop-filter: blur(12px);
    border-bottom: 1px solid var(--container-border);
    position: sticky;
    top: 0;
    z-index: 1000;
}

.nav-container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 1rem 2rem;
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.logo {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    text-decoration: none;
    color: var(--text-color);
    font-weight: 700;
    font-size: 1.5rem;
    transition: all 0.3s ease;
}

.logo:hover {
    transform: scale(1.05);
    text-shadow: var(--glow-shadow);
}

.logo-icon {
    font-size: 2rem;
    filter: drop-shadow(0 0 8px rgba(56, 189, 248, 0.6));
}

.logo-text {
    background: linear-gradient(90deg, #38bdf8, #7dd3fc, #38bdf8);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

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

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

.nav-link:hover,
.nav-link.active {
    color: var(--primary-color);
    text-shadow: 0 0 10px var(--primary-glow);
}

.nav-link.active::after {
    content: '';
    position: absolute;
    bottom: -4px;
    left: 0;
    right: 0;
    height: 2px;
    background: linear-gradient(90deg, transparent, var(--primary-color), transparent);
    box-shadow: 0 0 10px var(--primary-glow);
    border-radius: 2px;
}

/* Hero Section */
.hero {
    position: relative;
    min-height: 500px;
    display: flex;
    align-items: center;
    justify-content: center;
    overflow: hidden;
    background: var(--gradient-hero);
}

.hero::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: radial-gradient(ellipse at center, rgba(56, 189, 248, 0.08) 0%, transparent 70%);
    pointer-events: none;
}

.hero-content {
    position: relative;
    z-index: 10;
    text-align: center;
    padding: 3rem 2rem;
    max-width: 800px;
}

.hero-title {
    font-size: 3.5rem;
    font-weight: 800;
    margin-bottom: 1rem;
    background: linear-gradient(90deg, #38bdf8, #7dd3fc, #38bdf8);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
    text-shadow: none;
    filter: drop-shadow(0 0 30px rgba(56, 189, 248, 0.4));
    animation: fadeInUp 0.8s ease;
}

.hero-subtitle {
    font-size: 1.5rem;
    margin-bottom: 2rem;
    color: var(--text-light);
    animation: fadeInUp 1s ease;
}

.hero-cta {
    display: flex;
    gap: 1rem;
    justify-content: center;
    animation: fadeInUp 1.2s ease;
}

.btn {
    padding: 1rem 2rem;
    font-size: 1.1rem;
    font-weight: 600;
    border: none;
    border-radius: 12px;
    cursor: pointer;
    text-decoration: none;
    transition: all 0.3s ease;
    display: inline-block;
}

.btn-primary {
    background: linear-gradient(135deg, #38bdf8, #0ea5e9);
    color: #0a1628;
    box-shadow: 0 0 20px rgba(56, 189, 248, 0.4);
}

.btn-primary:hover {
    transform: translateY(-3px);
    box-shadow: 0 0 40px rgba(56, 189, 248, 0.6);
}

.btn-secondary {
    background: rgba(56, 189, 248, 0.1);
    color: var(--primary-color);
    border: 2px solid var(--primary-color);
    box-shadow: 0 0 15px rgba(56, 189, 248, 0.2);
}

.btn-secondary:hover {
    background: rgba(56, 189, 248, 0.2);
    transform: translateY(-3px);
    box-shadow: 0 0 30px rgba(56, 189, 248, 0.4);
}

/* Floating Animations */
.hero-background {
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    overflow: hidden;
}

.float-animation {
    position: absolute;
    font-size: 4rem;
    opacity: 0.15;
    animation: float 6s ease-in-out infinite;
    filter: drop-shadow(0 0 20px rgba(56, 189, 248, 0.5));
}

.float-1 { top: 10%; left: 10%; animation-delay: 0s; }
.float-2 { top: 20%; right: 15%; animation-delay: 1s; }
.float-3 { bottom: 20%; left: 20%; animation-delay: 2s; }
.float-4 { bottom: 10%; right: 10%; animation-delay: 3s; }

@keyframes float {
    0%, 100% { transform: translateY(0px); }
    50% { transform: translateY(-30px); }
}

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

/* Glow pulse animation */
@keyframes glowPulse {
    0%, 100% { box-shadow: 0 0 20px rgba(56, 189, 248, 0.3); }
    50% { box-shadow: 0 0 40px rgba(56, 189, 248, 0.6); }
}

/* Container */
.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 4rem 2rem;
}

/* Sections */
.intro-section {
    text-align: center;
    margin-bottom: 4rem;
}

.section-title {
    font-size: 2.5rem;
    font-weight: 700;
    margin-bottom: 1.5rem;
    background: linear-gradient(90deg, #e2e8f0, #94a3b8);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.intro-text {
    font-size: 1.2rem;
    color: var(--text-light);
    max-width: 700px;
    margin: 0 auto;
    line-height: 1.8;
}

/* Course Cards */
.courses-section {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 2rem;
    margin-top: 3rem;
}

.course-card {
    background: var(--container-bg);
    backdrop-filter: blur(12px);
    border: 1px solid var(--container-border);
    border-radius: 16px;
    padding: 2.5rem;
    transition: all 0.3s ease;
    cursor: pointer;
    position: relative;
    overflow: hidden;
}

.course-card::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    height: 3px;
    background: linear-gradient(90deg, transparent, var(--primary-color), transparent);
    transform: scaleX(0);
    transition: transform 0.3s ease;
}

.course-card:hover::before {
    transform: scaleX(1);
    box-shadow: 0 0 20px var(--primary-glow);
}

.course-card:hover {
    transform: translateY(-10px);
    border-color: rgba(56, 189, 248, 0.4);
    box-shadow: 0 20px 50px rgba(0, 0, 0, 0.4), 0 0 30px rgba(56, 189, 248, 0.15);
}

.card-icon {
    font-size: 3rem;
    margin-bottom: 1rem;
    filter: drop-shadow(0 0 10px rgba(56, 189, 248, 0.4));
}

.card-title {
    font-size: 2rem;
    font-weight: 700;
    margin-bottom: 1rem;
    color: var(--text-color);
}

.card-description {
    color: var(--text-light);
    font-size: 1.1rem;
    margin-bottom: 1.5rem;
    line-height: 1.6;
}

.card-footer {
    margin-top: 1.5rem;
}

.card-link {
    color: var(--primary-color);
    font-weight: 600;
    transition: all 0.3s ease;
    text-shadow: 0 0 10px transparent;
}

.course-card:hover .card-link {
    text-shadow: 0 0 10px var(--primary-glow);
}

/* Chapter Cards */
.chapters-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
    gap: 1.5rem;
    margin-top: 2rem;
}

.chapter-card {
    background: var(--container-bg);
    backdrop-filter: blur(12px);
    border: 1px solid var(--container-border);
    border-radius: 12px;
    padding: 1.5rem;
    transition: all 0.3s ease;
    cursor: pointer;
}

.chapter-card:hover {
    transform: translateY(-5px);
    border-color: rgba(56, 189, 248, 0.5);
    box-shadow: 0 15px 40px rgba(0, 0, 0, 0.3), 0 0 25px rgba(56, 189, 248, 0.15);
}

.chapter-icon {
    font-size: 2rem;
    margin-bottom: 0.5rem;
    filter: drop-shadow(0 0 8px rgba(56, 189, 248, 0.4));
}

.chapter-title {
    font-size: 1.3rem;
    font-weight: 600;
    margin-bottom: 0.5rem;
    color: var(--text-color);
}

.chapter-description {
    font-size: 0.95rem;
    color: var(--text-light);
    line-height: 1.5;
}

/* Simulation Page */
.simulation-container {
    background: var(--container-bg);
    backdrop-filter: blur(12px);
    border: 1px solid var(--container-border);
    border-radius: 16px;
    padding: 2rem;
    margin-top: 2rem;
}

.breadcrumb {
    margin-bottom: 2rem;
    color: var(--text-muted);
    font-size: 0.95rem;
}

.breadcrumb a {
    color: var(--primary-color);
    text-decoration: none;
    transition: all 0.3s ease;
}

.breadcrumb a:hover {
    color: var(--primary-dark);
    text-shadow: 0 0 10px var(--primary-glow);
}

/* Footer */
.footer {
    background: rgba(10, 15, 30, 0.9);
    backdrop-filter: blur(12px);
    border-top: 1px solid var(--container-border);
    color: var(--text-light);
    text-align: center;
    padding: 2rem;
    margin-top: 4rem;
}

/* Responsive Design */
@media (max-width: 768px) {
    .hero-title {
        font-size: 2.5rem;
    }

    .hero-subtitle {
        font-size: 1.2rem;
    }

    .hero-cta {
        flex-direction: column;
        align-items: center;
    }

    .nav-menu {
        gap: 1rem;
    }

    .section-title {
        font-size: 2rem;
    }

    .intro-text {
        font-size: 1rem;
    }

    .courses-section {
        grid-template-columns: 1fr;
    }

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

@media (max-width: 480px) {
    .nav-container {
        padding: 1rem;
        flex-direction: column;
        gap: 1rem;
    }

    .hero-title {
        font-size: 2rem;
    }

    .hero-content {
        padding: 2rem 1rem;
    }

    .container {
        padding: 2rem 1rem;
    }
}