:root {
    --bg-primary: #121212;
    --bg-secondary: #1e1e1e;
    --text-primary: #f5f5f5;
    --text-secondary: #a0a0a0;
    --accent: #7289da;
    --accent-light: #8ea1e1;
    --danger: #f04747;
    --success: #43b581;
    --card-bg: #2a2a2a;
    --card-border: #3a3a3a;
}

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

html {
    scroll-behavior: smooth;
}

body {
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    background-color: var(--bg-primary);
    color: var(--text-primary);
    line-height: 1.6;
}

.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 20px;
}

/* Navigation */
#navbar {
    position: sticky;
    top: 0;
    z-index: 1000;
    background-color: rgba(18, 18, 18, 0.95);
    backdrop-filter: blur(10px);
    box-shadow: 0 2px 10px rgba(0, 0, 0, 0.3);
    transition: all 0.3s ease;
}

.nav-container {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 1rem 0;
}

.nav-container h1 {
    font-size: 1.5rem;
    color: var(--accent);
}

.hamburger {
    display: none;
    cursor: pointer;
}

.hamburger .bar {
    width: 25px;
    height: 3px;
    background-color: var(--text-primary);
    margin: 5px 0;
    transition: all 0.3s ease;
}

.nav-links {
    display: flex;
    list-style: none;
    gap: 1.5rem;
    padding: 0.5rem 0;
    overflow-x: auto;
    scrollbar-width: thin;
}

.nav-links::-webkit-scrollbar {
    height: 3px;
}

.nav-links::-webkit-scrollbar-track {
    background: var(--bg-secondary);
}

.nav-links::-webkit-scrollbar-thumb {
    background: var(--accent);
}

.nav-links li a {
    color: var(--text-secondary);
    text-decoration: none;
    font-size: 0.9rem;
    transition: all 0.2s ease;
    white-space: nowrap;
}

.nav-links li a:hover {
    color: var(--accent-light);
}

/* Hero Section */
.hero {
    height: 80vh;
    display: flex;
    align-items: center;
    justify-content: center;
    text-align: center;
    background: linear-gradient(135deg, #2a2a72 0%, #1e1e2f 100%);
    margin-bottom: 2rem;
    border-radius: 0 0 10px 10px;
    position: relative;
    overflow: hidden;
    box-shadow: 0 5px 15px rgba(0,0,0,0.2);
}

.hero::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: url('https://images.unsplash.com/photo-1677442135406-a104a1ce2cff?ixlib=rb-4.0.3&auto=format&fit=crop&w=1470&q=80') no-repeat center center/cover;
    opacity: 0.15;
}

.hero-content {
    position: relative;
    z-index: 10;
    padding: 1rem;
    max-width: 800px;
}

.hero h1 {
    font-size: 3rem;
    margin-bottom: 1rem;
    background: linear-gradient(to right, var(--accent), #a0b5ff);
    -webkit-background-clip: text;
    background-clip: text;
    color: transparent;
}

.hero h2 {
    font-size: 1.5rem;
    margin-bottom: 2rem;
    color: var(--text-secondary);
}

.hero-buttons {
    display: flex;
    justify-content: center;
    gap: 1rem;
    margin-top: 2rem;
}

.btn {
    padding: 0.8rem 2rem;
    border-radius: 50px;
    font-weight: 600;
    text-decoration: none;
    transition: all 0.3s ease;
    background-color: var(--accent);
    color: white;
    border: 2px solid var(--accent);
}

.btn:hover {
    transform: translateY(-3px);
    box-shadow: 0 5px 15px rgba(0,0,0,0.3);
}

.btn-outline {
    background-color: transparent;
    color: var(--accent);
}

.btn-outline:hover {
    background-color: var(--accent);
    color: white;
}

/* Main Content */
main {
    padding: 1rem 0 3rem;
}

.card {
    background-color: var(--card-bg);
    border-radius: 10px;
    padding: 2rem;
    margin-bottom: 2rem;
    box-shadow: 0 4px 6px rgba(0,0,0,0.1);
    border: 1px solid var(--card-border);
    transition: transform 0.3s ease, box-shadow 0.3s ease;
}

.card:hover {
    transform: translateY(-5px);
    box-shadow: 0 10px 20px rgba(0,0,0,0.2);
}

.section-header {
    display: flex;
    align-items: center;
    margin-bottom: 1.5rem;
    border-bottom: 1px solid var(--card-border);
    padding-bottom: 0.5rem;
}

.section-header i {
    font-size: 1.8rem;
    color: var(--accent);
    margin-right: 1rem;
}

.section-header h2 {
    font-size: 1.8rem;
}

h3 {
    color: var(--accent-light);
    margin: 1.5rem 0 0.8rem;
    font-size: 1.4rem;
}

ul, ol {
    padding-left: 1.5rem;
    margin-bottom: 1rem;
}

li {
    margin-bottom: 0.5rem;
}

.pioneer, .milestone, .ai-category, .time-period {
    margin-bottom: 1.5rem;
    padding: 1rem;
    background-color: rgba(255,255,255,0.03);
    border-radius: 8px;
}

.facts-list li, .takeaway-list li {
    margin-bottom: 1rem;
    padding-left: 1.5rem;
    position: relative;
}

.facts-list li:before {
    content: "🔍";
    position: absolute;
    left: 0;
}

.takeaway-list li:before {
    content: "✓";
    position: absolute;
    left: 0;
    color: var(--success);
}

/* Presentation Slides Section */
.presentation-intro {
    margin-bottom: 2rem;
    font-style: italic;
    color: var(--text-secondary);
}

.slide {
    background-color: rgba(255, 255, 255, 0.05);
    border-radius: 8px;
    margin-bottom: 2rem;
    overflow: hidden;
    border: 1px solid var(--card-border);
    transition: transform 0.3s ease;
}

.slide:hover {
    transform: translateY(-5px);
    box-shadow: 0 8px 15px rgba(0, 0, 0, 0.2);
}

.slide-content {
    padding: 1.5rem;
}

.slide-content h3 {
    color: var(--accent);
    margin-top: 0;
    font-size: 1.5rem;
    border-bottom: 1px dashed var(--card-border);
    padding-bottom: 0.5rem;
}

.slide-content h4 {
    font-style: italic;
    color: var(--text-primary);
    margin: 1rem 0;
    font-weight: 400;
    font-size: 1.3rem;
}

.slide-speech {
    background-color: rgba(114, 137, 218, 0.1);
    border-left: 3px solid var(--accent);
    padding: 1rem;
    margin-top: 1.5rem;
    display: flex;
    align-items: flex-start;
    border-radius: 0 8px 8px 0;
}

.slide-speech i {
    margin-right: 1rem;
    font-size: 1.2rem;
    color: var(--accent);
    margin-top: 0.3rem;
}

.slide-speech p {
    margin: 0;
    line-height: 1.8;
}

.presentation-notes {
    background-color: rgba(255, 255, 255, 0.05);
    padding: 1.5rem;
    border-radius: 8px;
    margin-top: 2rem;
    border-left: 3px solid var(--success);
}

.presentation-notes p {
    margin-bottom: 0.5rem;
}

.presentation-notes p:last-child {
    margin-bottom: 0;
}

/* Q&A Section */
.qa-intro {
    margin-bottom: 2rem;
    font-style: italic;
    color: var(--text-secondary);
}

.qa-item {
    background-color: rgba(255, 255, 255, 0.05);
    border-radius: 8px;
    margin-bottom: 2rem;
    overflow: hidden;
    border: 1px solid var(--card-border);
    transition: transform 0.3s ease;
}

.qa-item:hover {
    transform: translateY(-5px);
    box-shadow: 0 8px 15px rgba(0, 0, 0, 0.2);
}

.question {
    padding: 1.5rem;
    background-color: rgba(0, 0, 0, 0.2);
    display: flex;
    align-items: flex-start;
    border-bottom: 1px solid var(--card-border);
}

.question i {
    margin-right: 1rem;
    font-size: 1.2rem;
    color: var(--accent);
    margin-top: 0.3rem;
}

.question h3 {
    margin: 0;
    font-size: 1.3rem;
    color: var(--text-primary);
    font-weight: 500;
}

.answer {
    padding: 1.5rem;
    display: flex;
    align-items: flex-start;
}

.answer i {
    margin-right: 1rem;
    font-size: 1.2rem;
    color: var(--success);
    margin-top: 0.3rem;
}

.answer p {
    margin: 0;
    line-height: 1.8;
}

/* Footer */
footer {
    text-align: center;
    padding: 2rem 0;
    background-color: var(--bg-secondary);
    border-radius: 10px 10px 0 0;
    margin-top: 2rem;
}

footer p {
    color: var(--text-secondary);
    margin-bottom: 1rem;
}

footer i.fa-heart {
    color: var(--danger);
}

.back-to-top a {
    color: var(--accent);
    text-decoration: none;
    display: inline-block;
    padding: 0.5rem 1rem;
    border-radius: 50px;
    transition: all 0.3s ease;
}

.back-to-top a:hover {
    background-color: rgba(114, 137, 218, 0.1);
}

/* Responsive Design */
@media (max-width: 768px) {
    .hamburger {
        display: block;
    }
    
    .nav-links {
        position: fixed;
        left: -100%;
        top: 70px;
        flex-direction: column;
        width: 100%;
        background-color: var(--bg-secondary);
        text-align: center;
        transition: 0.3s;
        box-shadow: 0 10px 20px rgba(0,0,0,0.2);
        padding: 1rem 0;
        gap: 0;
    }
    
    .nav-links.active {
        left: 0;
    }
    
    .nav-links li {
        margin: 1rem 0;
    }
    
    .hero h1 {
        font-size: 2.2rem;
    }
    
    .hero h2 {
        font-size: 1.2rem;
    }
    
    .hero-buttons {
        flex-direction: column;
        align-items: center;
    }

    .card {
        padding: 1.5rem;
    }

    .slide-content {
        padding: 1rem;
    }
    
    .slide-speech {
        flex-direction: column;
    }
    
    .slide-speech i {
        margin-bottom: 0.5rem;
    }
    
    .question, .answer {
        padding: 1rem;
    }
}

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

.card {
    animation: fadeIn 0.6s ease forwards;
    opacity: 0;
}

.card:nth-child(1) { animation-delay: 0.1s; }
.card:nth-child(2) { animation-delay: 0.2s; }
.card:nth-child(3) { animation-delay: 0.3s; }
.card:nth-child(4) { animation-delay: 0.4s; }
.card:nth-child(5) { animation-delay: 0.5s; }
.card:nth-child(6) { animation-delay: 0.6s; }
.card:nth-child(7) { animation-delay: 0.7s; }
.card:nth-child(8) { animation-delay: 0.8s; }
.card:nth-child(9) { animation-delay: 0.9s; }

/* Fix for Font Awesome presentation icon */
.fas.fa-presentation:before {
    content: "\f685"; /* This is the "chalkboard-teacher" icon */
}

/* Animation for the new sections */
#presentation, #qa-section {
    animation: fadeIn 0.8s ease forwards;
    opacity: 0;
}

#presentation { animation-delay: 1s; }
#qa-section { animation-delay: 1.1s; }