* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}
body {
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    min-height: 100vh;
    color: #333;
}
.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 20px;
}
.hero {
    text-align: center;
    margin-bottom: 50px;
    padding: 40px 20px;
    background: rgba(255, 255, 255, 0.1);
    backdrop-filter: blur(10px);
    border-radius: 20px;
    border: 1px solid rgba(255, 255, 255, 0.2);
    box-shadow: 0 8px 32px rgba(0, 0, 0, 0.1);
}
.hero h1 {
    font-size: 3rem;
    color: white;
    margin-bottom: 10px;
    text-shadow: 2px 2px 4px rgba(0, 0, 0, 0.3);
    animation: fadeInUp 1s ease-out;
}
.hero p {
    font-size: 1.2rem;
    color: rgba(255, 255, 255, 0.9);
    margin-bottom: 20px;
    animation: fadeInUp 1s ease-out 0.2s both;
}
.search-container {
    margin-bottom: 30px;
    animation: fadeInUp 1s ease-out 0.4s both;
}
.search-box {
    width: 100%;
    max-width: 500px;
    margin: 0 auto;
    position: relative;
}
.search-input {
    width: 100%;
    padding: 15px 50px 15px 20px;
    font-size: 16px;
    border: none;
    border-radius: 50px;
    background: rgba(255, 255, 255, 0.9);
    box-shadow: 0 4px 15px rgba(0, 0, 0, 0.1);
    outline: none;
    transition: all 0.3s ease;
}
.search-input:focus {
    transform: translateY(-2px);
    box-shadow: 0 6px 20px rgba(0, 0, 0, 0.15);
}
.search-icon {
    position: absolute;
    right: 20px;
    top: 50%;
    transform: translateY(-50%);
    color: #666;
}
.presentations-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(350px, 1fr));
    gap: 30px;
    margin-bottom: 40px;
}
.presentation-card {
    background: rgba(255, 255, 255, 0.95);
    border-radius: 15px;
    padding: 25px;
    box-shadow: 0 8px 30px rgba(0, 0, 0, 0.1);
    transition: all 0.3s ease;
    border: 1px solid rgba(255, 255, 255, 0.2);
    animation: slideInUp 0.6s ease-out;
}
.presentation-card:hover {
    transform: translateY(-5px);
    box-shadow: 0 15px 40px rgba(0, 0, 0, 0.15);
}
.card-header {
    display: flex;
    align-items: center;
    margin-bottom: 15px;
}
.youtube-icon {
    width: 40px;
    height: 40px;
    background: #ff0000;
    border-radius: 8px;
    display: flex;
    align-items: center;
    justify-content: center;
    margin-right: 15px;
    color: white;
    font-weight: bold;
}
.card-title {
    font-size: 1.3rem;
    font-weight: 600;
    color: #333;
    margin: 0;
}
.card-speaker {
    color: #666;
    font-size: 0.95rem;
    margin-bottom: 10px;
}
.card-description {
    color: #555;
    line-height: 1.6;
    margin-bottom: 20px;
}
.card-footer {
    display: flex;
    justify-content: space-between;
    align-items: center;
}
.watch-btn {
    background: linear-gradient(45deg, #ff0000, #cc0000);
    color: white;
    padding: 10px 20px;
    border: none;
    border-radius: 25px;
    cursor: pointer;
    font-weight: 600;
    text-decoration: none;
    display: inline-flex;
    align-items: center;
    gap: 8px;
    transition: all 0.3s ease;
}
.watch-btn:hover {
    background: linear-gradient(45deg, #cc0000, #990000);
    transform: translateY(-2px);
    box-shadow: 0 5px 15px rgba(255, 0, 0, 0.3);
}
.duration {
    background: rgba(0, 0, 0, 0.1);
    padding: 5px 12px;
    border-radius: 15px;
    font-size: 0.85rem;
    color: #666;
}
.add-presentation {
    background: rgba(255, 255, 255, 0.95);
    border: 2px dashed #ccc;
    border-radius: 15px;
    padding: 40px;
    text-align: center;
    transition: all 0.3s ease;
    cursor: pointer;
    min-height: 200px;
    display: flex;
    flex-direction: column;
    justify-content: center;
    align-items: center;
}
.add-presentation:hover {
    border-color: #667eea;
    background: rgba(102, 126, 234, 0.05);
}
.add-icon {
    font-size: 3rem;
    color: #ccc;
    margin-bottom: 15px;
    transition: color 0.3s ease;
}
.add-presentation:hover .add-icon {
    color: #667eea;
}
.stats {
    display: flex;
    justify-content: center;
    gap: 40px;
    margin-top: 40px;
    padding: 30px;
    background: rgba(255, 255, 255, 0.1);
    border-radius: 15px;
    backdrop-filter: blur(10px);
}
.stat-item {
    text-align: center;
}
.stat-number {
    font-size: 2.5rem;
    font-weight: bold;
    color: white;
    display: block;
}
.stat-label {
    color: rgba(255, 255, 255, 0.8);
    font-size: 0.9rem;
}
@keyframes fadeInUp {
    from {
        opacity: 0;
        transform: translateY(30px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}
@keyframes slideInUp {
    from {
        opacity: 0;
        transform: translateY(50px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}
@media (max-width: 768px) {
    .hero h1 { font-size: 2rem; }
    .presentations-grid { grid-template-columns: 1fr; }
    .stats { flex-direction: column; gap: 20px; }
}
.no-presentations {
    text-align: center;
    padding: 60px 20px;
    color: rgba(255, 255, 255, 0.8);
}
.no-presentations h3 {
    font-size: 1.5rem;
    margin-bottom: 10px;
}