/* --- Global Styles & Variables --- */
:root {
    --ted-red: #E62B1E;
    --dark-bg: #111111;
    --light-text: #FFFFFF;
    --dark-text: #333333;
    --grey-bg: #f9f9f9;
    --header-height: 80px;
}

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

html {
    scroll-behavior: smooth;
}

body {
    font-family: 'Helvetica Neue', Arial, sans-serif;
    line-height: 1.6;
    color: var(--dark-text);
    background-color: var(--light-text);
    overflow-x: hidden;
}

ul {
    list-style: none;
}

a {
    text-decoration: none;
    color: inherit;
}

.logo img {
    height: 40px;
}

.content-section {
    padding: 80px 20px;
    max-width: 1200px;
    margin: 0 auto;
    opacity: 0;
    transform: translateY(40px);
    transition: opacity 0.8s ease-out, transform 0.8s ease-out;
}

.content-section.visible {
    opacity: 1;
    transform: translateY(0);
}

.section-title {
    text-align: center;
    font-size: 2.8rem;
    margin-bottom: 50px;
    color: var(--dark-text);
    font-weight: bold;
}

/* --- Header & Navigation --- */
#main-header {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    z-index: 1000;
    background: transparent;
    transition: background-color 0.4s ease, padding 0.4s ease;
    padding: 20px 0;
}

#main-header.scrolled {
    background: rgba(17, 17, 17, 0.9);
    backdrop-filter: blur(10px);
    box-shadow: 0 2px 10px rgba(0, 0, 0, 0.3);
    padding: 15px 0;
}

.navbar {
    display: flex;
    justify-content: space-between;
    align-items: center;
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 20px;
}

.nav-links {
    display: flex;
    gap: 30px;
}

.nav-links a {
    color: var(--light-text);
    font-weight: bold;
    padding-bottom: 5px;
    position: relative;
    transition: color 0.3s ease;
}

.nav-links a:hover {
    color: var(--ted-red);
}

.nav-links a::after {
    content: '';
    position: absolute;
    bottom: 0;
    left: 0;
    width: 0;
    height: 2px;
    background-color: var(--ted-red);
    transition: width 0.3s ease;
}

.nav-links a:hover::after {
    width: 100%;
}

/* --- Hero Section & Carousel --- */
.hero {
    position: relative;
    height: 100vh;
    color: var(--light-text);
    display: flex;
    justify-content: center;
    align-items: center;
    text-align: center;
    padding: 0 20px;
    overflow: hidden;
}

.carousel {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    z-index: -1;
}

.carousel-inner {
    width: 100%;
    height: 100%;
}

.carousel-item {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background-size: cover;
    background-position: center;
    opacity: 0;
    transition: opacity 1.5s ease-in-out;
    transform: scale(1.1);
}

.carousel-item.active {
    opacity: 1;
    transform: scale(1);
    transition: opacity 1.5s ease-in-out, transform 8s linear;
}

.hero::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: rgba(0, 0, 0, 0.6);
    z-index: 1;
}

.hero-content {
    z-index: 2;
    position: relative;
}

.hero-content .headline {
    font-size: 4.5rem;
    font-weight: bold;
    margin-bottom: 1rem;
    text-shadow: 0 4px 15px rgba(0,0,0,0.5);
}

.hero-content .tagline {
    font-size: 1.6rem;
    margin-bottom: 2.5rem;
    text-shadow: 0 2px 10px rgba(0,0,0,0.5);
}

.cta-button {
    background: var(--ted-red);
    color: var(--light-text);
    border: none;
    padding: 18px 35px;
    font-size: 1.1rem;
    font-weight: bold;
    cursor: pointer;
    border-radius: 5px;
    transition: background-color 0.3s ease, transform 0.3s ease, box-shadow 0.3s ease;
    box-shadow: 0 4px 20px rgba(230, 43, 30, 0.4);
}

.cta-button:hover {
    background-color: #c02112;
    transform: translateY(-5px);
    box-shadow: 0 6px 25px rgba(230, 43, 30, 0.6);
}


/* --- About Section --- */
#about {
    background-color: var(--grey-bg);
}

.section-text {
    max-width: 800px;
    margin: 0 auto;
    text-align: center;
    font-size: 1.2rem;
    line-height: 1.8;
}

/* --- Speakers Section --- */
.speakers-grid {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 40px;
    perspective: 1000px;
}

.speaker-card {
    background: var(--light-text);
    border-radius: 15px;
    box-shadow: 0 5px 20px rgba(0, 0, 0, 0.08);
    overflow: hidden;
    transition: transform 0.4s ease, box-shadow 0.4s ease;
    transform-style: preserve-3d;
}

.speaker-card:hover {
    transform: translateY(-10px) rotateY(5deg) rotateX(5deg);
    box-shadow: 0 15px 35px rgba(0, 0, 0, 0.15);
}

.speaker-image {
    overflow: hidden;
}

.speaker-card img {
    width: 100%;
    height: 300px;
    object-fit: cover;
    transition: transform 0.4s ease;
}

.speaker-card:hover img {
    transform: scale(1.05);
}

.speaker-info {
    padding: 25px;
    text-align: center;
}

.speaker-info h3 {
    font-size: 1.6rem;
    margin-bottom: 5px;
}

.speaker-info p {
    color: #666;
    font-size: 1rem;
}

/* --- Event Teaser Section --- */
#event {
    background-color: var(--grey-bg);
}

.event-teaser {
    text-align: center;
}

.video-placeholder {
    position: relative;
    width: 100%;
    max-width: 800px;
    height: 450px;
    margin: 0 auto 20px;
    cursor: pointer;
    background-color: var(--dark-bg);
    border-radius: 15px;
    overflow: hidden;
    box-shadow: 0 10px 30px rgba(0,0,0,0.2);
}

.play-icon {
    position: absolute;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
    width: 80px;
    height: 80px;
    fill: var(--light-text);
    transition: transform 0.3s ease, fill 0.3s ease;
}

.video-placeholder:hover .play-icon {
    transform: translate(-50%, -50%) scale(1.2);
    fill: var(--ted-red);
}

.event-teaser h3 {
    font-size: 2.2rem;
    margin-bottom: 10px;
}

/* --- Footer --- */
footer {
    background-color: var(--dark-bg);
    color: var(--light-text);
    padding: 60px 20px 20px;
}

.footer-grid {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 40px;
    max-width: 1200px;
    margin: 0 auto 50px;
}

.footer-logo {
    height: 40px;
    margin-bottom: 15px;
}

.footer-column h4 {
    font-size: 1.4rem;
    margin-bottom: 20px;
    color: var(--ted-red);
}

.footer-column ul li {
    margin-bottom: 12px;
}

.footer-column ul li a:hover {
    color: var(--ted-red);
    padding-left: 5px;
    transition: all 0.3s ease;
}

.footer-disclaimer {
    text-align: center;
    border-top: 1px solid #444;
    padding-top: 25px;
    font-size: 0.9rem;
    color: #aaa;
}


/* --- Responsive Design (Media Queries) --- */
@media (max-width: 900px) {
    .speakers-grid {
        grid-template-columns: repeat(2, 1fr);
    }
    .footer-grid {
        grid-template-columns: 1fr;
        text-align: center;
    }
    .footer-logo {
        margin: 0 auto 15px;
    }
}

@media (max-width: 600px) {
    .hero-content .headline {
        font-size: 2.8rem;
    }

    .hero-content .tagline {
        font-size: 1.3rem;
    }

    .section-title {
        font-size: 2.2rem;
    }

    .nav-links {
        display: none; 
    }
    
    .speakers-grid {
        grid-template-columns: 1fr;
    }

    .video-placeholder {
        height: 300px;
    }
}