@import url('https://fonts.googleapis.com/css2?family=IBM+Plex+Sans:wght@400;500;600;700&display=swap');

/* ===========================
   VARIABLES & RESET
   =========================== */

:root {
    color-scheme: dark;
    --bg: #030817;
    --surface: #091126;
    --text: #f4f7ff;
    --muted: #a8b2cc;
    --cyan: #20d9ff;
    --blue: #287cff;
    --violet: #a855f7;
    --orange: #ff9d1c;
    --transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
}

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

html {
    scroll-behavior: smooth;
}

body {
    font-family: 'IBM Plex Sans', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
    color: var(--text);
    background:
        radial-gradient(circle at 25% 10%, rgb(32 217 255 / 10%), transparent 28rem),
        radial-gradient(circle at 78% 14%, rgb(255 157 28 / 9%), transparent 30rem),
        var(--bg);
    line-height: 1.6;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}

@media (prefers-reduced-motion: reduce) {
    *,
    *::before,
    *::after {
        scroll-behavior: auto !important;
        animation: none !important;
        transition: none !important;
    }
}

/* ===========================
   TYPOGRAPHY
   =========================== */

h1, h2, h3, h4, h5, h6 {
    font-weight: 600;
    line-height: 1.3;
    margin-bottom: 1rem;
}

h1 {
    font-size: 3rem;
    letter-spacing: -1px;
    color: var(--text);
}

h2 {
    font-size: 1.8rem;
    color: var(--text);
    text-align: center;
    margin-bottom: 3rem;
}

h3 {
    font-size: 1.5rem;
    color: var(--text);
}

h4 {
    font-size: 1.125rem;
    color: var(--text);
}

p {
    color: var(--muted);
    margin-bottom: 1rem;
}

a {
    color: var(--cyan);
    text-decoration: none;
    transition: var(--transition);
}

a:hover {
    color: var(--blue);
}

/* ===========================
   LAYOUT
   =========================== */

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

section {
    padding: 5rem 0;
}

/* ===========================
   SITE HEADER & NAVIGATION
   =========================== */

.site-header {
    position: sticky;
    top: 0;
    z-index: 100;
    background: var(--bg);
    border-bottom: 1px solid rgba(32, 217, 255, 0.1);
    backdrop-filter: blur(10px);
}

.navbar {
    width: 100%;
}

.navbar .container {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 1rem 2rem;
}

.nav-brand h1 {
    background: linear-gradient(135deg, var(--cyan), var(--blue));
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
    font-size: 1.5rem;
    margin: 0;
}

.nav-links {
    display: flex;
    list-style: none;
    gap: 2.5rem;
    align-items: center;
}

.nav-links a {
    font-size: 0.95rem;
    font-weight: 500;
    color: var(--muted);
    position: relative;
    transition: color 0.3s ease;
}

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

.nav-links a::after {
    content: '';
    position: absolute;
    bottom: -5px;
    left: 0;
    width: 0;
    height: 2px;
    background: linear-gradient(90deg, var(--cyan), var(--blue));
    transition: width 0.3s ease;
}

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

.nav-links li:last-child a {
    background: linear-gradient(135deg, var(--cyan), var(--blue));
    color: var(--bg);
    padding: 0.5rem 1.2rem;
    border-radius: 6px;
    font-weight: 600;
}

.nav-links li:last-child a:hover {
    color: var(--bg);
    opacity: 0.9;
}

.nav-links li:last-child a::after {
    display: none;
}

/* ===========================
   HERO SECTION
   =========================== */

.hero {
    display: flex;
    justify-content: center;
    align-items: center;
    min-height: 35vh;
    padding: clamp(1.5rem, 3vw, 2rem) clamp(1.25rem, 6vw, 6rem);
    background: transparent;
}

.hero-visual {
    display: block;
    width: 100%;
    height: auto;
    max-height: 480px;
    object-fit: contain;
    border-radius: 20px;
    filter: drop-shadow(0 22px 60px rgb(32 120 255 / 16%));
}

.page-content {
    position: relative;
    padding: clamp(1.5rem, 3vw, 2.5rem) clamp(1.25rem, 6vw, 6rem);
    background: var(--bg);
}

/* ===========================
   ABOUT SECTION
   =========================== */

.about {
    background: transparent;
}

.about-content {
    max-width: 800px;
    margin: 0 auto;
    text-align: center;
}

.about-content p {
    font-size: 1.05rem;
    line-height: 1.6;
    margin-bottom: 1rem;
    color: var(--muted);
}

/* ===========================
   TOPICS SECTION
   =========================== */

.topics {
    background: transparent;
}

.topics-grid {
    display: flex;
    flex-wrap: wrap;
    gap: 2rem;
    justify-content: center;
}

.topic-card {
    flex: 0 1 calc(20% - 1.6rem);
    min-width: 280px;
    background: rgba(9, 17, 38, 0.7);
    border: 1px solid rgba(32, 217, 255, 0.15);
    border-radius: 12px;
    padding: 2rem;
    transition: var(--transition);
    cursor: pointer;
    backdrop-filter: blur(10px);
}

.topic-card:hover {
    border-color: rgba(32, 217, 255, 0.4);
    background: rgba(9, 17, 38, 0.9);
    box-shadow: 0 8px 32px rgb(32 217 255 / 12%);
    transform: translateY(-4px);
}

.topic-card h3 {
    color: var(--cyan);
    margin-bottom: 0.75rem;
    font-size: 1.25rem;
}

.topic-card p {
    color: var(--muted);
    margin: 0;
}

/* ===========================
   SCHEDULE SECTION
   =========================== */

.schedule {
    background: transparent;
}

.schedule-details {
    max-width: 1100px;
    margin: 0 auto 2rem;
    display: flex;
    justify-content: center;
    gap: 3rem;
    flex-wrap: wrap;
}

.detail-item {
    display: flex;
    flex-direction: row;
    align-items: center;
    justify-content: center;
    gap: 0.5rem;
    text-align: center;
    padding: 1rem 0.75rem;
    border: 1px solid rgba(32, 217, 255, 0.2);
    border-radius: 8px;
    background: transparent;
    min-height: 60px;
}

.detail-icon {
    font-size: 1.5rem;
    flex-shrink: 0;
    margin: 0;
}

.detail-item p {
    color: var(--muted);
    font-size: 0.85rem;
    margin: 0;
    line-height: 1.3;
}

.schedule-table-wrapper {
    max-width: 1100px;
    margin: 0 auto;
    overflow-x: auto;
    border-radius: 12px;
    box-shadow: 0 8px 32px rgb(32 120 255 / 10%);
}

.schedule-table {
    width: 100%;
    border-collapse: collapse;
    background: rgba(9, 17, 38, 0.8);
    backdrop-filter: blur(10px);
}

.schedule-table thead {
    background: linear-gradient(135deg, var(--cyan), var(--blue));
    color: var(--bg);
}

.schedule-table th {
    padding: 1.5rem;
    text-align: left;
    font-weight: 600;
    letter-spacing: 0.5px;
}

.schedule-table th:first-child {
    width: 15%;
    padding-left: 2rem;
}

.schedule-table th:last-child {
    padding-right: 2rem;
}

.schedule-table tbody tr {
    border-bottom: 1px solid rgba(32, 217, 255, 0.1);
    transition: var(--transition);
}

.schedule-table tbody tr:last-child {
    border-bottom: none;
}

.schedule-table tbody tr:hover {
    background-color: rgba(32, 217, 255, 0.08);
}

.time-cell {
    font-weight: 600;
    color: var(--cyan);
    width: 15%;
    white-space: nowrap;
    padding: 1.25rem 2rem 1.25rem 2rem;
    font-size: 0.95rem;
}

.event-cell {
    padding: 1.25rem 2rem;
    color: var(--text);
    font-size: 0.95rem;
}

.event-row.break {
    background-color: rgba(255, 157, 28, 0.08);
}

.event-row.break .time-cell {
    color: var(--orange);
    font-weight: 700;
}

.event-row.keynote {
    background-color: rgba(32, 217, 255, 0.08);
}

.event-row.keynote .time-cell {
    color: var(--cyan);
    font-weight: 700;
}

.event-row.panel {
    background-color: rgba(168, 85, 247, 0.08);
}

.event-row.panel .time-cell {
    color: var(--violet);
    font-weight: 700;
}

.event-row.poster {
    background-color: rgba(40, 124, 255, 0.08);
}

.event-row.poster .time-cell {
    color: var(--blue);
    font-weight: 700;
}

.note {
    display: block;
    font-size: 0.85rem;
    color: var(--muted);
    margin-top: 0.25rem;
    font-weight: 400;
    font-style: italic;
}

/* ===========================
   SPEAKERS SECTION
   =========================== */

.speakers {
    background: transparent;
}

.speakers-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 3rem;
    max-width: 900px;
    margin: 0 auto;
}

.speaker-card {
    text-align: center;
    transition: var(--transition);
}

.speaker-card:hover {
    transform: translateY(-8px);
}

.speaker-image-link {
    text-decoration: none;
    cursor: pointer;
}

.speaker-image {
    width: 180px;
    height: 180px;
    margin: 0 auto 1.5rem;
    border-radius: 50%;
    overflow: hidden;
    box-shadow: 0 8px 32px rgb(32 217 255 / 15%);
    background: linear-gradient(135deg, var(--cyan), var(--blue));
    display: flex;
    align-items: center;
    justify-content: center;
    border: 2px solid rgba(32, 217, 255, 0.2);
    transition: var(--transition);
}

.speaker-image-link:hover .speaker-image {
    box-shadow: 0 12px 48px rgb(32 217 255 / 25%);
    transform: scale(1.05);
}

.speaker-photo {
    width: 100%;
    height: 100%;
    object-fit: cover;
    display: block;
}

.speaker-photo:not([src]) ~ .placeholder-image,
.speaker-photo[src=""] ~ .placeholder-image {
    display: flex !important;
}

.placeholder-image {
    width: 100%;
    height: 100%;
    background: linear-gradient(135deg, var(--cyan), var(--blue));
    display: flex;
    align-items: center;
    justify-content: center;
    color: var(--bg);
    font-weight: bold;
    font-size: 2rem;
}

.speaker-card h3 {
    margin-bottom: 0.5rem;
    color: var(--text);
}

.speaker-card h3 a {
    color: var(--text);
    text-decoration: none;
    transition: color 0.3s ease;
}

.speaker-card h3 a:hover {
    color: var(--cyan);
}

.speaker-title {
    font-size: 1rem;
    color: var(--cyan);
    font-weight: 600;
    margin-bottom: 1rem;
}

.speaker-bio {
    font-size: 0.95rem;
    line-height: 1.7;
    color: var(--muted);
}

/* ===========================
   CALL FOR PAPERS SECTION
   =========================== */

.cfp {
    background: transparent;
}

.cfp-content {
    display: flex;
    gap: 2rem;
    max-width: 1200px;
    margin: 0 auto;
}

.cfp-left {
    flex: 0.5;
}

.cfp-right {
    flex: 1.5;
    display: flex;
    flex-direction: column;
    gap: 2rem;
}

.cfp-box {
    background: rgba(9, 17, 38, 0.7);
    padding: 2rem;
    border-radius: 12px;
    box-shadow: 0 8px 24px rgb(32 120 255 / 8%);
    border-left: 4px solid var(--cyan);
    transition: var(--transition);
    backdrop-filter: blur(10px);
    border: 1px solid rgba(32, 217, 255, 0.15);
    border-left: 4px solid var(--cyan);
}

.cfp-box:hover {
    box-shadow: 0 12px 40px rgb(32 217 255 / 15%);
    transform: translateY(-4px);
    background: rgba(9, 17, 38, 0.9);
}

.cfp-box h3 {
    color: var(--cyan);
    margin-bottom: 1rem;
}

.cfp-box p {
    color: var(--muted);
}

.dates-list {
    list-style: none;
}

.dates-list li {
    padding: 0.75rem 0;
    border-bottom: 1px solid rgba(32, 217, 255, 0.1);
    color: var(--muted);
}

.dates-list li:last-child {
    border-bottom: none;
}

.date-placeholder {
    color: var(--cyan);
    font-weight: 600;
}

.cfp-guidelines {
    list-style: disc;
    padding-left: 1.5rem;
    margin-bottom: 1rem;
}

.cfp-guidelines li {
    color: var(--muted);
    margin-bottom: 0.75rem;
    line-height: 1.6;
}

.paper-category {
    margin-bottom: 1.5rem;
    padding-bottom: 1.5rem;
    border-bottom: 1px solid rgba(32, 217, 255, 0.1);
}

.paper-category:last-of-type {
    border-bottom: none;
}

.paper-category h4 {
    color: var(--cyan);
    margin-bottom: 0.5rem;
}

.paper-category p {
    color: var(--muted);
    margin-bottom: 0.75rem;
}

.submission-portal {
    border-left-color: var(--violet);
}

.submission-portal h3 {
    color: var(--violet);
}

.submission-portal .btn {
    margin-top: 1rem;
}

/* ===========================
   BUTTON STYLES
   =========================== */

.btn {
    display: inline-block;
    padding: 0.875rem 2rem;
    border-radius: 8px;
    font-weight: 600;
    text-align: center;
    transition: var(--transition);
    border: 2px solid transparent;
    cursor: pointer;
}

.btn-primary {
    background: linear-gradient(135deg, var(--cyan), var(--blue));
    color: var(--bg);
}

.btn-primary:hover {
    transform: translateY(-2px);
    box-shadow: 0 12px 40px rgb(32 217 255 / 25%);
}

.btn-secondary {
    background: transparent;
    color: var(--cyan);
    border-color: var(--cyan);
}

.btn-secondary:hover {
    background: rgba(32, 217, 255, 0.1);
    transform: translateY(-2px);
}

.btn:disabled {
    opacity: 0.6;
    cursor: not-allowed;
    pointer-events: none;
}

.btn:disabled:hover {
    transform: none;
}

/* ===========================
   ORGANIZERS SECTION
   =========================== */

.organizers {
    background: transparent;
}

.organizers-grid {
    display: flex;
    flex-wrap: wrap;
    gap: 2rem;
    max-width: 1200px;
    margin: 0 auto;
    justify-content: center;
}

.organizer-card {
    flex: 0 1 calc(25% - 1.5rem);
    min-width: 250px;
}

.organizer-card {
    text-align: center;
}

.organizer-image-link {
    text-decoration: none;
    cursor: pointer;
}

.organizer-image {
    width: 150px;
    height: 150px;
    margin: 0 auto 1rem;
    border-radius: 50%;
    overflow: hidden;
    box-shadow: 0 8px 24px rgb(32 217 255 / 12%);
    background: linear-gradient(135deg, var(--cyan), var(--blue));
    display: flex;
    align-items: center;
    justify-content: center;
    border: 2px solid rgba(32, 217, 255, 0.2);
    transition: var(--transition);
}

.organizer-image-link:hover .organizer-image {
    box-shadow: 0 12px 36px rgb(32 217 255 / 20%);
    transform: scale(1.05);
}

.organizer-photo {
    width: 100%;
    height: 100%;
    object-fit: cover;
    display: block;
}

.organizer-photo:not([src]) ~ .placeholder-image,
.organizer-photo[src=""] ~ .placeholder-image {
    display: flex !important;
}

.organizer-card h3 {
    margin-bottom: 0.5rem;
    font-size: 1.1rem;
    color: var(--text);
}

.organizer-card h3 a {
    color: var(--text);
    text-decoration: none;
    transition: color 0.3s ease;
}

.organizer-card h3 a:hover {
    color: var(--cyan);
}

.organizer-title {
    color: var(--cyan);
    font-size: 0.95rem;
    font-weight: 500;
    margin-bottom: 0.5rem;
}

.organizer-email {
    font-size: 0.85rem;
    color: var(--muted);
    margin-top: 0.5rem;
    margin-bottom: 0;
}

.organizer-email a {
    color: var(--cyan);
    text-decoration: none;
    transition: color 0.3s ease;
}

.organizer-email a:hover {
    color: var(--blue);
    text-decoration: underline;
}

/* ===========================
   FOOTER
   =========================== */

.footer {
    background: rgba(3, 8, 23, 0.8);
    color: var(--text);
    padding: 3rem 0 1rem;
    border-top: 1px solid rgba(32, 217, 255, 0.1);
}

.footer-content {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 3rem;
    margin-bottom: 2rem;
}

.footer-section h4 {
    color: var(--text);
    margin-bottom: 1rem;
}

.footer-section p {
    color: var(--muted);
}

.footer-section a {
    color: var(--cyan);
    transition: color 0.3s ease;
}

.footer-section a:hover {
    color: var(--blue);
}

.social-links {
    display: flex;
    gap: 2rem;
}

.footer-bottom {
    border-top: 1px solid rgba(32, 217, 255, 0.1);
    padding-top: 2rem;
    text-align: center;
    font-size: 0.9rem;
    color: var(--muted);
}

.footer-bottom p {
    margin-bottom: 0.5rem;
    color: inherit;
}

.footer-credit a {
    color: var(--cyan);
}

/* ===========================
   RESPONSIVE DESIGN
   =========================== */

@media (max-width: 768px) {
    h1 {
        font-size: 2rem;
    }

    h2 {
        font-size: 1.8rem;
        margin-bottom: 2rem;
    }

    .container {
        padding: 0 1.5rem;
    }

    section {
        padding: 3rem 0;
    }

    /* Navigation */
    .navbar .container {
        flex-direction: column;
        gap: 1rem;
    }

    .nav-links {
        flex-direction: column;
        gap: 1rem;
        text-align: center;
    }

    /* Hero */
    .hero-visual {
        width: 100%;
        max-width: 100%;
    }

    /* Topics */
    .topics-grid {
        grid-template-columns: 1fr;
        gap: 1.5rem;
    }

    /* Schedule */
    .schedule-table {
        font-size: 0.85rem;
    }

    .time-cell,
    .event-cell {
        padding: 1rem;
    }

    /* Speakers */
    .speakers-grid {
        grid-template-columns: 1fr;
        gap: 2rem;
    }

    /* CFP */
    .cfp-content {
        grid-template-columns: 1fr;
    }

    /* Organizers */
    .organizers-grid {
        grid-template-columns: repeat(2, 1fr);
        gap: 1.5rem;
    }

    .organizer-image {
        width: 80px;
        height: 80px;
    }
}

@media (max-width: 480px) {
    h1 {
        font-size: 1.5rem;
    }

    h2 {
        font-size: 1.4rem;
    }

    .btn {
        padding: 0.75rem 1.5rem;
        font-size: 0.9rem;
    }

    .hero-buttons {
        flex-direction: column;
    }

    .hero-buttons .btn {
        width: 100%;
    }

    .nav-brand h1 {
        font-size: 1.2rem;
    }

    .nav-links {
        gap: 0.75rem;
    }

    .nav-links a {
        font-size: 0.85rem;
    }

    /* Organizers */
    .organizers-grid {
        grid-template-columns: 1fr;
        gap: 1rem;
    }

    .organizer-card h3 {
        font-size: 1rem;
    }

    .organizer-title {
        font-size: 0.85rem;
    }
}