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

:root {
    --primary-color: #1e3a8a;
    --secondary-color: #0d9488;
    --accent-color: #06b6d4;
    --light-bg: #f8fafc;
    --text-dark: #1f2937;
    --text-light: #6b7280;
    --border-color: #e5e7eb;
}

html {
    scroll-behavior: smooth;
}

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

/* Navigation Bar */
.navbar {
    background: rgba(30, 58, 138, 0.85);
    backdrop-filter: blur(10px);
    -webkit-backdrop-filter: blur(10px);
    border-bottom: 1px solid rgba(255, 255, 255, 0.1);
    color: white;
    padding: 1rem 0;
    position: sticky;
    top: 0;
    z-index: 1000;
    box-shadow: 0 2px 8px rgba(0, 0, 0, 0.1);
}

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

.logo {
    font-size: 1.5rem;
    font-weight: bold;
    letter-spacing: 1px;
}

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

.nav-link {
    color: white;
    text-decoration: none;
    transition: color 0.3s ease;
}

.nav-link:hover {
    color: var(--accent-color);
}

.hamburger {
    display: none;
    background: none;
    border: none;
    cursor: pointer;
    flex-direction: column;
    gap: 5px;
}

.hamburger span {
    width: 25px;
    height: 3px;
    background: white;
    border-radius: 2px;
    transition: all 0.3s ease;
}

/* Hero Section */
.hero {
    background: linear-gradient(135deg, rgba(30, 58, 138, 0.85) 0%, rgba(30, 64, 175, 0.85) 100%), 
                url('514408086_1030849889158955_3815428664258281688_n.jpg');
    background-size: cover;
    background-position: center;
    background-attachment: fixed;
    color: white;
    padding: 8rem 2rem;
    text-align: center;
    min-height: 600px;
    display: flex;
    align-items: center;
    justify-content: center;
    position: relative;
}

.hero::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: url('514408086_1030849889158955_3815428664258281688_n.jpg');
    background-size: cover;
    background-position: center;
    filter: blur(8px);
    z-index: -1;
}

.hero-content h1 {
    font-size: 3.5rem;
    margin-bottom: 1rem;
    font-weight: 800;
    letter-spacing: -1px;
    position: relative;
    z-index: 1;
    text-shadow: 2px 2px 4px rgba(0, 0, 0, 0.3);
}

.hero-subtitle {
    font-size: 1.5rem;
    margin-bottom: 0.5rem;
    opacity: 0.95;
    position: relative;
    z-index: 1;
    text-shadow: 1px 1px 2px rgba(0, 0, 0, 0.3);
}

.hero-dates {
    font-size: 1.25rem;
    margin-bottom: 2rem;
    opacity: 0.9;
    position: relative;
    z-index: 1;
    text-shadow: 1px 1px 2px rgba(0, 0, 0, 0.3);
}

.hero-buttons {
    display: flex;
    gap: 1.5rem;
    justify-content: center;
    flex-wrap: wrap;
    position: relative;
    z-index: 1;
}

/* Buttons */
.btn {
    display: inline-block;
    padding: 0.875rem 2rem;
    border-radius: 0.5rem;
    text-decoration: none;
    font-weight: 600;
    transition: all 0.3s ease;
    border: 2px solid transparent;
    cursor: pointer;
}

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

.btn-primary:hover {
    background: #0891b2;
    transform: translateY(-2px);
    box-shadow: 0 8px 16px rgba(6, 182, 212, 0.3);
}

.btn-secondary {
    background: transparent;
    color: white;
    border-color: white;
}

.btn-secondary:hover {
    background: white;
    color: var(--primary-color);
}

/* Sections */
.section {
    padding: 4rem 2rem;
}

.section-alt {
    background: var(--light-bg);
}

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

.section-title {
    font-size: 2.5rem;
    margin-bottom: 1rem;
    text-align: center;
    color: var(--primary-color);
}

.section-subtitle {
    text-align: center;
    color: var(--text-light);
    font-size: 1.1rem;
    margin-bottom: 2rem;
}

/* Location Section */
.location-content {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 3rem;
    align-items: center;
}

.location-info h3 {
    color: var(--primary-color);
    margin-bottom: 0.5rem;
    font-size: 1.5rem;
}

.location-info p {
    color: var(--text-light);
    margin-bottom: 1.5rem;
    line-height: 1.8;
}

.location-info h4 {
    color: var(--primary-color);
    margin-top: 1.5rem;
    margin-bottom: 0.5rem;
}

/* Important Dates & Location Grid */
.dates-location-grid {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 3rem;
    margin-top: 2rem;
}

.subsection-title {
    font-size: 1.75rem;
    color: var(--primary-color);
    margin-bottom: 1.5rem;
    font-weight: 700;
}

.dates-container,
.location-container {
    background: white;
    padding: 2rem;
    border-radius: 1rem;
    box-shadow: 0 4px 12px rgba(0, 0, 0, 0.08);
}

/* Important Dates List */
.dates-list {
    list-style: none;
    padding: 0;
    margin: 0;
}

.dates-list li {
    font-size: 1.05rem;
    line-height: 1.8;
    padding: 0.875rem 0;
    border-bottom: 1px solid var(--border-color);
    color: var(--text-dark);
    position: relative;
    padding-left: 1.75rem;
}

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

.dates-list li::before {
    content: '•';
    color: var(--primary-color);
    font-size: 1.4rem;
    font-weight: bold;
    position: absolute;
    left: 0;
    top: 0.875rem;
}

.dates-list li strong {
    color: var(--primary-color);
    font-weight: 600;
    margin-right: 0.5rem;
}

.deadline {
    color: #dc2626 !important;
    font-weight: 700;
    background: rgba(220, 38, 38, 0.1);
    padding: 0.2rem 0.5rem;
    border-radius: 0.25rem;
}

/* Location Info */
.location-info {
    margin-bottom: 1.5rem;
}

.location-info h4 {
    color: var(--primary-color);
    font-size: 1.25rem;
    margin-bottom: 0.5rem;
    font-weight: 600;
}

.location-info p {
    color: var(--text-light);
    line-height: 1.7;
    margin-bottom: 1rem;
}

.location-map {
    border-radius: 0.5rem;
    overflow: hidden;
    box-shadow: 0 2px 8px rgba(0, 0, 0, 0.1);
}

/* Registration Content */
.registration-content {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 3rem;
    margin-top: 2rem;
}

.submission-types {
    display: grid;
    gap: 1.5rem;
}

.submission-card {
    background: var(--light-bg);
    padding: 1.5rem;
    border-radius: 0.5rem;
    border-left: 4px solid var(--secondary-color);
}

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

/* Registration Charges Styling */
.registration-charges {
    background: linear-gradient(135deg, #f0f9ff 0%, #e0f2fe 100%);
    border-left: 4px solid var(--accent-color);
}

.charges-list {
    margin: 1rem 0 0 0;
    display: flex;
    flex-direction: column;
    gap: 1rem;
}

.charge-item {
    background: white;
    padding: 1rem 1.25rem;
    border-radius: 0.5rem;
    box-shadow: 0 2px 6px rgba(0, 0, 0, 0.08);
    transition: all 0.3s ease;
}

.charge-item:hover {
    transform: translateY(-2px);
    box-shadow: 0 4px 12px rgba(0, 0, 0, 0.12);
}

.charge-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 0.75rem;
    flex-wrap: wrap;
    gap: 0.5rem;
}

.charge-type {
    font-weight: 600;
    color: var(--primary-color);
    font-size: 1.1rem;
}

.charge-price {
    font-size: 1.5rem;
    font-weight: 800;
    color: var(--accent-color);
    letter-spacing: -0.5px;
}

.charge-note {
    font-size: 0.9rem;
    color: var(--text-light);
    line-height: 1.5;
}

.refund-note {
    background: #f0fdf4;
    padding: 0.6rem 0.75rem;
    border-radius: 0.375rem;
    border-left: 3px solid #22c55e;
}

.refund-badge {
    display: inline-block;
    background: #22c55e;
    color: white;
    padding: 0.2rem 0.6rem;
    border-radius: 1rem;
    font-size: 0.8rem;
    font-weight: 600;
    margin-right: 0.5rem;
}

.registration-info {
    background: var(--light-bg);
    padding: 2rem;
    border-radius: 0.75rem;
    border-left: 4px solid var(--primary-color);
}

.registration-info h3 {
    color: var(--primary-color);
    margin-bottom: 1.5rem;
}

.submission-requirements {
    display: flex;
    flex-direction: column;
    gap: 1rem;
    margin-bottom: 2rem;
}

.requirement-item {
    background: white;
    padding: 1rem 1.25rem;
    border-radius: 0.5rem;
    box-shadow: 0 2px 6px rgba(0, 0, 0, 0.08);
    transition: all 0.3s ease;
}

.requirement-item:hover {
    transform: translateY(-2px);
    box-shadow: 0 4px 12px rgba(0, 0, 0, 0.12);
}

.requirement-label {
    font-weight: 700;
    color: var(--primary-color);
    font-size: 0.95rem;
    margin-bottom: 0.5rem;
    text-transform: uppercase;
    letter-spacing: 0.5px;
}

.requirement-text {
    color: var(--text-dark);
    line-height: 1.6;
    font-size: 0.95rem;
}

.format-link {
    color: var(--accent-color);
    text-decoration: none;
    font-weight: 600;
    border-bottom: 2px solid transparent;
    transition: border-bottom-color 0.3s ease;
}

.format-link:hover {
    border-bottom-color: var(--accent-color);
}

.submission-action {
    text-align: center;
    padding-top: 1rem;
    border-top: 2px solid var(--border-color);
}

.submission-action p {
    margin-bottom: 1.25rem;
    color: var(--text-dark);
    font-weight: 500;
}

/* Schedule Tabs */
.schedule-tabs {
    display: flex;
    gap: 1rem;
    margin-bottom: 2rem;
    flex-wrap: wrap;
}

.tab-button {
    padding: 0.75rem 1.5rem;
    background: var(--light-bg);
    border: 2px solid var(--border-color);
    border-radius: 0.5rem;
    cursor: pointer;
    font-weight: 600;
    color: var(--text-dark);
    transition: all 0.3s ease;
}

.tab-button.active {
    background: var(--primary-color);
    color: white;
    border-color: var(--primary-color);
}

.tab-button:hover {
    border-color: var(--primary-color);
}

.tab-content {
    display: none;
}

.tab-content.active {
    display: block;
}

/* Schedule Table */
.schedule-table {
    width: 100%;
    border-collapse: collapse;
    background: white;
    border-radius: 0.75rem;
    overflow: hidden;
    box-shadow: 0 2px 8px rgba(0, 0, 0, 0.08);
}

.schedule-table thead {
    background: var(--primary-color);
    color: white;
}

.schedule-table th {
    padding: 1rem;
    text-align: left;
    font-weight: 600;
}

.schedule-table td {
    padding: 1rem;
    border-bottom: 1px solid var(--border-color);
}

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

.schedule-table tbody tr:hover {
    background: var(--light-bg);
}

.schedule-table tr.keynote {
    background: #f0f9ff;
    font-weight: 500;
}

.schedule-table tr.spotlight {
    background: #f5f3ff;
}

.schedule-table tr.poster {
    background: #fef2f2;
}

.schedule-table tr.break {
    background: #fef3c7;
    opacity: 0.7;
}

.tbd {
    color: #dc2626;
    font-weight: 600;
}

/* Speakers Grid */
.speakers-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(200px, 350px));
    gap: 2rem;
    margin-top: 2rem;
    justify-content: center;
}

.speaker-card {
    background: white;
    padding: 1.5rem;
    border-radius: 0.75rem;
    text-align: center;
    box-shadow: 0 2px 8px rgba(0, 0, 0, 0.08);
    transition: all 0.3s ease;
}

.speaker-card:hover {
    transform: translateY(-5px);
    box-shadow: 0 8px 16px rgba(0, 0, 0, 0.12);
}

.speaker-placeholder {
    font-size: 3rem;
    margin-bottom: 1rem;
}

.speaker-card h4 {
    color: var(--primary-color);
    margin-bottom: 0.5rem;
}

.tbd-text {
    color: var(--secondary-color);
    font-weight: 600;
}

/* Organizers Grid */
.organizers-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 2rem;
    margin-top: 2rem;
}

.organizer-card {
    background: white;
    padding: 2rem;
    border-radius: 0.75rem;
    text-align: center;
    box-shadow: 0 2px 8px rgba(0, 0, 0, 0.08);
    border-top: 3px solid var(--secondary-color);
}

.organizer-card h4 {
    color: var(--primary-color);
    margin-bottom: 0.5rem;
    font-size: 1.25rem;
}

.organizer-card p {
    color: var(--text-light);
}

.organizers-note {
    text-align: center;
    color: var(--text-light);
    margin-top: 2rem;
    font-style: italic;
}

/* Sponsors */
.sponsors-placeholder {
    background: var(--light-bg);
    padding: 3rem;
    border-radius: 0.75rem;
    text-align: center;
    color: var(--text-light);
}

/* Footer */
.footer {
    background: var(--primary-color);
    color: white;
    text-align: center;
    padding: 2rem;
    margin-top: 3rem;
}

.footer a {
    color: var(--accent-color);
    text-decoration: none;
}

.footer a:hover {
    text-decoration: underline;
}

/* Scroll to Top Button */
.scroll-top {
    position: fixed;
    bottom: 2rem;
    right: 2rem;
    width: 50px;
    height: 50px;
    background: var(--primary-color);
    color: white;
    border: none;
    border-radius: 50%;
    cursor: pointer;
    display: none;
    font-size: 1.5rem;
    z-index: 999;
    transition: all 0.3s ease;
    box-shadow: 0 4px 12px rgba(0, 0, 0, 0.15);
}

.scroll-top:hover {
    background: var(--secondary-color);
    transform: scale(1.1);
}

.scroll-top.show {
    display: flex;
    align-items: center;
    justify-content: center;
}

/* Responsive Design */
@media (max-width: 768px) {
    .nav-menu {
        display: none;
        position: absolute;
        top: 100%;
        left: 0;
        right: 0;
        background: var(--primary-color);
        flex-direction: column;
        padding: 1rem;
        gap: 0.5rem;
    }

    .nav-menu.active {
        display: flex;
    }

    .hamburger {
        display: flex;
    }

    .hero {
        padding: 4rem 1rem;
    }

    .hero-content h1 {
        font-size: 2rem;
    }

    .hero-subtitle {
        font-size: 1.1rem;
    }

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

    .btn {
        width: 100%;
    }

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

    .location-content {
        grid-template-columns: 1fr;
    }

    .dates-location-grid {
        grid-template-columns: 1fr;
        gap: 2rem;
    }

    .dates-container,
    .location-container {
        padding: 1.5rem;
    }

    .subsection-title {
        font-size: 1.5rem;
    }

    .dates-list li {
        font-size: 1rem;
        padding: 0.75rem 0;
        padding-left: 1.5rem;
    }

    .dates-list li::before {
        top: 0.75rem;
    }

    .registration-content {
        grid-template-columns: 1fr;
    }

    .charge-header {
        flex-direction: column;
        align-items: flex-start;
        gap: 0.25rem;
    }

    .charge-price {
        font-size: 1.35rem;
    }

    .schedule-table {
        font-size: 0.9rem;
    }

    .schedule-table th,
    .schedule-table td {
        padding: 0.75rem 0.5rem;
    }

    .speakers-grid {
        grid-template-columns: repeat(2, 1fr);
    }

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

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

    .section-title {
        font-size: 1.5rem;
    }

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

    .schedule-table th,
    .schedule-table td {
        padding: 0.5rem;
        font-size: 0.85rem;
    }
}