/* ===== Global Styles ===== */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
    font-family: 'Poppins', Arial, sans-serif;
}

:root {
    --primary: #ee4a62;
    --primary-dark: #d73a50;
    --secondary: #1EB980;
    --secondary-dark: #18a26f;
    --dark: #333;
    --light: #f5f5f5;
    --white: #ffffff;
    --gray: #6c757d;
    --light-gray: #e9ecef;
    --transition: all 0.3s ease;
    --shadow: 0 5px 15px rgba(0, 0, 0, 0.1);
    --shadow-lg: 0 10px 30px rgba(0, 0, 0, 0.15);
    --offline-bg: #ffdddd;
    --offline-header: #ff6b6b;
    --online-bg: #d4edda;
    --online-header: #28a745;
    --morning-bg: #fff3cd;
    --afternoon-bg: #cce5ff;
}

html {
    scroll-behavior: smooth;
}

body {
    background-color: var(--light);
    color: var(--dark);
    line-height: 1.6;
    min-height: 100vh;
    overflow-x: hidden;
}

h1, h2, h3, h4, h5 {
    font-family: 'Montserrat', sans-serif;
    color: var(--dark);
    line-height: 1.3;
}

.container {
    width: 100%;
    max-width: 1400px;
    margin: 0 auto;
    padding: 0 20px;
}

section {
    padding: 80px 0;
}

/* ===== Navbar ===== */
.navbar {
    display: flex;
    align-items: center;
    justify-content: space-between;
    background-color: var(--white);
    padding: 12px 20px;
    border-radius: 40px;
    box-shadow: var(--shadow);
    max-width: 1200px;
    width: 90%;
    margin: 20px auto;
    position: relative;
    z-index: 100;
}

.mobile-menu-toggle {
    display: none;
    background: transparent;
    border: none;
    font-size: 1.5rem;
    cursor: pointer;
    color: var(--dark);
}

.nav-links {
    display: flex;
    align-items: center;
    gap: 15px;
}

.nav-item {
    display: flex;
    align-items: center;
    color: var(--dark);
    text-decoration: none;
    font-size: 0.95rem;
    font-weight: 500;
    padding: 8px 12px;
    border-radius: 50px;
    transition: var(--transition);
}

.nav-item i {
    margin-right: 6px;
    font-size: 1rem;
}

.nav-item:hover, .nav-item.active {
    background-color: #ffdddd;
    color: var(--primary);
}

.cta-button {
    background-color: var(--primary);
    color: var(--white);
    border: none;
    font-size: 1rem;
    padding: 10px 20px;
    border-radius: 50px;
    font-weight: 600;
    cursor: pointer;
    text-decoration: none;
    transition: var(--transition);
}

.cta-button:hover {
    background-color: var(--primary-dark);
    transform: translateY(-3px);
    box-shadow: var(--shadow);
    color: var(--white);
}

/* ===== Hero Section ===== */
.hero {
    background: url('https://www.vidyavision.com/CollegeUploads/Photos/2019-06-3-16-56-55_Screenshot%20(103).png') center/cover no-repeat;
    position: relative;
    height: 50vh;
    min-height: 300px;
    display: flex;
    align-items: center;
    justify-content: center;
    color: var(--white);
    overflow: hidden;
}

.hero-overlay {
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: linear-gradient(135deg, rgba(9, 9, 10, 0.9), rgba(53, 53, 55, 0.8));
    z-index: 1;
}

.hero-content {
    position: relative;
    z-index: 2;
    text-align: center;
    max-width: 900px;
    padding: 0 20px;
}

.hero h1 {
    font-size: 2.5rem;
    font-weight: 700;
    margin-bottom: 20px;
    color: var(--white);
    text-transform: uppercase;
}

.hero .subtitle {
    font-size: 1.8rem;
    font-weight: 500;
    margin-bottom: 20px;
    color: var(--white);
}

.hero .date {
    display: inline-block;
    font-size: 1.2rem;
    padding: 10px 30px;
    background-color: var(--primary);
    color: var(--white);
    border-radius: 50px;
    font-weight: 500;
    letter-spacing: 1px;
    margin-top: 20px;
    box-shadow: 0 5px 15px rgba(0, 0, 0, 0.2);
}

/* ===== Section Header ===== */
.section-header {
    text-align: center;
    margin-bottom: 50px;
}

.section-title {
    font-size: 2.5rem;
    font-weight: 700;
    color: var(--dark);
    margin-bottom: 15px;
    text-transform: uppercase;
}

.section-description {
    font-size: 1.1rem;
    color: var(--secondary);
    max-width: 800px;
    margin: 0 auto 15px;
}

.section-divider {
    display: flex;
    justify-content: center;
    margin-bottom: 30px;
}

.divider-decoration {
    width: 80px;
    height: 4px;
    background: linear-gradient(90deg, var(--primary), var(--secondary));
    border-radius: 2px;
}

/* ===== Day Tabs ===== */
.day-tabs {
    display: flex;
    justify-content: center;
    gap: 15px;
    margin-bottom: 40px;
    flex-wrap: wrap;
}

.day-tab {
    background-color: var(--white);
    border: 2px solid var(--primary);
    color: var(--primary);
    padding: 15px 30px;
    border-radius: 50px;
    font-size: 1rem;
    font-weight: 600;
    cursor: pointer;
    transition: var(--transition);
    display: flex;
    align-items: center;
    gap: 10px;
}

.day-tab:hover {
    background-color: var(--primary);
    color: var(--white);
    transform: translateY(-3px);
    box-shadow: var(--shadow);
}

.day-tab.active {
    background-color: var(--primary);
    color: var(--white);
    box-shadow: var(--shadow-lg);
}

.day-tab i {
    font-size: 1.1rem;
}

/* ===== Day Content ===== */
.day-content {
    display: none;
    animation: fadeIn 0.5s ease;
}

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

.day-header {
    background: linear-gradient(135deg, #00bcd4, #0097a7);
    color: var(--white);
    padding: 20px 30px;
    border-radius: 10px;
    margin-bottom: 30px;
    box-shadow: var(--shadow);
}

.day-header h3 {
    font-size: 1.5rem;
    font-weight: 700;
    color: var(--white);
    display: flex;
    align-items: center;
    gap: 15px;
}

.day-header h3 i {
    font-size: 1.3rem;
}

/* ===== Session Block ===== */
.session-block {
    margin-bottom: 40px;
    background-color: var(--white);
    border-radius: 10px;
    box-shadow: var(--shadow);
    overflow: hidden;
}

.session-title {
    padding: 15px 25px;
    background: linear-gradient(135deg, #ff9a9e, #fecfef);
}

.session-block.morning .session-title {
    background: linear-gradient(135deg, #ff9a9e, #fecfef);
}

.session-block.afternoon .session-title {
    background: linear-gradient(135deg, #a8edea, #fed6e3);
}

.session-title h4 {
    font-size: 1.2rem;
    font-weight: 600;
    color: var(--dark);
    display: flex;
    align-items: center;
    gap: 10px;
}

.session-title h4 i {
    color: var(--primary);
}

/* ===== Session Content ===== */
.session-content {
    padding: 30px;
}

.session-content.inaugural {
    display: flex;
    justify-content: center;
    align-items: center;
    min-height: 200px;
    background: linear-gradient(135deg, #fff3cd, #ffeeba);
}

.event-card.large {
    text-align: center;
    padding: 40px 60px;
}

.event-card.large h5 {
    font-size: 2rem;
    font-weight: 700;
    color: var(--dark);
    margin: 10px 0;
}

.event-card.large p {
    font-size: 1.5rem;
    color: var(--dark);
}

/* ===== Session Grid ===== */
.session-grid {
    display: grid;
    gap: 20px;
    padding: 25px;
}

.session-grid.three-col {
    grid-template-columns: repeat(3, 1fr);
}

.session-grid.four-col {
    grid-template-columns: repeat(4, 1fr);
}

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

/* ===== Technical Session Card ===== */
.technical-session {
    background-color: var(--light);
    border-radius: 10px;
    overflow: hidden;
    box-shadow: var(--shadow);
    transition: var(--transition);
}

.technical-session:hover {
    transform: translateY(-5px);
    box-shadow: var(--shadow-lg);
}

.technical-session.offline {
    border-top: 4px solid var(--offline-header);
}

.technical-session.online {
    border-top: 4px solid var(--online-header);
}

.session-header-card {
    padding: 15px;
    text-align: center;
}

.session-header-card .venue {
    display: block;
    font-size: 1rem;
    font-weight: 700;
    color: var(--dark);
    margin-bottom: 8px;
}

.session-header-card .session-type {
    display: inline-block;
    padding: 5px 15px;
    border-radius: 20px;
    font-size: 0.85rem;
    font-weight: 600;
    color: var(--white);
    background-color: #dc3545;
}

.session-header-card .session-type.online {
    background-color: var(--online-header);
}

.technical-session.online .session-header-card .session-type {
    background-color: var(--online-header);
}

/* ===== Coordinator Info ===== */
.coordinator-info {
    padding: 15px;
    background-color: var(--white);
    text-align: center;
    border-bottom: 1px solid var(--light-gray);
}

.coordinator-info p {
    font-size: 0.9rem;
    margin: 3px 0;
}

.coordinator-info strong {
    color: var(--primary);
}

/* ===== Session Chairs ===== */
.chairs {
    padding: 15px;
    background-color: #f8f9fa;
    border-bottom: 1px solid var(--light-gray);
}

.chairs .chair-title {
    font-weight: 600;
    color: var(--gray);
    text-align: center;
    margin-bottom: 10px;
    font-size: 0.85rem;
}

.chairs p {
    font-size: 0.9rem;
    margin: 5px 0;
    text-align: center;
}

/* ===== Invited Talk ===== */
.invited-talk {
    padding: 15px;
    background-color: #fff8e1;
    border-bottom: 1px solid var(--light-gray);
    text-align: center;
}

.invited-talk .talk-title {
    font-weight: 600;
    color: #ff8f00;
    margin-bottom: 8px;
    font-size: 0.9rem;
}

.invited-talk .speaker {
    font-size: 0.9rem;
    color: #d84315;
    font-weight: 500;
}

/* ===== Papers List ===== */
.papers {
    padding: 15px;
    background-color: var(--white);
}

.papers .paper {
    font-size: 0.85rem;
    padding: 8px 12px;
    margin: 5px 0;
    border-radius: 5px;
    text-align: center;
    transition: var(--transition);
}

.technical-session.offline .papers .paper {
    background-color: #ffebee;
    color: #c62828;
}

.technical-session.online .papers .paper {
    background-color: #e8f5e9;
    color: #2e7d32;
}

.papers .paper:hover {
    transform: scale(1.02);
}

/* ===== Valedictory Block ===== */
.valedictory-block {
    display: flex;
    align-items: center;
    justify-content: center;
    background: linear-gradient(135deg, #ff9a9e, #fecfef);
    border-radius: 10px;
    min-height: 300px;
}

.valedictory-label {
    writing-mode: vertical-rl;
    text-orientation: mixed;
    transform: rotate(180deg);
}

.valedictory-label span {
    font-size: 1.5rem;
    font-weight: 700;
    color: var(--dark);
    letter-spacing: 3px;
}

/* ===== Footer ===== */
.footer {
    background: linear-gradient(135deg, #1a1a2e, #16213e);
    color: var(--white);
    padding: 60px 20px 30px;
}

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

.footer-logo h2 {
    font-size: 1.8rem;
    color: var(--white);
    margin-bottom: 1rem;
}

.footer-logo span {
    color: var(--secondary);
}

.footer-info p {
    color: rgba(255, 255, 255, 0.7);
    margin-bottom: 1.5rem;
    line-height: 1.8;
}

.footer-links {
    display: flex;
    flex-wrap: wrap;
    gap: 15px;
}

.footer-links a {
    color: rgba(255, 255, 255, 0.7);
    text-decoration: none;
    transition: var(--transition);
}

.footer-links a:hover {
    color: var(--secondary);
}

.footer h3 {
    font-size: 1.3rem;
    margin-bottom: 1.5rem;
    color: var(--white);
    position: relative;
    padding-bottom: 10px;
}

.footer h3::after {
    content: '';
    position: absolute;
    bottom: 0;
    left: 0;
    width: 40px;
    height: 3px;
    background: var(--primary);
}

.contact-item {
    display: flex;
    align-items: flex-start;
    gap: 15px;
    margin-bottom: 1rem;
}

.contact-icon {
    width: 40px;
    height: 40px;
    border-radius: 50%;
    background: rgba(255, 255, 255, 0.1);
    display: flex;
    align-items: center;
    justify-content: center;
    flex-shrink: 0;
}

.contact-icon i {
    color: var(--secondary);
}

.contact-text {
    color: rgba(255, 255, 255, 0.7);
}

.social-icons {
    display: flex;
    gap: 0.8rem;
    margin-top: 1.5rem;
}

.social-icons a {
    display: flex;
    align-items: center;
    justify-content: center;
    width: 38px;
    height: 38px;
    border-radius: 50%;
    background-color: rgba(255, 255, 255, 0.1);
    color: var(--white);
    font-size: 1rem;
    transition: var(--transition);
    text-decoration: none;
}

.social-icons a:hover {
    background-color: var(--primary);
    transform: translateY(-3px);
    color: var(--white);
}

.newsletter {
    margin-top: 2rem;
}

.newsletter form {
    display: flex;
    max-width: 400px;
    margin-top: 1rem;
}

.newsletter input {
    flex: 1;
    padding: 0.8rem 1rem;
    border: none;
    background: rgba(255, 255, 255, 0.1);
    color: var(--white);
    border-radius: 4px 0 0 4px;
    outline: none;
}

.newsletter input::placeholder {
    color: rgba(255, 255, 255, 0.5);
}

.newsletter button {
    background: var(--white);
    color: var(--primary);
    border: none;
    padding: 0 1.2rem;
    font-weight: 600;
    border-radius: 0 4px 4px 0;
    cursor: pointer;
    transition: var(--transition);
}

.newsletter button:hover {
    background: var(--light-gray);
}

.footer-bottom {
    width: 100%;
    text-align: center;
    padding-top: 1.5rem;
    border-top: 1px solid rgba(255, 255, 255, 0.1);
    margin-top: 3rem;
    font-size: 0.9rem;
    color: rgba(255, 255, 255, 0.6);
}

.footer-bottom strong {
    color: var(--secondary);
    font-weight: 600;
}

/* ===== Scroll to Top Button ===== */
.scroll-to-top {
    position: fixed;
    bottom: 30px;
    right: 30px;
    width: 50px;
    height: 50px;
    background-color: var(--primary);
    color: var(--white);
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 1.2rem;
    box-shadow: var(--shadow);
    cursor: pointer;
    opacity: 0;
    visibility: hidden;
    transition: var(--transition);
    z-index: 999;
}

.scroll-to-top.visible {
    opacity: 1;
    visibility: visible;
}

.scroll-to-top:hover {
    background-color: var(--primary-dark);
    transform: translateY(-5px);
}

/* ===== Animation Classes ===== */
.animate-fade-in {
    opacity: 0;
    animation: fadeIn 1s ease forwards;
    animation-delay: 0.3s;
}

.animate-fade-up {
    opacity: 0;
    transform: translateY(30px);
    animation: fadeInUp 1s ease forwards;
    animation-delay: 0.5s;
}

.animate-fade-down {
    opacity: 0;
    transform: translateY(-30px);
    animation: fadeInDown 1s ease forwards;
    animation-delay: 0.3s;
}

@keyframes fadeIn {
    from { opacity: 0; }
    to { opacity: 1; }
}

@keyframes fadeInUp {
    from { 
        opacity: 0;
        transform: translateY(30px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

@keyframes fadeInDown {
    from { 
        opacity: 0;
        transform: translateY(-30px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

/* ===== Responsive Styles ===== */
@media (max-width: 1200px) {
    .session-grid.three-col,
    .session-grid.four-col {
        grid-template-columns: repeat(2, 1fr);
    }
    
    .section-title {
        font-size: 2rem;
    }
}

@media (max-width: 992px) {
    .navbar {
        width: 95%;
        padding: 10px 15px;
    }
    
    .nav-links {
        gap: 10px;
    }
    
    .nav-item {
        font-size: 0.85rem;
        padding: 6px 10px;
    }
}

@media (max-width: 768px) {
    .navbar {
        padding: 15px;
    }
    
    .mobile-menu-toggle {
        display: block;
    }
    
    .nav-links {
        position: absolute;
        top: 100%;
        left: 0;
        right: 0;
        background-color: var(--white);
        flex-direction: column;
        width: 100%;
        padding: 20px;
        border-radius: 0 0 20px 20px;
        box-shadow: var(--shadow);
        display: none;
        margin-top: 10px;
    }
    
    .nav-links.active {
        display: flex;
    }
    
    .nav-item {
        width: 100%;
        padding: 12px;
        justify-content: center;
    }
    
    .hero {
        height: 40vh;
    }
    
    .hero h1 {
        font-size: 1.8rem;
    }
    
    .hero .subtitle {
        font-size: 1.3rem;
    }
    
    .day-tabs {
        flex-direction: column;
        align-items: center;
    }
    
    .day-tab {
        width: 100%;
        max-width: 300px;
        justify-content: center;
    }
    
    .session-grid.three-col,
    .session-grid.four-col,
    .session-grid.two-col {
        grid-template-columns: 1fr;
    }
    
    .valedictory-block {
        min-height: 150px;
    }
    
    .valedictory-label {
        writing-mode: horizontal-tb;
        transform: none;
    }
    
    section {
        padding: 60px 0;
    }
    
    .section-title {
        font-size: 1.6rem;
    }
}

@media (max-width: 576px) {
    .navbar {
        border-radius: 20px;
        width: 95%;
        margin: 15px auto;
    }
    
    .cta-button {
        margin-left: auto;
    }
    
    .hero h1 {
        font-size: 1.4rem;
    }
    
    .hero .subtitle {
        font-size: 1.1rem;
    }
    
    .hero .date {
        font-size: 0.9rem;
        padding: 8px 20px;
    }
    
    .event-card.large h5 {
        font-size: 1.5rem;
    }
    
    .event-card.large p {
        font-size: 1.2rem;
    }
    
    .footer-container {
        grid-template-columns: 1fr;
    }
    
    .footer-info, .footer-contact, .footer-social {
        text-align: center;
    }
    
    .footer h3::after {
        left: 50%;
        transform: translateX(-50%);
    }
    
    .contact-item {
        justify-content: center;
    }
    
    .social-icons {
        justify-content: center;
    }
    
    .newsletter form {
        margin: 0 auto;
    }
}