/* AIVTA 2026 Conference Website Stylesheet */

/* ========================================
   CSS Variables
   ======================================== */
:root {
    --primary-color: #1a5276;
    --primary-dark: #154360;
    --accent-color: #d4ac0d;
    --accent-hover: #b7950b;
    --secondary-color: #2e86ab;
    --background-color: #ffffff;
    --background-light: #f8f9fa;
    --background-dark: #2c3e50;
    --text-color: #2c3e50;
    --text-light: #6c757d;
    --text-white: #ffffff;
    --border-color: #dee2e6;
    --shadow: 0 2px 10px rgba(0, 0, 0, 0.1);
    --shadow-hover: 0 4px 20px rgba(0, 0, 0, 0.15);
    --transition: all 0.3s ease;
    --max-width: 1200px;
    --header-height: 80px;
}

/* ========================================
   Reset & Base Styles
   ======================================== */
*, *::before, *::after {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
}

html {
    scroll-behavior: smooth;
}

body {
    font-family: "Open Sans", "PingFang SC", "Microsoft YaHei", sans-serif;
    font-size: 16px;
    line-height: 1.6;
    color: var(--text-color);
    background-color: var(--background-color);
}

h1, h2, h3, h4, h5, h6 {
    font-family: "Roboto", "Microsoft YaHei", sans-serif;
    font-weight: 700;
    line-height: 1.3;
    margin-bottom: 1rem;
}

h1 { font-size: 2.5rem; }
h2 { font-size: 2rem; }
h3 { font-size: 1.5rem; }
h4 { font-size: 1.25rem; }

p {
    margin-bottom: 1rem;
}

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

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

img {
    max-width: 100%;
    height: auto;
}

ul, ol {
    margin-bottom: 1rem;
    padding-left: 1.5rem;
}

li {
    margin-bottom: 0.5rem;
}

/* ========================================
   Container & Layout
   ======================================== */
.container {
    max-width: var(--max-width);
    margin: 0 auto;
    padding: 0 20px;
}

.section {
    padding: 60px 0;
}

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

.section-dark {
    background-color: var(--background-dark);
    color: var(--text-white);
}

.section-title {
    text-align: center;
    margin-bottom: 40px;
    position: relative;
}

.section-title::after {
    content: '';
    display: block;
    width: 60px;
    height: 3px;
    background-color: var(--accent-color);
    margin: 15px auto 0;
}

.section-title.text-left {
    text-align: left;
}

.section-title.text-left::after {
    margin: 15px 0 0;
}

/* Grid System */
.row {
    display: flex;
    flex-wrap: wrap;
    margin: 0 -15px;
}

.col {
    padding: 0 15px;
    flex: 1;
}

.col-50 {
    flex: 0 0 50%;
    max-width: 50%;
    padding: 0 15px;
}

.col-33 {
    flex: 0 0 33.333%;
    max-width: 33.333%;
    padding: 0 15px;
}

.col-25 {
    flex: 0 0 25%;
    max-width: 25%;
    padding: 0 15px;
}

/* ========================================
   Header & Navigation
   ======================================== */
.header {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    height: var(--header-height);
    background-color: var(--background-color);
    box-shadow: var(--shadow);
    z-index: 1000;
    transition: var(--transition);
}

.header.scrolled {
    height: 60px;
}

.header .container {
    display: flex;
    justify-content: space-between;
    align-items: center;
    height: 100%;
}

.logo {
    display: flex;
    align-items: center;
    gap: 10px;
}

.logo img {
    height: 50px;
}

.logo-text {
    font-family: "Roboto", sans-serif;
    font-weight: 700;
    font-size: 1.5rem;
    color: var(--primary-color);
}

.logo-text span {
    color: var(--accent-color);
}

.nav {
    display: flex;
    align-items: center;
    gap: 5px;
}

.nav a {
    padding: 10px 15px;
    color: var(--text-color);
    font-weight: 500;
    border-radius: 4px;
    transition: var(--transition);
}

.nav a:hover,
.nav a.active {
    color: var(--accent-color);
    background-color: rgba(212, 172, 13, 0.1);
}

.lang-switch {
    margin-left: 15px;
    padding: 8px 16px;
    background-color: var(--primary-color);
    color: var(--text-white) !important;
    border-radius: 4px;
    font-size: 0.9rem;
    cursor: pointer;
}

.lang-switch:hover {
    background-color: var(--primary-dark);
    color: var(--text-white) !important;
}

/* Mobile Menu */
.mobile-menu-btn {
    display: none;
    flex-direction: column;
    gap: 5px;
    cursor: pointer;
    padding: 10px;
}

.mobile-menu-btn span {
    width: 25px;
    height: 3px;
    background-color: var(--text-color);
    transition: var(--transition);
}

/* ========================================
   Hero Section
   ======================================== */
.hero {
    min-height: 100vh;
    display: flex;
    align-items: center;
    justify-content: center;
    background: linear-gradient(135deg, var(--primary-color) 0%, var(--secondary-color) 100%);
    color: var(--text-white);
    text-align: center;
    padding-top: var(--header-height);
    position: relative;
    overflow: hidden;
}

.hero::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: url('data:image/svg+xml,<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 100 100"><circle cx="50" cy="50" r="40" fill="none" stroke="rgba(255,255,255,0.05)" stroke-width="0.5"/></svg>');
    background-size: 100px;
    opacity: 0.5;
}

.hero-content {
    position: relative;
    z-index: 1;
    max-width: 900px;
    padding: 0 20px;
}

.hero-badge {
    display: inline-block;
    padding: 8px 20px;
    background-color: var(--accent-color);
    color: var(--text-color);
    border-radius: 30px;
    font-size: 0.9rem;
    font-weight: 600;
    margin-bottom: 20px;
}

.hero h1 {
    font-size: 3rem;
    margin-bottom: 15px;
    text-shadow: 2px 2px 4px rgba(0, 0, 0, 0.2);
}

.hero-subtitle {
    font-size: 1.5rem;
    margin-bottom: 10px;
    opacity: 0.95;
}

.hero-location {
    font-size: 1.2rem;
    margin-bottom: 30px;
    opacity: 0.9;
}

.hero-location i {
    margin-right: 8px;
}

/* Countdown Timer */
.countdown {
    display: flex;
    justify-content: center;
    gap: 20px;
    margin-bottom: 40px;
}

.countdown-item {
    background-color: rgba(255, 255, 255, 0.15);
    backdrop-filter: blur(10px);
    padding: 20px 25px;
    border-radius: 10px;
    min-width: 100px;
}

.countdown-number {
    font-size: 2.5rem;
    font-weight: 700;
    display: block;
    color: var(--accent-color);
}

.countdown-label {
    font-size: 0.9rem;
    text-transform: uppercase;
    letter-spacing: 1px;
    opacity: 0.9;
}

/* Hero Buttons */
.hero-buttons {
    display: flex;
    justify-content: center;
    gap: 15px;
    flex-wrap: wrap;
}

/* ========================================
   Buttons
   ======================================== */
.btn {
    display: inline-block;
    padding: 12px 30px;
    border-radius: 5px;
    font-weight: 600;
    text-transform: uppercase;
    letter-spacing: 1px;
    font-size: 0.9rem;
    cursor: pointer;
    transition: var(--transition);
    border: none;
}

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

.btn-primary:hover {
    background-color: var(--accent-hover);
    color: var(--text-color);
    transform: translateY(-2px);
    box-shadow: var(--shadow-hover);
}

.btn-outline {
    background-color: transparent;
    border: 2px solid var(--text-white);
    color: var(--text-white);
}

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

.btn-outline-dark {
    background-color: transparent;
    border: 2px solid var(--primary-color);
    color: var(--primary-color);
}

.btn-outline-dark:hover {
    background-color: var(--primary-color);
    color: var(--text-white);
}

/* ========================================
   Important Dates Section
   ======================================== */
.dates-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 20px;
}

.date-card {
    background-color: var(--background-color);
    padding: 25px;
    border-radius: 10px;
    box-shadow: var(--shadow);
    border-left: 4px solid var(--accent-color);
    transition: var(--transition);
}

.date-card:hover {
    transform: translateY(-5px);
    box-shadow: var(--shadow-hover);
}

.date-card h4 {
    color: var(--primary-color);
    margin-bottom: 10px;
}

.date-card .date {
    font-size: 1.2rem;
    font-weight: 700;
    color: var(--accent-color);
}

/* ========================================
   Topics Section
   ======================================== */
.topics-tabs {
    display: flex;
    flex-wrap: wrap;
    justify-content: center;
    gap: 10px;
    margin-bottom: 30px;
}

.topic-tab {
    padding: 10px 20px;
    background-color: var(--background-light);
    border: 2px solid transparent;
    border-radius: 30px;
    cursor: pointer;
    transition: var(--transition);
    font-weight: 500;
}

.topic-tab:hover,
.topic-tab.active {
    border-color: var(--accent-color);
    background-color: rgba(212, 172, 13, 0.1);
    color: var(--primary-color);
}

.topic-content {
    display: none;
    background-color: var(--background-color);
    padding: 30px;
    border-radius: 10px;
    box-shadow: var(--shadow);
}

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

.topic-content h3 {
    color: var(--primary-color);
    margin-bottom: 20px;
    padding-bottom: 10px;
    border-bottom: 2px solid var(--accent-color);
}

.topic-list {
    columns: 2;
    column-gap: 40px;
}

.topic-list li {
    break-inside: avoid;
    padding: 8px 0;
}

/* Topic Cards */
.topics-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: 25px;
}

.topic-card {
    background-color: var(--background-color);
    padding: 30px;
    border-radius: 10px;
    box-shadow: var(--shadow);
    transition: var(--transition);
    border-top: 4px solid var(--accent-color);
}

.topic-card:hover {
    transform: translateY(-5px);
    box-shadow: var(--shadow-hover);
}

.topic-card-icon {
    width: 60px;
    height: 60px;
    background-color: rgba(26, 82, 118, 0.1);
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    margin-bottom: 20px;
    font-size: 1.5rem;
    color: var(--primary-color);
}

.topic-card h4 {
    color: var(--primary-color);
    margin-bottom: 15px;
}

.topic-card p {
    color: var(--text-light);
    font-size: 0.95rem;
}

/* ========================================
   Highlights Section
   ======================================== */
.highlights-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 30px;
}

.highlight-item {
    text-align: center;
    padding: 30px;
}

.highlight-icon {
    width: 80px;
    height: 80px;
    background-color: var(--accent-color);
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    margin: 0 auto 20px;
    font-size: 2rem;
    color: var(--text-white);
}

.highlight-item h3 {
    color: var(--primary-color);
    margin-bottom: 10px;
}

.highlight-item p {
    color: var(--text-light);
}

/* ========================================
   Committee Section
   ======================================== */
.committee-category {
    margin-bottom: 50px;
}

.committee-category h3 {
    color: var(--primary-color);
    padding-bottom: 15px;
    border-bottom: 2px solid var(--accent-color);
    margin-bottom: 25px;
}

.committee-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 25px;
}

.committee-card {
    background-color: var(--background-color);
    padding: 25px;
    border-radius: 10px;
    box-shadow: var(--shadow);
    transition: var(--transition);
    display: flex;
    gap: 20px;
}

.committee-card:hover {
    transform: translateY(-3px);
    box-shadow: var(--shadow-hover);
}

.committee-avatar {
    width: 80px;
    height: 80px;
    border-radius: 50%;
    background-color: var(--primary-color);
    display: flex;
    align-items: center;
    justify-content: center;
    color: var(--text-white);
    font-size: 2rem;
    font-weight: 700;
    flex-shrink: 0;
}

.committee-info h4 {
    color: var(--primary-color);
    margin-bottom: 5px;
}

.committee-role {
    color: var(--accent-color);
    font-weight: 600;
    font-size: 0.9rem;
    margin-bottom: 5px;
}

.committee-affiliation {
    color: var(--text-light);
    font-size: 0.9rem;
}

/* ========================================
   Submission Page
   ======================================== */
.submission-info {
    background-color: var(--background-light);
    padding: 30px;
    border-radius: 10px;
    margin-bottom: 30px;
}

.submission-info h3 {
    color: var(--primary-color);
    margin-bottom: 20px;
}

.requirements-list {
    list-style: none;
    padding-left: 0;
}

.requirements-list li {
    padding: 10px 0;
    padding-left: 30px;
    position: relative;
    border-bottom: 1px solid var(--border-color);
}

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

.requirements-list li::before {
    content: '✓';
    position: absolute;
    left: 0;
    color: var(--accent-color);
    font-weight: bold;
}

.template-download {
    background-color: var(--primary-color);
    color: var(--text-white);
    padding: 30px;
    border-radius: 10px;
    display: flex;
    align-items: center;
    justify-content: space-between;
    flex-wrap: wrap;
    gap: 20px;
}

.template-download h4 {
    margin-bottom: 5px;
}

.template-download p {
    margin-bottom: 0;
    opacity: 0.9;
}

/* ========================================
   Publication Page
   ======================================== */
.publication-highlight {
    background: linear-gradient(135deg, var(--primary-color) 0%, var(--secondary-color) 100%);
    color: var(--text-white);
    padding: 50px;
    border-radius: 15px;
    text-align: center;
    margin-bottom: 40px;
}

.publication-highlight h2 {
    margin-bottom: 20px;
}

.indexing-badges {
    display: flex;
    justify-content: center;
    gap: 20px;
    flex-wrap: wrap;
    margin-top: 30px;
}

.indexing-badge {
    background-color: rgba(255, 255, 255, 0.2);
    padding: 15px 30px;
    border-radius: 10px;
    font-weight: 600;
}

/* ========================================
   Contact Page
   ======================================== */
.contact-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 30px;
}

.contact-card {
    background-color: var(--background-color);
    padding: 30px;
    border-radius: 10px;
    box-shadow: var(--shadow);
}

.contact-card h3 {
    color: var(--primary-color);
    margin-bottom: 20px;
    padding-bottom: 10px;
    border-bottom: 2px solid var(--accent-color);
}

.contact-item {
    display: flex;
    gap: 15px;
    margin-bottom: 15px;
}

.contact-icon {
    width: 40px;
    height: 40px;
    background-color: rgba(26, 82, 118, 0.1);
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    color: var(--primary-color);
    flex-shrink: 0;
}

.contact-details h4 {
    margin-bottom: 5px;
    font-size: 1rem;
}

.contact-details p {
    color: var(--text-light);
    margin-bottom: 0;
    font-size: 0.95rem;
}

/* Map placeholder */
.map-placeholder {
    height: 300px;
    background-color: var(--background-light);
    border-radius: 10px;
    display: flex;
    align-items: center;
    justify-content: center;
    color: var(--text-light);
    font-size: 1.2rem;
}

/* ========================================
   Page Header (for inner pages)
   ======================================== */
.page-header {
    background: linear-gradient(135deg, var(--primary-color) 0%, var(--secondary-color) 100%);
    color: var(--text-white);
    padding: 120px 0 60px;
    text-align: center;
    margin-top: var(--header-height);
}

.page-header h1 {
    margin-bottom: 10px;
}

.page-header p {
    opacity: 0.9;
    font-size: 1.1rem;
}

.breadcrumb {
    margin-top: 20px;
    font-size: 0.95rem;
}

.breadcrumb a {
    color: var(--text-white);
    opacity: 0.8;
}

.breadcrumb a:hover {
    opacity: 1;
}

.breadcrumb span {
    opacity: 0.6;
    margin: 0 10px;
}

/* ========================================
   Table Styles
   ======================================== */
.table-responsive {
    overflow-x: auto;
}

table {
    width: 100%;
    border-collapse: collapse;
    margin-bottom: 30px;
    background-color: var(--background-color);
    box-shadow: var(--shadow);
    border-radius: 10px;
    overflow: hidden;
}

th, td {
    padding: 15px 20px;
    text-align: left;
    border-bottom: 1px solid var(--border-color);
}

th {
    background-color: var(--primary-color);
    color: var(--text-white);
    font-weight: 600;
}

tr:last-child td {
    border-bottom: none;
}

tr:hover {
    background-color: var(--background-light);
}

/* ========================================
   Footer
   ======================================== */
.footer {
    background-color: var(--background-dark);
    color: var(--text-white);
    padding: 60px 0 30px;
}

.footer-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 40px;
    margin-bottom: 40px;
}

.footer-section h4 {
    color: var(--accent-color);
    margin-bottom: 20px;
}

.footer-section a {
    color: rgba(255, 255, 255, 0.8);
    display: block;
    margin-bottom: 10px;
}

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

.footer-bottom {
    border-top: 1px solid rgba(255, 255, 255, 0.1);
    padding-top: 30px;
    text-align: center;
    opacity: 0.8;
    font-size: 0.9rem;
}

.organizer-logos {
    display: flex;
    justify-content: center;
    gap: 30px;
    flex-wrap: wrap;
    margin-top: 20px;
}

.organizer-logos img {
    height: 50px;
    opacity: 0.8;
    transition: var(--transition);
}

.organizer-logos img:hover {
    opacity: 1;
}

/* ========================================
   Coming Soon Page
   ======================================== */
.coming-soon {
    text-align: center;
    padding: 100px 20px;
}

.coming-soon h2 {
    color: var(--primary-color);
    margin-bottom: 20px;
}

.coming-soon p {
    color: var(--text-light);
    font-size: 1.2rem;
}

/* ========================================
   Alert/Notice Boxes
   ======================================== */
.alert {
    padding: 20px 25px;
    border-radius: 10px;
    margin-bottom: 20px;
}

.alert-info {
    background-color: rgba(46, 134, 171, 0.1);
    border-left: 4px solid var(--secondary-color);
}

.alert-warning {
    background-color: rgba(212, 172, 13, 0.1);
    border-left: 4px solid var(--accent-color);
}

.alert-success {
    background-color: rgba(39, 174, 96, 0.1);
    border-left: 4px solid #27ae60;
}

/* ========================================
   Responsive Design
   ======================================== */
@media (max-width: 1024px) {
    h1 { font-size: 2rem; }
    h2 { font-size: 1.75rem; }

    .hero h1 {
        font-size: 2.5rem;
    }

    .hero-subtitle {
        font-size: 1.3rem;
    }

    .topic-list {
        columns: 1;
    }
}

@media (max-width: 768px) {
    :root {
        --header-height: 70px;
    }

    .nav {
        display: none;
        position: absolute;
        top: var(--header-height);
        left: 0;
        right: 0;
        background-color: var(--background-color);
        flex-direction: column;
        padding: 20px;
        box-shadow: var(--shadow);
    }

    .nav.active {
        display: flex;
    }

    .nav a {
        padding: 15px;
        border-bottom: 1px solid var(--border-color);
    }

    .lang-switch {
        margin: 15px 0 0;
        text-align: center;
    }

    .mobile-menu-btn {
        display: flex;
    }

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

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

    .countdown {
        gap: 10px;
    }

    .countdown-item {
        padding: 15px;
        min-width: 70px;
    }

    .countdown-number {
        font-size: 1.8rem;
    }

    .hero-buttons {
        flex-direction: column;
        align-items: center;
    }

    .col-50, .col-33, .col-25 {
        flex: 0 0 100%;
        max-width: 100%;
    }

    .committee-card {
        flex-direction: column;
        text-align: center;
    }

    .committee-avatar {
        margin: 0 auto;
    }

    .template-download {
        flex-direction: column;
        text-align: center;
    }

    .page-header {
        padding: 100px 0 40px;
    }
}

@media (max-width: 480px) {
    .section {
        padding: 40px 0;
    }

    .countdown-item {
        padding: 10px;
        min-width: 60px;
    }

    .countdown-number {
        font-size: 1.5rem;
    }

    .countdown-label {
        font-size: 0.75rem;
    }

    th, td {
        padding: 10px 15px;
        font-size: 0.9rem;
    }
}

/* ========================================
   Utility Classes
   ======================================== */
.text-center { text-align: center; }
.text-left { text-align: left; }
.text-right { text-align: right; }

.mb-0 { margin-bottom: 0; }
.mb-1 { margin-bottom: 0.5rem; }
.mb-2 { margin-bottom: 1rem; }
.mb-3 { margin-bottom: 1.5rem; }
.mb-4 { margin-bottom: 2rem; }

.mt-0 { margin-top: 0; }
.mt-1 { margin-top: 0.5rem; }
.mt-2 { margin-top: 1rem; }
.mt-3 { margin-top: 1.5rem; }
.mt-4 { margin-top: 2rem; }

.py-4 { padding-top: 2rem; padding-bottom: 2rem; }

.hidden { display: none; }

.sr-only {
    position: absolute;
    width: 1px;
    height: 1px;
    padding: 0;
    margin: -1px;
    overflow: hidden;
    clip: rect(0, 0, 0, 0);
    border: 0;
}