:root {
    --primary-color: #14418b;
    --secondary-color: #3364b7;
    --accent-color: #f5a700;
    --light-accent: #f8c846;
    --text-color: #333;
    --light-text: #666;
    --background-light: #f7f9fc;
    --background-white: #fff;
    --border-color: #e5e8ed;
    --box-shadow: 0 4px 12px rgba(0, 0, 0, .1);
    --transition: all .3s ease;
    --radius: 6px;
}

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

html {
    scroll-behavior: smooth;
    scroll-padding-top: 58px;
}

body {
    background-color: var(--background-light);
    color: var(--text-color);
    font-family: "Roboto", Arial, sans-serif;
    line-height: 1.6;
    margin: 0;
    overflow-x: hidden;
}

.container {
    margin: 0 auto;
    max-width: 1200px;
    padding: 0 15px;
    width: 90%;
}

header {
    height: 250px;
    overflow: hidden;
    position: relative;
    width: 100%;
}

.banner {
    background: url("1.jpg") no-repeat center center;
    background-size: cover;
    height: 100%;
    position: relative;
    width: 100%;
}

.overlay {
    background: rgba(10, 17, 53, .75);
    height: 100%;
    left: 0;
    position: absolute;
    top: 0;
    width: 100%;
}

.header-content {
    color: #fff;
    padding: 50px 20px;
    position: relative;
    text-align: center;
    z-index: 2;
}

.header-content h1 {
    font-family: "Lora", serif;
    font-size: 2.5rem;
    font-weight: 700;
    letter-spacing: 1px;
    margin: 0;
}

.header-content h3 {
    color: var(--light-accent);
    font-family: "Roboto", sans-serif;
    font-size: 1.5rem;
    font-weight: 400;
    margin-top: 10px;
}

nav {
    background-color: var(--primary-color);
    padding: 0;
    z-index: 1000;
}

.sticky {
    position: sticky;
    top: 0;
}

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

nav ul {
    display: flex;
    flex-wrap: nowrap;
    justify-content: center;
    list-style: none;
    margin: 0;
    min-width: max-content;
    padding: 0;
}

nav ul li {
    margin: 0;
}

nav ul li a {
    color: #fff;
    display: block;
    font-size: 15px;
    font-weight: 500;
    padding: 15px 18px;
    text-decoration: none;
    transition: background .3s;
    white-space: nowrap;
}

nav ul li a:hover,
nav ul li a:focus-visible {
    background-color: var(--secondary-color);
}

.hero-section {
    background-color: var(--background-white);
    border-bottom: 1px solid var(--border-color);
    padding: 60px 0;
}

.hero-content {
    align-items: center;
    display: flex;
    justify-content: center;
}

.hero-text {
    margin: 0 auto;
    max-width: 720px;
    text-align: center;
}

.hero-text h2 {
    color: var(--primary-color);
    font-family: "Lora", serif;
    font-size: 2rem;
    margin-bottom: 20px;
}

.tagline {
    color: var(--light-text);
    font-size: 1.2rem;
    margin-bottom: 30px;
}

.hero-buttons {
    display: flex;
    gap: 15px;
    justify-content: center;
}

.btn {
    border-radius: 4px;
    display: inline-block;
    font-weight: 500;
    padding: 12px 24px;
    text-align: center;
    text-decoration: none;
    transition: var(--transition);
}

.primary-btn {
    background-color: var(--primary-color);
    color: #fff;
}

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

.secondary-btn {
    background-color: #fff;
    border: 1px solid var(--primary-color);
    color: var(--primary-color);
}

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

main {
    padding: 40px 0;
}

.content-section {
    margin-bottom: 60px;
}

.section-header {
    margin-bottom: 25px;
    position: relative;
}

.section-header h2 {
    align-items: center;
    color: var(--primary-color);
    display: flex;
    font-family: "Lora", serif;
    font-size: 1.8rem;
    margin-bottom: 10px;
}

.section-header h2 i {
    color: var(--accent-color);
    margin-right: 10px;
}

.section-underline {
    background-color: var(--accent-color);
    height: 3px;
    margin-top: 5px;
    width: 70px;
}

.content-box {
    background-color: var(--background-white);
    border-radius: var(--radius);
    box-shadow: var(--box-shadow);
    padding: 30px;
}

.content-box > p + p {
    margin-top: 16px;
}

.challenge-tracks {
    display: flex;
    flex-wrap: wrap;
    gap: 20px;
    margin: 25px 0;
}

.track {
    align-items: center;
    background: var(--background-light);
    border-left: 4px solid var(--accent-color);
    border-radius: var(--radius);
    display: flex;
    flex: 1;
    min-width: 250px;
    padding: 20px;
}

.track-icon {
    color: var(--primary-color);
    font-size: 24px;
    margin-right: 15px;
}

.track-title {
    font-weight: 500;
}

.task-cards {
    display: flex;
    flex-wrap: wrap;
    gap: 30px;
    margin: 25px 0;
}

.task-card {
    background: var(--background-light);
    border-radius: var(--radius);
    border-top: 4px solid var(--primary-color);
    flex: 1;
    min-width: 280px;
    padding: 25px;
    position: relative;
    transition: var(--transition);
}

.task-card:hover {
    box-shadow: 0 8px 20px rgba(0, 0, 0, .15);
    transform: translateY(-5px);
}

.task-number {
    align-items: center;
    background: var(--accent-color);
    border-radius: 50%;
    color: #fff;
    display: flex;
    font-weight: 700;
    height: 36px;
    justify-content: center;
    position: absolute;
    right: 20px;
    top: -15px;
    width: 36px;
}

.task-card h3 {
    color: var(--primary-color);
    font-family: "Lora", serif;
    margin-bottom: 15px;
    padding-right: 28px;
}

code {
    background: #edf1f7;
    border-radius: 3px;
    font-family: "Courier New", monospace;
    font-size: .9em;
    padding: 2px 5px;
}

.subsection-title {
    color: var(--primary-color);
    margin-top: 28px;
}

.dataset-info {
    display: flex;
    flex-wrap: wrap;
    gap: 20px;
    margin: 18px 0 30px;
}

.dataset-item {
    background-color: var(--background-light);
    border-radius: var(--radius);
    flex: 1;
    min-width: 280px;
    padding: 20px;
}

.dataset-item h4 {
    align-items: center;
    color: var(--primary-color);
    display: flex;
    margin-bottom: 10px;
}

.dataset-item h4 i {
    color: var(--accent-color);
    margin-right: 10px;
}

.dataset-link {
    align-items: center;
    background-color: var(--primary-color);
    border-radius: 4px;
    color: #fff;
    display: inline-flex;
    font-size: .92rem;
    font-weight: 500;
    gap: 8px;
    margin-top: 16px;
    padding: 9px 14px;
    text-decoration: none;
    transition: var(--transition);
}

.dataset-link:hover,
.dataset-link:focus-visible {
    background-color: var(--secondary-color);
}

.dataset-link i {
    color: #fff;
}

.note-box {
    align-items: flex-start;
    background-color: #f8f5e6;
    border-left: 4px solid var(--accent-color);
    border-radius: 0 var(--radius) var(--radius) 0;
    display: flex;
    margin: 20px 0 0;
    padding: 15px;
}

.note-box i {
    color: var(--accent-color);
    font-size: 20px;
    margin-right: 15px;
    margin-top: 3px;
}

.note-box p {
    margin: 0;
}

.submission-flow {
    display: flex;
    gap: 30px;
    margin: 25px 0 0;
}

.submission-step {
    background-color: var(--background-light);
    border-radius: var(--radius);
    border-top: 4px solid var(--primary-color);
    flex: 1;
    padding: 25px;
    transition: var(--transition);
}

.submission-step:hover {
    box-shadow: 0 8px 20px rgba(0, 0, 0, .12);
    transform: translateY(-3px);
}

.step-header {
    align-items: center;
    display: flex;
    margin-bottom: 20px;
}

.step-number {
    align-items: center;
    background-color: var(--primary-color);
    border-radius: 50%;
    color: #fff;
    display: flex;
    flex-shrink: 0;
    font-size: 18px;
    font-weight: 700;
    height: 40px;
    justify-content: center;
    margin-right: 15px;
    width: 40px;
}

.step-header h4 {
    color: var(--primary-color);
    font-family: "Lora", serif;
    font-size: 1.2rem;
    margin: 0;
}

.evaluation-metrics {
    display: flex;
    flex-direction: column;
    gap: 20px;
    margin: 25px 0;
}

.metric {
    align-items: flex-start;
    background-color: var(--background-light);
    border-radius: var(--radius);
    display: flex;
    padding: 20px;
}

.metric-number {
    align-items: center;
    background-color: var(--primary-color);
    border-radius: 50%;
    color: #fff;
    display: flex;
    flex-shrink: 0;
    font-weight: 700;
    height: 40px;
    justify-content: center;
    margin-right: 20px;
    width: 40px;
}

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

.track-label {
    color: var(--light-text);
    font-size: .85em;
    font-weight: 400;
}

.timeline {
    margin: 30px 0;
    position: relative;
}

.timeline-item {
    display: flex;
    margin-bottom: 30px;
}

.timeline-date {
    background-color: var(--primary-color);
    border-radius: var(--radius);
    color: #fff;
    flex-shrink: 0;
    font-weight: 500;
    margin-right: 20px;
    padding: 8px 10px;
    text-align: center;
    width: 190px;
}

.timeline-content {
    background-color: var(--background-light);
    border-radius: var(--radius);
    flex-grow: 1;
    padding: 12px 20px;
}

.timeline-content h4 {
    color: var(--text-color);
    margin: 0;
}

footer {
    background-color: #1a1a2e;
    border-top: 4px solid #4a69bd;
    color: #f0f0f0;
    margin-top: 50px;
    padding: 40px 0 20px;
}

.footer-container {
    margin: 0 auto;
    max-width: 1200px;
    padding: 0 20px;
}

.footer-content {
    display: flex;
    flex-wrap: wrap;
    justify-content: space-between;
    margin-bottom: 20px;
}

.footer-section {
    flex: 1;
    margin-bottom: 20px;
    min-width: 200px;
    padding: 0 15px;
}

.footer-section h4 {
    color: #60a3bc;
    font-size: 18px;
    margin-bottom: 15px;
    padding-bottom: 8px;
    position: relative;
}

.footer-section h4::after {
    background-color: #4a69bd;
    bottom: 0;
    content: "";
    height: 2px;
    left: 0;
    position: absolute;
    width: 50px;
}

.footer-section p {
    line-height: 1.6;
    margin-bottom: 10px;
}

.footer-section i {
    color: #60a3bc;
    margin-right: 10px;
}

.footer-section a {
    color: #f0f0f0;
}

.footer-section.links ul {
    list-style: none;
    padding: 0;
}

.footer-section.links li {
    margin-bottom: 8px;
}

.footer-section.links a {
    text-decoration: none;
}

.footer-section.links a:hover {
    color: #60a3bc;
    text-decoration: underline;
}

.footer-bottom {
    border-top: 1px solid rgba(255, 255, 255, .1);
    padding-top: 20px;
    text-align: center;
}

@media (max-width: 768px) {
    .container {
        width: 94%;
    }

    .header-content {
        padding: 48px 15px;
    }

    .header-content h1 {
        font-size: 1.8rem;
    }

    .header-content h3 {
        font-size: 1.2rem;
    }

    nav ul {
        justify-content: flex-start;
    }

    .hero-section {
        padding: 45px 0;
    }

    .hero-text h2 {
        font-size: 1.65rem;
    }

    .hero-buttons,
    .submission-flow,
    .timeline-item,
    .footer-content {
        flex-direction: column;
    }

    .timeline-date {
        margin-bottom: 10px;
        margin-right: 0;
        width: 100%;
    }

    .content-box {
        padding: 22px;
    }

    .footer-section {
        margin-bottom: 30px;
    }
}

@media (prefers-reduced-motion: reduce) {
    html {
        scroll-behavior: auto;
    }

    * {
        transition: none !important;
    }
}