:root {
    --primary-color: #007BFF;
    --primary-dark: #0056b3;
    --secondary-color: #6c757d;
    --text-color: #212529;
    --light-bg: #f8f9fa;
    --white: #ffffff;
    --shadow: 0 8px 32px 0 rgba(0, 0, 0, 0.1);
    --shadow-hover: 0 12px 40px 0 rgba(0, 0, 0, 0.15);
    --transition: all 0.3s ease-in-out;
    --border-radius: 16px;
    --line-height: 1.7;
    --max-line-width: 75ch; /* Optimal line length for readability */
}

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

html { scroll-behavior: smooth; scroll-padding-top: 80px; }

body {
    font-family: 'Inter', sans-serif;
    line-height: var(--line-height);
    color: var(--text-color);
    background-color: var(--light-bg);
    font-size: 16px;
}

.container { 
    max-width: 1140px; 
    margin: 0 auto; 
    padding: 0 1.5rem; 
}

/* Enhanced Navigation - Top-Left Logo & Simplified Navigation */
.navbar { 
    position: fixed; 
    width: 100%; 
    top: 0; 
    left: 0; 
    z-index: 1000; 
    padding: 1rem 0; 
    transition: var(--transition);
    background: transparent;
}

.navbar.scrolled { 
    background: rgba(255, 255, 255, 0.95); 
    backdrop-filter: blur(10px); 
    -webkit-backdrop-filter: blur(10px); 
    box-shadow: 0 2px 20px rgba(0,0,0,0.1); 
}

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

/* Top-Left Logo */
.nav-brand {
    display: flex;
    flex-direction: column;
    align-items: flex-start;
}

.nav-logo { 
    font-size: 1.5rem; 
    font-weight: 700; 
    color: var(--white); 
    text-decoration: none; 
    transition: var(--transition);
}

.navbar.scrolled .nav-logo {
    color: var(--primary-color);
}

/* Simplified Navigation (5 ± 2 items) */
.nav-menu { 
    list-style: none; 
    display: flex; 
    gap: 2rem; 
    margin: 0;
    padding: 0;
}

.nav-menu a { 
    text-decoration: none; 
    color: var(--white); 
    font-weight: 500; 
    transition: var(--transition);
    padding: 0.5rem 1rem;
    border-radius: 6px;
    min-height: 44px; /* Fitts' Law */
    display: flex;
    align-items: center;
}

.navbar.scrolled .nav-menu a {
    color: var(--text-color);
}

.nav-menu a:hover { 
    color: var(--white);
    background: rgba(255, 255, 255, 0.2);
}

.navbar.scrolled .nav-menu a:hover {
    color: var(--primary-color);
    background: rgba(0, 123, 255, 0.1);
}

/* Mobile Navigation Toggle */
.nav-toggle {
    display: none;
    flex-direction: column;
    cursor: pointer;
    padding: 0.5rem;
    min-height: 44px; /* Fitts' Law */
}

.nav-toggle span {
    width: 25px;
    height: 3px;
    background: var(--white);
    margin: 3px 0;
    transition: var(--transition);
    border-radius: 2px;
}

.navbar.scrolled .nav-toggle span {
    background: var(--text-color);
}

.nav-toggle.active span:nth-child(1) {
    transform: rotate(45deg) translate(5px, 5px);
}

.nav-toggle.active span:nth-child(2) {
    opacity: 0;
}

.nav-toggle.active span:nth-child(3) {
    transform: rotate(-45deg) translate(7px, -6px);
}

/* Smooth Scrolling and Animations */
html { 
    scroll-behavior: smooth; 
    scroll-padding-top: 80px; /* Account for fixed navbar */
}

/* Enhanced scroll animations for "appear" effect */
.animate-on-scroll { 
    opacity: 0; 
    transform: translateY(50px); 
    transition: all 0.8s cubic-bezier(0.25, 0.46, 0.45, 0.94); 
}

.animate-on-scroll.visible { 
    opacity: 1; 
    transform: translateY(0); 
}

/* Different animation styles for variety */
.animate-on-scroll.fade-in {
    transform: translateY(0);
    opacity: 0;
}

.animate-on-scroll.fade-in.visible {
    opacity: 1;
}

.animate-on-scroll.slide-up {
    transform: translateY(80px);
    opacity: 0;
}

.animate-on-scroll.slide-up.visible {
    transform: translateY(0);
    opacity: 1;
}

.animate-on-scroll.slide-left {
    transform: translateX(-80px);
    opacity: 0;
}

.animate-on-scroll.slide-left.visible {
    transform: translateX(0);
    opacity: 1;
}

.animate-on-scroll.slide-right {
    transform: translateX(80px);
    opacity: 0;
}

.animate-on-scroll.slide-right.visible {
    transform: translateX(0);
    opacity: 1;
}

.animate-on-scroll.scale-in {
    transform: scale(0.8);
    opacity: 0;
}

.animate-on-scroll.scale-in.visible {
    transform: scale(1);
    opacity: 1;
}

.animate-on-scroll.rotate-in {
    transform: rotate(-10deg) scale(0.9);
    opacity: 0;
}

.animate-on-scroll.rotate-in.visible {
    transform: rotate(0deg) scale(1);
    opacity: 1;
}

/* Stagger animations for groups */
.animate-on-scroll.stagger-1 { transition-delay: 0.1s; }
.animate-on-scroll.stagger-2 { transition-delay: 0.2s; }
.animate-on-scroll.stagger-3 { transition-delay: 0.3s; }
.animate-on-scroll.stagger-4 { transition-delay: 0.4s; }

/* Hero Section - Above the Fold with Key Messages */
.hero { 
    min-height: 100vh; 
    color: var(--white); 
    display: flex; 
    align-items: center; 
    justify-content: center; 
    text-align: center; 
    position: relative; 
    overflow: hidden; 
    background: linear-gradient(135deg, #007BFF, #00C6FF, #007BFF);
    background-size: 400% 400%;
    animation: gradientAnimation 15s ease infinite;
    padding: 6rem 0 4rem;
}

@keyframes gradientAnimation { 
    0% { background-position: 0% 50%; } 
    50% { background-position: 100% 50%; } 
    100% { background-position: 0% 50%; } 
}

.hero-content { 
    max-width: 800px; 
    padding: 2rem; 
    position: relative; 
    z-index: 1; 
}

/* Clear Visual Hierarchy */
.hero-title { 
    font-size: 4rem; 
    margin-bottom: 1rem; 
    font-weight: 800; 
    text-shadow: 0 4px 8px rgba(0,0,0,0.1);
    line-height: 1.2;
}

.hero-subtitle { 
    font-size: 1.5rem; 
    font-weight: 400; 
    max-width: 600px; 
    margin: 0 auto 3rem; 
    line-height: 1.4;
}

/* Key Messages Above the Fold */
.hero-features {
    display: flex;
    justify-content: center;
    gap: 3rem;
    margin-bottom: 3rem;
    flex-wrap: wrap;
}

.feature-item {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 0.5rem;
    min-width: 120px;
}

.feature-item i {
    font-size: 2rem;
    color: rgba(255, 255, 255, 0.9);
}

.feature-item span {
    font-size: 0.875rem;
    font-weight: 500;
    text-align: center;
}

/* Primary CTA Buttons */
.hero-cta {
    margin-top: 2rem;
    display: flex;
    gap: 1rem;
    justify-content: center;
    flex-wrap: wrap;
}

.cta-button.primary {
    display: inline-block;
    background: var(--white);
    color: var(--primary-color);
    padding: 1rem 2.5rem;
    border-radius: 50px;
    text-decoration: none;
    font-weight: 700;
    font-size: 1.1rem;
    transition: var(--transition);
    box-shadow: var(--shadow);
    min-height: 56px; /* Fitts' Law - Large click area */
    line-height: 1;
    display: inline-flex;
    align-items: center;
    justify-content: center;
}

.cta-button.secondary {
    display: inline-block;
    background: transparent;
    color: var(--white);
    padding: 1rem 2.5rem;
    border-radius: 50px;
    text-decoration: none;
    font-weight: 700;
    font-size: 1.1rem;
    transition: var(--transition);
    box-shadow: var(--shadow);
    min-height: 56px; /* Fitts' Law - Large click area */
    line-height: 1;
    display: inline-flex;
    align-items: center;
    justify-content: center;
    border: 2px solid var(--white);
}

.cta-button.secondary i {
    margin-right: 0.5rem;
}

.cta-button.primary:hover {
    transform: translateY(-5px);
    box-shadow: var(--shadow-hover);
    background: var(--light-bg);
}

.cta-button.secondary:hover {
    transform: translateY(-5px);
    box-shadow: var(--shadow-hover);
    background: var(--white);
    color: var(--primary-color);
}

/* About Section - Clear Information Architecture */
.about {
    background: var(--white);
    padding: 6rem 0;
}

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

.about-content h2 {
    font-size: 2.75rem;
    margin-bottom: 2rem;
    font-weight: 700;
    text-align: center;
    color: var(--text-color);
    position: relative;
}

.about-content h2::after {
    content: '';
    display: block;
    width: 70px;
    height: 4px;
    background: var(--primary-color);
    margin: 1rem auto 0;
    border-radius: 2px;
}

.about-text {
    font-size: 1.15rem;
    line-height: 1.8;
    text-align: left;
    color: var(--secondary-color);
    max-width: var(--max-line-width);
    margin: 0 auto 3rem;
}

.about-text p {
    margin-bottom: 1.5rem;
}

/* Proximity Grouping for Related Info */
.download-section {
    margin-top: 3rem;
    padding: 2rem;
    background: var(--light-bg);
    border-radius: var(--border-radius);
    border: 1px solid rgba(0, 123, 255, 0.1);
    text-align: center;
}

.download-section h3 {
    color: var(--primary-color);
    font-size: 1.5rem;
    margin-bottom: 1rem;
}

.download-section p {
    margin-bottom: 1.5rem;
    color: var(--secondary-color);
}

.download-btn {
    display: inline-flex;
    align-items: center;
    background: var(--primary-color);
    color: var(--white);
    padding: 1rem 2rem;
    border-radius: 8px;
    text-decoration: none;
    font-weight: 600;
    transition: var(--transition);
    box-shadow: var(--shadow);
    min-height: 48px; /* Fitts' Law */
}

.download-btn:hover {
    background: var(--primary-dark);
    transform: translateY(-2px);
    box-shadow: var(--shadow-hover);
}

.download-btn i {
    margin-right: 0.5rem;
    font-size: 1.2rem;
}

/* Team Section - Similarity Principle */
.team {
    background-color: var(--light-bg);
    padding: 6rem 0;
}

.team h2 {
    font-size: 2.75rem;
    margin-bottom: 4rem;
    font-weight: 700;
    text-align: center;
    color: var(--text-color);
    position: relative;
}

.team h2::after {
    content: '';
    display: block;
    width: 70px;
    height: 4px;
    background: var(--primary-color);
    margin: 1rem auto 0;
    border-radius: 2px;
}

.team-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: 2rem;
}

.team-member {
    background: var(--white);
    border-radius: var(--border-radius);
    padding: 2rem;
    text-align: center;
    box-shadow: var(--shadow);
    transition: var(--transition);
    display: flex;
    flex-direction: column;
    align-items: center;
    min-height: 300px; /* Consistent height for similarity */
}

.team-member:hover {
    transform: translateY(-10px);
    box-shadow: var(--shadow-hover);
}

.member-image img {
    width: 120px;
    height: 120px;
    border-radius: 50%;
    object-fit: cover;
    margin-bottom: 1.5rem;
    border: 4px solid var(--white);
    box-shadow: 0 4px 15px rgba(0,0,0,0.1);
    transition: transform 0.3s ease-in-out;
}

.team-member:hover .member-image img {
    transform: scale(1.05);
}

.member-info h3 {
    font-size: 1.3rem;
    margin-bottom: 0.5rem;
    color: var(--text-color);
    font-weight: 600;
}

.member-info p {
    color: var(--secondary-color);
    font-weight: 500;
}

/* Sponsors Section - Moved Up for Visibility */
.sponsors {
    background: var(--white);
    padding: 6rem 0;
}

.sponsors h2 {
    font-size: 2.75rem;
    margin-bottom: 2rem;
    font-weight: 700;
    text-align: center;
    color: var(--text-color);
    position: relative;
}

.sponsors h2::after {
    content: '';
    display: block;
    width: 70px;
    height: 4px;
    background: var(--primary-color);
    margin: 1rem auto 0;
    border-radius: 2px;
}

.sponsor-intro {
    text-align: center;
    max-width: 600px;
    margin: 0 auto 3rem;
    color: var(--secondary-color);
    font-size: 1.1rem;
    line-height: 1.6;
}

.sponsor-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
    gap: 2rem;
    align-items: center;
    margin-bottom: 3rem;
}

.sponsor {
    background: var(--light-bg);
    padding: 2rem;
    border-radius: var(--border-radius);
    box-shadow: var(--shadow);
    text-align: center;
    transition: var(--transition);
    min-height: 120px; /* Consistent height */
    display: flex;
    align-items: center;
    justify-content: center;
}

.sponsor:hover {
    transform: translateY(-5px) scale(1.05);
    box-shadow: var(--shadow-hover);
}

.sponsor img {
    max-width: 100%;
    height: auto;
    max-height: 80px;
    object-fit: contain;
    transition: transform 0.3s cubic-bezier(0.25,0.46,0.45,0.94);
}

.sponsor:hover img {
    transform: scale(1.15);
}

.sponsor-cta {
    text-align: center;
    background: var(--light-bg);
    padding: 2.5rem;
    border-radius: var(--border-radius);
    box-shadow: var(--shadow);
    border: 2px solid var(--primary-color);
    margin-top: 2rem;
}

.sponsor-cta h3 {
    color: var(--primary-color);
    font-size: 1.8rem;
    margin-bottom: 1rem;
}

.sponsor-cta p {
    color: var(--secondary-color);
    font-size: 1.1rem;
    line-height: 1.6;
}

/* Contact Section - Clear Call to Action */
.contact {
    background: var(--light-bg);
    padding: 6rem 0;
}

.contact h2 {
    font-size: 2.75rem;
    margin-bottom: 3rem;
    font-weight: 700;
    text-align: center;
    color: var(--text-color);
    position: relative;
}

.contact h2::after {
    content: '';
    display: block;
    width: 70px;
    height: 4px;
    background: var(--primary-color);
    margin: 1rem auto 0;
    border-radius: 2px;
}

/* Direct Contact Methods (Fitts' Law - Large Click Areas) */
.contact-methods {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 2rem;
    margin-bottom: 3rem;
}

.contact-method {
    background: var(--white);
    padding: 2rem;
    border-radius: var(--border-radius);
    text-align: center;
    box-shadow: var(--shadow);
    transition: var(--transition);
    border: 2px solid transparent;
    min-height: 160px; /* Fitts' Law - Large click area */
    display: flex;
    flex-direction: column;
    justify-content: center;
    align-items: center;
}

.contact-method:hover {
    transform: translateY(-5px);
    border-color: var(--primary-color);
    box-shadow: var(--shadow-hover);
}

.contact-method i {
    font-size: 2.5rem;
    color: var(--primary-color);
    margin-bottom: 1rem;
}

.contact-method h3 {
    font-size: 1.3rem;
    margin-bottom: 0.5rem;
    color: var(--text-color);
    font-weight: 600;
}

.contact-method a {
    color: var(--primary-color);
    text-decoration: none;
    font-weight: 600;
    font-size: 1.1rem;
    transition: var(--transition);
    padding: 0.5rem 1rem;
    border-radius: 6px;
    min-height: 44px; /* Fitts' Law */
    display: flex;
    align-items: center;
}

.contact-method a:hover {
    color: var(--primary-dark);
    background: rgba(0, 123, 255, 0.1);
}

/* Contact Form */
.contact-form {
    background: var(--white);
    padding: 2.5rem;
    border-radius: var(--border-radius);
    box-shadow: var(--shadow);
    max-width: 600px;
    margin: 0 auto;
}

.contact-form .form-group {
    margin-bottom: 1.5rem;
}

.contact-form label {
    display: block;
    margin-bottom: 0.5rem;
    font-weight: 500;
    color: var(--text-color);
    font-size: 1rem;
}

.contact-form input,
.contact-form textarea {
    width: 100%;
    padding: 1rem;
    border: 2px solid #e2e8f0;
    border-radius: 8px;
    font-size: 1rem;
    font-family: 'Inter', sans-serif;
    transition: border-color 0.2s ease, box-shadow 0.2s ease;
    background: var(--white);
    min-height: 48px; /* Fitts' Law */
}

.contact-form textarea.auto-expand {
    overflow: hidden;
    resize: none;
    min-height: 50px;
    max-height: 300px;
    transition: border-color 0.2s ease, box-shadow 0.2s ease, height 0.2s ease;
    line-height: 1.5;
}

.contact-form input:focus,
.contact-form textarea:focus {
    outline: none;
    border-color: var(--primary-color);
    box-shadow: 0 0 0 3px rgba(0, 123, 255, 0.15);
}

.contact-form .submit-btn {
    background: var(--primary-color);
    color: var(--white);
    padding: 1rem 2.5rem;
    border: none;
    border-radius: 8px;
    font-size: 1.1rem;
    font-weight: 500;
    cursor: pointer;
    transition: var(--transition);
    display: inline-flex;
    align-items: center;
    justify-content: center;
    width: 100%;
    min-height: 56px; /* Fitts' Law - Large click area */
}

.contact-form .submit-btn:hover:not(:disabled) {
    background: var(--primary-dark);
    transform: translateY(-2px);
    box-shadow: var(--shadow-hover);
}

.contact-form .submit-btn:disabled {
    opacity: 0.7;
    cursor: not-allowed;
    transform: none;
}

.contact-form .submit-btn i {
    margin-right: 0.5rem;
}

/* Form Feedback styles */
.form-feedback {
    margin-top: 1rem;
    padding: 1rem;
    border-radius: 8px;
    display: none;
    transition: opacity 0.3s ease, transform 0.3s ease;
}

.form-feedback.show {
    display: block;
    animation: slideIn 0.3s ease-out;
}

@keyframes slideIn {
    from {
        opacity: 0;
        transform: translateY(-10px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

.form-feedback.success {
    background-color: #d1e7dd;
    border: 1px solid #a3cfbb;
}

.form-feedback.error {
    background-color: #f8d7da;
    border: 1px solid #f1aeb5;
}

.success-message, .error-message {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    font-weight: 500;
}

.success-message {
    color: #0a3622;
}

.error-message {
    color: #691c21;
}

/* Footer */
footer {
    background: var(--text-color);
    color: rgba(255, 255, 255, 0.7);
    padding: 3rem 0;
    text-align: center;
}

footer a {
    color: var(--white);
    text-decoration: none;
    font-weight: 500;
    transition: var(--transition);
}

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

.fa-spinner {
    animation: spin 1s linear infinite;
}

@keyframes spin {
    100% {
        transform: rotate(360deg);
    }
}

/* Responsive Design */
@media (max-width: 768px) {
    .navbar .container {
        flex-direction: column;
        gap: 1rem;
        align-items: flex-start;
    }
    
    .nav-brand {
        order: 1;
    }
    
    .nav-menu {
        display: none;
        position: absolute;
        top: 100%;
        left: 0;
        width: 100%;
        background: rgba(255, 255, 255, 0.95);
        backdrop-filter: blur(10px);
        -webkit-backdrop-filter: blur(10px);
        flex-direction: column;
        padding: 1rem 0;
        box-shadow: 0 2px 20px rgba(0,0,0,0.1);
        order: 2;
    }
    
    .nav-menu.active {
        display: flex;
    }
    
    .nav-menu li {
        width: 100%;
    }
    
    .nav-menu a {
        display: block;
        padding: 1rem 2rem;
        color: var(--text-color) !important;
        border-radius: 0;
        text-align: center;
        justify-content: center;
    }
    
    .nav-menu a:hover {
        background: rgba(0, 123, 255, 0.1);
        color: var(--primary-color) !important;
    }
    
    .nav-toggle {
        display: flex;
        order: 3;
        position: absolute;
        top: 1rem;
        right: 1rem;
    }
    
    .hero-title {
        font-size: 2.5rem;
    }
    
    .hero-subtitle {
        font-size: 1.2rem;
    }
    
    .hero-features {
        gap: 2rem;
    }
    
    .feature-item {
        min-width: 100px;
    }
    
    .feature-item i {
        font-size: 1.5rem;
    }
    
    .feature-item span {
        font-size: 0.8rem;
    }
    
    .hero-cta {
        flex-direction: column;
        align-items: center;
        gap: 1rem;
    }
    
    .cta-button.primary,
    .cta-button.secondary {
        width: 100%;
        max-width: 300px;
        text-align: center;
    }
    
    .about-content h2,
    .team h2,
    .sponsors h2,
    .contact h2 {
        font-size: 2.25rem;
    }
    
    .about-text {
        font-size: 1rem;
    }
    
    .team-grid {
        grid-template-columns: 1fr;
        gap: 1.5rem;
    }
    
    .contact-methods {
        grid-template-columns: 1fr;
        gap: 1.5rem;
    }
    
    .contact-method {
        min-height: 140px;
        padding: 1.5rem;
    }
    
    .contact-method i {
        font-size: 2rem;
    }
    
    .contact-method h3 {
        font-size: 1.2rem;
    }
    
    .contact-method a {
        font-size: 1rem;
    }
    
    .sponsor-grid {
        grid-template-columns: repeat(auto-fit, minmax(150px, 1fr));
        gap: 1.5rem;
    }
    
    .sponsor {
        padding: 1.5rem;
        min-height: 100px;
    }
    
    .sponsor-cta {
        padding: 2rem 1.5rem;
    }
    
    .sponsor-cta h3 {
        font-size: 1.5rem;
    }
    
    .sponsor-cta p {
        font-size: 1rem;
    }
    
    .contact-form {
        padding: 1.5rem;
        margin: 1rem 0;
    }
    
    .contact-form input,
    .contact-form textarea {
        padding: 0.875rem;
        font-size: 16px; /* Prevents zoom on iOS */
    }
    
    .contact-form .submit-btn {
        padding: 1rem;
        font-size: 1rem;
    }
    
    .container {
        padding: 0 1rem;
    }
    
    section {
        padding: 4rem 0;
    }
}