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

:root {
    --primary-color: #236960;
    --primary-dark: #1a4742;
    --secondary-color: #ac8255;
    --accent-color: #c49564;
    --text-dark: #2c2c2c;
    --text-light: #6b7280;
    --bg-light: #f1f0f0c4;
    --bg-white: #ffffff;
    --border-color: #e5e5e3;
    --shadow: 0 4px 6px -1px rgba(0, 0, 0, 0.1), 0 2px 4px -1px rgba(0, 0, 0, 0.06);
    --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.1), 0 4px 6px -2px rgba(0, 0, 0, 0.05);
}

body {
    font-family: 'Inter', sans-serif;
    line-height: 1.6;
    color: var(--text-dark);
    background-color: var(--bg-light);
}

/* Navigation */
nav {
    background-color: var(--bg-white);
    box-shadow: var(--shadow);
    position: sticky;
    top: 0;
    z-index: 1000;
}

.nav-container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 1rem 2rem;
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.logo {
    display: flex;
    align-items: center;
    gap: 0.75rem;
    text-decoration: none;
    color: var(--text-dark);
}

.logo img {
    width: 40px;
    height: 40px;
}

.logo h1 {
    font-size: 1.5rem;
    font-weight: 700;
    margin: 0;
}

.logo-title {
    display: flex;
    align-items: center;
    gap: 0.35rem;
}

.logo-icon {
    font-size: 1.5rem;
    vertical-align: -15%;
}

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

.nav-right {
    display: flex;
    align-items: center;
    gap: 2rem;
}

.nav-links {
    display: flex;
    gap: 2rem;
    align-items: center;
}

.nav-links--large {
    font-size: 1.25rem;
}

.nav-links a {
    text-decoration: none;
    color: var(--text-light);
    font-weight: 500;
    transition: color 0.3s;
}

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

.btn {
    padding: 0.75rem 1.5rem;
    text-decoration: none;
    font-weight: 600;
    display: inline-block;
}

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

.btn-primary:hover {
    background-color: var(--secondary-color);
    border-style: solid;
    border-color: white;
    border-width: 2px;
}

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

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

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

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

/* Hero Section */
.hero {
    background: var(--primary-dark);
    color: white;
    padding: 2rem 0 3rem;
    text-align: center;
}

.hero-container {
    margin: 0 auto;
    padding: 0 2rem;
}

.hero h2 {
    font-size: 3rem;
    margin-bottom: 1rem;
    font-weight: 300;
}

.hero p {
    font-size: 1.25rem;
    margin-bottom: 1rem;
    opacity: 0.95;
}

.hero-subtext {
    font-size: 1rem;
    opacity: 0.85;
    margin-bottom: 1.5rem;
}

.hero-actions {
    display: flex;
    gap: 1rem;
    justify-content: center;
    flex-wrap: wrap;
}

/* Badge */
.version-badge {
    display: inline-block;
    padding: 0.5rem 1rem;
    background-color: #f9d004;
    color: #1a1a1a;
    font-size: 0.875rem;
    font-weight: 700;
    margin-bottom: 1.5rem;
    border-radius: 999px;
}

/* Container */
.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 4rem 2rem;
}

.section {
    margin-bottom: 4rem;
}

.section-title {
    text-align: center;
    font-size: 2.5rem;
    margin-bottom: 3rem;
    font-weight: 700;
}

/* Features Grid */
.features-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 2rem;
}

.feature-card {
    background-color: var(--bg-white);
    padding: 2rem;
    box-shadow: var(--shadow);
    transition: transform 0.3s, box-shadow 0.3s;
}

.feature-card--student,
.feature-card--teacher,
.feature-card--about {
    text-align: center;
}

.feature-card--student {
    background-color: #2f4f7f;
}

.feature-card--teacher {
    background-color: var(--primary-color);
}

.feature-card--about {
    background-color: #703436;
}

.feature-card-icon {
    font-size: 48px;
}

.feature-icon {
    font-family: 'Material Symbols Outlined', sans-serif;
    font-variation-settings: 'FILL' 0, 'wght' 400, 'GRAD' 0, 'opsz' 24;
    font-size: 2.5rem;
    margin-bottom: 1rem;
    color: var(--primary-dark);
}

.feature-card h3 {
    font-size: 1.5rem;
    margin-bottom: 1rem;
    color: var(--text-dark);
}

.feature-card p {
    color: var(--text-light);
    line-height: 1.8;
}

.feature-badge {
    display: inline-block;
    background-color: var(--accent-color);
    color: white;
    padding: 0.2rem 0.6rem;
    border-radius: 0.75rem;
    font-size: 0.7rem;
    font-weight: 700;
    margin-left: 0.5rem;
    vertical-align: middle;
}

/* Screenshots */
.screenshots-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(400px, 1fr));
    gap: 2rem;
}

.screenshot-card {
    background-color: var(--bg-white);
    border-radius: 1rem;
    overflow: hidden;
    box-shadow: var(--shadow);
    transition: transform 0.3s;
}

.screenshot-card img {
    width: 100%;
    height: auto;
    display: block;
}

.screenshot-placeholder {
    background: white;
    position: relative;
    overflow: hidden;
    display: flex;
    align-items: center;
    justify-content: center;
    min-height: 300px;
}

.screenshot-placeholder img {
    width: 100%;
    height: auto;
    object-fit: contain;
    display: block;
}

.screenshot-modal {
    position: fixed;
    inset: 0;
    background: rgba(0, 0, 0, 0.6);
    display: none;
    align-items: center;
    justify-content: center;
    padding: 1.5rem;
    z-index: 2000;
}

.screenshot-modal.open {
    display: flex;
}

.screenshot-modal .modal-content {
    background: var(--bg-white);
    border-radius: 1rem;
    max-width: 960px;
    width: 100%;
    box-shadow: var(--shadow-lg);
    overflow: hidden;
}

.screenshot-modal header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 1rem 1.5rem;
    background: var(--primary-dark);
    color: white;
}

.screenshot-modal header h3 {
    margin: 0;
}

.screenshot-modal header button {
    background: transparent;
    border: none;
    color: white;
    font-size: 1.5rem;
    cursor: pointer;
}

.screenshot-modal .modal-body {
    padding: 1.5rem;
}

.screenshot-modal .modal-body img {
    width: 100%;
    height: auto;
    border-radius: 0.75rem;
    margin-bottom: 1rem;
    box-shadow: var(--shadow);
}

.screenshot-modal .modal-body p {
    color: var(--text-light);
    margin: 0;
}

.screenshot-card .caption {
    padding: 1.5rem;
}

.screenshot-card .caption h3 {
    margin-bottom: 0.5rem;
    color: var(--text-dark);
}

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

.phone-frame {
    background: #1a1a1a;
    border-radius: 2.5rem;
    padding: 1rem 0.75rem;
    box-shadow: 0 20px 60px rgba(0, 0, 0, 0.3);
    margin: 0 auto;
    width: 100%;
    max-width: 260px;
    position: relative;
}

.phone-frame::before {
    content: '';
    position: absolute;
    top: 0.5rem;
    left: 50%;
    transform: translateX(-50%);
    width: 60px;
    height: 6px;
    background: #333;
    border-radius: 3px;
}

.phone-frame img {
    border-radius: 2rem;
    display: block;
    width: 100%;
    height: auto;
}

.screenshot-card:has(.phone-frame) .screenshot-placeholder {
    align-items: flex-start;
    padding-top: 2rem;
    min-height: 500px;
}

/* Stats */
.stats {
    background-color: var(--bg-white);
    padding: 3rem 2rem;
    box-shadow: var(--shadow);
    margin-bottom: 4rem;
}

.stats-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
    gap: 2rem;
    text-align: center;
}

.stat h4 {
    font-size: 2.5rem;
    color: var(--primary-color);
    margin-bottom: 0.5rem;
    font-weight: 800;
}

.stat p {
    color: var(--text-light);
    font-size: 1rem;
}

/* Sign In Section */
.signin-grid {
    max-width: 900px;
    margin: 0 auto;
}

.signin-card {
    text-align: center;
}

.signin-card .btn {
    margin-top: 1rem;
}

.signin-note {
    text-align: center;
    color: var(--text-light);
    margin-top: 2rem;
}

.signin-note a {
    color: var(--secondary-color);
    text-decoration: none;
}

.signin-note a:hover {
    text-decoration: underline;
}

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

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

.footer-links {
    display: flex;
    gap: 2rem;
    justify-content: center;
    margin-bottom: 2rem;
    flex-wrap: wrap;
}

.footer-links a {
    color: white;
    text-decoration: none;
    opacity: 0.8;
    transition: opacity 0.3s;
}

.footer-links a:hover {
    opacity: 1;
}

footer p {
    opacity: 0.7;
}

.footer-release {
    margin-top: 1rem;
}

/* Responsive */
@media (max-width: 900px) {
    .nav-container {
        flex-direction: column;
        gap: 1rem;
    }

    .nav-right {
        flex-direction: column;
        gap: 1rem;
    }
}

@media (max-width: 768px) {
    .hero h2 {
        font-size: 2rem;
    }

    .hero p {
        font-size: 1rem;
    }

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

    .nav-links {
        display: none;
    }

    .features-grid,
    .screenshots-grid {
        grid-template-columns: 1fr;
    }

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