/* General Reset and Utilities */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

body {
    font-family: var(--primary-font-family);
    color: var(--color-primary-text);
    background-color: var(--color-bg-white);
    line-height: 1.6;
    -webkit-font-smoothing: antialiased;
    scroll-behavior: smooth;
}

.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 1rem;
}

section {
    padding: 4rem 0;
}

h1, h2, h3 {
    font-weight: 800; /* Extra bold for headings */
    line-height: 1.1;
    margin-bottom: 1rem;
}

h1 {
    font-size: 3.5rem;
}

h2 {
    font-size: 2.5rem;
    text-align: center;
}

h4 {
    font-weight: 700;
    font-size: 1.1rem;
}

.section-description {
    text-align: center;
    color: var(--color-secondary-text);
    margin-bottom: 2rem;
    font-size: 1.1rem;
}

/* Colors and Variables (Repeated for clarity, but defined in HTML style block) */
:root {
    --color-primary-text: #1f2937;
    --color-secondary-text: #6b7280;
    --color-accent-purple: #9333ea;
    --color-accent-blue: #3b82f6;
    --color-gradient-start: #3b82f6; /* Blue for 'AI' */
    --color-gradient-end: #06b6d4; /* Cyan for 'Projects' */
    --color-button-demo: #a855f7; /* Purple button */
    --color-button-explore-border: #10b981; /* Green border */
    --color-grade-9-10-border: #38bdf8; /* Light blue border */
    --color-grade-11-12-border: #f43f5e; /* Red border */
    --color-bg-white: #ffffff;
    --color-bg-light-gray: #f9fafb;
    --color-border-gray: #e5e7eb;
}

/* Buttons */
.btn {
    padding: 0.75rem 1.5rem;
    border-radius: 0.5rem;
    font-weight: 600;
    cursor: pointer;
    transition: all 0.2s ease-in-out;
    border: 2px solid transparent;
}

.btn-primary {
    background-color: var(--color-button-demo);
    color: var(--color-bg-white);
    border-color: var(--color-button-demo);
}

.btn-demo {
    background: linear-gradient(to right, #9333ea, #a855f7); /* Purple gradient */
    color: var(--color-bg-white);
    border: none;
    padding-right: 2rem;
}

.btn-explore {
    background-color: transparent;
    color: var(--color-primary-text);
    border-color: var(--color-button-explore-border);
}

.btn-secondary {
    background-color: transparent;
    color: var(--color-primary-text);
    border-color: var(--color-border-gray);
}

.btn-secondary-footer {
    background-color: transparent;
    color: var(--color-bg-white);
    border-color: var(--color-bg-white);
    margin-top: 1rem;
}

/* Header/Navigation */
.header {
    border-bottom: 1px solid var(--color-border-gray);
    padding: 1rem 0;
}

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

.logo {
    font-size: 1.5rem;
    font-weight: 900;
    text-decoration: none;
    color: var(--color-accent-purple);
}

.nav {
    display: flex;
    gap: 1.5rem;
    align-items: center;
}

.nav a {
    text-decoration: none;
    color: var(--color-primary-text);
    font-weight: 500;
}

.menu-toggle {
    display: none; /* Hide on desktop */
}

/* Hero Section */
.hero {
    padding: 6rem 0;
}

.hero .container {
    display: flex;
    align-items: center;
    gap: 4rem;
}

.hero-content {
    flex: 1;
}

.hero-content h1 {
    font-size: 4rem;
    margin-bottom: 1rem;
}

.ai-projects-gradient {
    /* Simulating the gradient text effect */
    background: linear-gradient(to right, var(--color-gradient-start), var(--color-gradient-end));
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
    color: transparent;
}

.hero-content .subtitle {
    font-size: 1.25rem;
    color: var(--color-secondary-text);
    margin-bottom: 2rem;
}

.hero-actions {
    display: flex;
    gap: 1rem;
}

.hero-image {
    flex: 1;
    text-align: right;
}

.hero-image img {
    max-width: 100%;
    height: auto;
    border-radius: 1rem;
    box-shadow: 0 20px 25px -5px rgba(0, 0, 0, 0.1), 0 10px 10px -5px rgba(0, 0, 0, 0.04);
}

/* Programs by Grade Level Section */
.programs-grade-level {
    background-color: var(--color-bg-light-gray);
}

.grade-buttons {
    display: flex;
    justify-content: center;
    gap: 1rem;
    margin-bottom: 3rem;
}

.btn-grade-9-10, .btn-grade-11-12 {
    background-color: var(--color-bg-white);
    color: var(--color-primary-text);
    font-weight: 600;
    padding: 0.5rem 1.5rem;
    border-radius: 0.5rem;
}

.btn-grade-9-10 {
    border-color: var(--color-grade-9-10-border);
}

.btn-grade-11-12 {
    border-color: var(--color-grade-11-12-border);
}

.program-cards {
    display: flex;
    gap: 2rem;
    justify-content: center;
    margin-bottom: 3rem;
}

.card {
    background-color: var(--color-bg-white);
    border-radius: 1rem;
    padding: 2rem;
    box-shadow: 0 10px 15px -3px rgba(0, 0, 0, 0.1), 0 4px 6px -2px rgba(0, 0, 0, 0.05);
    max-width: 400px;
    position: relative;
}

.card h3 {
    font-size: 1.5rem;
    margin-bottom: 0.5rem;
}

.card .duration {
    color: var(--color-secondary-text);
    font-weight: 500;
    margin-bottom: 1rem;
}

.card ul {
    list-style: none;
    padding-left: 0;
    margin-top: 1rem;
}

.card ul li {
    margin-bottom: 0.5rem;
    padding-left: 1.5rem;
    position: relative;
}

.card ul li::before {
    content: '✓'; /* Placeholder for checkmark icon */
    position: absolute;
    left: 0;
    color: var(--color-accent-purple);
    font-weight: bold;
}

.badge {
    position: absolute;
    top: 1rem;
    right: 1rem;
    background-color: var(--color-accent-purple);
    color: var(--color-bg-white);
    padding: 0.25rem 0.75rem;
    border-radius: 9999px;
    font-size: 0.75rem;
    font-weight: 700;
}

/* Why Choose Teen Theory Section */
.why-choose .features-grid {
    display: grid;
    grid-template-columns: repeat(2, 1fr);
    gap: 2rem;
    max-width: 800px;
    margin: 0 auto;
}

.feature-item {
    padding: 1.5rem;
    border-radius: 0.75rem;
    border: 1px solid var(--color-border-gray);
}

.feature-item h3 {
    font-size: 1.25rem;
    margin-bottom: 0.5rem;
}

/* Tutors Section */
.tutors {
    background-color: var(--color-bg-light-gray);
    text-align: center;
}

.tutor-section {
    display: flex;
    gap: 3rem;
    align-items: center;
    margin-bottom: 3rem;
}

.tutor-image {
    flex: 1;
}

.tutor-image img {
    max-width: 100%;
    height: auto;
    border-radius: 1rem;
    box-shadow: 0 20px 25px -5px rgba(0, 0, 0, 0.1);
}

.tutor-features {
    flex: 1;
    display: flex;
    flex-direction: column;
    gap: 2rem;
    text-align: left;
}

.tutor-item {
    max-width: 100%;
    text-align: left;
}

.tutor-item h3 {
    font-size: 1.25rem;
}

/* How Classes Work Section */
.how-it-works {
    text-align: center;
}

.video-placeholder {
    background: linear-gradient(135deg, #e0e7ff 0%, #cffafe 100%);
    height: 300px;
    display: flex;
    justify-content: center;
    align-items: center;
    border-radius: 1rem;
    max-width: 800px;
    margin: 2rem auto;
    position: relative;
}

.video-placeholder::before {
    content: '';
    position: absolute;
    width: 60px;
    height: 60px;
    background-color: var(--color-button-demo);
    border-radius: 50%;
    display: flex;
    justify-content: center;
    align-items: center;
    cursor: pointer;
}

.video-placeholder p {
    position: relative;
    z-index: 1;
    color: var(--color-secondary-text);
}

.stats-grid {
    display: flex;
    justify-content: center;
    gap: 4rem;
    margin-top: 3rem;
}

.stat-item {
    text-align: center;
}

.stat-number {
    font-size: 3rem;
    font-weight: 800;
    color: var(--color-accent-purple);
    line-height: 1;
}

.stat-label {
    font-size: 1rem;
    color: var(--color-secondary-text);
    margin-top: 0.5rem;
}

/* Subscription Section */
.subscription {
    background: linear-gradient(135deg, #e0e7ff 0%, #cffafe 100%);
    padding: 4rem 0;
}

.subscription-card {
    background-color: var(--color-bg-white);
    border-radius: 1rem;
    padding: 3rem;
    max-width: 600px;
    margin: 0 auto;
    text-align: center;
    box-shadow: 0 10px 15px -3px rgba(0, 0, 0, 0.1);
}

.subscription-card h2 {
    color: var(--color-primary-text);
}

.subscribe-form {
    display: flex;
    justify-content: center;
    gap: 0.5rem;
    margin-top: 2rem;
}

.subscribe-form input {
    padding: 0.75rem 1rem;
    border-radius: 0.5rem;
    border: 2px solid var(--color-button-explore-border);
    width: 300px;
    font-size: 1rem;
}

.subscribe-form input::placeholder {
    color: #9ca3af;
}

.subscribe-form .btn-primary {
    background-color: var(--color-button-demo);
    border-color: var(--color-button-demo);
}

.privacy-note {
    color: #6b7280;
    margin-top: 1rem;
    font-size: 0.9rem;
}

/* Footer Section */
.footer {
    background-color: var(--color-primary-text);
    color: var(--color-bg-white);
    padding: 4rem 0 2rem;
}

.footer-content {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 2rem;
    margin-bottom: 3rem;
}

.footer-section h3, .footer-section h4 {
    color: var(--color-bg-white);
    margin-bottom: 1rem;
}

.footer-section p {
    color: #d1d5db;
    line-height: 1.6;
}

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

.footer-section ul li {
    margin-bottom: 0.5rem;
}

.footer-section a {
    color: #d1d5db;
    text-decoration: none;
    transition: color 0.2s ease-in-out;
}

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

.footer-bottom {
    border-top: 1px solid #374151;
    padding-top: 2rem;
    text-align: center;
    color: #9ca3af;
}

/* Responsive Design */
@media (max-width: 1024px) {
    .hero .container {
        flex-direction: column;
        text-align: center;
    }

    .hero-content {
        order: 2;
    }

    .hero-image {
        order: 1;
        text-align: center;
        margin-bottom: 2rem;
    }

    .hero-actions {
        justify-content: center;
    }

    .nav {
        display: none;
    }

    .menu-toggle {
        display: block;
        background: none;
        border: none;
        font-size: 2rem;
        cursor: pointer;
        color: var(--color-primary-text);
    }

    .tutor-section {
        flex-direction: column;
    }

    .footer-content {
        grid-template-columns: repeat(2, 1fr);
    }
}

@media (max-width: 768px) {
    h1 {
        font-size: 3rem;
    }

    h2 {
        font-size: 2rem;
    }

    .program-cards {
        flex-direction: column;
        align-items: center;
    }

    .why-choose .features-grid {
        grid-template-columns: 1fr;
    }

    .tutor-features {
        flex-direction: column;
        align-items: center;
        gap: 1rem;
    }

    .stats-grid {
        flex-direction: column;
        gap: 2rem;
    }

    .subscribe-form {
        flex-direction: column;
        align-items: center;
    }

    .subscribe-form input {
        width: 100%;
        max-width: 300px;
    }

    .footer-content {
        grid-template-columns: 1fr;
    }
}