/* Eco-friendly CSS - Lightweight & Semantic */

:root {
    --bg-color: #f9fafb;
    --text-color: #1f2937;
    --heading-color: #111827;
    --primary-color: #2563eb;
    --primary-hover: #1d4ed8;
    --secondary-bg: #eff6ff;
    --secondary-text: #1e40af;
    --footer-bg: #111827;
    --footer-text: #9ca3af;
    --white: #ffffff;
    --max-width: 1100px;
}

/* Reset & Base */
* {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
}

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

h1,
h2,
h3 {
    font-family: 'Merriweather', serif;
    color: var(--heading-color);
    line-height: 1.2;
}

a {
    text-decoration: none;
    transition: all 0.2s ease;
}

/* Utilities */
.container {
    max-width: var(--max-width);
    margin: 0 auto;
    padding: 0 1.5rem;
}

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

/* Hero Section */
.hero {
    background: linear-gradient(135deg, #1e293b 0%, #0f172a 100%);
    color: var(--white);
    padding: 5rem 1.5rem 6rem;
    position: relative;
    overflow: hidden;
}

.lang-switcher {
    position: absolute;
    top: 1.5rem;
    right: 1.5rem;
    z-index: 10;
}

.lang-select {
    background: #1f2937;
    color: var(--white);
    border: 1px solid #4b5563;
    padding: 0.25rem 0.5rem;
    border-radius: 0.375rem;
    cursor: pointer;
}

.hero-content {
    max-width: 800px;
    margin: 0 auto;
    text-align: center;
    position: relative;
    z-index: 1;
}

.hero h1 {
    font-size: 2.5rem;
    font-weight: 700;
    margin-bottom: 1.5rem;
    color: var(--white);
}

.hero h1 span {
    color: #60a5fa;
    /* Blue-400 */
}

.hero p {
    font-size: 1.25rem;
    color: #d1d5db;
    /* Gray-300 */
    margin-bottom: 2.5rem;
    font-weight: 300;
}

.hero-tagline {
    font-size: 0.875rem;
    font-weight: 700;
    text-transform: uppercase;
    letter-spacing: 0.1em;
    color: #93c5fd;
    /* Blue-300 */
    display: block;
    margin-top: 1rem;
}

.hero-buttons {
    display: flex;
    flex-direction: column;
    gap: 1rem;
    justify-content: center;
    align-items: center;
}

.btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: 0.5rem;
    padding: 0.75rem 2rem;
    border-radius: 9999px;
    font-weight: 700;
    font-size: 1rem;
    box-shadow: 0 4px 6px rgba(0, 0, 0, 0.1);
}

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

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

.btn-secondary {
    background-color: var(--white);
    color: #111827;
}

.btn-secondary:hover {
    background-color: #f3f4f6;
}

/* Features Grid */
.features {
    padding: 5rem 0;
}

.features-grid {
    display: grid;
    grid-template-columns: 1fr;
    gap: 2rem;
}

.feature-card {
    background: var(--white);
    padding: 1.5rem;
    border-radius: 1rem;
    box-shadow: 0 1px 3px rgba(0, 0, 0, 0.1);
    transition: transform 0.2s, box-shadow 0.2s;
    text-align: center;
}

.feature-card:hover {
    transform: translateY(-2px);
    box-shadow: 0 4px 6px rgba(0, 0, 0, 0.1);
}

.feature-icon {
    font-size: 3.5rem;
    margin-bottom: 1rem;
    display: block;
}

/* Experimentation Section */
.experiment {
    background-color: var(--secondary-bg);
    padding: 5rem 1.5rem;
    text-align: center;
}

.experiment h2 {
    font-size: 2rem;
    margin-bottom: 1.5rem;
}

.experiment p {
    font-size: 1.125rem;
    color: #374151;
    margin-bottom: 2.5rem;
    max-width: 700px;
    margin-left: auto;
    margin-right: auto;
}

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

.tag {
    background: var(--white);
    color: var(--secondary-text);
    padding: 0.5rem 1rem;
    border-radius: 0.5rem;
    font-weight: 500;
    box-shadow: 0 1px 2px rgba(0, 0, 0, 0.05);
}

/* Free Library Section */
.free-library {
    padding: 5rem 1.5rem;
    background-color: var(--white);
    text-align: center;
}

.free-library h2 {
    font-size: 2rem;
    margin-bottom: 1.5rem;
}

.free-library p {
    font-size: 1.125rem;
    max-width: 700px;
    margin: 0 auto 2.5rem;
}

.platform-logos {
    display: flex;
    justify-content: center;
    gap: 2rem;
    flex-wrap: wrap;
    margin-bottom: 3rem;
}

.platform-logo {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 0.5rem;
    font-weight: 600;
    color: var(--text-color);
}

.platform-logo span {
    font-size: 2.5rem;
}

/* Footer */
.footer {
    background-color: var(--footer-bg);
    color: var(--footer-text);
    padding: 4rem 1.5rem;
    text-align: center;
}

.footer h2 {
    color: var(--white);
    margin-bottom: 1.5rem;
}

.footer a {
    color: #60a5fa;
    text-decoration: underline;
    font-size: 1.25rem;
    font-weight: bold;
}

.footer-bottom {
    margin-top: 3rem;
    padding-top: 2rem;
    border-top: 1px solid #374151;
    font-size: 0.875rem;
}

/* Responsive */
@media (min-width: 768px) {
    .hero hr {
        margin-bottom: 0;
    }

    .hero h1 {
        font-size: 3.5rem;
    }

    .hero-buttons {
        flex-direction: row;
    }

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

@media (min-width: 1024px) {
    .features-grid {
        grid-template-columns: repeat(4, 1fr);
    }

    /* 4 columns for modularity */
}