:root {
    /* Dark Theme (Default) */
    --bg-color: #0d1117;
    --text-color: #c9d1d9;
    --primary-color: #2ea44f;
    /* Green */
    --accent-color: #8b949e;
    --card-bg: #161b22;
    --nav-bg: rgba(22, 27, 34, 0.8);
    --border-color: #30363d;
    --gradient-start: #2ea44f;
    --gradient-end: #218bff;
    /* Green to Blue */
    --shadow-color: rgba(0, 0, 0, 0.3);
}

body.light-theme {
    /* Light Theme Overrides */
    --bg-color: #f9f9f9;
    --text-color: #24292f;
    --primary-color: #1a7f37;
    /* Darker Green for light mode contrast */
    --accent-color: #57606a;
    --card-bg: #f6f8fa;
    --nav-bg: rgba(255, 255, 255, 0.8);
    --border-color: #d0d7de;
    --gradient-start: #1a7f37;
    --gradient-end: #0969da;
    --shadow-color: rgba(140, 149, 159, 0.2);
}

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

body {
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol";
    background-color: var(--bg-color);
    color: var(--text-color);
    line-height: 1.6;
}

/* Navbar */
header {
    position: fixed;
    top: 0;
    width: 100%;
    background-color: var(--nav-bg);
    backdrop-filter: blur(10px);
    border-bottom: 1px solid var(--border-color);
    z-index: 1000;
}

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

.logo {
    font-size: 1.5rem;
    font-weight: bold;
    color: var(--primary-color);
    text-decoration: none;
}

.nav-links {
    list-style: none;
    display: flex;
    gap: 2rem;
}

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

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

select#langSelect {
    background-color: var(--card-bg);
    color: var(--text-color);
    border: 1px solid var(--border-color);
    padding: 0.5rem;
    border-radius: 6px;
    cursor: pointer;
}

.theme-btn {
    background: none;
    border: none;
    color: var(--text-color);
    font-size: 1.2rem;
    cursor: pointer;
    padding: 0.5rem;
    border-radius: 50%;
    transition: background-color 0.3s;
    display: flex;
    align-items: center;
    justify-content: center;
}

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

/* Hero Section */
.hero {
    padding: 160px 2rem 80px;
    text-align: center;
    background: radial-gradient(circle at top center, var(--card-bg) 0%, var(--bg-color) 70%);
}

.hero h1 {
    font-size: 4rem;
    margin-bottom: 1rem;
    color: var(--primary-color);
}

.hero p {
    font-size: 1.5rem;
    color: var(--accent-color);
    max-width: 800px;
    margin: 0 auto 2rem;
}

.cta-button {
    display: inline-block;
    background-color: var(--primary-color);
    color: white;
    padding: 1rem 2rem;
    border-radius: 50px;
    text-decoration: none;
    font-weight: bold;
    font-size: 1.1rem;
    transition: transform 0.2s, box-shadow 0.2s;
}

.cta-button:hover {
    transform: translateY(-2px);
    box-shadow: 0 10px 20px rgba(121, 40, 202, 0.3);
}

/* Features */
section {
    padding: 80px 2rem;
    max-width: 1200px;
    margin: 0 auto;
}

h2 {
    font-size: 2.5rem;
    text-align: center;
    margin-bottom: 3rem;
    color: var(--primary-color);
}

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

.feature-card {
    background-color: var(--card-bg);
    padding: 2rem;
    border-radius: 12px;
    border: 1px solid var(--border-color);
    transition: transform 0.3s;
}

.feature-card:hover {
    transform: translateY(-5px);
    border-color: var(--primary-color);
}

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

/* How it works */
.steps {
    display: flex;
    flex-direction: column;
    gap: 1.5rem;
    max-width: 800px;
    margin: 0 auto;
}

.step {
    background-color: var(--card-bg);
    padding: 1.5rem;
    border-radius: 8px;
    border-left: 4px solid var(--primary-color);
}

/* Support */
.support {
    text-align: center;
}

.secondary-button {
    display: inline-block;
    margin-top: 1rem;
    padding: 0.8rem 1.6rem;
    background-color: var(--card-bg);
    color: var(--primary-color);
    border: 1px solid var(--border-color);
    border-radius: 6px;
    text-decoration: none;
    transition: all 0.3s;
}

.secondary-button:hover {
    border-color: var(--primary-color);
    background-color: rgba(88, 166, 255, 0.1);
}

/* Footer */
footer {
    text-align: center;
    padding: 3rem 2rem;
    color: var(--accent-color);
    border-top: 1px solid var(--border-color);
    margin-top: 4rem;
}

@media (max-width: 768px) {
    .nav-links {
        display: none;
    }

    .hero h1 {
        font-size: 2.5rem;
    }
}