/* --- CSS Variables (Theme) --- */
:root {
    --primary-color: #007bff;
    --primary-hover: #0056b3;
    --bg-color: #ffffff;
    --text-color: #333;
    --text-light: #555;
    --border-color: #eee;
    --card-bg: #f9f9f9;
}

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

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

/* --- Utility Classes --- */
.container {
    max-width: 1100px;
    margin: 0 auto;
    padding: 0 1.5rem;
}

/* --- Buttons --- */
.btn-primary, .btn-secondary {
    display: inline-block;
    padding: 0.75rem 1.5rem;
    border-radius: 8px;
    text-decoration: none;
    font-weight: 600;
    transition: all 0.3s ease;
}

.btn-primary {
    background-color: var(--primary-color);
    color: #fff;
    border: 1px solid var(--primary-color);
}
.btn-primary:hover {
    background-color: var(--primary-hover);
    transform: translateY(-2px);
    box-shadow: 0 4px 10px rgba(0,0,0,0.1);
}

.btn-secondary {
    background-color: #fff;
    color: var(--text-color);
    border: 1px solid var(--border-color);
}
.btn-secondary:hover {
    background-color: var(--card-bg);
}

/* --- Navigation --- */
nav {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding-top: 1rem;
    padding-bottom: 1rem;
}
.logo {
    font-size: 1.25rem;
    font-weight: 700;
}
.nav-links {
    display: flex;
    align-items: center;
    list-style: none;
}
.nav-links li {
    margin-left: 1.5rem;
}
.nav-links a {
    text-decoration: none;
    color: var(--text-light);
    font-weight: 600;
}

/* --- Hero Section --- */
.hero {
    text-align: center;
    padding: 5rem 1rem;
    background-color: var(--card-bg);
    border-bottom: 1px solid var(--border-color);
}
.hero h1 {
    font-size: 3rem;
    margin-bottom: 1rem;
}
.hero .subtitle {
    font-size: 1.2rem;
    color: var(--text-light);
    max-width: 600px;
    margin: 0 auto 2rem auto;
}

/* --- Features Section --- */
main {
    padding: 4rem 0;
}
main h2 {
    text-align: center;
    font-size: 2.2rem;
    margin-bottom: 3rem;
}
.features-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 2rem;
}
.feature-card {
    background: #fff;
    border: 1px solid var(--border-color);
    border-radius: 12px;
    padding: 2rem;
    text-align: center;
    box-shadow: 0 2px 5px rgba(0,0,0,0.03);
    transition: transform 0.3s ease, box-shadow 0.3s ease;
}
.feature-card:hover {
    transform: translateY(-5px);
    box-shadow: 0 8px 20px rgba(0,0,0,0.07);
}
.feature-card h3 {
    font-size: 1.5rem;
    margin-bottom: 0.5rem;
}
.feature-card p {
    color: var(--text-light);
}

/* --- Footer --- */
footer {
    text-align: center;
    padding: 2rem 0;
    margin-top: 3rem;
    border-top: 1px solid var(--border-color);
    color: var(--text-light);
}

/* --- Mobile Responsiveness --- */
@media (max-width: 768px) {
    .hero h1 {
        font-size: 2.5rem;
    }
    .nav-links {
        display: none; /* Simplifies demo. A real app would use a hamburger menu */
    }
}