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

body {
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI",
        Roboto, sans-serif;
    line-height: 1.6;
    color: #1e293b;
    background: #f8fafc;
}

/* Navbar */
.navbar {
    background: #fff;
    border-bottom: 1px solid #e2e8f0;
    position: sticky;
    top: 0;
    z-index: 100;
}

.nav-container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 1rem 1.5rem;
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.logo {
    font-size: 1.5rem;
    font-weight: 800;
    color: #4f46e5;
    text-decoration: none;
}

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

.nav-links a {
    color: #334155;
    text-decoration: none;
    font-weight: 500;
    font-size: 0.95rem;
    transition: color 0.15s;
}

.nav-links a:hover {
    color: #4f46e5;
}

/* Hero */
.hero {
    max-width: 800px;
    margin: 0 auto;
    padding: 5rem 1.5rem 3rem;
    text-align: center;
}

.hero h1 {
    font-size: 3rem;
    font-weight: 800;
    margin-bottom: 1rem;
    color: #0f172a;
    letter-spacing: -0.02em;
}

.hero p {
    font-size: 1.15rem;
    color: #475569;
    margin-bottom: 2rem;
}

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

.btn {
    padding: 0.85rem 1.75rem;
    border-radius: 0.5rem;
    text-decoration: none;
    font-weight: 600;
    transition: transform 0.15s, box-shadow 0.15s;
    display: inline-block;
}

.btn:hover {
    transform: translateY(-2px);
    box-shadow: 0 8px 20px rgba(0, 0, 0, 0.1);
}

.btn-primary {
    background: #4f46e5;
    color: #fff;
}

.btn-secondary {
    background: #fff;
    color: #1e293b;
    border: 1px solid #cbd5e1;
}

/* Cards */
.cards {
    max-width: 1200px;
    margin: 2rem auto 4rem;
    padding: 0 1.5rem;
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: 1.5rem;
}

.card {
    background: #fff;
    padding: 2rem;
    border-radius: 0.75rem;
    text-decoration: none;
    color: inherit;
    border: 1px solid #e2e8f0;
    transition: transform 0.15s, box-shadow 0.15s;
}

.card:hover {
    transform: translateY(-4px);
    box-shadow: 0 12px 24px rgba(0, 0, 0, 0.08);
}

.card h3 {
    color: #4f46e5;
    margin-bottom: 0.5rem;
    font-size: 1.25rem;
}

.card p {
    color: #64748b;
    font-size: 0.95rem;
}

/* Article pages */
.article {
    max-width: 760px;
    margin: 3rem auto;
    padding: 2.5rem;
    background: #fff;
    border-radius: 0.75rem;
    border: 1px solid #e2e8f0;
}

.article h1 {
    font-size: 2.25rem;
    margin-bottom: 1.5rem;
    color: #0f172a;
}

.article h2 {
    font-size: 1.5rem;
    margin: 2rem 0 0.75rem;
    color: #1e293b;
}

.article p,
.article li {
    color: #334155;
    margin-bottom: 1rem;
    font-size: 1.05rem;
}

.article ul {
    padding-left: 1.5rem;
    margin-bottom: 1rem;
}

.article .formula {
    background: #f1f5f9;
    padding: 1rem;
    border-radius: 0.5rem;
    text-align: center;
    font-family: "Courier New", monospace;
}

/* Map page */
.map-wrapper {
    max-width: 1200px;
    margin: 2rem auto;
    padding: 0 1.5rem;
}

.map-wrapper h1 {
    margin-bottom: 1rem;
    color: #0f172a;
}

#map {
    height: 550px;
    border-radius: 0.75rem;
    border: 1px solid #e2e8f0;
}

.location-list {
    margin-top: 2rem;
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: 1rem;
}

.location-item {
    background: #fff;
    padding: 1.25rem;
    border-radius: 0.5rem;
    border: 1px solid #e2e8f0;
}

.location-item strong {
    display: block;
    color: #4f46e5;
    margin-bottom: 0.25rem;
}

.location-item span {
    color: #64748b;
    font-size: 0.95rem;
}

/* City selector dropdown */
.city-selector {
    margin: 1.5rem 0;
    display: flex;
    align-items: center;
    gap: 0.75rem;
}

.city-selector label {
    font-weight: 600;
    color: #334155;
}

.city-selector select {
    padding: 0.6rem 1rem;
    border: 1px solid #cbd5e1;
    border-radius: 0.5rem;
    background: #fff;
    font-size: 1rem;
    color: #1e293b;
    cursor: pointer;
}

.city-selector select:focus {
    outline: none;
    border-color: #4f46e5;
    box-shadow: 0 0 0 3px rgba(79, 70, 229, 0.15);
}

/* Footer */
footer {
    text-align: center;
    padding: 2rem 1.5rem;
    color: #94a3b8;
    font-size: 0.9rem;
    border-top: 1px solid #e2e8f0;
    background: #fff;
}

/* Responsive */
@media (max-width: 640px) {
    .hero h1 {
        font-size: 2rem;
    }
    .nav-links {
        gap: 1rem;
        font-size: 0.85rem;
    }
}