:root {
    --primary: #1e3a8a;
    --primary-light: #3b82f6;
    --bg: #f8fafc;
    --card-bg: #ffffff;
    --text: #1e293b;
    --border: #e2e8f0;
}

* { box-sizing: border-box; }

body {
    margin: 0;
    font-family: 'Segoe UI', system-ui, sans-serif;
    background: var(--bg);
    color: var(--text);
}

.navbar {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 1rem 2rem;
    background: var(--primary);
    color: white;
    flex-wrap: wrap;
}

.navbar a {
    color: white;
    text-decoration: none;
    margin-left: 1.5rem;
    font-weight: 500;
}

.nav-brand a { margin-left: 0; font-size: 1.2rem; font-weight: 700; }

.container {
    max-width: 1100px;
    margin: 0 auto;
    padding: 2rem 1rem;
}

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

.module-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(240px, 1fr));
    gap: 1.5rem;
}

.module-card {
    display: block;
    background: var(--card-bg);
    border: 1px solid var(--border);
    border-radius: 12px;
    padding: 1.5rem;
    text-decoration: none;
    color: var(--text);
    transition: transform 0.15s ease, box-shadow 0.15s ease;
}

.module-card:hover {
    transform: translateY(-4px);
    box-shadow: 0 8px 20px rgba(30, 58, 138, 0.15);
}

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

@media (max-width: 768px) {
    .module-layout { grid-template-columns: 1fr; }
    .navbar { flex-direction: column; align-items: flex-start; }
    .nav-links { margin-top: 0.5rem; }
    .navbar a { margin-left: 0; margin-right: 1rem; }
}

.input-panel, .output-panel {
    background: var(--card-bg);
    border: 1px solid var(--border);
    border-radius: 12px;
    padding: 1.5rem;
}

form label {
    display: block;
    margin-bottom: 1rem;
    font-weight: 500;
    font-size: 0.9rem;
}

form input, form select, form textarea {
    display: block;
    width: 100%;
    margin-top: 0.4rem;
    padding: 0.5rem;
    border: 1px solid var(--border);
    border-radius: 6px;
    font-family: inherit;
}

button {
    background: var(--primary-light);
    color: white;
    border: none;
    padding: 0.6rem 1.2rem;
    border-radius: 6px;
    cursor: pointer;
    font-weight: 600;
    margin-right: 0.5rem;
}

button:hover { background: var(--primary); }

.error-message { color: #dc2626; font-weight: 500; }
.success-message { color: #16a34a; font-weight: 500; }

footer {
    text-align: center;
    padding: 1.5rem;
    color: #64748b;
    font-size: 0.85rem;
}