/* ===== ROOT VARIABLES (MINIMALIST THEME) ===== */
:root {
    /* Brand Colors - deeply saturated for contrast */
    --primary: #2563EB;       /* Vivid Blue */
    --primary-hover: #1D4ED8;
    
    /* Neutral Scale (The core of minimalist design) */
    --base-white: #ffffff;
    --base-50: #F9FAFB;
    --base-100: #F3F4F6;
    --base-200: #E5E7EB;      /* Borders */
    --base-800: #1F2937;
    --base-900: #111827;      /* Main Text */
    
    /* Functional Colors */
    --success: #10B981;
    --text-primary: var(--base-900);
    --text-secondary: #6B7280;
    
    /* UI Properties */
    --radius: 8px;            /* Moderate rounding (cleaner than full pill) */
    --header-height: 72px;
    --container-width: 1100px;
    
    /* Subtle Shadows */
    --shadow-xs: 0 1px 2px rgba(0, 0, 0, 0.05);
    --shadow-sm: 0 4px 6px -1px rgba(0, 0, 0, 0.05);
    --focus-ring: 0 0 0 4px rgba(37, 99, 235, 0.15);
    
    --transition: all 0.2s ease-in-out;
}

/* Dark Mode - High Contrast */
@media (prefers-color-scheme: dark) {
    :root {
        --base-white: #0f172a;    /* Dark Slate */
        --base-50: #1e293b;
        --base-100: #334155;
        --base-200: #334155;
        --base-800: #F3F4F6;
        --base-900: #F9FAFB;
        
        --text-primary: #F9FAFB;
        --text-secondary: #94A3B8;
    }
}

/* ===== RESET & BASE ===== */
* { margin: 0; padding: 0; box-sizing: border-box; }

body {
    font-family: 'Inter', -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
    background-color: var(--base-white);
    color: var(--text-primary);
    line-height: 1.6;
    -webkit-font-smoothing: antialiased;
}

.container {
    max-width: var(--container-width);
    margin: 0 auto;
    padding: 0 24px;
}

/* ===== HEADER (CLEAN & STICKY) ===== */
.header {
    height: var(--header-height);
    background: var(--base-white);
    border-bottom: 1px solid var(--base-200);
    position: sticky;
    top: 0;
    z-index: 100;
}

.navbar, .nav-content {
    height: 100%;
}

.nav-content {
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.logo {
    font-weight: 700;
    font-size: 1.25rem;
    color: var(--text-primary);
    text-decoration: none;
    display: flex;
    align-items: center;
    gap: 0.5rem;
    letter-spacing: -0.02em;
}

.logo i { color: var(--primary); }

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

.nav-menu a {
    text-decoration: none;
    color: var(--text-secondary);
    font-size: 0.95rem;
    font-weight: 500;
    transition: var(--transition);
}

.nav-menu a:hover, .nav-menu a.active {
    color: var(--primary);
}

.mobile-menu-btn { display: none; background: none; border: none; font-size: 1.5rem; color: var(--text-primary); }

/* ===== HERO SECTION (MODERN SAAS LOOK) ===== */
.hero {
    padding: 6rem 0 4rem;
    text-align: center;
    background: radial-gradient(circle at 50% 0%, var(--base-50) 0%, var(--base-white) 100%);
}

.hero-content h1 {
    font-size: clamp(2.5rem, 5vw, 3.5rem);
    font-weight: 800;
    letter-spacing: -0.03em;
    line-height: 1.1;
    margin-bottom: 1.5rem;
    color: var(--text-primary);
}

.hero-content h2 {
    font-size: 1.25rem;
    font-weight: 400;
    color: var(--text-secondary);
    margin-bottom: 2.5rem;
}

.hero-description {
    color: var(--text-secondary);
    max-width: 600px;
    margin: 0 auto 2.5rem;
    font-size: 1.1rem;
}

.cta-button {
    display: inline-block;
    background: var(--primary);
    color: white;
    padding: 0.875rem 2rem;
    border-radius: var(--radius);
    font-weight: 600;
    text-decoration: none;
    transition: var(--transition);
    box-shadow: 0 2px 10px rgba(37, 99, 235, 0.2);
}

.cta-button:hover {
    background: var(--primary-hover);
    transform: translateY(-1px);
    box-shadow: 0 4px 12px rgba(37, 99, 235, 0.3);
}

/* ===== SECTIONS GENERIC ===== */
.calculators-section, .features-section { padding: 5rem 0; }

.section-title {
    font-size: 2rem;
    font-weight: 700;
    letter-spacing: -0.02em;
    text-align: center;
    margin-bottom: 0.5rem;
    color: var(--text-primary);
}

.section-subtitle {
    text-align: center;
    color: var(--text-secondary);
    margin-bottom: 3rem;
}

/* ===== CARDS (CLEAN BORDER STYLE) ===== */
.calculators-grid, .features-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
    gap: 1.5rem;
}

.calculator-card {
    background: var(--base-white);
    border: 1px solid var(--base-200);
    border-radius: var(--radius);
    padding: 2rem;
    transition: var(--transition);
    text-align: left; /* Modern cards often align left */
}

.calculator-card:hover {
    border-color: var(--primary);
    box-shadow: var(--shadow-sm);
    transform: translateY(-2px);
}

.card-icon {
    width: 48px;
    height: 48px;
    background: var(--base-50);
    border-radius: var(--radius);
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 1.5rem;
    margin-bottom: 1.5rem;
    color: var(--primary);
    /* No heavy gradients, just clean colors */
}

.card-icon.health { color: #10B981; background: #ECFDF5; }
.card-icon.finance { color: #2563EB; background: #EFF6FF; }
.card-icon.math { color: #8B5CF6; background: #F5F3FF; }

.calculator-card h3 {
    margin-bottom: 0.5rem;
    font-size: 1.1rem;
    color: var(--text-primary);
}

.calculator-card p {
    font-size: 0.9rem;
    color: var(--text-secondary);
    margin-bottom: 1.5rem;
}

.card-link {
    color: var(--primary);
    text-decoration: none;
    font-weight: 600;
    font-size: 0.9rem;
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

/* ===== CALCULATOR FORMS (INPUTS) ===== */
.calculator-page { padding: 4rem 0; }

.calculator-container {
    background: var(--base-white);
    border: 1px solid var(--base-200);
    border-radius: var(--radius);
    padding: 2.5rem;
    max-width: 700px;
    margin: 0 auto;
}

.form-group label {
    display: block;
    font-size: 0.875rem;
    font-weight: 500;
    color: var(--text-primary);
    margin-bottom: 0.5rem;
}

.form-group input, 
.form-group select,
.contact-form textarea {
    width: 100%;
    padding: 0.75rem;
    border: 1px solid var(--base-200);
    border-radius: var(--radius);
    font-size: 1rem;
    background: var(--base-white);
    color: var(--text-primary);
    transition: var(--transition);
}

.form-group input:focus, 
.form-group select:focus,
.contact-form textarea:focus {
    outline: none;
    border-color: var(--primary);
    box-shadow: var(--focus-ring);
}

.form-row {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 1.5rem;
}

/* Buttons */
.btn {
    border: none;
    padding: 0.75rem 1.5rem;
    border-radius: var(--radius);
    font-weight: 600;
    cursor: pointer;
    font-size: 1rem;
    transition: var(--transition);
    width: 100%;
}

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

.btn-secondary { background: var(--base-100); color: var(--text-primary); }
.btn-secondary:hover { background: var(--base-200); }

.button-group { display: flex; gap: 1rem; margin-top: 2rem; }

/* Results */
.result-section {
    margin-top: 2rem;
    padding: 1.5rem;
    background: var(--base-50);
    border-radius: var(--radius);
    border: 1px solid var(--base-200);
}

.result-label { font-size: 0.875rem; color: var(--text-secondary); text-transform: uppercase; letter-spacing: 0.05em; }
.result-value { font-size: 2rem; font-weight: 700; color: var(--text-primary); margin-top: 0.25rem; }

/* ===== FOOTER ===== */
.footer {
    border-top: 1px solid var(--base-200);
    padding: 4rem 0 2rem;
    background: var(--base-white);
    margin-top: 4rem;
}

.footer-section h4 { color: var(--text-primary); margin-bottom: 1rem; font-size: 1rem; }
.footer-section ul { list-style: none; }
.footer-section a { color: var(--text-secondary); text-decoration: none; font-size: 0.9rem; transition: var(--transition); }
.footer-section a:hover { color: var(--primary); }

.footer-bottom { 
    margin-top: 3rem; 
    padding-top: 2rem; 
    border-top: 1px solid var(--base-200); 
    text-align: center; 
    font-size: 0.875rem; 
    color: var(--text-secondary); 
}

/* ===== MOBILE ===== */
@media (max-width: 768px) {
    .mobile-menu-btn { display: block; }
    
    .nav-menu {
        position: fixed;
        top: var(--header-height);
        left: 0; width: 100%; height: calc(100vh - var(--header-height));
        background: var(--base-white);
        flex-direction: column;
        padding: 2rem;
        gap: 1.5rem;
        transform: translateX(100%);
        transition: transform 0.3s ease;
        border-top: 1px solid var(--base-200);
    }
    
    .nav-menu.active { transform: translateX(0); }
    .nav-menu a { font-size: 1.25rem; color: var(--text-primary); display: block; padding-bottom: 1rem; border-bottom: 1px solid var(--base-200); }
    
    .hero-content h1 { font-size: 2.25rem; }
    .form-row { grid-template-columns: 1fr; gap: 1rem; }
    .button-group { flex-direction: column; }
    .calculator-card { text-align: center; } /* Center align cards on mobile for balance */
    .card-icon { margin: 0 auto 1.5rem; }
}