/* ===========================
   ROOT VARIABLES & THEME
=========================== */
:root {
    /* Brand Colors */
    --primary-color: #326fa8;
    --accent-color: #d11f66;
    --dark-neutral: #323b34;
    
    /* Light Theme */
    --bg-primary: #ffffff;
    --bg-secondary: #f8f9fa;
    --bg-tertiary: #e9ecef;
    --text-primary: #212529;
    --text-secondary: #6c757d;
    --text-tertiary: #adb5bd;
    --border-color: #dee2e6;
    --shadow: rgba(0, 0, 0, 0.1);
    --shadow-lg: rgba(0, 0, 0, 0.15);
    
    /* Spacing */
    --container-width: 1200px;
    --section-padding: 80px 0;
    --card-padding: 30px;
    
    /* Typography */
    --font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
    --font-size-base: 16px;
    --font-size-sm: 14px;
    --font-size-lg: 18px;
    --font-size-xl: 24px;
    --font-size-2xl: 32px;
    --font-size-3xl: 42px;
    
    /* Transitions */
    --transition-speed: 0.3s;
    --transition-ease: cubic-bezier(0.4, 0, 0.2, 1);
}

/* Dark Theme */
[data-theme="dark"] {
    --bg-primary: #1a1d23;
    --bg-secondary: #252932;
    --bg-tertiary: #2f3542;
    --text-primary: #f8f9fa;
    --text-secondary: #adb5bd;
    --text-tertiary: #6c757d;
    --border-color: #404654;
    --shadow: rgba(0, 0, 0, 0.3);
    --shadow-lg: rgba(0, 0, 0, 0.5);
}

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

html {
    scroll-behavior: smooth;
    font-size: var(--font-size-base);
}

body {
    font-family: var(--font-family);
    background-color: var(--bg-primary);
    color: var(--text-primary);
    line-height: 1.6;
    transition: background-color var(--transition-speed) var(--transition-ease),
                color var(--transition-speed) var(--transition-ease);
}

.container {
    max-width: var(--container-width);
    margin: 0 auto;
    padding: 0 20px;
}

a {
    text-decoration: none;
    color: inherit;
    transition: color var(--transition-speed) var(--transition-ease);
}

img {
    max-width: 100%;
    height: auto;
}

/* ===========================
   HEADER & NAVIGATION
=========================== */
.header {
    background-color: var(--bg-primary);
    border-bottom: 1px solid var(--border-color);
    position: sticky;
    top: 0;
    z-index: 1000;
    transition: background-color var(--transition-speed) var(--transition-ease),
                box-shadow var(--transition-speed) var(--transition-ease);
}

.header.scrolled {
    box-shadow: 0 4px 12px var(--shadow);
}

.navbar {
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: 20px;
}

.nav-brand {
    display: flex;
    align-items: center;
    gap: 10px;
    font-size: var(--font-size-xl);
    font-weight: 700;
    color: var(--primary-color);
}

.nav-brand i {
    font-size: 28px;
}

.nav-menu {
    display: flex;
    list-style: none;
    gap: 30px;
}

.nav-link {
    font-weight: 500;
    padding: 8px 0;
    position: relative;
    display: flex;
    align-items: center;
    gap: 5px;
}

.nav-link::after {
    content: '';
    position: absolute;
    bottom: 0;
    left: 0;
    width: 0;
    height: 2px;
    background-color: var(--primary-color);
    transition: width var(--transition-speed) var(--transition-ease);
}

.nav-link:hover::after,
.nav-link.active::after {
    width: 100%;
}

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

/* Dropdown Menu */
.nav-dropdown {
    position: relative;
}

.nav-dropdown .nav-link i {
    font-size: 12px;
    transition: transform var(--transition-speed) var(--transition-ease);
}

.nav-dropdown:hover .nav-link i {
    transform: rotate(180deg);
}

.dropdown-content {
    position: absolute;
    top: 100%;
    left: 0;
    background-color: var(--bg-primary);
    border: 1px solid var(--border-color);
    border-radius: 8px;
    box-shadow: 0 10px 30px var(--shadow-lg);
    opacity: 0;
    visibility: hidden;
    transform: translateY(-10px);
    transition: all var(--transition-speed) var(--transition-ease);
    min-width: 800px;
    padding: 20px;
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 20px;
    margin-top: 10px;
}

.nav-dropdown:hover .dropdown-content {
    opacity: 1;
    visibility: visible;
    transform: translateY(0);
}

.dropdown-section h4 {
    font-size: 14px;
    font-weight: 700;
    color: var(--text-primary);
    margin-bottom: 12px;
    padding-bottom: 8px;
    border-bottom: 2px solid var(--primary-color);
}

.dropdown-section a {
    display: block;
    padding: 8px 12px;
    color: var(--text-secondary);
    border-radius: 6px;
    font-size: 14px;
    transition: all var(--transition-speed) var(--transition-ease);
}

.dropdown-section a:hover {
    background-color: var(--bg-secondary);
    color: var(--primary-color);
    padding-left: 16px;
}

.nav-actions {
    display: flex;
    align-items: center;
    gap: 15px;
}

.theme-toggle,
.mobile-toggle {
    background: var(--bg-secondary);
    border: 1px solid var(--border-color);
    width: 40px;
    height: 40px;
    border-radius: 50%;
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 18px;
    color: var(--text-primary);
    transition: all var(--transition-speed) var(--transition-ease);
}

.theme-toggle:hover,
.mobile-toggle:hover {
    background-color: var(--primary-color);
    color: white;
    transform: scale(1.1);
}

.mobile-toggle {
    display: none;
}

/* ===========================
   BREADCRUMB
=========================== */
.breadcrumb {
    padding: 15px 20px;
    background-color: var(--bg-secondary);
    display: flex;
    align-items: center;
    gap: 10px;
    font-size: var(--font-size-sm);
    color: var(--text-secondary);
}

.breadcrumb a {
    color: var(--primary-color);
}

.breadcrumb a:hover {
    text-decoration: underline;
}

.breadcrumb i {
    font-size: 10px;
}

/* ===========================
   HERO SECTION
=========================== */
.hero {
    position: relative;
    padding: 120px 0 100px;
    background: linear-gradient(135deg, var(--primary-color) 0%, var(--accent-color) 100%);
    overflow: hidden;
    color: white;
}

.particles {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    pointer-events: none;
}

.particle {
    position: absolute;
    font-size: 24px;
    opacity: 0.3;
    animation: float-particle 15s infinite ease-in-out;
}

@keyframes float-particle {
    0%, 100% {
        transform: translate(0, 0) rotate(0deg);
    }
    25% {
        transform: translate(30px, -30px) rotate(90deg);
    }
    50% {
        transform: translate(-20px, -60px) rotate(180deg);
    }
    75% {
        transform: translate(-40px, -30px) rotate(270deg);
    }
}

.hero-content {
    position: relative;
    z-index: 1;
    text-align: center;
    animation: fadeInUp 0.8s ease-out;
}

@keyframes fadeInUp {
    from {
        opacity: 0;
        transform: translateY(30px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

.hero-title {
    font-size: var(--font-size-3xl);
    font-weight: 800;
    margin-bottom: 20px;
    line-height: 1.2;
}

.hero-subtitle {
    font-size: var(--font-size-lg);
    margin-bottom: 40px;
    opacity: 0.95;
}

.hero-buttons {
    display: flex;
    gap: 20px;
    justify-content: center;
    flex-wrap: wrap;
}

/* ===========================
   BUTTONS
=========================== */
.btn {
    padding: 14px 32px;
    border: none;
    border-radius: 8px;
    font-size: var(--font-size-base);
    font-weight: 600;
    cursor: pointer;
    display: inline-flex;
    align-items: center;
    gap: 10px;
    transition: all var(--transition-speed) var(--transition-ease);
}

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

.btn-primary:hover {
    transform: translateY(-2px);
    box-shadow: 0 8px 20px rgba(0, 0, 0, 0.2);
}

.btn-secondary {
    background-color: transparent;
    color: white;
    border: 2px solid white;
}

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

/* ===========================
   CALCULATORS SECTION
=========================== */
.calculators-section {
    padding: var(--section-padding);
}

.section-title {
    font-size: var(--font-size-2xl);
    font-weight: 700;
    text-align: center;
    margin-bottom: 15px;
    color: var(--text-primary);
}

.section-subtitle {
    text-align: center;
    color: var(--text-secondary);
    margin-bottom: 50px;
    font-size: var(--font-size-lg);
}

.calculator-tabs {
    display: flex;
    justify-content: center;
    gap: 15px;
    margin-bottom: 50px;
    flex-wrap: wrap;
}

.tab-btn {
    padding: 12px 28px;
    background-color: var(--bg-secondary);
    border: 2px solid var(--border-color);
    border-radius: 30px;
    font-size: var(--font-size-base);
    font-weight: 600;
    cursor: pointer;
    display: flex;
    align-items: center;
    gap: 8px;
    color: var(--text-primary);
    transition: all var(--transition-speed) var(--transition-ease);
}

.tab-btn:hover {
    border-color: var(--primary-color);
    color: var(--primary-color);
}

.tab-btn.active {
    background-color: var(--primary-color);
    color: white;
    border-color: var(--primary-color);
}

.calculator-cards {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(300px, 1fr));
    gap: 30px;
}

.calc-card {
    background-color: var(--bg-secondary);
    border: 1px solid var(--border-color);
    border-radius: 12px;
    padding: var(--card-padding);
    text-align: center;
    transition: all var(--transition-speed) var(--transition-ease);
    cursor: pointer;
}

.calc-card:hover {
    transform: translateY(-5px);
    box-shadow: 0 10px 30px var(--shadow-lg);
    border-color: var(--primary-color);
}

.card-icon {
    width: 70px;
    height: 70px;
    background: linear-gradient(135deg, var(--primary-color), var(--accent-color));
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    margin: 0 auto 20px;
    font-size: 32px;
    color: white;
}

.calc-card h3 {
    font-size: var(--font-size-xl);
    margin-bottom: 10px;
    color: var(--text-primary);
}

.calc-card p {
    color: var(--text-secondary);
    margin-bottom: 20px;
}

.calc-btn {
    background-color: var(--primary-color);
    color: white;
    border: none;
    padding: 10px 24px;
    border-radius: 6px;
    font-weight: 600;
    cursor: pointer;
    transition: all var(--transition-speed) var(--transition-ease);
}

.calc-btn:hover {
    background-color: var(--accent-color);
}

/* ===========================
   INSIGHTS SECTION
=========================== */
.insights-section {
    padding: var(--section-padding);
    background-color: var(--bg-secondary);
}

.insights-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(320px, 1fr));
    gap: 30px;
    margin-bottom: 60px;
}

.insight-card {
    background-color: var(--bg-primary);
    border: 1px solid var(--border-color);
    border-radius: 12px;
    padding: var(--card-padding);
    transition: all var(--transition-speed) var(--transition-ease);
}

.insight-card:hover {
    box-shadow: 0 8px 25px var(--shadow-lg);
    transform: translateY(-3px);
}

.insight-icon {
    width: 60px;
    height: 60px;
    background: linear-gradient(135deg, var(--primary-color), var(--accent-color));
    border-radius: 12px;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 28px;
    color: white;
    margin-bottom: 20px;
}

.insight-card h3 {
    font-size: var(--font-size-xl);
    margin-bottom: 12px;
    color: var(--text-primary);
}

.insight-card p {
    color: var(--text-secondary);
    line-height: 1.7;
}

.cta-section {
    text-align: center;
    padding: 60px 30px;
    background: linear-gradient(135deg, var(--primary-color), var(--accent-color));
    border-radius: 16px;
    color: white;
}

.cta-section h3 {
    font-size: var(--font-size-2xl);
    margin-bottom: 15px;
}

.cta-section p {
    font-size: var(--font-size-lg);
    margin-bottom: 30px;
    opacity: 0.95;
    max-width: 800px;
    margin-left: auto;
    margin-right: auto;
}

/* ===========================
   FOOTER
=========================== */
.footer {
    background-color: var(--dark-neutral);
    color: white;
    padding: 60px 0 0;
}

.footer-content {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 40px;
    padding-bottom: 40px;
    border-bottom: 1px solid rgba(255, 255, 255, 0.1);
}

.footer-brand {
    display: flex;
    align-items: center;
    gap: 10px;
    font-size: var(--font-size-xl);
    font-weight: 700;
    margin-bottom: 15px;
}

.footer-brand i {
    font-size: 28px;
    color: var(--primary-color);
}

.footer-desc {
    color: rgba(255, 255, 255, 0.7);
    margin-bottom: 20px;
    line-height: 1.7;
}

.social-links {
    display: flex;
    gap: 12px;
}

.social-links a {
    width: 40px;
    height: 40px;
    background-color: rgba(255, 255, 255, 0.1);
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 18px;
    transition: all var(--transition-speed) var(--transition-ease);
}

.social-links a:hover {
    background-color: var(--primary-color);
    transform: translateY(-3px);
}

.footer-col h4 {
    font-size: var(--font-size-lg);
    margin-bottom: 20px;
    font-weight: 600;
}

.footer-links {
    list-style: none;
}

.footer-links li {
    margin-bottom: 12px;
}

.footer-links a,
.footer-links li {
    color: rgba(255, 255, 255, 0.7);
    transition: color var(--transition-speed) var(--transition-ease);
    display: flex;
    align-items: center;
    gap: 8px;
}

.footer-links a:hover {
    color: white;
    padding-left: 5px;
}

.footer-bottom {
    padding: 25px 0;
    text-align: center;
    color: rgba(255, 255, 255, 0.6);
}

.footer-bottom i {
    color: var(--accent-color);
}

/* ===========================
   BACK TO TOP BUTTON
=========================== */
.back-to-top {
    position: fixed;
    bottom: 30px;
    right: 30px;
    width: 50px;
    height: 50px;
    background: linear-gradient(135deg, var(--primary-color), var(--accent-color));
    color: white;
    border: none;
    border-radius: 50%;
    cursor: pointer;
    font-size: 20px;
    display: none;
    align-items: center;
    justify-content: center;
    box-shadow: 0 4px 15px var(--shadow-lg);
    transition: all var(--transition-speed) var(--transition-ease);
    z-index: 999;
}

.back-to-top:hover {
    transform: translateY(-5px);
    box-shadow: 0 6px 20px var(--shadow-lg);
}

.back-to-top.show {
    display: flex;
}

/* ===========================
   UTILITY CLASSES
=========================== */
.text-center {
    text-align: center;
}

.text-primary {
    color: var(--primary-color);
}

.text-accent {
    color: var(--accent-color);
}

.mt-1 { margin-top: 10px; }
.mt-2 { margin-top: 20px; }
.mt-3 { margin-top: 30px; }
.mb-1 { margin-bottom: 10px; }
.mb-2 { margin-bottom: 20px; }
.mb-3 { margin-bottom: 30px; }