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

:root {
    --primary-color: #2563eb;
    --secondary-color: #1e40af;
    --accent-color: #10b981;
    --danger-color: #ef4444;
    --warning-color: #f59e0b;
    --dark-color: #1f2937;
    --light-color: #f3f4f6;
    --text-color: #374151;
    --border-color: #e5e7eb;
    --shadow: 0 4px 6px rgba(0, 0, 0, 0.1);
    --shadow-lg: 0 10px 25px rgba(0, 0, 0, 0.15);
}

body {
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    line-height: 1.6;
    color: var(--text-color);
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    background-attachment: fixed;
}

.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 20px;
}

/* Header & Navigation */
header {
    background: rgba(255, 255, 255, 0.98);
    box-shadow: var(--shadow);
    position: sticky;
    top: 0;
    z-index: 1000;
    -webkit-backdrop-filter: blur(10px);
    backdrop-filter: blur(10px);
}

.navbar {
    padding: 1rem 0;
}

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

.logo {
    display: flex;
    align-items: center;
    gap: 10px;
    font-size: 1.5rem;
    font-weight: bold;
    color: var(--primary-color);
}

.logo i {
    font-size: 2rem;
}

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

.nav-menu a {
    text-decoration: none;
    color: var(--text-color);
    font-weight: 500;
    transition: color 0.3s;
    position: relative;
}

.nav-menu a::after {
    content: '';
    position: absolute;
    bottom: -5px;
    left: 0;
    width: 0;
    height: 2px;
    background: var(--primary-color);
    transition: width 0.3s;
}

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

.nav-menu a:hover::after {
    width: 100%;
}

.hamburger {
    display: none;
    flex-direction: column;
    cursor: pointer;
    gap: 5px;
}

.hamburger span {
    width: 25px;
    height: 3px;
    background: var(--primary-color);
    border-radius: 3px;
    transition: all 0.3s;
}

/* Hero Section */
.hero {
    text-align: center;
    padding: 100px 20px;
    color: white;
}

.hero h1 {
    font-size: 3rem;
    margin-bottom: 1rem;
    text-shadow: 2px 2px 10px rgba(0, 0, 0, 0.3);
}

.hero p {
    font-size: 1.3rem;
    margin-bottom: 2rem;
    opacity: 0.95;
}

.btn-primary {
    display: inline-block;
    padding: 15px 40px;
    background: white;
    color: var(--primary-color);
    text-decoration: none;
    border-radius: 50px;
    font-weight: bold;
    font-size: 1.1rem;
    transition: all 0.3s;
    box-shadow: var(--shadow-lg);
}

.btn-primary:hover {
    transform: translateY(-3px);
    box-shadow: 0 15px 35px rgba(0, 0, 0, 0.2);
}

.btn-primary i {
    margin-left: 10px;
}

/* Calculator Sections */
.calculator-section {
    padding: 80px 20px;
    background: white;
    margin: 20px 0;
    border-radius: 20px;
}

.calculator-section:nth-child(even) {
    background: var(--light-color);
}

.section-header {
    text-align: center;
    margin-bottom: 3rem;
}

.section-header i {
    font-size: 3rem;
    color: var(--primary-color);
    margin-bottom: 1rem;
}

.section-header h2 {
    font-size: 2.5rem;
    color: var(--dark-color);
    margin-bottom: 0.5rem;
}

.section-header p {
    font-size: 1.1rem;
    color: var(--text-color);
    opacity: 0.8;
}

/* Calculator Card */
.calculator-card {
    max-width: 800px;
    margin: 0 auto;
    background: white;
    padding: 40px;
    border-radius: 20px;
    box-shadow: var(--shadow-lg);
}

.input-group {
    margin-bottom: 2rem;
}

.input-group label {
    display: flex;
    align-items: center;
    gap: 10px;
    font-weight: 600;
    margin-bottom: 0.5rem;
    color: var(--dark-color);
}

.input-group label i {
    color: var(--primary-color);
    font-size: 1.2rem;
}

.input-group input,
.input-group select {
    width: 100%;
    padding: 15px;
    border: 2px solid var(--border-color);
    border-radius: 10px;
    font-size: 1rem;
    transition: all 0.3s;
    background: white;
}

.input-group input:focus,
.input-group select:focus {
    outline: none;
    border-color: var(--primary-color);
    box-shadow: 0 0 0 3px rgba(37, 99, 235, 0.1);
}

/* Checkbox Group */
.checkbox-group {
    margin: 2rem 0;
    padding: 20px;
    background: var(--light-color);
    border-radius: 10px;
}

.checkbox-group h4 {
    margin-bottom: 1rem;
    color: var(--dark-color);
}

.checkbox-label {
    display: flex;
    align-items: center;
    gap: 10px;
    padding: 10px;
    cursor: pointer;
    transition: background 0.3s;
    border-radius: 5px;
}

.checkbox-label:hover {
    background: rgba(37, 99, 235, 0.05);
}

.checkbox-label input[type="checkbox"] {
    width: 20px;
    height: 20px;
    cursor: pointer;
    accent-color: var(--primary-color);
}

/* Calculate Button */
.btn-calculate {
    width: 100%;
    padding: 18px;
    background: linear-gradient(135deg, var(--primary-color), var(--secondary-color));
    color: white;
    border: none;
    border-radius: 10px;
    font-size: 1.1rem;
    font-weight: bold;
    cursor: pointer;
    transition: all 0.3s;
    margin-top: 1rem;
}

.btn-calculate:hover {
    transform: translateY(-2px);
    box-shadow: var(--shadow-lg);
}

.btn-calculate i {
    margin-right: 10px;
}

/* Result Box */
.result-box {
    margin-top: 2rem;
    padding: 30px;
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    border-radius: 15px;
    color: white;
    animation: slideDown 0.5s ease;
}

@keyframes slideDown {
    from {
        opacity: 0;
        transform: translateY(-20px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

.result-box h3 {
    font-size: 1.8rem;
    margin-bottom: 1.5rem;
    text-align: center;
    text-shadow: 2px 2px 4px rgba(0, 0, 0, 0.2);
}

.result-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
    gap: 1.5rem;
    margin-bottom: 1.5rem;
}

.result-item {
    background: rgba(255, 255, 255, 0.15);
    padding: 20px;
    border-radius: 10px;
    -webkit-backdrop-filter: blur(10px);
    backdrop-filter: blur(10px);
}

.result-item.highlight {
    background: rgba(255, 255, 255, 0.25);
    border: 2px solid rgba(255, 255, 255, 0.5);
}

.result-label {
    display: block;
    font-size: 0.9rem;
    opacity: 0.9;
    margin-bottom: 0.5rem;
}

.result-value {
    display: block;
    font-size: 1.8rem;
    font-weight: bold;
}

.result-description {
    padding: 20px;
    background: rgba(255, 255, 255, 0.2);
    border-radius: 10px;
    line-height: 1.8;
    -webkit-backdrop-filter: blur(10px);
    backdrop-filter: blur(10px);
}

.result-description p {
    margin-bottom: 0.5rem;
}

/* Footer */
footer {
    background: var(--dark-color);
    color: white;
    padding: 40px 20px 20px;
    margin-top: 50px;
}

.footer-content {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 2rem;
    margin-bottom: 2rem;
}

.footer-section h3,
.footer-section h4 {
    margin-bottom: 1rem;
    color: var(--accent-color);
}

.footer-section p {
    margin-bottom: 0.5rem;
    opacity: 0.8;
}

.footer-section i {
    margin-right: 10px;
    color: var(--accent-color);
}

.footer-bottom {
    text-align: center;
    padding-top: 20px;
    border-top: 1px solid rgba(255, 255, 255, 0.1);
    opacity: 0.7;
}

/* Responsive Design */
@media (max-width: 768px) {
    .hamburger {
        display: flex;
    }

    .nav-menu {
        position: absolute;
        left: -100%;
        top: 70px;
        flex-direction: column;
        background: white;
        width: 100%;
        text-align: center;
        transition: 0.3s;
        box-shadow: var(--shadow);
        padding: 20px;
        gap: 1rem;
    }

    .nav-menu.active {
        left: 0;
    }

    .hero h1 {
        font-size: 2rem;
    }

    .hero p {
        font-size: 1rem;
    }

    .section-header h2 {
        font-size: 1.8rem;
    }

    .calculator-card {
        padding: 25px;
    }

    .result-grid {
        grid-template-columns: 1fr;
    }

    .result-value {
        font-size: 1.5rem;
    }
}

@media (max-width: 480px) {
    .hero {
        padding: 60px 20px;
    }

    .calculator-section {
        padding: 40px 15px;
    }

    .btn-primary {
        padding: 12px 30px;
        font-size: 1rem;
    }

    .section-header i {
        font-size: 2rem;
    }
}

/* Smooth Scrolling */
html {
    scroll-behavior: smooth;
}

/* Custom Scrollbar */
::-webkit-scrollbar {
    width: 10px;
}

::-webkit-scrollbar-track {
    background: var(--light-color);
}

::-webkit-scrollbar-thumb {
    background: var(--primary-color);
    border-radius: 5px;
}

::-webkit-scrollbar-thumb:hover {
    background: var(--secondary-color);
}