:root {
    --primary: #10b981;
    --primary-dark: #059669;
    --primary-light: #d1fae5;
    --secondary: #3b82f6;
    --accent: #8b5cf6;
    --dark: #1f2937;
    --text: #374151;
    --text-light: #6b7280;
    --white: #ffffff;
    --bg: #f9fafb;
    --border: #e5e7eb;
    --shadow: 0 4px 6px -1px rgba(0, 0, 0, 0.1);
    --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.1);
    --radius: 12px;
}

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

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Oxygen, Ubuntu, Cantarell, sans-serif;
    color: var(--text);
    background: var(--white);
    line-height: 1.6;
}

/* Header & Navigation */
.header {
    background: var(--white);
    border-bottom: 1px solid var(--border);
    position: sticky;
    top: 0;
    z-index: 100;
    box-shadow: var(--shadow);
}

.container {
    max-width: 960px;
    /* Reduced from 1200px for concise/zoomed-out look */
    margin: 0 auto;
    padding: 0 20px;
}

.nav {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 20px 0;
}

.logo {
    display: flex;
    align-items: center;
    gap: 12px;
    text-decoration: none;
    color: var(--dark);
    font-size: 24px;
    font-weight: 700;
}

.logo-icon {
    font-size: 36px;
}

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

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

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

/* Dropdown Menu Styles */
.nav-menu li {
    position: relative;
}

.nav-menu .sub-menu {
    display: none;
    position: absolute;
    top: 100%;
    left: 0;
    min-width: 220px;
    background: white;
    box-shadow: 0 10px 15px -3px rgba(0, 0, 0, 0.1);
    border-radius: 8px;
    padding: 10px 0;
    list-style: none;
    z-index: 1000;
    border: 1px solid var(--border);
}

.nav-menu li:hover>.sub-menu {
    display: block;
    animation: fadeIn 0.2s ease-out;
}

.nav-menu .sub-menu li {
    margin: 0;
}

.nav-menu .sub-menu a {
    display: block;
    padding: 10px 20px;
    color: var(--text);
    font-size: 14px;
    white-space: nowrap;
}

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

/* Second Level Dropdown */
.nav-menu .sub-menu .sub-menu {
    left: 100%;
    top: 0;
    margin-top: -10px;
    /* Align slightly better */
}

.nav-menu .arrow {
    font-size: 10px;
    margin-left: 4px;
    vertical-align: middle;
}

/* Hero Section */
.hero {
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    color: white;
    padding: 80px 0;
    text-align: center;
}

.hero h1 {
    font-size: 48px;
    margin-bottom: 20px;
    font-weight: 800;
}

.hero p {
    font-size: 20px;
    opacity: 0.95;
    max-width: 600px;
    margin: 0 auto 40px;
}

.btn {
    display: inline-block;
    padding: 14px 32px;
    background: white;
    color: var(--primary);
    text-decoration: none;
    border-radius: var(--radius);
    font-weight: 600;
    transition: all 0.3s;
    border: none;
    cursor: pointer;
    font-size: 16px;
}

.btn:hover {
    transform: translateY(-2px);
    box-shadow: 0 10px 25px rgba(0, 0, 0, 0.2);
}

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

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

/* Calculator Cards */
.calculators-section {
    padding: 80px 0;
    background: var(--bg);
}

.section-header {
    text-align: center;
    margin-bottom: 50px;
}

.section-header h2 {
    font-size: 36px;
    color: var(--dark);
    margin-bottom: 15px;
}

.section-header p {
    font-size: 18px;
    color: var(--text-light);
}

.calculator-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: 30px;
}

.calculator-card {
    background: white;
    border-radius: var(--radius);
    padding: 30px;
    text-align: center;
    transition: all 0.3s;
    border: 1px solid var(--border);
    text-decoration: none;
    color: var(--text);
}

.calculator-card:hover {
    transform: translateY(-5px);
    box-shadow: var(--shadow-lg);
}

.calc-icon {
    font-size: 48px;
    margin-bottom: 20px;
}

.calculator-card h3 {
    font-size: 24px;
    color: var(--dark);
    margin-bottom: 10px;
}

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

/* Calculator Interface */
.calculator-container {
    max-width: 900px;
    margin: 50px auto;
    background: white;
    border-radius: var(--radius);
    box-shadow: var(--shadow-lg);
    overflow: hidden;
}

.calculator-header {
    background: linear-gradient(135deg, var(--primary), var(--primary-dark));
    color: white;
    padding: 30px;
    text-align: center;
}

.calculator-header h1 {
    font-size: 32px;
    margin-bottom: 10px;
}

.calculator-body {
    padding: 40px;
}

/* Shape Selector */
.shape-selector {
    margin-bottom: 30px;
}

.shape-selector h3 {
    margin-bottom: 15px;
    color: var(--dark);
}

.shape-buttons {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 15px;
}

.shape-btn {
    padding: 20px;
    background: var(--bg);
    border: 2px solid var(--border);
    border-radius: var(--radius);
    cursor: pointer;
    transition: all 0.3s;
    font-size: 16px;
    font-weight: 600;
}

.shape-btn:hover {
    border-color: var(--primary);
    background: var(--primary-light);
}

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

/* Material Selector */
.material-selector {
    margin-bottom: 30px;
}

.material-buttons {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(150px, 1fr));
    gap: 10px;
}

.material-btn {
    padding: 12px 20px;
    background: var(--bg);
    border: 2px solid var(--border);
    border-radius: 8px;
    cursor: pointer;
    transition: all 0.3s;
    font-size: 14px;
    font-weight: 500;
}

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

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

/* Form Fields */
.form-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
    gap: 20px;
    margin-bottom: 30px;
}

.form-group {
    margin-bottom: 20px;
}

.form-group label {
    display: block;
    margin-bottom: 8px;
    font-weight: 600;
    color: var(--dark);
}

.form-group input,
.form-group select {
    width: 100%;
    padding: 12px;
    border: 2px solid var(--border);
    border-radius: 8px;
    font-size: 15px;
    transition: border-color 0.3s;
}

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

.dimension-group {
    display: none;
}

.dimension-group.active {
    display: block;
}

/* Results Display */
.results-container {
    display: none;
    margin-top: 40px;
    padding: 30px;
    background: var(--primary-light);
    border-radius: var(--radius);
    border: 2px solid var(--primary);
}

.results-container.show {
    display: block;
    animation: slideDown 0.4s ease-out;
}

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

    to {
        opacity: 1;
        transform: translateY(0);
    }
}

.results-header {
    text-align: center;
    margin-bottom: 30px;
}

.results-header h2 {
    color: var(--primary-dark);
    font-size: 28px;
}

.results-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
    gap: 20px;
    margin-bottom: 20px;
}

.result-item {
    background: white;
    padding: 20px;
    border-radius: 8px;
    text-align: center;
}

.result-label {
    display: block;
    font-size: 14px;
    color: var(--text-light);
    margin-bottom: 8px;
}

.result-value {
    font-size: 32px;
    font-weight: 700;
    color: var(--primary-dark);
}

.result-value.updated {
    animation: pulse 0.3s;
}

@keyframes pulse {

    0%,
    100% {
        transform: scale(1);
    }

    50% {
        transform: scale(1.1);
    }
}

.result-actions {
    display: flex;
    justify-content: center;
    gap: 15px;
    margin-top: 20px;
}

/* Alert */
.alert {
    padding: 15px 20px;
    border-radius: 8px;
    margin-bottom: 20px;
}

.alert-error {
    background: #fee2e2;
    color: #991b1b;
    border: 1px solid #fca5a5;
}

.alert-success {
    background: #d1fae5;
    color: #065f46;
    border: 1px solid #6ee7b7;
}

/* Footer */
.footer {
    background: var(--dark);
    color: white;
    padding: 50px 0 20px;
    margin-top: 80px;
}

.footer-content {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 40px;
    margin-bottom: 30px;
}

.footer-section h3 {
    margin-bottom: 20px;
    font-size: 20px;
}

.footer-section ul {
    list-style: none;
}

.footer-section ul li {
    margin-bottom: 10px;
}

.footer-section a {
    color: rgba(255, 255, 255, 0.8);
    text-decoration: none;
    transition: color 0.3s;
}

.footer-section a:hover {
    color: white;
}

.footer-bottom {
    text-align: center;
    padding-top: 20px;
    border-top: 1px solid rgba(255, 255, 255, 0.1);
    color: rgba(255, 255, 255, 0.6);
}

/* Responsive */
@media (max-width: 768px) {
    .hero h1 {
        font-size: 32px;
    }

    .hero p {
        font-size: 16px;
    }

    .nav-menu {
        display: none;
    }

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

    .shape-buttons {
        grid-template-columns: 1fr;
    }

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

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

/* Loading State */
.loading {
    opacity: 0.6;
    pointer-events: none;
}

/* Animations */
.fade-in {
    animation: fadeIn 0.5s ease-in;
}

@keyframes fadeIn {
    from {
        opacity: 0;
    }

    to {
        opacity: 1;
    }
}