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

:root {
    --primary-color: #6366f1;
    --primary-dark: #4f46e5;
    --secondary-color: #f8fafc;
    --accent-color: #10b981;
    --danger-color: #ef4444;
    --warning-color: #f59e0b;
    --text-primary: #1e293b;
    --text-secondary: #64748b;
    --text-light: #94a3b8;
    --border-color: #e2e8f0;
    --bg-white: #ffffff;
    --bg-gray: #f8fafc;
    --shadow-sm: 0 1px 2px 0 rgb(0 0 0 / 0.05);
    --shadow-md: 0 4px 6px -1px rgb(0 0 0 / 0.1), 0 2px 4px -2px rgb(0 0 0 / 0.1);
    --shadow-lg: 0 10px 15px -3px rgb(0 0 0 / 0.1), 0 4px 6px -4px rgb(0 0 0 / 0.1);
    --shadow-xl: 0 20px 25px -5px rgb(0 0 0 / 0.1), 0 8px 10px -6px rgb(0 0 0 / 0.1);
    --border-radius: 8px;
    --border-radius-lg: 12px;
    --transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
}

body {
    font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
    line-height: 1.6;
    color: var(--text-primary);
    background-color: var(--bg-gray);
    font-size: 16px;
}

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

/* Header */
.header {
    background: var(--bg-white);
    border-bottom: 1px solid var(--border-color);
    position: sticky;
    top: 0;
    z-index: 100;
    backdrop-filter: blur(10px);
    background-color: rgba(255, 255, 255, 0.95);
}

.header .container {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 1rem 20px;
}

.logo h1 {
    font-size: 1.5rem;
    font-weight: 700;
    color: var(--primary-color);
    background: linear-gradient(135deg, var(--primary-color), var(--primary-dark));
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.nav {
    display: flex;
    gap: 2rem;
}

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

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

.nav a::after {
    content: '';
    position: absolute;
    bottom: -4px;
    left: 0;
    width: 0;
    height: 2px;
    background: var(--primary-color);
    transition: var(--transition);
}

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

/* Hero Section */
.hero {
    background: linear-gradient(135deg, var(--primary-color) 0%, var(--primary-dark) 100%);
    color: white;
    padding: 4rem 0;
    text-align: center;
}

.hero-content h2 {
    font-size: 3rem;
    font-weight: 800;
    margin-bottom: 1rem;
    line-height: 1.2;
}

.hero-content p {
    font-size: 1.25rem;
    opacity: 0.9;
    max-width: 600px;
    margin: 0 auto;
}

/* Calculator Section */
.calculator-section {
    padding: 4rem 0;
}

.calculator-card {
    background: var(--bg-white);
    border-radius: var(--border-radius-lg);
    box-shadow: var(--shadow-xl);
    padding: 2.5rem;
    max-width: 600px;
    margin: 0 auto;
    border: 1px solid var(--border-color);
}

.calculator-card h3 {
    font-size: 1.875rem;
    font-weight: 700;
    text-align: center;
    margin-bottom: 2rem;
    color: var(--text-primary);
}

.calculator-form {
    display: flex;
    flex-direction: column;
    gap: 1.5rem;
}

.input-group {
    display: flex;
    flex-direction: column;
    gap: 0.5rem;
}

.input-group label {
    font-weight: 600;
    color: var(--text-primary);
    font-size: 0.875rem;
    text-transform: uppercase;
    letter-spacing: 0.05em;
}

.form-select {
    padding: 0.875rem 1rem;
    border: 2px solid var(--border-color);
    border-radius: var(--border-radius);
    font-size: 1rem;
    background: var(--bg-white);
    color: var(--text-primary);
    transition: var(--transition);
    cursor: pointer;
    appearance: none;
    background-image: url("data:image/svg+xml,%3csvg xmlns='http://www.w3.org/2000/svg' fill='none' viewBox='0 0 20 20'%3e%3cpath stroke='%236b7280' stroke-linecap='round' stroke-linejoin='round' stroke-width='1.5' d='m6 8 4 4 4-4'/%3e%3c/svg%3e");
    background-position: right 0.5rem center;
    background-repeat: no-repeat;
    background-size: 1.5em 1.5em;
    padding-right: 2.5rem;
}

.form-select:focus {
    outline: none;
    border-color: var(--primary-color);
    box-shadow: 0 0 0 3px rgba(99, 102, 241, 0.1);
}

.form-select:hover {
    border-color: var(--primary-color);
}

.calculate-btn {
    background: linear-gradient(135deg, var(--primary-color), var(--primary-dark));
    color: white;
    border: none;
    padding: 1rem 2rem;
    border-radius: var(--border-radius);
    font-size: 1.125rem;
    font-weight: 600;
    cursor: pointer;
    transition: var(--transition);
    margin-top: 1rem;
    position: relative;
    overflow: hidden;
}

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

.calculate-btn:active {
    transform: translateY(0);
}

.calculate-btn::before {
    content: '';
    position: absolute;
    top: 0;
    left: -100%;
    width: 100%;
    height: 100%;
    background: linear-gradient(90deg, transparent, rgba(255, 255, 255, 0.2), transparent);
    transition: left 0.5s;
}

.calculate-btn:hover::before {
    left: 100%;
}

/* Results Section */
.results-section {
    margin-top: 2rem;
    animation: slideIn 0.5s ease-out;
}

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

.result-card {
    background: var(--bg-gray);
    border-radius: var(--border-radius);
    padding: 1.5rem;
    border: 1px solid var(--border-color);
}

.result-card h4 {
    font-size: 1.25rem;
    font-weight: 600;
    margin-bottom: 1.5rem;
    text-align: center;
    color: var(--text-primary);
}

.bottleneck-meter {
    margin-bottom: 1.5rem;
}

.meter-bar {
    width: 100%;
    height: 20px;
    background: var(--border-color);
    border-radius: 10px;
    overflow: hidden;
    position: relative;
}

.meter-fill {
    height: 100%;
    background: linear-gradient(90deg, var(--accent-color), var(--warning-color), var(--danger-color));
    border-radius: 10px;
    transition: width 1s ease-out;
    width: 0%;
}

.meter-labels {
    display: flex;
    justify-content: space-between;
    margin-top: 0.5rem;
    font-size: 0.75rem;
    color: var(--text-light);
}

.percentage-display {
    text-align: center;
    font-size: 2.5rem;
    font-weight: 800;
    margin-bottom: 0.5rem;
    background: linear-gradient(135deg, var(--primary-color), var(--primary-dark));
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.status-display {
    text-align: center;
    font-size: 1.125rem;
    font-weight: 600;
    margin-bottom: 1.5rem;
    padding: 0.75rem;
    border-radius: var(--border-radius);
    background: var(--bg-white);
    border: 1px solid var(--border-color);
}

.recommendations h5 {
    font-size: 1rem;
    font-weight: 600;
    margin-bottom: 0.75rem;
    color: var(--text-primary);
}

.recommendations ul {
    list-style: none;
    padding: 0;
}

.recommendations li {
    padding: 0.5rem 0;
    border-bottom: 1px solid var(--border-color);
    color: var(--text-secondary);
}

.recommendations li:last-child {
    border-bottom: none;
}

.recommendations li::before {
    content: '✓';
    color: var(--accent-color);
    font-weight: bold;
    margin-right: 0.5rem;
}

/* Content Section */
.content-section {
    background: var(--bg-white);
    padding: 4rem 0;
}

.content-grid {
    max-width: 800px;
    margin: 0 auto;
}

.content-article {
    line-height: 1.8;
}

.content-article h2 {
    font-size: 2.25rem;
    font-weight: 700;
    margin-bottom: 2rem;
    color: var(--text-primary);
    text-align: center;
}

.content-article h3 {
    font-size: 1.5rem;
    font-weight: 600;
    margin: 2rem 0 1rem 0;
    color: var(--text-primary);
}

.content-article h4 {
    font-size: 1.25rem;
    font-weight: 600;
    margin: 1.5rem 0 0.75rem 0;
    color: var(--text-primary);
}

.content-article p {
    margin-bottom: 1.25rem;
    color: var(--text-secondary);
    text-align: justify;
}

.content-article a {
    color: var(--primary-color);
    text-decoration: none;
    font-weight: 600;
    transition: var(--transition);
    border-bottom: 1px solid transparent;
}

.content-article a:hover {
    color: var(--primary-dark);
    border-bottom-color: var(--primary-color);
}

/* Footer */
.footer {
    background: var(--text-primary);
    color: white;
    padding: 3rem 0 1rem 0;
}

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

.footer-section h4 {
    font-size: 1.125rem;
    font-weight: 600;
    margin-bottom: 1rem;
    color: white;
}

.footer-section p {
    color: var(--text-light);
    line-height: 1.6;
}

.footer-section ul {
    list-style: none;
    padding: 0;
}

.footer-section ul li {
    margin-bottom: 0.5rem;
}

.footer-section ul li a {
    color: var(--text-light);
    text-decoration: none;
    transition: var(--transition);
}

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

.footer-bottom {
    border-top: 1px solid #374151;
    padding-top: 1rem;
    text-align: center;
    color: var(--text-light);
}

/* Responsive Design */
@media (max-width: 768px) {
    .container {
        padding: 0 15px;
    }
    
    .header .container {
        flex-direction: column;
        gap: 1rem;
        padding: 1rem 15px;
    }
    
    .nav {
        gap: 1rem;
    }
    
    .hero-content h2 {
        font-size: 2rem;
    }
    
    .hero-content p {
        font-size: 1rem;
    }
    
    .calculator-card {
        margin: 0 15px;
        padding: 1.5rem;
    }
    
    .calculator-card h3 {
        font-size: 1.5rem;
    }
    
    .content-article h2 {
        font-size: 1.875rem;
    }
    
    .content-article h3 {
        font-size: 1.25rem;
    }
    
    .footer-content {
        grid-template-columns: 1fr;
        text-align: center;
    }
}

@media (max-width: 480px) {
    .hero {
        padding: 2rem 0;
    }
    
    .hero-content h2 {
        font-size: 1.75rem;
    }
    
    .calculator-section {
        padding: 2rem 0;
    }
    
    .calculator-card {
        padding: 1rem;
    }
    
    .percentage-display {
        font-size: 2rem;
    }
    
    .content-section {
        padding: 2rem 0;
    }
    
    .content-article p {
        text-align: left;
    }
}

/* Loading Animation */
.loading {
    display: inline-block;
    width: 20px;
    height: 20px;
    border: 3px solid rgba(255, 255, 255, 0.3);
    border-radius: 50%;
    border-top-color: white;
    animation: spin 1s ease-in-out infinite;
}

@keyframes spin {
    to {
        transform: rotate(360deg);
    }
}

/* Status Colors */
.status-excellent {
    background: linear-gradient(135deg, #10b981, #059669);
    color: white;
}

.status-good {
    background: linear-gradient(135deg, #3b82f6, #2563eb);
    color: white;
}

.status-moderate {
    background: linear-gradient(135deg, #f59e0b, #d97706);
    color: white;
}

.status-high {
    background: linear-gradient(135deg, #ef4444, #dc2626);
    color: white;
}

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

/* Focus Styles for Accessibility */
.calculate-btn:focus,
.form-select:focus {
    outline: 2px solid var(--primary-color);
    outline-offset: 2px;
}

/* Hover Effects for Interactive Elements */
.calculator-card {
    transition: var(--transition);
}

.calculator-card:hover {
    box-shadow: var(--shadow-xl);
    transform: translateY(-2px);
}