/* Reset and base styles */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

body {
    font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    min-height: 100vh;
    color: #333;
    line-height: 1.6;
}

.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 2rem 1rem;
}

/* Header */
.header {
    text-align: center;
    margin-bottom: 3rem;
    color: white;
}

.header h1 {
    font-size: 2.5rem;
    font-weight: 700;
    margin-bottom: 0.5rem;
    text-shadow: 0 2px 4px rgba(0, 0, 0, 0.3);
}

.subtitle {
    font-size: 1.1rem;
    font-weight: 300;
    opacity: 0.9;
}

/* Main content */
.main-content {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 2rem;
    align-items: start;
}

@media (max-width: 768px) {
    .main-content {
        grid-template-columns: 1fr;
    }
}

/* Calculator card */
.calculator-card {
    background: white;
    border-radius: 16px;
    box-shadow: 0 20px 40px rgba(0, 0, 0, 0.1);
    overflow: hidden;
    transition: transform 0.3s ease, box-shadow 0.3s ease;
}

.calculator-card:hover {
    transform: translateY(-2px);
    box-shadow: 0 25px 50px rgba(0, 0, 0, 0.15);
}

.input-section {
    padding: 2rem;
    border-bottom: 1px solid #e5e7eb;
}

.input-section h2 {
    font-size: 1.5rem;
    font-weight: 600;
    margin-bottom: 1.5rem;
    color: #1f2937;
}

/* Form styles */
.input-group {
    margin-bottom: 1.5rem;
}

.input-group label {
    display: block;
    font-weight: 500;
    margin-bottom: 0.5rem;
    color: #374151;
    font-size: 0.95rem;
}

.input-group input {
    width: 100%;
    padding: 0.75rem 1rem;
    border: 2px solid #e5e7eb;
    border-radius: 8px;
    font-size: 1rem;
    transition: border-color 0.3s ease, box-shadow 0.3s ease;
    background: #f9fafb;
}

.input-group input:focus {
    outline: none;
    border-color: #667eea;
    box-shadow: 0 0 0 3px rgba(102, 126, 234, 0.1);
    background: white;
}

.input-help {
    display: block;
    margin-top: 0.25rem;
    font-size: 0.8rem;
    color: #6b7280;
    font-style: italic;
}

/* Button */
.calculate-btn {
    width: 100%;
    padding: 1rem 2rem;
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    color: white;
    border: none;
    border-radius: 8px;
    font-size: 1rem;
    font-weight: 600;
    cursor: pointer;
    transition: all 0.3s ease;
    text-transform: uppercase;
    letter-spacing: 0.5px;
}

.calculate-btn:hover {
    transform: translateY(-1px);
    box-shadow: 0 10px 20px rgba(102, 126, 234, 0.3);
}

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

/* Results section */
.results-section {
    padding: 2rem;
    background: #f8fafc;
}

.results-section h2 {
    font-size: 1.5rem;
    font-weight: 600;
    margin-bottom: 1.5rem;
    color: #1f2937;
}

.results-grid {
    display: grid;
    gap: 1rem;
}

.result-item {
    background: white;
    padding: 1.25rem;
    border-radius: 8px;
    border-left: 4px solid #667eea;
    box-shadow: 0 2px 4px rgba(0, 0, 0, 0.05);
    transition: transform 0.2s ease;
}

.result-item:hover {
    transform: translateX(2px);
}

.result-label {
    font-weight: 600;
    color: #374151;
    margin-bottom: 0.25rem;
    font-size: 0.9rem;
    text-transform: uppercase;
    letter-spacing: 0.5px;
}

.result-value {
    font-size: 1.5rem;
    font-weight: 700;
    color: #1f2937;
}

.result-unit {
    font-size: 0.9rem;
    color: #6b7280;
    font-weight: 400;
}

.result-description {
    font-size: 0.8rem;
    color: #6b7280;
    margin-top: 0.5rem;
    font-style: italic;
}

/* Error section */
.error-section {
    padding: 2rem;
    background: #fef2f2;
    border-top: 1px solid #fecaca;
}

.error-message {
    background: #fee2e2;
    color: #dc2626;
    padding: 1rem;
    border-radius: 8px;
    border-left: 4px solid #dc2626;
    font-weight: 500;
}

/* Info card */
.info-card {
    background: white;
    border-radius: 16px;
    padding: 2rem;
    box-shadow: 0 20px 40px rgba(0, 0, 0, 0.1);
    height: fit-content;
}

.info-card h3 {
    font-size: 1.25rem;
    font-weight: 600;
    margin-bottom: 1rem;
    color: #1f2937;
}

.info-card ol,
.info-card ul {
    margin-left: 1.5rem;
    margin-bottom: 1.5rem;
}

.info-card li {
    margin-bottom: 0.5rem;
    color: #4b5563;
}

.info-card strong {
    color: #1f2937;
    font-weight: 600;
}

/* Preset styles */
.preset-container {
    margin-top: 1.5rem;
    padding-top: 1.5rem;
    border-top: 1px solid #e5e7eb;
}

.preset-container h3 {
    font-size: 1rem;
    font-weight: 600;
    margin-bottom: 1rem;
    color: #374151;
}

.preset-buttons {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 0.5rem;
}

.preset-btn {
    padding: 0.5rem 0.75rem;
    background: #f3f4f6;
    border: 1px solid #d1d5db;
    border-radius: 6px;
    font-size: 0.8rem;
    cursor: pointer;
    transition: all 0.2s ease;
}

.preset-btn:hover {
    background: #e5e7eb;
    border-color: #9ca3af;
}

/* Responsive design */
@media (max-width: 640px) {
    .container {
        padding: 1rem 0.5rem;
    }
    
    .header h1 {
        font-size: 2rem;
    }
    
    .input-section,
    .results-section,
    .info-card {
        padding: 1.5rem;
    }
    
    .result-value {
        font-size: 1.25rem;
    }
    
    .preset-buttons {
        grid-template-columns: 1fr;
    }
}

/* Animation for results */
@keyframes fadeInUp {
    from {
        opacity: 0;
        transform: translateY(20px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

.results-section {
    animation: fadeInUp 0.5s ease-out;
}

.result-item {
    animation: fadeInUp 0.5s ease-out;
    animation-fill-mode: both;
}

.result-item:nth-child(1) { animation-delay: 0.1s; }
.result-item:nth-child(2) { animation-delay: 0.2s; }
.result-item:nth-child(3) { animation-delay: 0.3s; }
.result-item:nth-child(4) { animation-delay: 0.4s; }
.result-item:nth-child(5) { animation-delay: 0.5s; }