/* CSS Variables for Theme Support */
:root {
    --primary-color: #2563eb;
    --primary-hover: #1d4ed8;
    --secondary-color: #64748b;
    --background-color: #ffffff;
    --surface-color: #f8fafc;
    --text-primary: #0f172a;
    --text-secondary: #475569;
    --border-color: #e2e8f0;
    --shadow-light: 0 1px 3px rgba(0, 0, 0, 0.1);
    --shadow-medium: 0 4px 6px rgba(0, 0, 0, 0.1);
    --shadow-heavy: 0 10px 15px rgba(0, 0, 0, 0.1);
    --transition: all 0.3s ease;
    --border-radius: 8px;
    --border-radius-large: 12px;
}

[data-theme="dark"] {
    --primary-color: #3b82f6;
    --primary-hover: #2563eb;
    --secondary-color: #94a3b8;
    --background-color: #0f172a;
    --surface-color: #1e293b;
    --text-primary: #f1f5f9;
    --text-secondary: #cbd5e1;
    --border-color: #334155;
    --shadow-light: 0 1px 3px rgba(0, 0, 0, 0.3);
    --shadow-medium: 0 4px 6px rgba(0, 0, 0, 0.3);
    --shadow-heavy: 0 10px 15px rgba(0, 0, 0, 0.3);
}

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

html {
    scroll-behavior: smooth;
    font-size: 16px;
}

body {
    font-family: system-ui, -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
    line-height: 1.6;
    color: var(--text-primary);
    background-color: var(--background-color);
    transition: var(--transition);
    animation: fadeIn 0.5s ease-in;
}

@keyframes fadeIn {
    from { opacity: 0; }
    to { opacity: 1; }
}

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

/* Header */
.header {
    background-color: var(--surface-color);
    border-bottom: 1px solid var(--border-color);
    padding: 1rem 0;
    position: sticky;
    top: 0;
    z-index: 100;
    transition: var(--transition);
}

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

.main-title {
    font-size: 2rem;
    font-weight: 700;
    color: var(--primary-color);
    margin: 0;
}

.back-link {
    color: var(--text-secondary);
    text-decoration: none;
    font-weight: 500;
    transition: var(--transition);
    padding: 0.5rem;
    border-radius: var(--border-radius);
}

.back-link:hover {
    color: var(--primary-color);
    background-color: var(--border-color);
    transform: translateX(-2px);
}

.theme-toggle {
    background: none;
    border: 2px solid var(--border-color);
    border-radius: var(--border-radius);
    padding: 0.5rem;
    cursor: pointer;
    font-size: 1.2rem;
    transition: var(--transition);
    color: var(--text-primary);
}

.theme-toggle:hover {
    border-color: var(--primary-color);
    transform: scale(1.05);
}

/* Main Content */
.main-content {
    min-height: calc(100vh - 140px);
    padding: 2rem 0;
}

/* Search Section */
.search-section {
    margin-bottom: 3rem;
}

.search-container {
    position: relative;
    max-width: 600px;
    margin: 0 auto;
}

.search-input {
    width: 100%;
    padding: 1rem 1.5rem;
    font-size: 1.1rem;
    border: 2px solid var(--border-color);
    border-radius: var(--border-radius-large);
    background-color: var(--surface-color);
    color: var(--text-primary);
    transition: var(--transition);
    box-shadow: var(--shadow-light);
}

.search-input:focus {
    outline: none;
    border-color: var(--primary-color);
    box-shadow: var(--shadow-medium);
}

.search-suggestions {
    position: absolute;
    top: 100%;
    left: 0;
    right: 0;
    background-color: var(--surface-color);
    border: 1px solid var(--border-color);
    border-top: none;
    border-radius: 0 0 var(--border-radius) var(--border-radius);
    max-height: 300px;
    overflow-y: auto;
    z-index: 10;
    display: none;
}

.search-suggestion {
    padding: 0.75rem 1rem;
    cursor: pointer;
    transition: var(--transition);
    border-bottom: 1px solid var(--border-color);
}

.search-suggestion:hover {
    background-color: var(--primary-color);
    color: white;
}

.search-suggestion:last-child {
    border-bottom: none;
}

/* Converters Section */
.converters-section {
    margin-bottom: 3rem;
}

.section-title {
    font-size: 2.5rem;
    font-weight: 700;
    text-align: center;
    margin-bottom: 3rem;
    color: var(--text-primary);
}

.converter-category {
    margin-bottom: 3rem;
}

.category-title {
    font-size: 1.8rem;
    font-weight: 600;
    margin-bottom: 1.5rem;
    color: var(--text-primary);
    border-bottom: 2px solid var(--primary-color);
    padding-bottom: 0.5rem;
}

/* Converter Grid */
.converter-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 1.5rem;
    margin-bottom: 2rem;
}

.converter-grid.specialized {
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 1rem;
}

.converter-card {
    background-color: var(--surface-color);
    border: 1px solid var(--border-color);
    border-radius: var(--border-radius-large);
    padding: 1.5rem;
    text-decoration: none;
    color: var(--text-primary);
    transition: var(--transition);
    box-shadow: var(--shadow-light);
    display: block;
}

.converter-card:hover {
    transform: translateY(-4px) scale(1.02);
    box-shadow: var(--shadow-heavy);
    border-color: var(--primary-color);
}

.converter-card.small {
    padding: 1rem;
    text-align: center;
}

.converter-icon {
    font-size: 2rem;
    margin-bottom: 0.5rem;
    text-align: center;
}

.converter-card h4 {
    font-size: 1.2rem;
    font-weight: 600;
    margin-bottom: 0.5rem;
    color: var(--primary-color);
}

.converter-card p {
    color: var(--text-secondary);
    font-size: 0.9rem;
    line-height: 1.4;
}

.converter-card.small h4 {
    font-size: 1rem;
    margin-bottom: 0;
}

/* Converter Interface */
.converter-interface {
    max-width: 1000px;
    margin: 0 auto;
}

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

.converter-header h2 {
    font-size: 2rem;
    margin-bottom: 0.5rem;
    color: var(--text-primary);
}

.converter-header p {
    color: var(--text-secondary);
    font-size: 1.1rem;
}

/* Conversion Grid */
.conversion-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 2rem;
    margin-bottom: 2rem;
}

.unit-group {
    background-color: var(--surface-color);
    border: 1px solid var(--border-color);
    border-radius: var(--border-radius-large);
    padding: 1.5rem;
    box-shadow: var(--shadow-light);
}

.unit-group h3 {
    font-size: 1.3rem;
    font-weight: 600;
    margin-bottom: 1rem;
    color: var(--primary-color);
    border-bottom: 1px solid var(--border-color);
    padding-bottom: 0.5rem;
}

.unit-input-group {
    margin-bottom: 1rem;
}

.unit-input-group:last-child {
    margin-bottom: 0;
}

.unit-input-group label {
    display: block;
    font-weight: 500;
    margin-bottom: 0.3rem;
    color: var(--text-primary);
    font-size: 0.9rem;
}

.unit-input-group input {
    width: 100%;
    padding: 0.75rem;
    border: 1px solid var(--border-color);
    border-radius: var(--border-radius);
    font-size: 1rem;
    background-color: var(--background-color);
    color: var(--text-primary);
    transition: var(--transition);
}

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

.unit-input-group input:hover {
    border-color: var(--primary-hover);
}

/* Temperature Reference */
.temperature-info,
.angle-info,
.fuel-info,
.numbers-info,
.storage-info {
    background-color: var(--surface-color);
    border: 1px solid var(--border-color);
    border-radius: var(--border-radius-large);
    padding: 1.5rem;
    margin-bottom: 2rem;
    box-shadow: var(--shadow-light);
}

.temperature-info h3,
.angle-info h3,
.fuel-info h3,
.numbers-info h3,
.storage-info h3 {
    font-size: 1.3rem;
    margin-bottom: 1rem;
    color: var(--primary-color);
}

.reference-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 1rem;
}

.reference-item {
    padding: 0.75rem;
    background-color: var(--background-color);
    border-radius: var(--border-radius);
    border: 1px solid var(--border-color);
}

.reference-item strong {
    display: block;
    color: var(--text-primary);
    margin-bottom: 0.25rem;
}

.reference-item span {
    color: var(--text-secondary);
    font-size: 0.9rem;
}

/* Clear Button */
.clear-button-container {
    text-align: center;
    margin-top: 2rem;
}

.clear-button {
    background-color: var(--primary-color);
    color: white;
    border: none;
    padding: 0.75rem 2rem;
    border-radius: var(--border-radius);
    font-size: 1rem;
    font-weight: 600;
    cursor: pointer;
    transition: var(--transition);
    box-shadow: var(--shadow-light);
}

.clear-button:hover {
    background-color: var(--primary-hover);
    transform: translateY(-2px);
    box-shadow: var(--shadow-medium);
}

/* Footer */
.footer {
    background-color: var(--surface-color);
    border-top: 1px solid var(--border-color);
    padding: 2rem 0;
    text-align: center;
    color: var(--text-secondary);
    margin-top: auto;
}

/* Responsive Design */
@media (max-width: 768px) {
    .container {
        padding: 0 15px;
    }

    .main-title {
        font-size: 1.5rem;
    }

    .section-title {
        font-size: 2rem;
    }

    .converter-grid {
        grid-template-columns: 1fr;
        gap: 1rem;
    }

    .converter-grid.specialized {
        grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
    }

    .conversion-grid {
        grid-template-columns: 1fr;
        gap: 1.5rem;
    }

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

    .header .container {
        flex-wrap: wrap;
        gap: 1rem;
    }

    .converter-card {
        padding: 1rem;
    }

    .unit-group {
        padding: 1rem;
    }
}

@media (max-width: 480px) {
    .main-title {
        font-size: 1.3rem;
    }

    .search-input {
        padding: 0.75rem 1rem;
        font-size: 1rem;
    }

    .converter-card h4 {
        font-size: 1.1rem;
    }

    .converter-card p {
        font-size: 0.85rem;
    }

    .converter-grid.specialized {
        grid-template-columns: 1fr;
    }
}

/* Accessibility */
@media (prefers-reduced-motion: reduce) {
    * {
        animation-duration: 0.01ms !important;
        animation-iteration-count: 1 !important;
        transition-duration: 0.01ms !important;
    }
    
    html {
        scroll-behavior: auto;
    }
}

/* Focus Styles for Accessibility */
button:focus,
input:focus,
a:focus {
    outline: 2px solid var(--primary-color);
    outline-offset: 2px;
}

/* High Contrast Mode Support */
@media (prefers-contrast: high) {
    :root {
        --border-color: #000000;
        --shadow-light: none;
        --shadow-medium: none;
        --shadow-heavy: none;
    }
    
    [data-theme="dark"] {
        --border-color: #ffffff;
    }
}

/* Info Section */
.info-section {
    background: var(--surface-color);
    border-top: 1px solid var(--border-color);
    padding: 3rem 0;
    margin-top: 3rem;
}

.info-content {
    max-width: 800px;
    margin: 0 auto;
    text-align: center;
}

.info-content h2 {
    color: var(--primary-color);
    font-size: 2rem;
    font-weight: 600;
    margin-bottom: 1.5rem;
}

.info-content p {
    color: var(--text-color);
    font-size: 1.1rem;
    line-height: 1.7;
    margin-bottom: 1.5rem;
    text-align: left;
}

.info-content p:last-child {
    margin-bottom: 0;
}

.info-link {
    color: var(--primary-color);
    text-decoration: underline;
    font-weight: 600;
}

.info-link:hover {
    color: var(--primary-hover);
    text-decoration: none;
}

/* Unit Systems Page */
.unit-systems-content {
    max-width: 900px;
    margin: 0 auto;
    padding: 2rem 0;
}

.unit-systems-content section {
    margin-bottom: 3rem;
    padding-bottom: 2rem;
    border-bottom: 1px solid var(--border-color);
}

.unit-systems-content section:last-child {
    border-bottom: none;
}

.unit-systems-content h2 {
    color: var(--primary-color);
    font-size: 1.8rem;
    font-weight: 600;
    margin-bottom: 1.5rem;
    padding-bottom: 0.5rem;
    border-bottom: 2px solid var(--primary-color);
}

.unit-systems-content h3 {
    color: var(--primary-color);
    font-size: 1.4rem;
    font-weight: 600;
    margin-top: 2rem;
    margin-bottom: 1rem;
}

.unit-systems-content h4 {
    color: var(--text-color);
    font-size: 1.2rem;
    font-weight: 600;
    margin-top: 1.5rem;
    margin-bottom: 1rem;
}

.unit-systems-content p {
    color: var(--text-color);
    font-size: 1rem;
    line-height: 1.7;
    margin-bottom: 1.2rem;
}

.unit-list {
    list-style: none;
    padding-left: 0;
}

.unit-list li {
    color: var(--text-color);
    font-size: 1rem;
    line-height: 1.6;
    margin-bottom: 0.5rem;
    padding-left: 1.5rem;
    position: relative;
}

.unit-list li::before {
    content: "•";
    color: var(--primary-color);
    font-weight: bold;
    position: absolute;
    left: 0;
}

.timeline-list {
    list-style: none;
    padding-left: 0;
    margin-left: 1rem;
}

.timeline-list li {
    color: var(--text-color);
    font-size: 1rem;
    line-height: 1.6;
    margin-bottom: 1rem;
    padding-left: 1rem;
    position: relative;
    border-left: 2px solid var(--primary-color);
}

.timeline-list li::before {
    content: "";
    background: var(--primary-color);
    width: 8px;
    height: 8px;
    border-radius: 50%;
    position: absolute;
    left: -5px;
    top: 0.5rem;
}

.table-container {
    overflow-x: auto;
    margin: 1.5rem 0;
    border-radius: var(--border-radius);
    box-shadow: var(--shadow-light);
}

.units-table {
    width: 100%;
    border-collapse: collapse;
    background: var(--surface-color);
    border: 1px solid var(--border-color);
}

.units-table th,
.units-table td {
    padding: 0.75rem 1rem;
    text-align: left;
    border-bottom: 1px solid var(--border-color);
}

.units-table th {
    background: var(--primary-color);
    color: white;
    font-weight: 600;
    font-size: 0.9rem;
}

.units-table td {
    color: var(--text-color);
    font-size: 0.9rem;
}

.units-table tr:last-child td {
    border-bottom: none;
}

.units-table tr:hover {
    background: var(--border-color);
}

.timeline-section {
    background: var(--surface-color);
    border: 1px solid var(--border-color);
    border-radius: var(--border-radius);
    padding: 1.5rem;
    margin: 1.5rem 0;
}

@media (max-width: 768px) {
    .unit-systems-content {
        padding: 1rem 0;
    }
    
    .unit-systems-content h2 {
        font-size: 1.5rem;
    }
    
    .unit-systems-content h3 {
        font-size: 1.2rem;
    }
    
    .units-table {
        font-size: 0.8rem;
    }
    
    .units-table th,
    .units-table td {
        padding: 0.5rem;
    }
}