
:root {
    --primary-color: #2563eb;
    --primary-color-dark: #1d4ed8;
    --secondary-color: #f97316;
    --background-color: #f8fafc;
    --text-color: #0f172a;
    --card-background: #ffffff;
    --border-color: #e2e8f0;
    --input-background: #f1f5f9;
    --shadow-color: rgba(37, 99, 235, 0.1);
    --success-color: #22c55e;
    --toast-background: rgba(15, 23, 42, 0.8);
}

[data-theme="dark"] {
    --primary-color: #3b82f6;
    --primary-color-dark: #2563eb;
    --secondary-color: #fb923c;
    --background-color: #0b1120;
    --text-color: #e2e8f0;
    --card-background: #1e293b;
    --border-color: #334155;
    --input-background: #334155;
    --shadow-color: rgba(59, 130, 246, 0.15);
    --toast-background: rgba(226, 232, 240, 0.9);
}

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

body {
    font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
    background-color: var(--background-color);
    color: var(--text-color);
    line-height: 1.6;
    transition: background-color 0.3s, color 0.3s;
    min-height: 100vh;
    display: flex;
    flex-direction: column;
}

.container {
    max-width: 800px;
    width: 100%;
    margin: 0 auto;
    padding: 20px;
}

/* Header */
.header {
    padding-bottom: 20px;
    border-bottom: 1px solid var(--border-color);
    margin-bottom: 30px;
}

.header .container {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 0;
}

.logo {
    font-size: 1.75rem;
    font-weight: 700;
    color: var(--primary-color);
}

.nav {
    display: flex;
    align-items: center;
    gap: 16px;
}

.lang-selector select, .theme-toggle {
    background-color: var(--card-background);
    border: 1px solid var(--border-color);
    border-radius: 8px;
    padding: 8px 12px;
    font-size: 14px;
    color: var(--text-color);
    cursor: pointer;
    transition: border-color 0.2s, box-shadow 0.2s;
}

.theme-toggle {
    font-size: 1.2rem;
    line-height: 1;
    padding: 6px;
}

.lang-selector select:focus, .theme-toggle:focus {
    outline: none;
    border-color: var(--primary-color);
    box-shadow: 0 0 0 3px var(--shadow-color);
}

/* Main Content */
.main {
    flex: 1;
}

.converter {
    background-color: var(--card-background);
    padding: 24px;
    border-radius: 12px;
    box-shadow: 0 4px 15px var(--shadow-color);
    border: 1px solid var(--border-color);
}

.converter-header {
    text-align: center;
    margin-bottom: 24px;
}

.converter-header h2 {
    font-size: 1.5rem;
    margin-bottom: 4px;
}

.converter-header p {
    font-size: 0.9rem;
    opacity: 0.7;
}

.category-selector {
    margin-bottom: 20px;
    display: flex;
    flex-direction: column;
    gap: 8px;
}

.category-selector label {
    font-weight: 500;
}

.category-select {
    width: 100%;
    padding: 12px;
    border-radius: 8px;
    border: 1px solid var(--border-color);
    background-color: var(--input-background);
    font-size: 1rem;
    cursor: pointer;
}

.conversion-grid {
    display: grid;
    grid-template-columns: 1fr auto 1fr;
    align-items: center;
    gap: 16px;
    margin-bottom: 20px;
}

.input-group, .output-group {
    display: flex;
    flex-direction: column;
    gap: 8px;
}

.input-wrapper, .output-wrapper {
    display: flex;
    flex-direction: column;
    gap: 8px;
}

.value-input, .value-output, .unit-select {
    width: 100%;
    padding: 12px;
    border-radius: 8px;
    border: 1px solid var(--border-color);
    background-color: var(--input-background);
    font-size: 1rem;
    color: var(--text-color);
}

.value-input:focus, .unit-select:focus {
    outline: none;
    border-color: var(--primary-color);
    box-shadow: 0 0 0 3px var(--shadow-color);
}

.value-output {
    font-weight: 500;
    background-color: var(--background-color);
}

.swap-btn {
    background-color: transparent;
    border: 1px solid var(--border-color);
    border-radius: 50%;
    width: 44px;
    height: 44px;
    font-size: 1.5rem;
    cursor: pointer;
    color: var(--primary-color);
    transition: background-color 0.2s, transform 0.2s;
    display: flex;
    align-items: center;
    justify-content: center;
}

.swap-btn:hover {
    background-color: var(--input-background);
    transform: rotate(180deg);
}

.action-buttons {
    display: flex;
    gap: 12px;
    margin-bottom: 24px;
}

.copy-btn, .clear-btn {
    flex-grow: 1;
    padding: 12px;
    border-radius: 8px;
    border: none;
    font-size: 1rem;
    font-weight: 500;
    cursor: pointer;
    transition: background-color 0.2s;
}

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

.copy-btn:hover {
    background-color: var(--primary-color-dark);
}

.clear-btn {
    background-color: var(--border-color);
    color: var(--text-color);
}

.clear-btn:hover {
    background-color: #d1d5db;
}

[data-theme="dark"] .clear-btn:hover {
    background-color: #4b5563;
}

.history-section h3, .popular-conversions h3 {
    font-size: 1.1rem;
    margin-bottom: 12px;
    border-bottom: 1px solid var(--border-color);
    padding-bottom: 8px;
}

.history-list {
    max-height: 150px;
    overflow-y: auto;
    padding-right: 10px;
}

.history-item {
    padding: 8px;
    border-radius: 6px;
    font-size: 0.9rem;
    transition: background-color 0.2s;
}

.history-item:hover {
    background-color: var(--input-background);
}

.history-item small {
    display: block;
    opacity: 0.6;
    font-size: 0.8rem;
}

.popular-conversions {
    margin-top: 30px;
}

.popular-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(150px, 1fr));
    gap: 12px;
}

.popular-item {
    padding: 10px;
    border: 1px solid var(--border-color);
    background-color: var(--card-background);
    border-radius: 8px;
    text-align: center;
    cursor: pointer;
    transition: all 0.2s;
    font-size: 0.9rem;
}

.popular-item:hover {
    border-color: var(--primary-color);
    color: var(--primary-color);
    transform: translateY(-2px);
    box-shadow: 0 2px 8px var(--shadow-color);
}

/* Footer */
.footer {
    border-top: 1px solid var(--border-color);
    margin-top: 40px;
    padding: 30px 0;
    background-color: var(--card-background);
}

.footer-content {
    text-align: center;
}

.copyright {
    font-size: 0.9rem;
    opacity: 0.8;
    margin-bottom: 20px;
}

.footer-links {
    display: flex;
    justify-content: center;
    gap: 20px;
    flex-wrap: wrap;
}

.footer-details {
    width: 100%;
    max-width: 700px;
    margin: 0 auto;
    background-color: var(--background-color);
    border-radius: 8px;
    border: 1px solid var(--border-color);
    margin-bottom: 10px;
}

.footer-details summary {
    padding: 12px 16px;
    font-weight: 500;
    cursor: pointer;
    outline: none;
    transition: background-color 0.2s;
}

.footer-details summary:hover {
    background-color: var(--input-background);
}

.footer-details[open] summary {
    border-bottom: 1px solid var(--border-color);
}

.details-content {
    padding: 16px;
    text-align: left;
    font-size: 0.85rem;
    line-height: 1.7;
}

.details-content h5 {
    font-size: 1.1rem;
    margin-bottom: 10px;
    color: var(--primary-color);
}

.details-content h6 {
    font-size: 0.9rem;
    font-weight: 700;
    margin-top: 15px;
    margin-bottom: 5px;
}

.details-content p {
    margin-bottom: 10px;
}

.details-content a {
    color: var(--primary-color);
    text-decoration: none;
}

.details-content a:hover {
    text-decoration: underline;
}

/* Toast Message */
.toast-message {
    position: fixed;
    bottom: 20px;
    left: 50%;
    transform: translateX(-50%);
    background-color: var(--toast-background);
    color: var(--background-color);
    padding: 12px 20px;
    border-radius: 8px;
    z-index: 1000;
    opacity: 0;
    transition: opacity 0.3s, transform 0.3s;
    pointer-events: none;
}

.toast-message.show {
    opacity: 1;
    transform: translate(-50%, -10px);
}

/* Responsive */
@media (max-width: 600px) {
    .conversion-grid {
        grid-template-columns: 1fr;
    }
    .swap-btn {
        width: 100%;
        transform: rotate(90deg);
    }
    .swap-btn:hover {
        transform: rotate(90deg) scale(1.05);
    }
    .logo {
        font-size: 1.5rem;
    }
    .nav {
        gap: 8px;
    }
}

/* Related Sites Section */
.related-sites-section {
    margin-bottom: 2rem;
    padding: 1.5rem 0;
    border-bottom: 1px solid var(--border-color);
}

.related-sites-section h3 {
    color: var(--primary-color);
    margin-bottom: 1rem;
    font-size: 1.25rem;
    text-align: center;
}

.related-sites-description {
    color: var(--text-color);
    opacity: 0.8;
    margin-bottom: 1.5rem;
    text-align: center;
    font-size: 0.9rem;
}

.sites-categories {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 1.5rem;
}

.category {
    background-color: var(--card-background);
    border: 1px solid var(--border-color);
    border-radius: 8px;
    padding: 1rem;
    box-shadow: 0 2px 4px var(--shadow-color);
}

.category h4 {
    color: var(--primary-color);
    margin-bottom: 0.75rem;
    font-size: 1rem;
    font-weight: 600;
    border-bottom: 1px solid var(--border-color);
    padding-bottom: 0.5rem;
}

.sites-list {
    list-style: none;
    padding: 0;
    margin: 0;
}

.sites-list li {
    margin-bottom: 0.5rem;
}

.sites-list a {
    color: var(--primary-color);
    text-decoration: none;
    font-size: 0.9rem;
    transition: color 0.2s ease;
}

.sites-list a:hover {
    color: var(--primary-color-dark);
    text-decoration: underline;
}

.current-site {
    color: var(--success-color);
    font-weight: 500;
    font-size: 0.9rem;
}

/* モバイル対応 */
@media (max-width: 768px) {
    .sites-categories {
        grid-template-columns: 1fr;
        gap: 1rem;
    }

    .category {
        padding: 0.75rem;
    }
    
    .related-sites-section {
        padding: 1rem 0;
    }
}
