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

:root {
    --primary-color: #2563eb;
    --primary-hover: #1d4ed8;
    --secondary-color: #64748b;
    --background-color: #f8fafc;
    --surface-color: #ffffff;
    --border-color: #e2e8f0;
    --text-primary: #1e293b;
    --text-secondary: #64748b;
    --success-color: #10b981;
    --shadow-sm: 0 1px 2px 0 rgba(0, 0, 0, 0.05);
    --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.1), 0 2px 4px -1px rgba(0, 0, 0, 0.06);
    --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.1), 0 4px 6px -2px rgba(0, 0, 0, 0.05);
    --radius: 0.5rem;
}

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, sans-serif;
    background-color: var(--background-color);
    color: var(--text-primary);
    line-height: 1.6;
    min-height: 100vh;
}

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

header {
    background-color: var(--surface-color);
    border-bottom: 1px solid var(--border-color);
    padding: 1.5rem 0;
    position: sticky;
    top: 0;
    z-index: 100;
    box-shadow: var(--shadow-sm);
}

header h1 {
    font-size: 2rem;
    font-weight: 700;
    color: var(--text-primary);
    margin-bottom: 0.25rem;
}

.subtitle {
    color: var(--text-secondary);
    font-size: 1.125rem;
}

.language-selector {
    position: absolute;
    top: 50%;
    right: 1rem;
    transform: translateY(-50%);
}

.language-selector select {
    padding: 0.5rem 1rem;
    border: 1px solid var(--border-color);
    border-radius: var(--radius);
    background-color: var(--surface-color);
    font-size: 0.875rem;
    cursor: pointer;
    transition: all 0.2s;
}

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

main {
    padding: 2rem 0;
}

section {
    background-color: var(--surface-color);
    border-radius: var(--radius);
    padding: 2rem;
    margin-bottom: 2rem;
    box-shadow: var(--shadow-md);
}

section h2 {
    font-size: 1.5rem;
    font-weight: 600;
    margin-bottom: 1.5rem;
    color: var(--text-primary);
}

.converter-grid {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 1.5rem;
    margin-bottom: 2rem;
}

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

.input-group label {
    font-size: 0.875rem;
    font-weight: 500;
    color: var(--text-secondary);
    margin-bottom: 0.5rem;
}

input[type="number"],
select {
    padding: 0.75rem 1rem;
    border: 2px solid var(--border-color);
    border-radius: var(--radius);
    font-size: 1rem;
    transition: all 0.2s;
    background-color: var(--surface-color);
}

input[type="number"]:focus,
select:focus {
    outline: none;
    border-color: var(--primary-color);
    box-shadow: 0 0 0 3px rgba(37, 99, 235, 0.1);
}

.results-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(150px, 1fr));
    gap: 1rem;
    margin-bottom: 2rem;
}

.result-card {
    background-color: var(--background-color);
    border: 1px solid var(--border-color);
    border-radius: var(--radius);
    padding: 1.5rem;
    text-align: center;
    transition: all 0.2s;
}

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

.result-label {
    display: block;
    font-size: 0.875rem;
    color: var(--text-secondary);
    margin-bottom: 0.5rem;
}

.result-value {
    display: block;
    font-size: 1.5rem;
    font-weight: 600;
    color: var(--primary-color);
    word-break: break-all;
}

.binary-decimal-toggle {
    display: flex;
    gap: 2rem;
    justify-content: center;
}

.toggle-label {
    display: flex;
    align-items: center;
    cursor: pointer;
    font-size: 0.875rem;
    color: var(--text-secondary);
}

.toggle-label input[type="radio"] {
    margin-right: 0.5rem;
    cursor: pointer;
}

.calculator-grid {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 1.5rem;
    margin-bottom: 2rem;
}

.input-with-unit {
    display: flex;
    gap: 0.5rem;
}

.input-with-unit input {
    flex: 1;
}

.input-with-unit select {
    width: auto;
}

.download-result {
    background-color: var(--background-color);
    border-radius: var(--radius);
    padding: 1.5rem;
    text-align: center;
    font-size: 1.125rem;
}

.time-value {
    font-weight: 600;
    color: var(--primary-color);
    font-size: 1.5rem;
    margin-left: 0.5rem;
}

.storage-examples {
    margin-top: 2rem;
}

.storage-examples h3 {
    font-size: 1.125rem;
    font-weight: 600;
    margin-bottom: 1rem;
}

.example-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
    gap: 1rem;
}

.example-item {
    background-color: var(--background-color);
    border-radius: var(--radius);
    padding: 1.5rem;
    text-align: center;
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 0.5rem;
}

.example-icon {
    font-size: 2rem;
    margin-bottom: 0.5rem;
}

.example-label {
    font-size: 0.875rem;
    color: var(--text-secondary);
}

.example-value {
    font-size: 1.25rem;
    font-weight: 600;
    color: var(--primary-color);
}

footer {
    text-align: center;
    padding: 2rem 0;
    color: var(--text-secondary);
    font-size: 0.875rem;
}

/* レスポンシブデザイン */
@media (max-width: 768px) {
    header h1 {
        font-size: 1.5rem;
    }
    
    .subtitle {
        font-size: 1rem;
    }
    
    .language-selector {
        position: static;
        transform: none;
        margin-top: 1rem;
    }
    
    .converter-grid,
    .calculator-grid {
        grid-template-columns: 1fr;
    }
    
    .results-grid {
        grid-template-columns: repeat(auto-fit, minmax(120px, 1fr));
    }
    
    .binary-decimal-toggle {
        flex-direction: column;
        gap: 1rem;
        align-items: flex-start;
    }
    
    section {
        padding: 1.5rem;
    }
    
    .example-grid {
        grid-template-columns: 1fr 1fr;
    }
}

@media (max-width: 480px) {
    .container {
        padding: 0 0.75rem;
    }
    
    header {
        padding: 1rem 0;
    }
    
    header h1 {
        font-size: 1.25rem;
    }
    
    .subtitle {
        font-size: 0.875rem;
    }
    
    section {
        padding: 1rem;
        margin-bottom: 1rem;
    }
    
    section h2 {
        font-size: 1.25rem;
    }
    
    .result-value {
        font-size: 1.25rem;
    }
    
    .example-grid {
        grid-template-columns: 1fr;
    }
}

/* ダークモード対応 */
@media (prefers-color-scheme: dark) {
    :root {
        --primary-color: #3b82f6;
        --primary-hover: #2563eb;
        --background-color: #0f172a;
        --surface-color: #1e293b;
        --border-color: #334155;
        --text-primary: #f1f5f9;
        --text-secondary: #94a3b8;
    }
    
    input[type="number"],
    select {
        background-color: var(--background-color);
        color: var(--text-primary);
    }
}

/* アニメーション */
@keyframes fadeIn {
    from {
        opacity: 0;
        transform: translateY(10px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

section {
    animation: fadeIn 0.5s ease-out;
}

.result-card {
    animation: fadeIn 0.3s ease-out;
}

/* アクセシビリティ */
:focus-visible {
    outline: 2px solid var(--primary-color);
    outline-offset: 2px;
}

@media (prefers-reduced-motion: reduce) {
    * {
        animation: none !important;
        transition: none !important;
    }
}