:root {
    /* Color Palette */
    --bg-primary: #ffffff;
    --bg-secondary: #f8f9fa;
    --text-primary: #1a1a1a;
    --text-secondary: #4a4a4a;
    --accent-color: #2563eb;
    --border-color: #e5e7eb;
    
    /* Spacing */
    --spacing-sm: 0.5rem;
    --spacing-md: 1rem;
    --spacing-lg: 2rem;
    --max-width: 1200px;
    
    /* Typography */
    --font-main: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
}

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

body {
    font-family: var(--font-main);
    background-color: var(--bg-primary);
    color: var(--text-primary);
    line-height: 1.6;
}

/* Layout Modules */
.container {
    max-width: var(--max-width);
    margin: 0 auto;
    padding: 0 var(--spacing-md);
}

header {
    background-color: var(--bg-primary);
    border-bottom: 1px solid var(--border-color);
    padding: var(--spacing-md) 0;
    position: sticky;
    top: 0;
    z-index: 100;
}

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

.logo {
    font-size: 1.5rem;
    font-weight: 800;
    letter-spacing: -0.05em;
    color: var(--text-primary);
    text-decoration: none;
}

main.layout-main {
    display: grid;
    grid-template-columns: 1fr 300px;
    gap: var(--spacing-lg);
    margin-top: var(--spacing-lg);
}

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

.content-column {
    min-height: 80vh;
}

.sidebar-column {
    padding: var(--spacing-md);
    background-color: var(--bg-secondary);
    border-radius: 8px;
}

footer {
    background-color: var(--bg-secondary);
    border-top: 1px solid var(--border-color);
    padding: var(--spacing-lg) 0;
    margin-top: var(--spacing-lg);
    text-align: center;
    color: var(--text-secondary);
}

/* Sidebar Accordion */
.sidebar-section {
    margin-bottom: 2rem;
}

.sidebar-title {
    font-size: 0.9rem;
    font-weight: 700;
    color: var(--text-secondary);
    text-transform: uppercase;
    letter-spacing: 0.05em;
    margin-bottom: 1rem;
    padding-bottom: 0.5rem;
    border-bottom: 1px solid var(--border-color);
}

.accordion-item {
    border-bottom: 1px solid rgba(0,0,0,0.03);
}

.accordion-header {
    width: 100%;
    padding: 12px 0;
    display: flex;
    justify-content: space-between;
    align-items: center;
    cursor: pointer;
    background: none;
    border: none;
    text-align: left;
    font-size: 0.95rem;
    font-weight: 600;
    color: var(--text-primary);
    transition: color 0.2s;
}

.accordion-header:hover {
    color: var(--accent-color);
}

.accordion-icon {
    font-size: 0.8rem;
    transition: transform 0.3s cubic-bezier(0.4, 0, 0.2, 1);
    color: var(--text-secondary);
}

.accordion-item.active .accordion-icon {
    transform: rotate(90deg);
}

.accordion-content {
    max-height: 0;
    overflow: hidden;
    transition: max-height 0.3s cubic-bezier(0.4, 0, 0.2, 1);
    background-color: rgba(0,0,0,0.01);
}

.accordion-item.active .accordion-content {
    max-height: 1000px; /* 十分な高さ */
}

.sidebar-service-list {
    list-style: none;
    padding: 8px 0 16px 12px;
}

.sidebar-service-item {
    margin-bottom: 6px;
}

.sidebar-service-link {
    display: block;
    padding: 6px 0;
    color: var(--text-secondary);
    text-decoration: none;
    font-size: 0.85rem;
    transition: color 0.2s, transform 0.2s;
}

.sidebar-service-link:hover {
    color: var(--accent-color);
    transform: translateX(4px);
}