* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
    font-family: 'Segoe UI', system-ui, sans-serif;
}

body {
    background-color: #0f172a;
    color: #e2e8f0;
    line-height: 1.6;
    min-height: 100vh;
    padding: 1.25rem;
}

.app-container {
    max-width: 75rem;
    margin: 0 auto;
}

.header {
    text-align: center;
    margin-bottom: 2.5rem;
    padding: 1.875rem 0;
}

.page-title {
    font-size: 2.5rem;
    color: #60a5fa;
    margin-bottom: 0.625rem;
}

.subtitle {
    color: #94a3b8;
    font-size: 1.1rem;
}

.content-container {
    display: flex;
    gap: 1.875rem;
    min-height: 31.25rem;
}

.user-list-container {
    flex: 1;
    background: #1e293b;
    border-radius: 1rem;
    padding: 1.5625rem;
    border: 1px solid #334155;
}

.user-details-container {
    flex: 1;
    background: #1e293b;
    border-radius: 1rem;
    padding: 1.875rem;
    border: 1px solid #334155;
}

.section-title {
    font-size: 1.5rem;
    color: #f8fafc;
    margin-bottom: 1.5625rem;
    padding-bottom: 0.9375rem;
    border-bottom: 2px solid #334155;
}

.user-list {
    list-style: none;
}

.user-item {
    padding: 1.125rem 1.25rem;
    margin-bottom: 0.75rem;
    background: #334155;
    border-radius: 0.75rem;
    cursor: pointer;
    transition: all 0.2s ease;
    border: 1px solid #475569;
}

.user-item:hover {
    background: #475569;
    border-color: #60a5fa;
}

.user-item.active {
    background: #3b82f6;
    border-color: #60a5fa;
}

.user-name {
    font-weight: 600;
    font-size: 1.1rem;
    color: #f1f5f9;
}

.user-username {
    font-size: 0.9rem;
    color: #e2e8f0;
    margin-top: 0.3125rem;
}

.no-selection {
    text-align: center;
    color: #64748b;
    padding: 3.75rem 1.25rem;
    font-style: italic;
    font-size: 1.1rem;
}

.user-detail {
    margin-bottom: 1.5625rem;
    padding-bottom: 0.9375rem;
    border-bottom: 1px solid #334155;
}

.detail-label {
    font-weight: 600;
    color: #cbd5e1;
    margin-bottom: 0.5rem;
    font-size: 0.95rem;
}

.detail-value {
    color: #f8fafc;
    font-size: 1.1rem;
}

.address-section, .company-section {
    background: #0f172a;
    padding: 1.25rem;
    border-radius: 0.75rem;
    margin-top: 0.625rem;
    border: 1px solid #334155;
}

.section-title-small {
    font-weight: 600;
    color: #cbd5e1;
    margin-bottom: 0.625rem;
    font-size: 1rem;
}

.loading {
    text-align: center;
    color: #94a3b8;
    padding: 2.5rem 1.25rem;
    font-size: 1.1rem;
}

.error {
    text-align: center;
    padding: 1.875rem;
    background: #7f1d1d;
    color: #fecaca;
    border-radius: 0.75rem;
    border: 1px solid #dc2626;
}

.retry-btn {
    background: #3b82f6;
    color: white;
    border: none;
    padding: 0.75rem 1.5rem;
    border-radius: 0.5rem;
    cursor: pointer;
    margin-top: 1.25rem;
    font-weight: 500;
    transition: background-color 0.2s;
}

.retry-btn:hover {
    background: #2563eb;
}

@media (max-width: 48rem) {
    .content-container {
        flex-direction: column;
    }
    
    .user-list-container {
        margin-bottom: 1.25rem;
    }
}

.footer {
    text-align: center;
    padding: 1.5rem;
    margin-top: 2rem;
    color: #94a3b8;
    border-top: 1px solid #334155;
}

.footer-text {
    margin: 0;
    font-size: 1rem;
}

.github-link {
    color: #60a5fa;
    text-decoration: none;
    transition: color 0.2s ease;
}

.github-link:hover {
    color: #3b82f6;
    text-decoration: underline;
}