/* 서브페이지 공통 스타일 */
*, *::before, *::after { box-sizing: border-box; }

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', 'Noto Sans KR', sans-serif;
    background: #f4f6fb;
    color: #1e2330;
    margin: 0;
    min-height: 100vh;
    display: flex;
    flex-direction: column;
    line-height: 1.8;
    font-size: 15px;
}

.sub-header {
    background: linear-gradient(135deg, #4f7ef8, #7c3aed);
    color: #fff;
    padding: 2rem 2rem 1.5rem;
    text-align: center;
}

.back-link {
    display: inline-block;
    color: rgba(255,255,255,0.85);
    text-decoration: none;
    font-size: 0.875rem;
    margin-bottom: 1rem;
    transition: color 0.2s;
}
.back-link:hover { color: #fff; }

.sub-header h1 {
    margin: 0.25rem 0;
    font-size: 1.75rem;
    font-weight: 800;
}

.last-updated {
    margin: 0.5rem 0 0;
    font-size: 0.85rem;
    opacity: 0.8;
}

.sub-main {
    flex: 1;
    max-width: 800px;
    width: 100%;
    margin: 0 auto;
    padding: 2rem 1.5rem;
}

section {
    margin-bottom: 2.5rem;
    background: #fff;
    border-radius: 12px;
    padding: 1.75rem 2rem;
    box-shadow: 0 1px 4px rgba(0,0,0,0.07);
}

section h2 {
    margin: 0 0 1rem;
    font-size: 1.15rem;
    font-weight: 700;
    color: #4f7ef8;
    border-bottom: 2px solid #eef2ff;
    padding-bottom: 0.5rem;
}

section h3 {
    margin: 1.25rem 0 0.5rem;
    font-size: 1rem;
    font-weight: 600;
    color: #1e2330;
}

p { margin: 0 0 0.75rem; }

ul, ol {
    padding-left: 1.5rem;
    margin: 0 0 0.75rem;
}

li { margin-bottom: 0.4rem; }

a { color: #4f7ef8; text-decoration: none; }
a:hover { text-decoration: underline; }

code {
    background: #f0f3fa;
    border-radius: 4px;
    padding: 0.15em 0.4em;
    font-size: 0.875em;
    font-family: 'Courier New', monospace;
}

/* About 페이지 특수 스타일 */
.about-hero { background: linear-gradient(135deg, #eef2ff, #f3e8ff); }
.about-hero h2 { color: #4f7ef8; }

.feature-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(220px, 1fr));
    gap: 1.25rem;
    margin-top: 1rem;
}

.feature-card {
    background: #f4f6fb;
    border-radius: 10px;
    padding: 1.25rem;
    text-align: center;
}

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

.feature-card h3 {
    margin: 0 0 0.5rem;
    font-size: 0.95rem;
    color: #1e2330;
}

.feature-card p {
    font-size: 0.85rem;
    color: #6b7280;
    margin: 0;
}

.user-list li { margin-bottom: 0.6rem; }

.how-to-list { padding-left: 1.5rem; }
.how-to-list li { margin-bottom: 0.75rem; }

.sub-footer {
    background: #fff;
    border-top: 1px solid #dde1ea;
    text-align: center;
    padding: 1.25rem;
    font-size: 0.85rem;
    color: #6b7280;
}
.sub-footer p { margin: 0.25rem 0; }
.sub-footer a { color: #4f7ef8; text-decoration: none; }
.sub-footer a:hover { text-decoration: underline; }

@media (max-width: 640px) {
    .sub-header { padding: 1.5rem 1rem 1rem; }
    .sub-header h1 { font-size: 1.35rem; }
    .sub-main { padding: 1rem; }
    section { padding: 1.25rem; }
    .feature-grid { grid-template-columns: 1fr; }
}