/* VOD Master — 기능 소개 페이지 */
:root {
    --bg: #0f1419;
    --sidebar: #1a2332;
    --sidebar-hover: #243044;
    --accent: #3b82f6;
    --accent-soft: rgba(59, 130, 246, 0.15);
    --text: #e7ecf3;
    --text-muted: #94a3b8;
    --card: #1e293b;
    --border: #334155;
}

* {
    box-sizing: border-box;
}

html {
    scroll-behavior: smooth;
}

body {
    margin: 0;
    font-family: 'Segoe UI', 'Malgun Gothic', sans-serif;
    background: var(--bg);
    color: var(--text);
    min-height: 100vh;
    line-height: 1.6;
}

.features-layout {
    display: flex;
    min-height: 100vh;
    align-items: stretch;
}

/* 좌측 목차 — 본문과 동일한 세로 높이(최소 100vh)로 채움 */
.feature-sidebar {
    width: 280px;
    min-width: 280px;
    flex-shrink: 0;
    background: var(--sidebar);
    border-right: 1px solid var(--border);
    padding: 1.25rem 0;
    min-height: 100vh;
    display: flex;
    flex-direction: column;
}

.feature-sidebar h1 {
    font-size: 1rem;
    font-weight: 700;
    margin: 0 1rem 1rem;
    padding-bottom: 0.75rem;
    border-bottom: 1px solid var(--border);
    color: var(--text);
}

.feature-sidebar h1 a {
    color: inherit;
    text-decoration: none;
}

.feature-sidebar h1 a:hover {
    color: var(--accent);
}

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

.feature-nav li {
    margin: 0;
}

.feature-nav button {
    width: 100%;
    text-align: left;
    padding: 0.65rem 1.25rem;
    border: none;
    background: transparent;
    color: var(--text-muted);
    font-size: 0.9rem;
    cursor: pointer;
    transition: background 0.15s, color 0.15s;
    border-left: 3px solid transparent;
}

.feature-nav button:hover {
    background: var(--sidebar-hover);
    color: var(--text);
}

.feature-nav button.active {
    background: var(--accent-soft);
    color: var(--accent);
    border-left-color: var(--accent);
    font-weight: 600;
}

.feature-nav .nav-label-soop {
    font-size: 0.7rem;
    color: #64748b;
    margin-left: 0.35rem;
    font-weight: 400;
}

/* 소개와 분리된 그룹: 기능 살펴보기 + 하위 기능 목록 */
.feature-nav-group-block {
    list-style: none;
    margin: 0;
    padding: 0;
    border-top: 1px solid var(--border);
    margin-top: 0.35rem;
    padding-top: 0.65rem;
}

.feature-nav-group-title {
    font-size: 0.82rem;
    font-weight: 700;
    letter-spacing: 0.03em;
    color: #94a3b8;
    padding: 0.35rem 1.25rem 0.5rem;
    margin: 0;
    line-height: 1.3;
}

.feature-nav-group-items {
    list-style: none;
    margin: 0;
    padding: 0 0 0.25rem 0;
    border-left: 2px solid rgba(59, 130, 246, 0.25);
    margin-left: 1rem;
}

.feature-nav-group-items li {
    margin: 0;
}

.feature-nav-group-items button {
    padding-left: 1.35rem;
}

/* 본문 */
.feature-main {
    flex: 1;
    padding: 2rem 2.5rem 4rem;
    max-width: 900px;
}

.feature-panel {
    display: none;
    animation: fadeIn 0.2s ease;
}

.feature-panel.active {
    display: block;
}

@keyframes fadeIn {
    from { opacity: 0; transform: translateY(6px); }
    to { opacity: 1; transform: translateY(0); }
}

.feature-panel h2 {
    font-size: 1.75rem;
    margin: 0 0 0.5rem;
    color: #fff;
}

.feature-panel .lead {
    color: var(--text-muted);
    font-size: 1.05rem;
    margin: 0 0 1.5rem;
}

.feature-panel h3 {
    font-size: 1.1rem;
    margin: 1.5rem 0 0.5rem;
    color: #cbd5e1;
}

.feature-panel ul {
    margin: 0.5rem 0 1rem;
    padding-left: 1.25rem;
}

.feature-panel li {
    margin: 0.35rem 0;
}

.feature-panel li > ul {
    margin: 0.45rem 0 0.35rem;
    padding-left: 1.2rem;
    list-style: disc;
}

.feature-panel li > ul > li {
    margin: 0.28rem 0;
}

.feature-panel .platform-tag {
    display: inline-block;
    font-size: 0.75rem;
    padding: 0.15rem 0.5rem;
    border-radius: 4px;
    margin-right: 0.35rem;
    vertical-align: middle;
}

.platform-tag.soop {
    background: #7c3aed33;
    color: #c4b5fd;
}

.platform-tag.chzzk {
    background: #0ea5e933;
    color: #7dd3fc;
}

.platform-tag.both {
    background: var(--accent-soft);
    color: var(--accent);
}

.feature-panel img {
    max-width: 100%;
    height: auto;
    border-radius: 8px;
    margin: 1rem 0;
    border: 1px solid var(--border);
}

.feature-panel .img-row {
    display: flex;
    flex-wrap: wrap;
    gap: 1rem;
    margin: 1rem 0;
}

.feature-panel .img-row img {
    flex: 1;
    min-width: 200px;
    margin: 0;
}

/* 기능 설명 <li> 안 보조 스크린샷 */
.feature-panel li .feature-li-img {
    display: block;
    width: auto;
    max-width: 100%;
    height: auto;
    margin: 0.6rem 0 0;
    border-radius: 6px;
    border: 1px solid var(--border);
}

.feature-panel li .feature-li-img--compact {
    max-width: 100%;
}

.feature-panel li .feature-li-img--wide {
    max-width: 100%;
}

.feature-panel li .feature-li-img-row {
    display: flex;
    flex-wrap: wrap;
    gap: 0.75rem;
    margin: 0.6rem 0 0;
}

.feature-panel li .feature-li-img-row img {
    flex: 1 1 180px;
    width: auto;
    max-width: 100%;
    height: auto;
    margin: 0;
    border-radius: 6px;
    border: 1px solid var(--border);
}

/* 문장·목록 안에 끼워 넣는 작은 스크린샷 */
.feature-panel .feature-inline-img {
    display: inline-block;
    vertical-align: middle;
    max-height: 1.8rem;
    width: auto;
    margin: 0 0.15em;
    border-radius: 4px;
    border: 1px solid var(--border);
}

.feature-panel .feature-inline-img--md {
    max-height: 2.85rem;
}

.feature-panel .feature-inline-img--lg {
    max-height: 4rem;
}

.feature-panel a {
    color: var(--accent);
}

.video-embed-wrap {
    width: 100%;
    max-width: 720px;
    margin: 1.25rem 0;
    aspect-ratio: 16 / 9;
    border-radius: 8px;
    overflow: hidden;
    border: 1px solid var(--border);
    background: #000;
}

.video-embed-wrap iframe {
    display: block;
    width: 100%;
    height: 100%;
    border: none;
}

.video-embed-caption {
    font-size: 0.9rem;
    color: var(--text-muted);
    margin: -0.5rem 0 1rem;
}

.feature-panel kbd {
    display: inline-block;
    padding: 0.1em 0.45em;
    font-size: 0.85em;
    font-family: ui-monospace, monospace;
    background: var(--card);
    border: 1px solid var(--border);
    border-radius: 4px;
}

.feature-panel .note {
    background: var(--card);
    border-left: 3px solid var(--accent);
    padding: 0.75rem 1rem;
    margin: 1rem 0;
    border-radius: 0 8px 8px 0;
    font-size: 0.95rem;
    color: var(--text-muted);
}

.feature-suspended-notice {
    background: rgba(234, 179, 8, 0.12);
    border: 1px solid rgba(234, 179, 8, 0.35);
    border-radius: 8px;
    padding: 0.85rem 1rem;
    margin: 0 0 1.25rem;
    font-size: 0.95rem;
    color: #fcd34d;
    line-height: 1.5;
}

.mobile-nav-toggle {
    display: none;
}

@media (max-width: 768px) {
    .features-layout {
        flex-direction: column;
    }

    .mobile-nav-toggle {
        display: flex;
        align-items: center;
        justify-content: space-between;
        width: 100%;
        padding: 1rem 1.25rem;
        background: var(--sidebar);
        border: none;
        border-bottom: 1px solid var(--border);
        color: var(--text);
        font-size: 1rem;
        font-weight: 600;
        cursor: pointer;
    }

    .feature-sidebar {
        position: relative;
        min-height: 0;
        width: 100%;
        min-width: 0;
        border-right: none;
        border-bottom: 1px solid var(--border);
        padding: 0;
        display: block;
    }

    .feature-sidebar.collapsed .feature-nav,
    .feature-sidebar.collapsed h1 {
        display: none;
    }

    .feature-sidebar h1 {
        margin: 1rem 1.25rem;
    }

    .feature-nav {
        padding-bottom: 0.5rem;
    }

    .feature-main {
        padding: 1.5rem 1.25rem 3rem;
    }
}