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

body {
    font-family: 'Inter', sans-serif;
    background: rgb(245, 245, 247);
    color: rgb(29, 29, 31);
    min-height: 100vh;
}

/* ── Header ── */
.site-header {
    position: sticky;
    top: 0;
    z-index: 100;
    background: rgba(245, 245, 247, 0.88);
    backdrop-filter: blur(16px);
    -webkit-backdrop-filter: blur(16px);
    border-bottom: 1px solid rgba(0, 0, 0, 0.08);
    padding: 0 32px;
    height: 56px;
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: 16px;
}

.header-left {
    display: flex;
    align-items: center;
    gap: 14px;
}

.header-left img { height: 26px; }

.header-title {
    font-size: 13px;
    font-weight: 500;
    color: rgba(0, 0, 0, 0.45);
    letter-spacing: 0.04em;
    text-transform: uppercase;
}

.header-sep {
    width: 1px;
    height: 18px;
    background: rgba(0, 0, 0, 0.15);
}

.back-link {
    font-size: 13px;
    color: rgba(0, 0, 0, 0.45);
    text-decoration: none;
    display: flex;
    align-items: center;
    gap: 5px;
    transition: color 0.15s;
}

.back-link:hover { color: rgba(0, 0, 0, 0.75); }

/* ── Layout ── */
.layout {
    display: flex;
    max-width: 1100px;
    margin: 0 auto;
    padding: 40px 24px 80px;
    gap: 40px;
}

/* ── Sidebar ── */
.sidebar {
    width: 200px;
    flex-shrink: 0;
}

.sidebar-inner {
    position: sticky;
    top: 76px;
    max-height: calc(100vh - 96px);
    overflow-y: auto;
}

.sidebar-label {
    font-size: 10px;
    font-weight: 600;
    color: rgba(0, 0, 0, 0.35);
    letter-spacing: 0.1em;
    text-transform: uppercase;
    margin-bottom: 10px;
    padding-left: 10px;
}

.nav-list {
    list-style: none;
    display: flex;
    flex-direction: column;
    gap: 2px;
}

.nav-list a {
    display: block;
    padding: 7px 10px;
    border-radius: 8px;
    font-size: 13px;
    color: rgba(0, 0, 0, 0.55);
    text-decoration: none;
    transition: background 0.15s, color 0.15s;
    line-height: 1.4;
}

.nav-list a:hover,
.nav-list a.active {
    background: rgba(0, 0, 0, 0.06);
    color: rgba(0, 0, 0, 0.85);
}

/* ── Content ── */
.content {
    flex: 1;
    min-width: 0;
}

.section {
    margin-bottom: 56px;
    scroll-margin-top: 76px;
}

.section-header {
    display: flex;
    align-items: center;
    gap: 10px;
    margin-bottom: 20px;
    padding-bottom: 12px;
    border-bottom: 1px solid rgba(0, 0, 0, 0.08);
}

.section-number {
    width: 26px;
    height: 26px;
    border-radius: 50%;
    background: rgba(0, 0, 0, 0.07);
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 11px;
    font-weight: 600;
    color: rgba(0, 0, 0, 0.45);
    flex-shrink: 0;
}

.section h2 {
    font-size: 17px;
    font-weight: 600;
    color: rgb(29, 29, 31);
    line-height: 1.35;
}

.section p {
    font-size: 15px;
    line-height: 1.75;
    color: rgba(0, 0, 0, 0.65);
    margin-bottom: 16px;
}

.section p:last-child { margin-bottom: 0; }

.section strong { color: rgba(0, 0, 0, 0.82); }

.section a { color: rgba(0, 0, 0, 0.6); }

/* ── Images ── */
.img-wrap {
    margin: 20px 0;
    text-align: center;
}

.img-wrap img {
    max-width: 100%;
    border-radius: 12px;
    box-shadow: 0 8px 32px rgba(0, 0, 0, 0.12), 0 0 0 1px rgba(0, 0, 0, 0.05);
}

.img-wrap figcaption {
    margin-top: 8px;
    font-size: 12px;
    color: rgba(0, 0, 0, 0.38);
}

.img-row {
    display: flex;
    align-items: flex-start;
    gap: 16px;
    margin: 20px 0;
    flex-wrap: wrap;
    justify-content: center;
}

.img-row figure {
    text-align: center;
}

.img-row figure img {
    max-width: 100%;
    border-radius: 10px;
    box-shadow: 0 6px 20px rgba(0, 0, 0, 0.1), 0 0 0 1px rgba(0, 0, 0, 0.05);
}

.img-row figure figcaption {
    margin-top: 8px;
    font-size: 12px;
    color: rgba(0, 0, 0, 0.38);
}

img.flat { border-radius: 0 !important; box-shadow: none !important; }

/* ── Callout ── */
.callout {
    background: rgba(0, 0, 0, 0.04);
    border-left: 3px solid rgba(0, 0, 0, 0.12);
    border-radius: 0 8px 8px 0;
    padding: 14px 18px;
    margin: 16px 0;
    font-size: 14px;
    color: rgba(0, 0, 0, 0.6);
    line-height: 1.65;
}

/* ── Skins grid ── */
.skins-grid {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 12px;
    margin: 20px 0;
}

.skins-grid img {
    width: 100%;
    border-radius: 8px;
    box-shadow: 0 4px 14px rgba(0, 0, 0, 0.1), 0 0 0 1px rgba(0, 0, 0, 0.05);
}

/* ── Footer ── */
.guide-footer {
    text-align: center;
    padding: 32px;
    font-size: 12px;
    color: rgba(0, 0, 0, 0.3);
    border-top: 1px solid rgba(0, 0, 0, 0.07);
}

.guide-footer a { color: inherit; }

/* ── Mobile ── */
@media (max-width: 720px) {
    .sidebar { display: none; }
    .layout { padding: 24px 16px 60px; }
    .site-header { padding: 0 16px; }
    .skins-grid { grid-template-columns: repeat(2, 1fr); }
}