.page-header { margin: 8px 0 24px; }
.page-header h1 {
    font-size: var(--text-h2);
    font-weight: var(--fw-semibold);
    letter-spacing: -0.028em;
    color: var(--color-text-primary);
    margin: 0 0 8px;
    line-height: 1.1;
}
.page-header .page-subtitle {
    font-size: var(--text-lg);
    color: var(--color-text-secondary);
    letter-spacing: -0.01em;
    line-height: 1.45;
    margin: 0;
    max-width: 560px;
}

.kb-split {
    display: grid;
    grid-template-columns: 240px 1fr;
    gap: 24px;
    align-items: start;
}
body[data-subnav="off"] .kb-split { grid-template-columns: 1fr; }
body[data-subnav="off"] .kb-split > .kb-aside { display: none; }
body[data-subnav-side="right"] .kb-split { grid-template-columns: 1fr 240px; }
body[data-subnav-side="right"] .kb-split > .kb-aside { grid-column: 2; grid-row: 1; }
body[data-subnav-side="right"] .kb-split > .kb-main { grid-column: 1; grid-row: 1; }
body[data-subnav-side="outside"] .kb-split,
body[data-subnav-side="outside-left"] .kb-split { grid-template-columns: 1fr; position: relative; }
body[data-subnav-side="outside"] .kb-split > .kb-aside,
body[data-subnav-side="outside-left"] .kb-split > .kb-aside { position: absolute; top: 0; width: 240px; }
body[data-subnav-side="outside"] .kb-split > .kb-aside { left: calc(100% + 24px); }
body[data-subnav-side="outside-left"] .kb-split > .kb-aside { right: calc(100% + 24px); left: auto; }
body[data-subnav-side="outside"]:not([data-layout="top"]):not([data-align="left"]):not([data-align="content"]) .ph-main-wrap .content-area { transform: translateX(-132px); }
body[data-subnav-side="outside-left"]:not([data-layout="top"]):not([data-align="left"]):not([data-align="content"]) .ph-main-wrap .content-area { transform: translateX(132px); }

.kb-aside { display: flex; flex-direction: column; gap: 16px; }
.kb-main { display: flex; flex-direction: column; gap: 12px; }

/* Sub-nav */
.subnav-card { padding: 8px; }
.subnav-heading {
    font-size: var(--text-xs);
    font-weight: var(--fw-semibold);
    color: var(--color-text-tertiary);
    text-transform: uppercase;
    letter-spacing: 0.06em;
    padding: 10px 12px 8px;
}
.subnav-item {
    display: flex;
    align-items: center;
    gap: 10px;
    padding: 8px 12px;
    border-radius: var(--radius-sm);
    color: var(--color-text-primary);
    font-size: var(--text-base);
    letter-spacing: -0.008em;
    text-decoration: none;
    transition: background var(--transition-fast);
}
.subnav-item:hover { background: var(--sidebar-item-hover); color: var(--color-text-primary); text-decoration: none; }
.subnav-item.active { background: var(--sidebar-item-active); font-weight: var(--fw-medium); }
.subnav-item svg { width: 14px; height: 14px; color: var(--color-text-tertiary); flex-shrink: 0; }
.subnav-item.active svg { color: var(--color-accent); }

/* Popular articles in sidebar */
.pop-row {
    display: flex;
    align-items: flex-start;
    gap: 10px;
    padding: 10px 12px;
    border-radius: var(--radius-sm);
    text-decoration: none;
    color: var(--color-text-primary);
    transition: background var(--transition-fast);
}
.pop-row:hover { background: var(--sidebar-item-hover); color: var(--color-text-primary); text-decoration: none; }
.pop-row .pop-rank {
    font-size: var(--text-base);
    font-weight: var(--fw-semibold);
    color: var(--color-text-tertiary);
    min-width: 18px;
    text-align: right;
    margin-top: 1px;
    flex-shrink: 0;
}
.pop-row:hover .pop-rank { color: var(--color-accent); }
.pop-row-info { flex: 1; min-width: 0; }
.pop-row-title { font-size: var(--text-base); letter-spacing: -0.008em; line-height: 1.35; }
.pop-row-meta { font-size: var(--text-xs); color: var(--color-text-tertiary); margin-top: 3px; }

/* KB hero search */
.kb-hero {
    padding: 28px 28px 24px;
    text-align: center;
}
.kb-hero-title {
    font-size: var(--text-3xl);
    font-weight: var(--fw-semibold);
    letter-spacing: -0.02em;
    color: var(--color-text-primary);
    margin: 0 0 6px;
}
.kb-hero-sub {
    font-size: var(--text-md);
    color: var(--color-text-secondary);
    margin: 0 0 20px;
}
.kb-hero-search {
    position: relative;
    max-width: 520px;
    margin: 0 auto;
    display: flex;
    align-items: center;
}
.kb-hero-search svg {
    position: absolute;
    left: 18px;
    width: 16px;
    height: 16px;
    color: var(--color-text-tertiary);
    pointer-events: none;
}
.kb-hero-search input {
    width: 100%;
    height: 44px;
    padding: 0 18px 0 44px;
    border-radius: var(--radius-pill);
    border: 1px solid var(--color-border);
    background: var(--color-surface);
    font-size: var(--text-md);
    color: var(--color-text-primary);
    font-family: inherit;
    transition: all var(--transition-fast);
}
.kb-hero-search input:focus {
    outline: none;
    border-color: var(--color-accent);
    box-shadow: 0 0 0 3px var(--color-accent-light);
}

/* Category grid */
.kb-grid {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 12px;
    padding: 12px 22px 24px;
}
.kb-card {
    padding: 20px;
    display: flex;
    flex-direction: column;
    align-items: flex-start;
    gap: 10px;
    background: var(--color-surface-secondary);
    border-radius: var(--radius-lg);
    border: 1px solid var(--color-border-card);
    text-decoration: none;
    color: inherit;
    transition: background var(--transition-fast), transform var(--transition-fast), box-shadow var(--transition-fast);
}
.kb-card:hover {
    background: var(--color-surface);
    transform: translateY(-1px);
    box-shadow: var(--shadow-card-hover);
    color: inherit;
    text-decoration: none;
}
.kb-card .tile-icon {
    width: 36px;
    height: 36px;
    border-radius: 10px;
    background: var(--color-accent-light);
    color: var(--color-accent);
    display: inline-flex;
    align-items: center;
    justify-content: center;
}
.kb-card .tile-icon svg { width: 18px; height: 18px; }
.kb-card-title {
    font-size: var(--text-lg);
    font-weight: var(--fw-semibold);
    letter-spacing: -0.01em;
    color: var(--color-text-primary);
    margin-top: 4px;
}
.kb-card-count {
    font-size: var(--text-sm);
    color: var(--color-text-secondary);
}

/* Empty state */
.kb-empty {
    padding: 56px 24px 48px;
    text-align: center;
    color: var(--color-text-secondary);
}
.kb-empty-ico {
    width: 52px;
    height: 52px;
    border-radius: 50%;
    background: var(--color-surface-secondary);
    color: var(--color-text-tertiary);
    display: inline-flex;
    align-items: center;
    justify-content: center;
    margin-bottom: 14px;
}
.kb-empty-ico svg { width: 22px; height: 22px; }
.kb-empty-title {
    font-size: var(--text-lg);
    font-weight: var(--fw-medium);
    color: var(--color-text-primary);
    margin: 0 0 4px;
    letter-spacing: -0.01em;
}
.kb-empty-sub {
    font-size: var(--text-base);
    color: var(--color-text-tertiary);
    margin: 0 auto 18px;
    max-width: 340px;
    line-height: 1.45;
}
.kb-empty .btn-secondary,
.kb-empty .btn-primary {
    height: 32px;
    padding: 0 16px;
    font-size: var(--text-base);
}

@media (max-width: 1100px) {
    body[data-subnav-side="outside"] .kb-split,
    body[data-subnav-side="outside-left"] .kb-split { grid-template-columns: 240px 1fr; gap: 24px; position: static; }
    body[data-subnav-side="outside"] .kb-split > .kb-aside,
    body[data-subnav-side="outside-left"] .kb-split > .kb-aside { position: static; width: auto; left: auto; right: auto; }
    body[data-subnav-side="outside"]:not([data-layout="top"]):not([data-align="left"]):not([data-align="content"]) .ph-main-wrap .content-area,
    body[data-subnav-side="outside-left"]:not([data-layout="top"]):not([data-align="left"]):not([data-align="content"]) .ph-main-wrap .content-area { transform: none; }
}

@media (max-width: 880px) {
    .kb-split,
    body[data-subnav-side="right"] .kb-split,
    body[data-subnav-side="outside"] .kb-split,
    body[data-subnav-side="outside-left"] .kb-split { grid-template-columns: 1fr; }
    /* Stacked: show the content first, push the sub-nav below. */
    .kb-split > .kb-main { order: 1; }
    .kb-split > .kb-aside { order: 2; }
    body[data-subnav-side="right"] .kb-split > .kb-main,
    body[data-subnav-side="right"] .kb-split > .kb-aside { grid-column: auto; grid-row: auto; }
    .page-header h1 { font-size: var(--text-h3); }
}

@media (max-width: 720px) {
    .kb-grid { grid-template-columns: repeat(2, 1fr); }
}

@media (max-width: 480px) {
    .page-header h1 { font-size: var(--text-h4); }
    .kb-grid { grid-template-columns: 1fr; }
}