/* ==========================================================================
   Table of contents — a right rail beside the reading column when there is room,
   a collapsible block above the content otherwise. Filled by toc.js.
   ========================================================================== */

.toc-container {
    /* Floated with a negative right margin: sits beside the reading column without taking
       vertical space; sticky keeps it in view while reading. toc.js detects the stacked
       layout from the computed position, so the breakpoint lives only here. */
    --toc-width: 220px;
    float: right;
    position: sticky;
    top: var(--spacing-lg);
    width: var(--toc-width);
    max-height: calc(100vh - var(--spacing-xl) * 2);
    margin-right: calc(-1 * (var(--toc-width) + var(--spacing-xl)));
    padding: var(--spacing-sm) 0 var(--spacing-sm) var(--spacing-md);
    border-left: 1px solid var(--color-border);
    overflow-y: auto;
    scrollbar-width: thin;
}

.toc-header {
    display: flex;
    align-items: center;
    justify-content: space-between;
    margin-bottom: var(--spacing-sm);
}
.toc-title {
    font-family: var(--font-mono);
    font-size: 0.7rem;
    letter-spacing: 0.06em;
    color: var(--color-text-muted);
}
.toc-toggle {
    display: none;
    align-items: center;
    justify-content: center;
    width: 28px;
    height: 28px;
    border-radius: var(--radius-md);
    color: var(--color-text-muted);
}
.toc-toggle svg { transition: transform var(--transition-fast); }
.toc-container.collapsed .toc-toggle svg { transform: rotate(-90deg); }

.toc-list { list-style: none; }
.toc-item a {
    display: block;
    padding: 3px 0 3px var(--spacing-sm);
    margin-left: calc(-1 * var(--spacing-md) - 1px);
    padding-left: calc(var(--spacing-md) + var(--spacing-sm));
    border-left: 2px solid transparent;
    font-size: 0.8rem;
    line-height: 1.45;
    color: var(--color-text-secondary);
    transition: color var(--transition-fast), border-color var(--transition-fast);
}
.toc-item a:hover { color: var(--color-text); }
.toc-item a.active { color: var(--color-text); border-left-color: var(--cat-color, var(--color-accent)); font-weight: 500; }
.toc-h3 a { padding-left: calc(var(--spacing-md) + var(--spacing-lg)); font-size: 0.76rem; }

/* Reading progress (toc.js) */
.toc-progress {
    height: 2px;
    margin-top: var(--spacing-sm);
    background: var(--color-border);
    border-radius: 1px;
    overflow: hidden;
}
.toc-progress-bar {
    height: 100%;
    width: 0;
    background: var(--cat-color, var(--color-accent));
    transition: width 80ms linear;
}

/* Not enough room beside the column: stack above the content as a collapsible block */
@media (max-width: 1439px) {
    .toc-container {
        float: none;
        position: relative;
        top: auto;
        width: 100%;
        max-height: none;
        margin: 0 0 var(--spacing-xl);
        padding: var(--spacing-sm) var(--spacing-md);
        border: 1px solid var(--color-border);
        border-radius: var(--radius-md);
        background: var(--color-bg-secondary);
        overflow: visible;
    }
    .toc-header { margin-bottom: 0; }
    .toc-toggle { display: flex; }
    .toc-nav { padding-top: var(--spacing-sm); }
    .toc-container.collapsed .toc-nav,
    .toc-container.collapsed .toc-progress { display: none; }
    .toc-item a { margin-left: 0; padding-left: var(--spacing-sm); }
    .toc-h3 a { padding-left: var(--spacing-lg); }
    .toc-progress { margin-top: var(--spacing-sm); }
}