/* ── Focus Mode Toggle Button ─────────────────────────────────── */

.focus-mode-btn {
    position: fixed;
    bottom: 96px;
    right: 35px;
    z-index: 101;
    width: 47px;
    height: 47px;
    box-sizing: border-box;
    border: 1px solid var(--fb-border-accent, var(--fb-blue));
    border-radius: 15%;
    background-color: var(--fb-bg-accent, var(--fb-blue));
    color: var(--fb-text-invert, #fff);
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
    opacity: 0;
    visibility: hidden;
    transform: scale(0);
    transform-origin: center;
    transition: opacity 0.3s ease, visibility 0.3s ease, background-color 0.3s ease, transform 0.3s ease, color 0.3s ease;
    box-shadow: var(--fb-shadow-md, 0 4px 6px -1px rgba(0,0,0,0.08));
    -webkit-tap-highlight-color: transparent;
    touch-action: manipulation;
}

.focus-mode-btn.visible {
    opacity: 1;
    visibility: visible;
    transform: scale(1);
}

.focus-mode-btn:hover {
    background-color: var(--fb-bg-accent-subtle, var(--fb-blue-low));
    color: var(--fb-text-accent, var(--fb-blue));
    border-color: var(--fb-border-accent, var(--fb-blue));
    box-shadow: var(--fb-shadow-lg, 0 10px 15px -3px rgba(0,0,0,0.08));
}

.focus-mode-btn:active {
    background-color: var(--fb-blue-high);
    color: var(--fb-text-invert, #fff);
    transition: background-color 0.1s ease, transform 0.1s ease;
}

.focus-mode-btn.keyboard-focus {
    outline: var(--fb-focus-ring-width, 2px) solid var(--fb-focus-ring, var(--fb-blue));
    outline-offset: var(--fb-focus-ring-offset, 2px);
}

.focus-mode-btn svg {
    width: 24px;
    height: 24px;
    fill: none;
    stroke: currentColor;
    stroke-width: 2;
    stroke-linecap: round;
    stroke-linejoin: round;
    transition: opacity 0.2s ease;
}

/* Icon swap: show expand when in focus mode, compress when not */
.focus-mode-btn .icon-enter { display: block; }
.focus-mode-btn .icon-exit  { display: none; }

body.focus-mode .focus-mode-btn .icon-enter { display: none; }
body.focus-mode .focus-mode-btn .icon-exit  { display: block; }

/* Active state styling */
body.focus-mode .focus-mode-btn {
    background-color: var(--fb-bg-accent-subtle, var(--fb-blue-low));
    color: var(--fb-text-accent, var(--fb-blue));
    border-color: var(--fb-border-accent, var(--fb-blue));
}

body.focus-mode .focus-mode-btn:hover {
    background-color: var(--fb-bg-accent, var(--fb-blue));
    color: var(--fb-text-invert, #fff);
}

/* Left position variant — offset by sidebar width so it's not hidden behind it */
.focus-mode-btn.pos-bottom-left {
    right: auto;
    left: calc(var(--fb-sidebar-width) + 20px);
    transition: opacity 0.3s ease, visibility 0.3s ease, background-color 0.3s ease, transform 0.3s ease, color 0.3s ease, left var(--focus-mode-speed, 300ms) ease;
}

/* When sidebar is hidden, slide button to the true left edge */
body.focus-mode .focus-mode-btn.pos-bottom-left {
    left: 35px;
}

/* ── Tooltip ──────────────────────────────────────────────────── */

.focus-mode-tooltip {
    position: absolute;
    right: -10px;
    top: -42px;
    background-color: var(--fb-gray-7, #1e293b);
    color: var(--fb-text-invert, #fff);
    padding: 5px 10px;
    border-radius: var(--fb-radius-sm, 4px);
    font-weight: var(--fb-weight-normal, 400);
    font-size: var(--fb-text-sm, 14px);
    white-space: nowrap;
    opacity: 0;
    visibility: hidden;
    transition: opacity 0.2s, visibility 0.3s;
    pointer-events: none;
}

.focus-mode-tooltip.visible {
    opacity: 1;
    visibility: visible;
}

.focus-mode-tooltip-arrow {
    position: absolute;
    top: 100%;
    left: 50%;
    transform: translateX(-50%);
    width: 0;
    height: 0;
    border-left: 6px solid transparent;
    border-right: 6px solid transparent;
    border-top: 6px solid var(--fb-gray-7, #1e293b);
}

:root.dark .focus-mode-tooltip {
    background-color: var(--fb-gray-7);
    color: var(--fb-gray-1);
}

:root.dark .focus-mode-tooltip-arrow {
    border-top-color: var(--fb-gray-7);
}

/* ── Focus Mode Layout Changes ────────────────────────────────── */

body.focus-mode .sidebar {
    transform: translateX(-100%);
    opacity: 0;
    visibility: hidden;
    pointer-events: none;
}

body.focus-mode .toc-column {
    transform: translateX(100%);
    opacity: 0;
    visibility: hidden;
    pointer-events: none;
    position: absolute;
}

body.focus-mode .main-wrapper {
    padding-left: 0;
}

body.focus-mode .content-column {
    max-width: 55rem;
    margin: 0 auto;
}

/* Smooth transitions for entering/exiting focus mode */
.sidebar {
    transition: transform var(--focus-mode-speed, 300ms) ease,
                opacity var(--focus-mode-speed, 300ms) ease,
                visibility var(--focus-mode-speed, 300ms) ease;
}

.toc-column {
    transition: transform var(--focus-mode-speed, 300ms) ease,
                opacity var(--focus-mode-speed, 300ms) ease,
                visibility var(--focus-mode-speed, 300ms) ease;
}

.main-wrapper {
    transition: padding-left var(--focus-mode-speed, 300ms) ease;
}

.content-column {
    transition: max-width var(--focus-mode-speed, 300ms) ease,
                margin var(--focus-mode-speed, 300ms) ease;
}

/* ── Mobile ───────────────────────────────────────────────────── */

@media (max-width: 1023px) {
    /* Sidebar and TOC are already hidden on mobile, so focus mode
       only hides the header toggle and gives a wider content area */
    .focus-mode-btn {
        bottom: 1.25rem;
        right: 1.25rem;
        width: 40px;
        height: 40px;
    }

    .focus-mode-btn.pos-bottom-left {
        right: auto;
        left: 1.25rem;
    }

    .focus-mode-btn svg {
        width: 20px;
        height: 20px;
    }
}

/* ── Print ────────────────────────────────────────────────────── */

@media print {
    .focus-mode-btn {
        display: none !important;
    }
}