/*  viz-system.css
 *  Apple-aligned design system for algorithm visualizations.
 *  Import from any problem folder:
 *    <link rel="stylesheet" href="../../../shared/viz/viz-system.css">
 */

/* ── Tokens ─────────────────────────────────────────────── */

:root {
    --black: #000000;
    --ink: #1D1D1F;
    --ink-secondary: #1D1D1F;
    --ink-tertiary: #48484A;
    --ink-quaternary: #48484A;
    --fill-tertiary: #636366;
    --fill-secondary: #8E8E93;
    --bg-secondary: #F5F5F7;
    --bg-tertiary: #FAFAFA;
    --white: #FFFFFF;

    --shadow-card: none;
    --shadow-elevated: none;
    --shadow-tile: none;
    --shadow-tile-active: none;

    --radius-sm: 12px;
    --radius-md: 18px;
    --radius-lg: 24px;
    --radius-xl: 28px;

    --ease: cubic-bezier(0.25, 0.1, 0.25, 1);

    --font-serif: ui-serif, "New York", "Iowan Old Style", Georgia, serif;
    --font-sans: -apple-system, BlinkMacSystemFont, "SF Pro Text", "SF Pro Display", "Helvetica Neue", sans-serif;
    --font-mono: Menlo, "SF Mono", Monaco, Consolas, monospace;
}

/* ── Reset & Base ───────────────────────────────────────── */

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

html {
    background: var(--white);
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
    text-rendering: optimizeLegibility;
}

body {
    color: var(--ink);
    font-family: var(--font-serif);
    font-size: 1.1rem;
    line-height: 1.8;
}

/* ── Page Layout ────────────────────────────────────────── */

.page {
    max-width: 1000px;
    margin: 0 auto;
    padding: 80px 32px 100px;
}

.divider {
    border: none;
    height: 0.5px;
    background: rgba(0, 0, 0, 0.08);
    margin: 88px 0;
}

/* ── Typography ─────────────────────────────────────────── */

h1, h2, h3, h4 {
    font-family: var(--font-serif);
    color: var(--black);
    font-weight: 700;
}

h1 {
    font-size: clamp(3.2rem, 7vw, 4.8rem);
    line-height: 1.0;
    letter-spacing: -0.05em;
}

h2 {
    font-size: clamp(2rem, 4.2vw, 2.8rem);
    line-height: 1.06;
    letter-spacing: -0.04em;
    margin-bottom: 20px;
}

h3 {
    font-size: 1.2rem;
    line-height: 1.15;
    letter-spacing: -0.025em;
}

h4 {
    font-size: 1.05rem;
    line-height: 1.2;
    letter-spacing: -0.02em;
}

p {
    color: var(--ink-secondary);
    font-size: 1.15rem;
    line-height: 1.85;
}

code {
    padding: 0.12em 0.4em;
    border-radius: 5px;
    background: transparent;
    color: var(--ink);
    font-family: var(--font-mono);
    font-size: 0.82em;
}

.label {
    display: inline-block;
    margin-bottom: 14px;
    font-family: var(--font-sans);
    font-size: 0.7rem;
    font-weight: 600;
    letter-spacing: 0.1em;
    text-transform: uppercase;
    color: var(--ink-quaternary);
}

/* ── Hero ───────────────────────────────────────────────── */

.hero {
    display: grid;
    grid-template-columns: 1fr auto;
    gap: 64px;
    align-items: center;
}

.hero.hero-full {
    display: block;
}

.hero-text {
    margin-top: 28px;
    max-width: 48ch;
    font-size: 1.18rem;
}

.hero-full .hero-text {
    max-width: 56ch;
}

.concept-svg {
    display: block;
    width: 300px;
    height: auto;
    flex-shrink: 0;
}

/* ── Section ────────────────────────────────────────────── */

.section-intro {
    margin-top: 0;
    max-width: 56ch;
}

/* ── Concept Cards ──────────────────────────────────────── */

.concept-cards {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 32px;
    margin-top: 48px;
}

.concept-card {
    display: flex;
    flex-direction: column;
    padding: 0;
    background: transparent;
}

.concept-card .line-sample {
    order: -1;
    margin-top: 0;
    margin-bottom: 20px;
}

.concept-card h3 {
    font-family: var(--font-mono);
    font-size: 1.05rem;
    font-weight: 600;
    margin-bottom: 12px;
}

.concept-card p {
    font-size: 0.98rem;
    line-height: 1.6;
}

.concept-card .guard-code {
    display: block;
    margin-top: 14px;
    font-family: var(--font-mono);
    font-size: 0.78rem;
    color: var(--ink-tertiary);
}

/* ── Line-style Utilities ───────────────────────────────── */

.line-sample {
    display: block;
    width: 100%;
    margin-top: 16px;
}

.line-sample.solid     { height: 3px; background: var(--ink); }
.line-sample.double-ln { height: 5px; background: linear-gradient(180deg, var(--ink) 0 1px, transparent 1px 4px, var(--ink) 4px 5px); }
.line-sample.dashed    { height: 2px; background: repeating-linear-gradient(90deg, var(--ink) 0 10px, transparent 10px 16px); }
.line-sample.dotted    { height: 3px; background: radial-gradient(circle closest-side, var(--ink) 100%, transparent 100%); background-size: 8px 3px; }

.legend-line.solid     { height: 3px; border: none; background: var(--ink); }
.legend-line.double-ln { height: 5px; border: none; background: linear-gradient(180deg, var(--ink) 0 1px, transparent 1px 4px, var(--ink) 4px 5px); }
.legend-line.dashed    { height: 2px; border: none; background: repeating-linear-gradient(90deg, var(--ink) 0 8px, transparent 8px 13px); }
.legend-line.dotted    { height: 3px; border: none; background: radial-gradient(circle closest-side, var(--ink) 100%, transparent 100%); background-size: 6px 3px; }

.dir-indicator.solid     { height: 3px; border: none; background: var(--ink); }
.dir-indicator.double-ln { height: 5px; border: none; background: linear-gradient(180deg, var(--ink) 0 1px, transparent 1px 4px, var(--ink) 4px 5px); }
.dir-indicator.dashed    { height: 2px; border: none; background: repeating-linear-gradient(90deg, var(--ink) 0 6px, transparent 6px 10px); }
.dir-indicator.dotted    { height: 3px; border: none; background: radial-gradient(circle closest-side, var(--ink) 100%, transparent 100%); background-size: 6px 3px; }

.dir-indicator {
    display: inline-block;
    width: 16px;
    height: 0;
}

/* ── Algorithm Steps ────────────────────────────────────── */

.steps {
    list-style: none;
    margin-top: 40px;
    position: relative;
}

.steps::before {
    content: "";
    position: absolute;
    left: 17px;
    top: 36px;
    bottom: 36px;
    width: 1px;
    background: rgba(0, 0, 0, 0.08);
}

.step {
    display: grid;
    grid-template-columns: 36px 1fr;
    gap: 20px;
    padding: 22px 0;
    position: relative;
}

.step-marker {
    width: 36px;
    height: 36px;
    display: grid;
    place-items: center;
    border-radius: 50%;
    background: var(--white);
    border: 1px solid rgba(0, 0, 0, 0.1);
    font-family: var(--font-mono);
    font-size: 0.82rem;
    font-weight: 600;
    color: var(--ink);
    position: relative;
    z-index: 1;
}

.step-body h4 { margin-bottom: 8px; }
.step-body p  { font-size: 1rem; line-height: 1.7; }

.step-guard {
    display: inline-block;
    margin-bottom: 8px;
    padding: 0;
    border-radius: 0;
    background: transparent;
    font-family: var(--font-mono);
    font-size: 0.78rem;
    color: var(--ink-tertiary);
}

.step-shrink-values {
    display: flex;
    gap: 8px;
    flex-wrap: wrap;
    margin-top: 6px;
}

.step-shrink-values code { font-size: 0.84em; }

/* ── Interactive Panel ──────────────────────────────────── */

.interactive {
    margin-top: 48px;
    padding: 0;
}

/* ── Toolbar ────────────────────────────────────────────── */

.toolbar {
    display: flex;
    flex-wrap: wrap;
    justify-content: space-between;
    align-items: center;
    gap: 16px;
    margin-bottom: 32px;
}

.transport {
    display: flex;
    gap: 8px;
}

select {
    font-family: var(--font-sans);
    font-size: 0.88rem;
    padding: 10px 38px 10px 16px;
    min-width: 260px;
    border: 1px solid var(--ink);
    border-radius: 980px;
    background: transparent;
    color: var(--ink);
    cursor: pointer;
    appearance: none;
    -webkit-appearance: none;
    background-image: url("data:image/svg+xml,%3Csvg width='10' height='6' viewBox='0 0 10 6' fill='none' xmlns='http://www.w3.org/2000/svg'%3E%3Cpath d='M1 1L5 5L9 1' stroke='%231D1D1F' stroke-width='1.5' stroke-linecap='round' stroke-linejoin='round'/%3E%3C/svg%3E");
    background-repeat: no-repeat;
    background-position: right 14px center;
    transition: background 200ms var(--ease);
    touch-action: manipulation;
    -webkit-tap-highlight-color: transparent;
}

select:hover { border-color: var(--black); }

button {
    font-family: var(--font-sans);
    font-size: 0.88rem;
    font-weight: 400;
    padding: 10px 22px;
    border: 1px solid var(--ink);
    border-radius: 980px;
    background: transparent;
    color: var(--ink);
    cursor: pointer;
    transition: background 200ms var(--ease), transform 200ms var(--ease);
    touch-action: manipulation;
    -webkit-tap-highlight-color: transparent;
}

button:hover  { background: var(--ink); color: var(--white); }
button:active { transform: scale(0.96); }

button.primary {
    background: var(--ink);
    color: var(--white);
    font-weight: 500;
}

button.primary:hover { background: var(--black); }

/* ── Legend ──────────────────────────────────────────────── */

.legend {
    display: flex;
    flex-wrap: wrap;
    gap: 20px;
    margin-bottom: 28px;
    font-family: var(--font-sans);
    font-size: 0.8rem;
    color: var(--ink-tertiary);
}

.legend-item {
    display: inline-flex;
    align-items: center;
    gap: 8px;
}

.legend-line {
    display: inline-block;
    width: 24px;
}

.legend-dot {
    width: 10px;
    height: 10px;
    border-radius: 50%;
    background: var(--ink);
}

/* ── Section-Based Layout (alternate to .page) ─────────── */

.viz-section {
    max-width: 1000px;
    margin: 0 auto;
    padding: 0 32px;
}

.viz-section:first-of-type {
    padding-top: 80px;
}

.viz-section:last-of-type {
    padding-bottom: 88px;
}

.viz-section + .viz-section {
    margin-top: 64px;
}

.viz-section .viz-container {
    padding: 0;
    margin-bottom: 0;
    overflow-x: visible;
}

.viz-title {
    font-family: var(--font-serif);
    font-size: clamp(3.2rem, 7vw, 4.8rem);
    line-height: 1.0;
    letter-spacing: -0.05em;
    color: var(--black);
    font-weight: 700;
}

.viz-subtitle {
    display: block;
    margin-top: 14px;
    font-family: var(--font-sans);
    font-size: 0.72rem;
    font-weight: 600;
    letter-spacing: 0.08em;
    text-transform: uppercase;
    color: var(--ink-quaternary);
}

.viz-body {
    margin-top: 20px;
    max-width: 56ch;
    font-size: 1.15rem;
    line-height: 1.85;
    color: var(--ink-secondary);
}

.viz-heading {
    font-family: var(--font-serif);
    font-size: clamp(2rem, 4.2vw, 2.8rem);
    line-height: 1.06;
    letter-spacing: -0.04em;
    color: var(--black);
    font-weight: 700;
    margin-bottom: 20px;
}

.viz-code-block {
    margin-top: 24px;
    padding: 28px 32px;
    border-radius: var(--radius-sm);
    background: var(--bg-secondary);
    overflow-x: auto;
}

.viz-code-block pre {
    font-family: var(--font-mono);
    font-size: 0.82rem;
    line-height: 1.72;
    color: var(--ink);
    white-space: pre;
    margin: 0;
}

/* ── Body-level interactive mount (Pattern B pages) ─────── */

body > #interactiveMount {
    max-width: 1000px;
    margin: 0 auto;
    padding: 0 32px;
}

/* ── Viz Container (grid-based visualizations) ──────────── */

.viz-container {
    position: relative;
    padding: 80px;
    margin-bottom: 40px;
    overflow-x: auto;
    border-radius: 0;
    background: transparent;
}

.viz-placeholder {
    position: absolute;
    inset: 0;
    display: grid;
    place-content: center;
    justify-items: center;
    gap: 14px;
    padding: 32px;
    text-align: center;
    pointer-events: none;
    z-index: 1;
}

.viz-placeholder[hidden] {
    display: none;
}

.viz-placeholder-label {
    display: inline-block;
    font-family: var(--font-sans);
    font-size: 0.68rem;
    font-weight: 600;
    letter-spacing: 0.12em;
    text-transform: uppercase;
    color: var(--ink-quaternary);
}

.viz-placeholder-cta {
    padding: 10px 18px;
    border: 1px solid rgba(0, 0, 0, 0.08);
    border-radius: 980px;
    background: var(--white);
    font-family: var(--font-sans);
    font-size: 0.9rem;
    line-height: 1.2;
    color: var(--ink);
}

.viz-placeholder-preset {
    max-width: 34rem;
    font-family: var(--font-mono);
    font-size: 0.8rem;
    line-height: 1.6;
    color: var(--ink-tertiary);
}

.viz-grid {
    display: grid;
    gap: 20px;
    width: fit-content;
    margin: 0 auto;
}

/* ── Boundary Labels ────────────────────────────────────── */

.boundary-label {
    position: absolute;
    font-family: var(--font-sans);
    font-size: 0.78rem;
    font-weight: 500;
    letter-spacing: 0.04em;
    color: var(--ink-tertiary);
    white-space: nowrap;
    z-index: 2;
    transition: top 350ms var(--ease), left 350ms var(--ease);
}

.boundary-label .bval {
    font-family: var(--font-mono);
    font-weight: 600;
    color: var(--ink);
}

.label-top    { transform: translateX(-50%) translateY(-100%); }
.label-bottom { transform: translateX(-50%); }
.label-left   { transform: translateX(-100%) translateY(-50%); text-align: right; }
.label-right  { transform: translateY(-50%); }

/* ── Boundary Frame Overlay ─────────────────────────────── */

.boundary-frame {
    position: absolute;
    pointer-events: none;
    z-index: 4;
    transition: top 350ms var(--ease), left 350ms var(--ease),
                width 350ms var(--ease), height 350ms var(--ease),
                opacity 350ms var(--ease);
}

.frame-top    { height: 3px; background: var(--ink); }
.frame-right  { width: 5px; background: linear-gradient(90deg, var(--ink) 0 1px, transparent 1px 4px, var(--ink) 4px 5px); }
.frame-bottom { height: 2px; background: repeating-linear-gradient(90deg, var(--ink) 0 10px, transparent 10px 16px); }
.frame-left   { width: 4px; background: radial-gradient(circle closest-side, var(--ink) 100%, transparent 100%); background-size: 4px 8px; }

/* ── Cells ──────────────────────────────────────────────── */

.cell {
    position: relative;
    width: 80px;
    height: 80px;
    display: grid;
    place-items: center;
    border-radius: 16px;
    background: transparent;
    transition: transform 250ms var(--ease), background 250ms var(--ease);
}

.cell-value {
    position: relative;
    z-index: 1;
    font-family: var(--font-mono);
    font-size: 1.15rem;
    font-weight: 600;
    color: var(--ink);
    transition: color 250ms var(--ease);
}

.cell.visited {
    background: transparent;
}

.cell.visited .cell-value {
    color: var(--fill-tertiary);
}

.cell.current {
    background: var(--ink);
    transform: scale(1.06);
    z-index: 3;
}

.cell.current .cell-value {
    color: var(--white);
}

.cell.sweep {
    background: transparent;
}

.cell.outer-layer {
    opacity: 0.15;
    transform: scale(0.92);
    pointer-events: none;
}

.cell.outer-layer.current {
    opacity: 1;
    transform: scale(1.06);
}

.visit-badge {
    position: absolute;
    top: 6px;
    left: 7px;
    min-width: 20px;
    height: 20px;
    padding: 0 5px;
    display: inline-grid;
    place-items: center;
    border-radius: 999px;
    background: var(--ink);
    color: var(--white);
    font-family: var(--font-mono);
    font-size: 0.62rem;
    font-weight: 600;
    opacity: 0;
    transform: translateY(-3px);
    transition: opacity 250ms var(--ease), transform 250ms var(--ease);
}

.cell.visited .visit-badge,
.cell.current .visit-badge {
    opacity: 1;
    transform: translateY(0);
}

.cell.current .visit-badge {
    background: var(--white);
    color: var(--ink);
}

/* Array cells: badge positioned outside top-left corner (iOS notification style) */
.viz-array .visit-badge {
    top: -8px;
    left: -6px;
    min-width: 18px;
    height: 18px;
    font-size: 0.56rem;
    z-index: 4;
}

/* ── Array Layout (1D horizontal strip) ────────────────── */

.viz-container:has(.viz-array) {
    padding-top: 104px;
    padding-bottom: 104px;
    overflow-x: auto;
}

.viz-array {
    display: grid;
    justify-content: center;
    gap: 8px;
    width: fit-content;
    margin: 0 auto;
}

.viz-array .cell {
    position: relative;
    width: var(--array-cell-size, 80px);
    height: var(--array-cell-size, 80px);
}

.cell-index {
    display: block;
    font-family: var(--font-mono);
    font-size: 0.65rem;
    font-weight: 500;
    letter-spacing: 0.02em;
    color: var(--ink-quaternary);
    position: absolute;
    bottom: -20px;
    left: 50%;
    transform: translateX(-50%);
}

/* ── Array Pointers ────────────────────────────────────── */

.array-pointer {
    position: absolute;
    display: flex;
    flex-direction: column;
    align-items: center;
    transform: translateX(-50%);
    pointer-events: none;
    z-index: 5;
    gap: 2px;
    transition: left 350ms var(--ease), top 350ms var(--ease), opacity 300ms var(--ease);
}

.ptr-label {
    font-family: var(--font-mono);
    font-size: 0.72rem;
    font-weight: 600;
    color: var(--ink);
    white-space: nowrap;
    letter-spacing: 0.02em;
}

.ptr-arrow {
    font-size: 0.65rem;
    color: var(--ink);
    line-height: 1;
}

/* ── Hash Map Display ──────────────────────────────────── */

.hash-display {
    margin-top: 24px;
    padding: 24px;
    border: 1px solid var(--ink);
    border-radius: var(--radius-md);
}

.hash-display-title {
    font-family: var(--font-mono);
    font-size: 0.72rem;
    font-weight: 600;
    color: var(--ink);
    margin-bottom: 16px;
    letter-spacing: 0.06em;
    text-transform: uppercase;
}

.hash-entries {
    display: flex;
    flex-wrap: wrap;
    gap: 8px;
    min-height: 36px;
}

.hash-entry {
    display: flex;
    align-items: center;
    gap: 4px;
    font-family: var(--font-mono);
    font-size: 0.82rem;
    padding: 6px 14px;
    border: 1px solid var(--ink);
    border-radius: 980px;
    transition: background 200ms var(--ease), color 200ms var(--ease);
}

.hash-key { font-weight: 600; color: var(--ink); }
.hash-sep { color: var(--ink-tertiary); }
.hash-val { color: var(--ink-tertiary); }

.hash-entry.hash-found {
    background: var(--ink);
}

.hash-entry.hash-found .hash-key,
.hash-entry.hash-found .hash-val,
.hash-entry.hash-found .hash-sep {
    color: var(--white);
}

.hash-entry.hash-current {
    border-width: 2px;
}

.hash-empty {
    font-family: var(--font-serif);
    font-size: 0.92rem;
    color: var(--ink-quaternary);
    font-style: italic;
}

/* ── Timeline / Slider ──────────────────────────────────── */

.timeline {
    margin-bottom: 40px;
}

.timeline-labels {
    display: flex;
    justify-content: space-between;
    gap: 16px;
    margin-bottom: 12px;
    font-family: var(--font-sans);
    font-size: 0.84rem;
    color: var(--ink-tertiary);
}

input[type="range"] {
    -webkit-appearance: none;
    appearance: none;
    width: 100%;
    height: 2px;
    background: rgba(0, 0, 0, 0.08);
    border-radius: 1px;
    outline: none;
    touch-action: manipulation;
    -webkit-tap-highlight-color: transparent;
}

input[type="range"]::-webkit-slider-thumb {
    -webkit-appearance: none;
    width: 14px;
    height: 14px;
    background: var(--ink);
    border-radius: 50%;
    border: none;
    cursor: pointer;
}

/* ── Info Grid ──────────────────────────────────────────── */

.info-grid {
    display: grid;
    gap: 0;
    margin-bottom: 40px;
}

.status-bar {
    display: flex;
    background: transparent;
    overflow: hidden;
}

.status-item {
    flex: 1;
    padding: 18px 0;
}

.status-item + .status-item {
    border-left: 0.5px solid rgba(0, 0, 0, 0.08);
}

.status-item small {
    display: block;
    margin-bottom: 4px;
    font-family: var(--font-sans);
    font-size: 0.66rem;
    font-weight: 600;
    letter-spacing: 0.08em;
    text-transform: uppercase;
    color: var(--ink-quaternary);
}

.status-value {
    display: flex;
    align-items: center;
    gap: 8px;
    font-family: var(--font-mono);
    font-size: 0.95rem;
    font-weight: 600;
    color: var(--ink);
}

.values-bar {
    display: flex;
    background: transparent;
    overflow: hidden;
}

.values-bar .val-cell {
    flex: 1;
    padding: 18px 0;
}

.values-bar .val-cell + .val-cell {
    border-left: 0.5px solid rgba(0, 0, 0, 0.08);
}

.values-bar .val-cell small {
    display: block;
    margin-bottom: 4px;
    font-family: var(--font-sans);
    font-size: 0.66rem;
    font-weight: 600;
    letter-spacing: 0.08em;
    text-transform: uppercase;
    color: var(--ink-quaternary);
}

.values-bar .val-cell strong {
    font-family: var(--font-mono);
    font-size: 1.1rem;
    font-weight: 600;
    color: var(--ink);
}

.val-cell.accent-solid  { border-top: 1.5px solid var(--ink); }
.val-cell.accent-double { border-top: 1.5px double var(--ink); }
.val-cell.accent-dashed { border-top: 1.5px dashed var(--ink); }
.val-cell.accent-dotted { border-top: 1.5px dotted var(--ink); }

/* ── Explanation Note ───────────────────────────────────── */

.note {
    padding: 0 0 0 22px;
    margin-bottom: 40px;
    border-left: 2px solid var(--ink);
    background: transparent;
    color: var(--ink-secondary);
    font-size: 1rem;
    line-height: 1.7;
}

/* ── Order Strip ────────────────────────────────────────── */

.order-section h3 {
    font-size: 1rem;
    margin-bottom: 16px;
    letter-spacing: -0.02em;
}

.order-strip {
    display: flex;
    flex-wrap: wrap;
    gap: 4px 14px;
}

.token {
    display: inline-flex;
    align-items: center;
    padding: 6px 0;
    font-family: var(--font-mono);
    font-size: 0.84rem;
    color: var(--ink);
    transition: color 200ms var(--ease), opacity 200ms var(--ease);
}

.token.current {
    font-weight: 700;
    text-decoration: underline;
    text-underline-offset: 4px;
    text-decoration-thickness: 1.5px;
}

.token.future {
    color: var(--fill-tertiary);
}

/* ── Guard / Edge-Case Cards ────────────────────────────── */

.guard-cards {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 48px;
    margin-top: 48px;
}

.guard-card {
    padding: 0;
    border-radius: 0;
    background: transparent;
}

.guard-card h3 { margin-bottom: 18px; }
.guard-card p  { font-size: 1.05rem; line-height: 1.75; }
.guard-card p + p { margin-top: 18px; }

.guard-hint {
    color: var(--ink-quaternary);
    font-family: var(--font-sans);
    font-size: 0.88rem !important;
}

.guard-diagram {
    margin: 22px 0 14px;
    padding: 16px 0 16px 22px;
    border-left: 2px solid var(--ink);
    border-radius: 0;
    background: transparent;
    font-family: var(--font-mono);
    font-size: 0.82rem;
    line-height: 1.7;
    color: var(--ink-secondary);
    white-space: pre;
    overflow-x: auto;
}

/* ── Guard Visuals (row & column diagrams) ──────────────── */

.guard-visual {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 0;
    margin: 36px 0 28px;
    padding: 40px 0;
}

.guard-cells-row {
    display: flex;
    gap: 2px;
}

.guard-cell {
    width: 64px;
    height: 64px;
    display: grid;
    place-items: center;
    border: 1.5px solid var(--ink);
    border-radius: 12px;
    font-family: var(--font-mono);
    font-size: 1.05rem;
    font-weight: 600;
    color: var(--ink);
}

.guard-sweep {
    display: flex;
    align-items: center;
    gap: 10px;
    padding: 10px 0;
    font-family: var(--font-sans);
    font-size: 0.82rem;
    font-weight: 500;
    letter-spacing: 0.02em;
}

.guard-sweep-label {
    font-family: var(--font-mono);
    font-weight: 600;
    color: var(--ink);
}

.guard-sweep-arrow {
    font-size: 1.1rem;
    color: var(--ink);
}

.guard-sweep-valid {
    position: relative;
    margin-bottom: 18px;
    padding-bottom: 12px;
    color: var(--ink);
}

.guard-sweep-valid::after {
    content: '';
    position: absolute;
    bottom: 0;
    left: 50%;
    transform: translateX(-50%);
    width: 32px;
    height: 3px;
    background: var(--ink);
}

.guard-sweep-blocked {
    position: relative;
    margin-top: 18px;
    padding-top: 12px;
    color: var(--ink-quaternary);
}

.guard-sweep-blocked::before {
    content: '';
    position: absolute;
    top: 0;
    left: 50%;
    transform: translateX(-50%);
    width: 32px;
    height: 2px;
    background: repeating-linear-gradient(90deg, var(--ink-quaternary) 0 6px, transparent 6px 10px);
}

.guard-sweep-blocked .guard-sweep-label,
.guard-sweep-blocked .guard-sweep-arrow {
    color: var(--ink-quaternary);
    text-decoration: line-through;
    text-decoration-thickness: 1px;
}

.guard-blocked-badge {
    font-family: var(--font-sans);
    font-size: 0.72rem;
    font-weight: 500;
    letter-spacing: 0.06em;
    text-transform: uppercase;
    color: var(--ink-quaternary);
    border: 1px solid var(--ink-quaternary);
    border-radius: 980px;
    padding: 3px 10px;
    margin-left: 6px;
}

/* Column guard visual */

.guard-visual-col {
    flex-direction: row;
    align-items: center;
    gap: 0;
}

.guard-cells-col {
    display: flex;
    flex-direction: column;
    gap: 2px;
}

.guard-sweep-col {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 8px;
    padding: 0 10px;
    font-family: var(--font-sans);
    font-size: 0.82rem;
    font-weight: 500;
    letter-spacing: 0.02em;
}

.guard-sweep-col .guard-sweep-label {
    font-family: var(--font-mono);
    font-weight: 600;
    color: var(--ink);
}

.guard-sweep-col .guard-sweep-arrow {
    font-size: 1.1rem;
    color: var(--ink);
}

.guard-sweep-valid-col {
    position: relative;
    margin-right: 18px;
    padding-right: 16px;
    color: var(--ink);
}

.guard-sweep-valid-col::after {
    content: '';
    position: absolute;
    right: 0;
    top: 50%;
    transform: translateY(-50%);
    width: 5px;
    height: 28px;
    background: linear-gradient(90deg, var(--ink) 0 1px, transparent 1px 4px, var(--ink) 4px 5px);
}

.guard-sweep-blocked-col {
    position: relative;
    margin-left: 18px;
    padding-left: 16px;
    color: var(--ink-quaternary);
}

.guard-sweep-blocked-col::before {
    content: '';
    position: absolute;
    left: 0;
    top: 50%;
    transform: translateY(-50%);
    width: 4px;
    height: 28px;
    background: radial-gradient(circle closest-side, var(--ink-quaternary) 100%, transparent 100%);
    background-size: 4px 8px;
}

.guard-sweep-blocked-col .guard-sweep-label,
.guard-sweep-blocked-col .guard-sweep-arrow {
    color: var(--ink-quaternary);
    text-decoration: line-through;
    text-decoration-thickness: 1px;
}

/* ── Responsive ─────────────────────────────────────────── */

@media (max-width: 960px) {
    .page { padding: 48px 24px 72px; }
    .viz-section { padding-left: 24px; padding-right: 24px; }
    body > #interactiveMount { padding-left: 24px; padding-right: 24px; }
    .viz-section:first-of-type { padding-top: 48px; }

    .hero {
        grid-template-columns: 1fr;
        gap: 40px;
    }

    .concept-svg { margin: 0 auto; }
    .concept-cards { grid-template-columns: 1fr 1fr; }

    .cell {
        width: 68px;
        height: 68px;
        border-radius: 14px;
    }

    .viz-container { padding: 64px; }

    .status-bar, .values-bar { flex-wrap: wrap; }

    .status-item, .values-bar .val-cell { flex-basis: calc(50% - 0.25px); }

    .status-item:nth-child(2)          { border-left: none; }
    .status-item:nth-child(3),
    .status-item:nth-child(4)          { border-top: 0.5px solid rgba(0, 0, 0, 0.06); }
    .status-item:nth-child(3)          { border-left: none; }

    .values-bar .val-cell:nth-child(2)          { border-left: none; }
    .values-bar .val-cell:nth-child(3),
    .values-bar .val-cell:nth-child(4)          { border-top: 0.5px solid rgba(0, 0, 0, 0.06); }
    .values-bar .val-cell:nth-child(3)          { border-left: none; }
}

@media (max-width: 640px) {
    .page { padding: 36px 16px 56px; }
    .divider { margin: 56px 0; }
    .viz-section { padding-left: 16px; padding-right: 16px; }
    body > #interactiveMount { padding-left: 16px; padding-right: 16px; }
    .viz-section:first-of-type { padding-top: 36px; }
    .viz-section:last-of-type { padding-bottom: 56px; }
    .viz-section + .viz-section { margin-top: 48px; }
    .viz-code-block { padding: 20px 16px; }

    .interactive { padding: 0; }

    .toolbar {
        flex-direction: column;
        align-items: stretch;
    }

    select { min-width: 0; width: 100%; }
    .transport { justify-content: center; }

    .concept-cards,
    .guard-cards { grid-template-columns: 1fr; }

    .viz-container {
        padding: 48px 20px;
    }

    /* Larger touch targets on mobile */
    button {
        padding: 12px 20px;
        min-height: 44px;
        font-size: 16px;
    }

    select {
        padding: 12px 38px 12px 14px;
        min-height: 44px;
        font-size: 16px;
    }

    input[type="range"] { height: 4px; }
    input[type="range"]::-webkit-slider-thumb { width: 24px; height: 24px; }

    .boundary-label { font-size: 0.68rem; }

    .cell {
        width: 56px;
        height: 56px;
        border-radius: 12px;
    }

    .viz-grid { gap: 14px; }

    .viz-array .cell {
        width: var(--array-cell-size, 56px);
        height: var(--array-cell-size, 56px);
    }

    .viz-array { gap: 6px; }

    .cell-index { font-size: 0.58rem; bottom: -16px; }

    .ptr-label { font-size: 0.62rem; }
    .ptr-arrow { font-size: 0.56rem; }

    .hash-display { padding: 16px; }
    .hash-entry { font-size: 0.72rem; padding: 4px 10px; }

    .cell-value { font-size: 0.92rem; }

    .visit-badge {
        min-width: 16px;
        height: 16px;
        font-size: 0.56rem;
        top: 4px;
        left: 4px;
    }

    .viz-array .visit-badge {
        top: -6px;
        left: -4px;
        min-width: 15px;
        height: 15px;
        font-size: 0.5rem;
    }

    .status-bar, .values-bar { flex-direction: column; }

    .status-item + .status-item,
    .values-bar .val-cell + .val-cell {
        border-left: none;
        border-top: 0.5px solid rgba(0, 0, 0, 0.06);
    }

    .status-item:nth-child(3),
    .status-item:nth-child(4),
    .values-bar .val-cell:nth-child(3),
    .values-bar .val-cell:nth-child(4) {
        border-left: none;
    }
}

/* ── Footer ─────────────────────────────────────────────── */

.page-footer {
    margin-top: 80px;
    padding-top: 20px;
    border-top: 0.5px solid rgba(0, 0, 0, 0.08);
    text-align: center;
}

.page-footer p {
    font-family: var(--font-sf);
    font-size: 0.7rem;
    color: var(--ink-secondary);
    letter-spacing: 0.02em;
    line-height: 1.6;
}

.page-footer a {
    color: var(--ink-secondary);
    text-decoration: none;
    border-bottom: 0.5px solid rgba(0, 0, 0, 0.12);
    transition: border-color 200ms ease;
}

.page-footer a:hover {
    border-color: var(--ink-tertiary);
}