/* Bytecode puzzles. Builds on the blog's theme variables (--paper, --surface, --ink, ...),
   so light and dark mode come for free. Tiles keep their pastel colours in both themes,
   like the peach buttons do. */

.bp {
    --hand: 255px 15px 225px 15px / 15px 225px 15px 255px;
    --hand-small: 255px 12px 225px 12px / 12px 225px 12px 255px;
    --tile-text: #0F3460;
    --tile-const: #FCE3C5;
    --tile-local: #8BBCCC;
    --tile-math: #D9C2E3;
    --tile-shuffle: #B9E4C9;
    --good: #2E7D5B;
    --bad: #B3364A;
    /* Width and side gutters come from the blog's .container; top matches .section-heading. */
    padding-top: 32px;
    padding-bottom: 200px; /* room so the result card never covers the end of the page */
    color: var(--text);
}

:root[data-theme="dark"] .bp { --good: #7FD3A8; --bad: #FF8FA0; }
@media (prefers-color-scheme: dark) {
    :root:not([data-theme="light"]) .bp { --good: #7FD3A8; --bad: #FF8FA0; }
}

.bp-visually-hidden {
    position: absolute;
    width: 1px;
    height: 1px;
    overflow: hidden;
    clip: rect(0 0 0 0);
}

/* ---------- Top: title and level picker ---------- */
/* The title uses the blog's own .hand-heading + squiggle, like other pages. */

.bp-top {
    display: flex;
    flex-wrap: wrap;
    align-items: center;
    justify-content: space-between;
    gap: 12px 24px;
    margin-bottom: 28px;
}

.bp-level-label {
    margin: 12px 0 0;
    font-family: 'IBM Plex Mono', monospace;
    font-weight: 600;
    font-size: 18px;
    color: var(--text);
}

.bp-levels {
    display: flex;
    flex-wrap: wrap;
    gap: 8px;
}

.bp-level-dot {
    position: relative;
    width: 38px;
    height: 38px;
    font-family: 'IBM Plex Mono', monospace;
    font-weight: 600;
    font-size: 15px;
    color: var(--text);
    background: var(--surface);
    border: 2px solid var(--line);
    border-radius: var(--hand-small);
    cursor: pointer;
    transition: transform 0.15s;
}

.bp-level-dot:hover { transform: translateY(-2px) rotate(-2deg); }

.bp-level-dot.solved {
    color: var(--tile-text);
    background: var(--tile-shuffle);
    border-color: var(--ink);
}

.bp-level-dot.solved::after {
    content: '✓';
    position: absolute;
    top: -9px;
    right: -7px;
    font-size: 13px;
    color: var(--good);
}

.bp-level-dot.current {
    border: 2.5px solid var(--ink);
    box-shadow: 3px 3px 0 var(--shadow);
    transform: rotate(-3deg);
}

/* ---------- Board ---------- */

.bp-board {
    display: grid;
    grid-template-columns: minmax(0, 1fr) minmax(0, 1.15fr) minmax(0, 1.3fr);
    gap: 20px;
    align-items: start;
}

@media (max-width: 900px) {
    .bp-board { grid-template-columns: minmax(0, 1fr) minmax(0, 1fr); }
    .bp-machine-panel { grid-column: 1 / -1; }
}

@media (max-width: 600px) {
    .bp-board { grid-template-columns: minmax(0, 1fr); }
}

.bp-panel {
    min-width: 0;
    padding: 16px;
    background: var(--surface);
    border: 2px solid var(--line);
    border-radius: var(--hand);
}

.bp-panel h2,
.bp-machine h3 {
    margin: 0 0 4px;
    font-family: 'Silkscreen', 'Courier New', monospace;
    font-size: 15px;
    font-weight: 700;
    color: var(--accent);
    letter-spacing: 0.5px;
}

.bp-hint,
.bp-code-header {
    margin: 0 0 12px;
    font-size: 13px;
    color: var(--muted);
}

.bp-code-header { font-family: 'IBM Plex Mono', monospace; }

/* ---------- Tiles ---------- */

.bp-tile {
    position: relative;
    display: inline-flex;
    align-items: center;
    min-height: 40px;
    padding: 0 14px;
    font-family: 'IBM Plex Mono', monospace;
    font-weight: 500;
    font-size: 15px;
    color: var(--tile-text);
    background: var(--tile-math);
    border: 2.5px solid #1A1A1A;
    border-radius: var(--hand-small);
    box-shadow: 3px 3px 0 var(--shadow);
    cursor: grab;
    user-select: none;
    -webkit-user-select: none;
    touch-action: none;
    white-space: nowrap;
    transition: transform 0.12s, opacity 0.15s;
}

.bp-tile-const { background: var(--tile-const); }
.bp-tile-local { background: var(--tile-local); }
.bp-tile-math { background: var(--tile-math); }
.bp-tile-shuffle { background: var(--tile-shuffle); }

.bp-toolbox {
    display: flex;
    flex-wrap: wrap;
    gap: 12px 10px;
}

.bp-source:hover,
.bp-source:focus-visible { transform: translateY(-2px) rotate(-1.5deg); }
.bp-source:focus-visible { outline: 3px solid var(--accent); outline-offset: 3px; }

.bp-source.empty {
    opacity: 0.35;
    cursor: default;
    box-shadow: none;
    transform: none;
}

.bp-source.bp-lifting { transform: scale(0.94); }

.bp-count {
    position: absolute;
    top: -10px;
    right: -9px;
    min-width: 22px;
    padding: 0 5px;
    font-size: 11px;
    font-weight: 600;
    line-height: 20px;
    text-align: center;
    color: #FFFFFF;
    background: #5C2E7E;
    border-radius: 999px;
}

.bp-help {
    min-height: 3em;
    margin: 16px 0 0;
    padding-top: 10px;
    font-size: 14px;
    color: var(--text-soft);
    border-top: 2px dashed var(--line);
}

.bp-help code {
    font-family: 'IBM Plex Mono', monospace;
    font-weight: 600;
    color: var(--accent);
    background: none;
    padding: 0;
}

.bp-ghost {
    position: fixed;
    top: 0;
    left: 0;
    z-index: 1000;
    pointer-events: none;
    box-shadow: 6px 8px 0 var(--shadow);
    transition: none;
}

body.bp-dragging,
body.bp-dragging * { cursor: grabbing !important; }

/* ---------- Program ---------- */

.bp-program {
    min-height: 220px;
    margin: 0 0 16px;
    padding: 10px 8px;
    list-style: none;
    background-color: var(--code-bg);
    background-image: repeating-linear-gradient(transparent 0 47px, var(--grid) 47px 48px);
    border: 2px dashed var(--line);
    border-radius: var(--hand-small);
    transition: border-color 0.15s, background-color 0.15s;
}

.bp-program.drop-target {
    border-color: var(--accent);
    background-color: var(--chip-bg);
}

.bp-empty {
    padding: 70px 0;
    text-align: center;
    font-family: 'IBM Plex Mono', monospace;
    font-size: 14px;
    color: var(--muted);
}

.bp-line {
    display: flex;
    align-items: center;
    gap: 10px;
    min-height: 48px;
    padding: 0 4px;
    border-radius: var(--hand-small);
    transition: background-color 0.2s;
}

.bp-offset {
    width: 2.6em;
    text-align: right;
    font-family: 'IBM Plex Mono', monospace;
    font-size: 13px;
    color: var(--muted);
}

.bp-line.ran .bp-tile { opacity: 0.55; }
.bp-line.next { background: var(--chip-bg); }
.bp-line.next .bp-offset::before { content: '▸ '; color: var(--accent); }
.bp-line.failed { background: color-mix(in srgb, var(--bad) 16%, transparent); }
.bp-line.failed .bp-tile { animation: bp-shake 0.4s; }

.bp-line:has(.bp-lifted) { display: none; }

.bp-remove {
    margin-left: auto;
    width: 32px;
    height: 32px;
    font-size: 20px;
    line-height: 1;
    color: var(--muted);
    background: none;
    border: none;
    border-radius: 50%;
    cursor: pointer;
    opacity: 0.5;
}

.bp-line:hover .bp-remove,
.bp-remove:focus-visible { opacity: 1; }
.bp-remove:hover { color: var(--bad); }

.bp-placeholder {
    height: 40px;
    margin: 4px 4px 4px 3.6em;
    border: 2.5px dashed var(--accent);
    border-radius: var(--hand-small);
    opacity: 0.7;
}

/* Four equal columns, so the buttons stay on one row and line up at any width. */
.bp-controls {
    display: grid;
    grid-template-columns: repeat(4, minmax(0, 1fr));
    gap: 8px;
}

.bp-controls .hand-button {
    justify-content: center;
    min-height: 40px;
    padding: 0 6px;
    font-size: 15px;
    cursor: pointer;
}

.bp-controls .hand-button:disabled {
    opacity: 0.45;
    cursor: default;
    transform: none;
    box-shadow: none;
}

/* Paper-coloured, so it reads as the quiet one next to run/step/reset. */
.bp-controls .bp-clear { background: #F1EEE9; }
.bp-controls .bp-clear:hover { background: #E4DFD6; }

/* ---------- Machine: stack and locals ---------- */

.bp-machines {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 16px;
}

.bp-machine {
    min-width: 0;
    padding: 4px;
}

.bp-goal {
    padding: 4px 4px 4px 16px;
    border-left: 2px dashed var(--line);
}

.bp-stack-label,
.bp-locals-label {
    margin: 10px 0 6px;
    font-size: 12px;
    text-transform: lowercase;
    color: var(--muted);
}

.bp-stack {
    position: relative;
    display: flex;
    flex-direction: column;
    gap: 6px;
    min-height: 50px;
    padding: 8px 8px 10px;
    border: 2.5px solid var(--ink);
    border-top: none;
    border-radius: 0 0 14px 18px / 0 0 10px 14px;
}

.bp-stack.is-empty::after {
    content: 'empty';
    position: absolute;
    bottom: 14px;
    left: 0;
    right: 0;
    text-align: center;
    font-family: 'IBM Plex Mono', monospace;
    font-size: 13px;
    color: var(--muted);
}

.bp-cell {
    display: flex;
    align-items: center;
    justify-content: center;
    min-height: 36px;
    padding: 0 6px;
    font-family: 'IBM Plex Mono', monospace;
    font-weight: 600;
    font-size: 16px;
    color: var(--tile-text);
    background: var(--tile-const);
    border: 2px solid #1A1A1A;
    border-radius: var(--hand-small);
    overflow-wrap: anywhere;
}

.bp-goal .bp-cell { background: var(--tile-shuffle); }

.bp-cell.bp-slot {
    background: none;
    border: 2px dashed var(--line);
}

.bp-stack.is-empty .bp-slot:last-child { visibility: hidden; }

.bp-cell.pushed { animation: bp-drop 0.3s cubic-bezier(.3, 1.6, .5, 1); }

.bp-locals {
    display: flex;
    flex-wrap: wrap;
    gap: 6px;
}

.bp-local {
    display: flex;
    flex-direction: column;
    align-items: center;
    min-width: 48px;
    padding: 4px 8px 6px;
    background: var(--code-bg);
    border: 2px solid var(--line);
    border-radius: var(--hand-small);
}

.bp-local-index {
    font-size: 11px;
    color: var(--muted);
}

.bp-local-value {
    font-family: 'IBM Plex Mono', monospace;
    font-weight: 600;
    font-size: 16px;
}

.bp-local.any .bp-local-value {
    font-weight: 400;
    font-size: 13px;
    color: var(--muted);
}

.bp-local.changed { animation: bp-flash 0.6s; }

/* ---------- Status ---------- */

/* A card pinned to the bottom of the screen, so the result is visible without scrolling. */
.bp-status {
    position: fixed;
    left: 50%;
    bottom: 16px;
    z-index: 900;
    width: min(560px, calc(100% - 32px));
    padding: 16px 44px 16px 20px;
    text-align: center;
    background: var(--surface);
    border: 2.5px solid var(--ink);
    border-radius: var(--hand);
    box-shadow: 4px 5px 0 var(--shadow);
    transform: translateX(-50%);
    animation: bp-slide-up 0.35s cubic-bezier(.3, 1.4, .5, 1);
}

.bp-status:empty { display: none; }

.bp-status > p {
    margin: 0;
    font-family: 'IBM Plex Mono', monospace;
    font-weight: 500;
    overflow-wrap: anywhere;
}

.bp-status.error { border-color: var(--bad); border-style: dashed; }
.bp-status.error > p { color: var(--bad); }
.bp-status.miss > p { color: var(--text-soft); }

.bp-status.win > p {
    font-family: 'Silkscreen', 'Courier New', monospace;
    font-size: 20px;
    color: var(--good);
}

.bp-dismiss {
    position: absolute;
    top: 6px;
    right: 8px;
    width: 32px;
    height: 32px;
    font-size: 20px;
    line-height: 1;
    color: var(--muted);
    background: none;
    border: none;
    border-radius: 50%;
    cursor: pointer;
}

.bp-dismiss:hover { color: var(--text); }

.bp-win-extra p { margin: 6px 0; }
.bp-outro { color: var(--text-soft); font-style: italic; }
.bp-win-extra .hand-button { margin-top: 6px; cursor: pointer; }

.bp-confetti {
    position: absolute;
    top: 30px;
    left: 50%;
    pointer-events: none;
}

.bp-confetti span {
    position: absolute;
    width: 9px;
    height: 14px;
    border: 1.5px solid #1A1A1A;
    border-radius: 2px;
    animation: bp-confetti 1.3s cubic-bezier(.2, .7, .4, 1) forwards;
}

/* ---------- Animations ---------- */

@keyframes bp-drop {
    from { transform: translateY(-14px) scale(0.85); opacity: 0; }
    to { transform: none; opacity: 1; }
}

@keyframes bp-flash {
    0%, 100% { background: var(--code-bg); }
    30% { background: var(--tile-const); color: var(--tile-text); }
}

@keyframes bp-shake {
    0%, 100% { transform: none; }
    25% { transform: translateX(-5px) rotate(-2deg); }
    75% { transform: translateX(5px) rotate(2deg); }
}

@keyframes bp-slide-up {
    from { transform: translate(-50%, 40px); opacity: 0; }
    to { transform: translateX(-50%); opacity: 1; }
}

@keyframes bp-confetti {
    from { transform: translate(0, 0) rotate(0); opacity: 1; }
    to { transform: translate(var(--dx), calc(var(--dy) + 260px)) rotate(var(--rot)); opacity: 0; }
}

@media (prefers-reduced-motion: reduce) {
    .bp *,
    .bp *::before,
    .bp *::after { animation: none !important; transition: none !important; }
}