/* ── Difficulty card selector ──────────────────────────────────────────────── */
.killer-diff-cards {
    display: flex;
    gap: .75rem;
    justify-content: center;
    flex-wrap: wrap;
    margin-bottom: 1.25rem;
}

.killer-diff-card {
    display: flex;
    align-items: center;
    gap: .75rem;
    flex: 1;
    min-width: 160px;
    max-width: 220px;
    padding: .9rem 1.1rem;
    border: 2px solid var(--border);
    border-radius: 14px;
    background: var(--card);
    cursor: pointer;
    transition: border-color .15s, background .15s, transform .12s, box-shadow .15s;
    user-select: none;
    -webkit-user-select: none;
    -webkit-tap-highlight-color: transparent;
    text-align: left;
}
.killer-diff-card:hover {
    border-color: var(--accent);
    background: var(--card-hover);
    transform: translateY(-2px);
    box-shadow: 0 6px 18px var(--accent-glow);
}
.killer-diff-card.active {
    border-color: var(--accent);
    box-shadow: 0 2px 14px var(--accent-glow);
    background: color-mix(in srgb, var(--accent-glow) 60%, var(--card));
}
.kdc-dot {
    width: 10px; height: 10px;
    border-radius: 50%;
    flex-shrink: 0;
}
.kdc-body { flex: 1; min-width: 0; }
.kdc-name {
    font-family: 'Space Grotesk', sans-serif;
    font-weight: 700;
    font-size: 1rem;
    color: var(--fg);
    line-height: 1.2;
}
.kdc-meta {
    font-size: .78rem;
    color: var(--muted);
    margin-top: .2rem;
}
.kdc-play {
    color: var(--muted);
    flex-shrink: 0;
    transition: color .15s;
}
.killer-diff-card:hover .kdc-play,
.killer-diff-card.active .kdc-play { color: var(--accent); }

@media (max-width: 520px) {
    .killer-diff-card { min-width: 130px; padding: .75rem .9rem; }
    .kdc-name { font-size: .9rem; }
}

/* ── Grid hint (matches sudoku-solver.css) ─────────────────────────────────── */
.grid-hint {
    position: absolute; inset: 0;
    display: flex; align-items: center; justify-content: center;
    pointer-events: none; z-index: 5;
    transition: opacity .4s ease;
}
.grid-hint.hidden { opacity: 0; pointer-events: none; }
.grid-hint span {
    font-size: 14px; color: var(--muted); text-align: center;
    line-height: 1.6; padding: 20px;
    background: rgba(255,255,255,.9);
    backdrop-filter: blur(4px); border-radius: 10px;
}

/* ── Killer Sudoku Grid ────────────────────────────────────────────────────── */
.killer-grid {
    width: min(94vw, 540px);
    aspect-ratio: 1;
    display: grid;
    grid-template-columns: repeat(9, 1fr);
    grid-template-rows: repeat(9, 1fr);
    border: 2.5px solid var(--accent);
    border-radius: 12px;
    overflow: hidden;
    box-shadow: 0 2px 20px var(--accent-glow), 0 8px 32px rgba(0,0,0,.06);
    background: var(--border);
    gap: 1px;
    position: relative;
    container-type: inline-size;
}

/* ── Killer cells ─────────────────────────────────────────────────────────── */
.k-cell {
    display: flex;
    align-items: center;
    justify-content: center;
    background: var(--card);
    font-family: 'Space Grotesk', sans-serif;
    font-size: 6cqi;
    font-weight: 600;
    cursor: pointer;
    transition: background .1s, transform .1s;
    user-select: none;
    -webkit-user-select: none;
    position: relative;
    border-right: 1px solid var(--border);
    border-bottom: 1px solid var(--border);
    color: var(--fg);
    -webkit-tap-highlight-color: transparent;
    min-height: 0; min-width: 0; overflow: hidden;
}
.k-cell:hover { background: var(--card-hover); }

/* Box borders */
.k-cell.box-right  { border-right:  2.5px solid var(--accent); }
.k-cell.box-bottom { border-bottom: 2.5px solid var(--accent); }
.k-cell:last-child { border-right: none; }

/* Value states */
.k-cell.user       { color: var(--accent); }
.k-cell.solver-fill{ color: var(--success); }
.k-cell.error-cell { color: var(--error) !important; background: var(--error-bg) !important; }
.k-cell.selected   { background: var(--accent-glow) !important; box-shadow: inset 0 0 0 2px var(--accent); z-index: 2; }
.k-cell.highlighted{ background: rgba(194,65,12,.03); }
.k-cell.same-number{ background: rgba(194,65,12,.07); }
.k-cell.trying     { color: var(--accent-light) !important; background: rgba(194,65,12,.08) !important; transform: scale(1.05); }
.k-cell.backtracking{ background: var(--error-bg) !important; transform: scale(.92); opacity: .6; }
.k-cell.solved-cell { color: var(--success) !important; animation: cellPop .3s cubic-bezier(.34,1.56,.64,1); }

/* ── Cage overlay ─────────────────────────────────────────────────────────── */
.k-cell.cage-tl  { outline: 2px dashed; outline-offset: -3px; }
/* Cage colors (cyclic) */
.k-cell[data-cage="0"]  { --cage-c: rgba(59,130,246,.13); }
.k-cell[data-cage="1"]  { --cage-c: rgba(16,185,129,.13); }
.k-cell[data-cage="2"]  { --cage-c: rgba(245,158,11,.13); }
.k-cell[data-cage="3"]  { --cage-c: rgba(239,68,68,.11); }
.k-cell[data-cage="4"]  { --cage-c: rgba(168,85,247,.12); }
.k-cell[data-cage="5"]  { --cage-c: rgba(20,184,166,.13); }
.k-cell[data-cage="6"]  { --cage-c: rgba(249,115,22,.12); }
.k-cell[data-cage="7"]  { --cage-c: rgba(99,102,241,.12); }
.k-cell[data-cage="8"]  { --cage-c: rgba(34,197,94,.12);  }
.k-cell[data-cage="9"]  { --cage-c: rgba(251,191,36,.13); }
.k-cell[data-cage="10"] { --cage-c: rgba(59,130,246,.13); }
.k-cell[data-cage="11"] { --cage-c: rgba(16,185,129,.13); }
.k-cell[data-cage="12"] { --cage-c: rgba(245,158,11,.13); }
.k-cell[data-cage="13"] { --cage-c: rgba(239,68,68,.11);  }
.k-cell[data-cage="14"] { --cage-c: rgba(168,85,247,.12); }
.k-cell[data-cage="15"] { --cage-c: rgba(20,184,166,.13); }
.k-cell[data-cage="16"] { --cage-c: rgba(249,115,22,.12); }
.k-cell[data-cage="17"] { --cage-c: rgba(99,102,241,.12); }
.k-cell[data-cage="18"] { --cage-c: rgba(34,197,94,.12);  }
.k-cell[data-cage="19"] { --cage-c: rgba(251,191,36,.13); }
.k-cell[data-cage="20"] { --cage-c: rgba(59,130,246,.13); }
.k-cell[data-cage="21"] { --cage-c: rgba(16,185,129,.13); }
.k-cell[data-cage="22"] { --cage-c: rgba(245,158,11,.13); }
.k-cell[data-cage="23"] { --cage-c: rgba(239,68,68,.11);  }
.k-cell[data-cage="24"] { --cage-c: rgba(168,85,247,.12); }
.k-cell[data-cage="25"] { --cage-c: rgba(20,184,166,.13); }
.k-cell[data-cage="26"] { --cage-c: rgba(249,115,22,.12); }
.k-cell[data-cage="27"] { --cage-c: rgba(99,102,241,.12); }
.k-cell[data-cage="28"] { --cage-c: rgba(34,197,94,.12);  }
.k-cell[data-cage="29"] { --cage-c: rgba(251,191,36,.13); }
.k-cell[data-cage="30"] { --cage-c: rgba(59,130,246,.13); }
.k-cell[data-cage="31"] { --cage-c: rgba(16,185,129,.13); }
.k-cell[data-cage="32"] { --cage-c: rgba(245,158,11,.13); }
.k-cell[data-cage="33"] { --cage-c: rgba(239,68,68,.11);  }
.k-cell[data-cage="34"] { --cage-c: rgba(168,85,247,.12); }
.k-cell[data-cage="35"] { --cage-c: rgba(20,184,166,.13); }
.k-cell[data-cage="36"] { --cage-c: rgba(249,115,22,.12); }
.k-cell[data-cage="37"] { --cage-c: rgba(99,102,241,.12); }
.k-cell[data-cage="38"] { --cage-c: rgba(34,197,94,.12);  }
.k-cell[data-cage="39"] { --cage-c: rgba(251,191,36,.13); }

.k-cell[data-cage] { background: var(--cage-c, var(--card)); }
.k-cell[data-cage].selected { background: var(--accent-glow) !important; }
.k-cell[data-cage].highlighted { background: color-mix(in srgb, var(--cage-c, transparent), rgba(194,65,12,.06)); }

/* Cage sum label */
.cage-sum {
    position: absolute;
    top: 2px;
    left: 3px;
    font-size: 1.6cqi;
    font-weight: 700;
    color: var(--fg);
    opacity: .75;
    line-height: 1;
    pointer-events: none;
    z-index: 3;
}

/* Cage dashed border segments — drawn by JS via border classes */
.k-cell.cage-border-top    { border-top:    1.5px dashed var(--fg); }
.k-cell.cage-border-right  { border-right:  1.5px dashed var(--fg) !important; }
.k-cell.cage-border-bottom { border-bottom: 1.5px dashed var(--fg) !important; }
.k-cell.cage-border-left   { border-left:   1.5px dashed var(--fg); }

@keyframes cellPop {
    0%  { transform: scale(1); }
    50% { transform: scale(1.2); }
    100%{ transform: scale(1); }
}

@media (max-width: 480px) {
    .killer-grid { width: min(96vw, 420px); }
}

/* Custom puzzle editor */
.editor-toolbar{display:flex;gap:.5rem;flex-wrap:wrap;justify-content:center;padding:.75rem;margin:.75rem auto;border:1.5px dashed var(--border);border-radius:10px;max-width:600px;}
.k-cell.edit-uncaged{background:var(--card);color:var(--muted);}
.k-cell.edit-selected{background:var(--accent)!important;color:#fff!important;outline:2px solid var(--accent);}