/* ==========================================================================
   Chunkorz – Dark Theme Stylesheet
   ========================================================================== */

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

:root {
    --bg-primary: #0f1117;
    --bg-secondary: #1a1d27;
    --bg-card: #242836;
    --bg-input: #1e2230;
    --bg-hover: #2e3348;

    --accent: #7c6aef;
    --accent-hover: #9585f5;
    --accent-glow: rgba(124, 106, 239, 0.25);

    --success: #34d399;
    --success-bg: rgba(52, 211, 153, 0.1);

    --error: #f87171;
    --error-bg: rgba(248, 113, 113, 0.1);

    --text-primary: #e8eaf0;
    --text-secondary: #9ca3b4;
    --text-muted: #5f6678;

    --border: #2e3348;
    --border-focus: #7c6aef;

    --radius-sm: 8px;
    --radius-md: 12px;
    --radius-lg: 16px;

    --shadow-sm: 0 1px 3px rgba(0, 0, 0, 0.3);
    --shadow-md: 0 4px 12px rgba(0, 0, 0, 0.4);
    --shadow-glow: 0 0 20px var(--accent-glow);

    --font-main:
        "Inter", -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Oxygen,
        Ubuntu, Cantarell, "Helvetica Neue", sans-serif;
    --font-mono: "JetBrains Mono", "Fira Code", "SF Mono", Consolas, monospace;

    --transition: 0.2s ease;
}

html {
    font-size: 16px;
    -webkit-text-size-adjust: 100%;
}

body {
    font-family: var(--font-main);
    background-color: var(--bg-primary);
    color: var(--text-primary);
    line-height: 1.6;
    min-height: 100dvh;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}

.sr-only {
    position: absolute;
    width: 1px;
    height: 1px;
    padding: 0;
    margin: -1px;
    overflow: hidden;
    clip: rect(0, 0, 0, 0);
    white-space: nowrap;
    border: 0;
}

/* ---------- Layout ---------- */

.container {
    width: 100%;
    max-width: 560px;
    margin: 0 auto;
    padding: 24px 20px 40px;
    display: flex;
    flex-direction: column;
    gap: 24px;
    min-height: 100dvh;
}

header {
    text-align: center;
}

.logo-svg {
    display: block;
    width: 100%;
    max-width: 420px;
    height: auto;
    margin: 0 auto;
}

.subtitle {
    margin-top: 6px;
    font-size: 0.95rem;
    color: var(--text-secondary);
}

.subtitle .math {
    font-weight: 600;
    color: var(--accent-hover);
    letter-spacing: 0.08em;
}

main {
    display: flex;
    flex-direction: column;
    gap: 20px;
}

footer {
    text-align: center;
    padding-top: 8px;
}

footer p {
    font-size: 0.78rem;
    color: var(--text-muted);
    letter-spacing: 0.02em;
}

/* ---------- Form & Input ---------- */

#solve-form {
    display: flex;
    flex-direction: column;
    gap: 8px;
}

.input-group {
    display: flex;
    gap: 8px;
    align-items: stretch;
}

#submit-btn {
    padding: 14px 22px;
    font-size: 1rem;
    font-weight: 700;
    color: #fff;
    background: var(--accent);
    border: none;
    border-radius: var(--radius-md);
    cursor: pointer;
    white-space: nowrap;
    transition:
        background var(--transition),
        transform var(--transition),
        box-shadow var(--transition),
        opacity var(--transition);
}

#submit-btn:hover:not(:disabled) {
    background: var(--accent-hover);
    box-shadow: var(--shadow-glow);
    transform: translateY(-1px);
}

#submit-btn:active:not(:disabled) {
    transform: translateY(0);
}

#submit-btn:disabled {
    opacity: 0.4;
    cursor: not-allowed;
}

#submit-btn.loading {
    position: relative;
    color: transparent;
}

#submit-btn.loading::after {
    content: "";
    position: absolute;
    top: 50%;
    left: 50%;
    width: 18px;
    height: 18px;
    margin: -9px 0 0 -9px;
    border: 2px solid rgba(255, 255, 255, 0.3);
    border-top-color: #fff;
    border-radius: 50%;
    animation: spin 0.6s linear infinite;
}

@keyframes spin {
    to { transform: rotate(360deg); }
}

/* ---------- Feedback ---------- */

.feedback {
    min-height: 0;
    overflow: hidden;
    text-align: center;
    font-size: 0.95rem;
    font-weight: 600;
    border-radius: var(--radius-md);
    transition: all 0.3s ease;
}

.feedback:empty {
    padding: 0;
    margin: 0;
}

.feedback.success {
    padding: 14px 18px;
    color: var(--success);
    background: var(--success-bg);
    border: 1px solid rgba(52, 211, 153, 0.25);
    animation: feedback-appear 0.3s ease;
}

.feedback.error {
    padding: 14px 18px;
    color: var(--error);
    background: var(--error-bg);
    border: 1px solid rgba(248, 113, 113, 0.25);
    animation: feedback-appear 0.3s ease;
}

@keyframes feedback-appear {
    from { opacity: 0; transform: translateY(-6px); }
    to   { opacity: 1; transform: translateY(0); }
}

/* ---------- Solutions Count ---------- */

.solutions-count {
    text-align: center;
    font-size: 0.88rem;
    color: var(--text-muted);
}

.solutions-count strong {
    color: var(--accent-hover);
    font-weight: 700;
}

/* ---------- Skeleton ---------- */

.skeleton {
    background: linear-gradient(
        90deg,
        var(--bg-card) 25%,
        var(--bg-hover) 50%,
        var(--bg-card) 75%
    );
    background-size: 200% 100%;
    animation: skeleton-pulse 1.5s ease-in-out infinite;
    color: transparent !important;
    border-radius: var(--radius-sm);
}

@keyframes skeleton-pulse {
    0%   { background-position: 200% 0; }
    100% { background-position: -200% 0; }
}

/* ---------- Yesterday Section ---------- */

.yesterday-section {
    border-top: 1px solid var(--border);
    padding-top: 8px;
}

.yesterday-toggle {
    width: 100%;
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: 14px 4px;
    font-size: 0.95rem;
    font-weight: 600;
    color: var(--text-secondary);
    background: transparent;
    border: none;
    cursor: pointer;
    transition: color var(--transition);
}

.yesterday-toggle:hover { color: var(--text-primary); }

.yesterday-toggle-icon {
    font-size: 0.7rem;
    transition: transform 0.3s ease;
}

.yesterday-toggle.open .yesterday-toggle-icon {
    transform: rotate(180deg);
}

.yesterday-content {
    display: none;
    flex-direction: column;
    gap: 12px;
    padding-bottom: 8px;
}

.yesterday-toggle.open + .yesterday-content {
    display: flex;
    animation: slide-down 0.3s ease;
}

@keyframes slide-down {
    from { opacity: 0; transform: translateY(-8px); }
    to   { opacity: 1; transform: translateY(0); }
}

.yesterday-header {
    font-size: 0.85rem;
    color: var(--text-muted);
    text-align: center;
    letter-spacing: 0.02em;
}

.yesterday-list {
    display: flex;
    flex-direction: column;
    gap: 6px;
}

.loading-text {
    text-align: center;
    color: var(--text-muted);
    font-size: 0.88rem;
    padding: 12px 0;
}

.no-solutions {
    text-align: center;
    color: var(--text-muted);
    font-size: 0.88rem;
    padding: 16px 0;
    font-style: italic;
}

.solution-item {
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: 10px 14px;
    background: var(--bg-secondary);
    border: 1px solid var(--border);
    border-radius: var(--radius-sm);
    gap: 12px;
}

.solution-player {
    font-size: 0.9rem;
    font-weight: 600;
    color: var(--text-primary);
}

.solution-meta {
    font-size: 0.8rem;
    color: var(--text-muted);
    white-space: nowrap;
    flex-shrink: 0;
}

.load-more-btn {
    width: 100%;
    padding: 12px;
    margin-top: 4px;
    font-size: 0.88rem;
    font-weight: 600;
    color: var(--accent-hover);
    background: var(--bg-secondary);
    border: 1px dashed var(--border);
    border-radius: var(--radius-sm);
    cursor: pointer;
    transition:
        background var(--transition),
        border-color var(--transition),
        color var(--transition);
}

.load-more-btn:hover {
    background: var(--bg-hover);
    border-color: var(--accent);
    color: var(--text-primary);
}

.load-more-btn:active { transform: scale(0.98); }

/* ---------- Puzzle Meta ---------- */

.puzzle-meta {
    display: flex;
    justify-content: center;
    align-items: center;
    gap: 10px;
    flex-wrap: wrap;
}

.puzzle-date {
    font-size: 0.85rem;
    color: var(--text-muted);
    font-weight: 500;
    letter-spacing: 0.04em;
    text-transform: uppercase;
}

.difficulty {
    font-size: 0.75rem;
    font-weight: 700;
    letter-spacing: 0.06em;
    text-transform: uppercase;
    color: var(--accent-hover);
    background: var(--accent-glow);
    padding: 3px 10px;
    border-radius: 999px;
}

.difficulty:empty { display: none; }

/* ---------- How to Play ---------- */

.help-section {
    border-top: none;
    padding-top: 0;
    background: var(--bg-secondary);
    border: 1px solid var(--border);
    border-radius: var(--radius-md);
}

.help-section .yesterday-toggle { padding: 12px 16px; font-size: 0.88rem; }

.help-list {
    list-style: none;
    display: flex;
    flex-direction: column;
    gap: 8px;
    padding: 0 16px 14px;
    font-size: 0.86rem;
    color: var(--text-secondary);
}

.help-list li::before {
    content: "›";
    color: var(--accent-hover);
    font-weight: 700;
    margin-right: 8px;
}

.help-list strong { color: var(--text-primary); }

.chip {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    width: 16px;
    height: 16px;
    border-radius: 4px;
    font-size: 0.7rem;
    vertical-align: -2px;
    color: #34d399;
    background: #3a4062;
}

.chip-fragile { background: #f0a04b; }

/* ---------- Game Controls ---------- */

.game-controls {
    display: flex;
    align-items: stretch;
    gap: 8px;
}

.start-btn {
    flex: 1;
    padding: 12px 18px;
    font-size: 1rem;
    font-weight: 700;
    color: #fff;
    background: var(--accent);
    border: none;
    border-radius: var(--radius-md);
    cursor: pointer;
    white-space: nowrap;
    user-select: none;
    -webkit-tap-highlight-color: transparent;
    transition:
        background var(--transition),
        transform var(--transition),
        box-shadow var(--transition),
        opacity var(--transition);
}

.start-btn:hover:not(:disabled) {
    background: var(--accent-hover);
    box-shadow: var(--shadow-glow);
    transform: translateY(-1px);
}

.start-btn:disabled { opacity: 0.4; cursor: not-allowed; }

.stat {
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    min-width: 78px;
    padding: 6px 12px;
    background: var(--bg-secondary);
    border: 1px solid var(--border);
    border-radius: var(--radius-md);
    user-select: none;
}

.stat-label {
    font-size: 0.62rem;
    font-weight: 700;
    letter-spacing: 0.1em;
    text-transform: uppercase;
    color: var(--text-muted);
}

.stat-value {
    font-family: var(--font-mono);
    font-size: 1.05rem;
    font-weight: 700;
    color: var(--accent-hover);
    font-variant-numeric: tabular-nums;
}

.icon-btn {
    width: 48px;
    font-size: 1.3rem;
    font-weight: 700;
    color: var(--text-secondary);
    background: var(--bg-secondary);
    border: 1px solid var(--border);
    border-radius: var(--radius-md);
    cursor: pointer;
    transition: color var(--transition), border-color var(--transition);
}

.icon-btn:hover:not(:disabled) { color: var(--text-primary); border-color: var(--accent); }
.icon-btn:disabled { opacity: 0.35; cursor: not-allowed; }

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

.puzzle-board {
    position: relative;
    width: 100%;
    aspect-ratio: 4 / 3;
    background: radial-gradient(ellipse at 50% 35%, var(--bg-hover) 0%, var(--bg-card) 45%, var(--bg-secondary) 100%);
    border: 2px solid var(--border);
    border-radius: var(--radius-lg);
    overflow: hidden;
    box-shadow: var(--shadow-md);
    touch-action: none;
    outline: none;
    transition: border-color var(--transition), box-shadow var(--transition);
}

.puzzle-board:focus-visible { border-color: var(--border-focus); }

.puzzle-board canvas {
    display: block;
    width: 100%;
    height: 100%;
}

.puzzle-board.celebrate { animation: celebrate-pulse 0.9s ease; }

@keyframes celebrate-pulse {
    0%   { border-color: var(--border); box-shadow: var(--shadow-md); }
    40%  { border-color: var(--success); box-shadow: 0 0 28px rgba(52, 211, 153, 0.35); }
    100% { border-color: var(--border); box-shadow: var(--shadow-md); }
}

.board-overlay {
    position: absolute;
    inset: 0;
    display: flex;
    align-items: center;
    justify-content: center;
    padding: 20px;
    text-align: center;
    background: rgba(15, 17, 23, 0.55);
    -webkit-backdrop-filter: blur(14px);
    backdrop-filter: blur(14px);
    color: var(--text-secondary);
    font-size: 1rem;
    font-weight: 600;
    transition: opacity 0.35s ease;
}

.board-overlay.hidden { opacity: 0; pointer-events: none; }

/* ---------- D-pad ---------- */

.dpad {
    display: grid;
    grid-template-columns: repeat(3, 56px);
    grid-template-rows: repeat(3, 44px);
    gap: 6px;
    justify-content: center;
    user-select: none;
    -webkit-user-select: none;
}

.dpad button {
    font-size: 1.05rem;
    color: var(--text-secondary);
    background: var(--bg-secondary);
    border: 1px solid var(--border);
    border-radius: var(--radius-sm);
    cursor: pointer;
    touch-action: manipulation;
    -webkit-tap-highlight-color: transparent;
    transition: background var(--transition), color var(--transition), border-color var(--transition);
}

.dpad button:active,
.dpad button.pressed { background: var(--accent); color: #fff; border-color: var(--accent); }

.dpad [data-dir="U"] { grid-area: 1 / 2; }
.dpad [data-dir="L"] { grid-area: 2 / 1; }
.dpad [data-dir="R"] { grid-area: 2 / 3; }
.dpad [data-dir="D"] { grid-area: 3 / 2; }

/* Keyboard users on desktop don't need the pad. */
@media (hover: hover) and (pointer: fine) {
    .dpad { display: none; }
}

/* ---------- Result Panel ---------- */

.result-panel {
    display: flex;
    flex-direction: column;
    gap: 12px;
    padding: 16px;
    background: var(--bg-secondary);
    border: 1px solid rgba(52, 211, 153, 0.3);
    border-radius: var(--radius-md);
    animation: feedback-appear 0.3s ease;
}

.result-panel[hidden],
#solve-form[hidden] { display: none; }

.result-panel h2 {
    text-align: center;
    font-size: 1.1rem;
    color: var(--success);
}

.result-stats {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 8px;
}

.result-stats .stat { min-width: 0; background: var(--bg-card); }

#player-name {
    flex: 1;
    min-width: 0;
    padding: 12px 14px;
    font-size: 0.95rem;
    color: var(--text-primary);
    background: var(--bg-input);
    border: 2px solid var(--border);
    border-radius: var(--radius-md);
    outline: none;
    transition: border-color var(--transition), box-shadow var(--transition);
}

#player-name:focus { border-color: var(--border-focus); box-shadow: var(--shadow-glow); }
#player-name::placeholder { color: var(--text-muted); }

.share-btn {
    align-self: center;
    padding: 6px 14px;
    font-size: 0.82rem;
    font-weight: 600;
    color: var(--accent-hover);
    background: transparent;
    border: 1px dashed var(--border);
    border-radius: var(--radius-sm);
    cursor: pointer;
}

.share-btn:hover { border-color: var(--accent); color: var(--text-primary); }

/* ---------- Yesterday extras ---------- */

.yesterday-map {
    display: flex;
    justify-content: center;
}

.yesterday-map svg {
    width: 100%;
    max-width: 360px;
    height: auto;
}

.yesterday-solution {
    text-align: center;
    font-size: 0.82rem;
    color: var(--text-secondary);
}

.yesterday-solution .moves-seq {
    display: block;
    margin-top: 4px;
    font-family: var(--font-mono);
    font-size: 0.95rem;
    letter-spacing: 0.08em;
    color: var(--accent-hover);
    word-break: break-all;
}

.results-table {
    width: 100%;
    border-collapse: separate;
    border-spacing: 0 6px;
    font-size: 0.88rem;
}

.results-table th {
    font-size: 0.68rem;
    font-weight: 700;
    letter-spacing: 0.08em;
    text-transform: uppercase;
    color: var(--text-muted);
    text-align: left;
    padding: 0 12px;
}

.results-table td {
    padding: 9px 12px;
    background: var(--bg-secondary);
    border-top: 1px solid var(--border);
    border-bottom: 1px solid var(--border);
}

.results-table td:first-child {
    border-left: 1px solid var(--border);
    border-radius: var(--radius-sm) 0 0 var(--radius-sm);
    color: var(--text-muted);
    width: 2.5em;
}

.results-table td:last-child {
    border-right: 1px solid var(--border);
    border-radius: 0 var(--radius-sm) var(--radius-sm) 0;
}

.results-table .num {
    font-family: var(--font-mono);
    text-align: right;
    white-space: nowrap;
    font-variant-numeric: tabular-nums;
}

.results-table th.num { text-align: right; }
.results-table .player { font-weight: 600; word-break: break-word; }
.results-table tr.gold td:first-child { color: #facc15; }
.results-table .under-par { color: var(--success); }

/* ---------- Responsive ---------- */

@media (max-width: 500px) {
    .puzzle-board { aspect-ratio: 1 / 1; }
    .stat { min-width: 66px; padding: 6px 8px; }
    .start-btn { padding: 12px; min-width: 0; }
    .icon-btn { width: 44px; }
}

@media (max-width: 380px) {
    .container { padding: 16px 14px 32px; gap: 18px; }
    .stat { min-width: 58px; }
    .stat-value { font-size: 0.95rem; }
}

@media (min-width: 600px) {
    .container { padding: 40px 24px 60px; gap: 28px; }
}

@media (prefers-reduced-motion: reduce) {
    *, *::before, *::after {
        animation-duration: 0.01ms !important;
        animation-iteration-count: 1 !important;
        transition-duration: 0.01ms !important;
    }
}