/**
 * Nonograms/Picross - Modern Puzzle Game Design
 * Design system focused on clarity, hierarchy, and playability
 */

:root {
    /* Color System - High contrast, puzzle-focused */
    --color-bg: #0a0e1a;
    --color-surface: #141824;
    --color-surface-raised: #1a1f2e;
    --color-border: #2a3244;
    --color-border-heavy: #3d4557;

    --color-text-primary: #e4e7ec;
    --color-text-secondary: #a1a8b8;
    --color-text-muted: #6b7280;

    --color-filled: #3b82f6;
    --color-filled-hover: #2563eb;
    --color-marked: #64748b;
    --color-empty: #1a1f2e;

    --color-complete: #10b981;
    --color-contradiction: #ef4444;
    --color-warning: #f59e0b;

    --color-accent: #3b82f6;
    --color-accent-hover: #2563eb;

    /* Spacing System - 4px base unit */
    --space-1: 4px;
    --space-2: 8px;
    --space-3: 12px;
    --space-4: 16px;
    --space-5: 20px;
    --space-6: 24px;
    --space-8: 32px;
    --space-12: 48px;

    /* Grid System */
    --cell-size: min(48px, 7vw);
    --grid-border-thin: 1px;
    --grid-border-medium: 2px;
    --grid-border-thick: 3px;

    /* Typography */
    --font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
    --font-mono: ui-monospace, SFMono-Regular, "SF Mono", Menlo, Consolas, "Liberation Mono", monospace;

    /* Radius - Minimal, functional */
    --radius-sm: 4px;
    --radius-md: 6px;
    --radius-lg: 8px;

    /* Transitions */
    --transition-fast: 100ms ease-in-out;
    --transition-base: 200ms ease-in-out;
}

/* Light theme override */
@media (prefers-color-scheme: light) {
    :root {
        --color-bg: #f8fafc;
        --color-surface: #ffffff;
        --color-surface-raised: #f1f5f9;
        --color-border: #e2e8f0;
        --color-border-heavy: #cbd5e1;

        --color-text-primary: #0f172a;
        --color-text-secondary: #475569;
        --color-text-muted: #94a3b8;

        --color-filled: #3b82f6;
        --color-marked: #94a3b8;
        --color-empty: #ffffff;
    }
}

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

body {
    font-family: var(--font-family);
    background: var(--color-bg);
    color: var(--color-text-primary);
    min-height: 100vh;
    line-height: 1.5;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}

/* Layout Container */
.app-shell {
    max-width: 1200px;
    margin: 0 auto;
    padding: var(--space-6);
    display: flex;
    flex-direction: column;
    gap: var(--space-6);
}

/* Header */
.hero {
    display: flex;
    flex-direction: column;
    gap: var(--space-3);
}

.eyebrow {
    text-transform: uppercase;
    letter-spacing: 0.1em;
    font-size: 11px;
    font-weight: 600;
    color: var(--color-accent);
    margin: 0;
}

.hero h1 {
    font-size: clamp(28px, 5vw, 42px);
    font-weight: 700;
    line-height: 1.1;
    letter-spacing: -0.02em;
    margin: 0;
}

.hero p {
    font-size: 15px;
    color: var(--color-text-secondary);
    max-width: 600px;
    margin: 0;
}

/* Controls Section */
.controls {
    background: var(--color-surface);
    border: 1px solid var(--color-border);
    border-radius: var(--radius-lg);
    padding: var(--space-4);
    display: flex;
    flex-wrap: wrap;
    gap: var(--space-4);
    align-items: center;
}

.controls label {
    display: flex;
    flex-direction: column;
    gap: var(--space-2);
    font-size: 13px;
    font-weight: 600;
    color: var(--color-text-secondary);
}

.controls select {
    min-width: 220px;
    font-family: var(--font-family);
    font-size: 14px;
    font-weight: 500;
    padding: var(--space-2) var(--space-3);
    background: var(--color-surface-raised);
    border: 1px solid var(--color-border);
    border-radius: var(--radius-md);
    color: var(--color-text-primary);
    cursor: pointer;
    transition: border-color var(--transition-fast);
}

.controls select:hover {
    border-color: var(--color-border-heavy);
}

.controls select:focus {
    outline: 2px solid var(--color-accent);
    outline-offset: 2px;
}

.control-buttons {
    display: flex;
    gap: var(--space-2);
}

.controls button {
    font-family: var(--font-family);
    font-size: 14px;
    font-weight: 600;
    padding: var(--space-2) var(--space-4);
    background: var(--color-surface-raised);
    border: 1px solid var(--color-border);
    border-radius: var(--radius-md);
    color: var(--color-text-primary);
    cursor: pointer;
    transition: all var(--transition-fast);
}

.controls button:hover {
    background: var(--color-border);
    border-color: var(--color-border-heavy);
}

.controls button:active {
    transform: translateY(1px);
}

.checkbox {
    display: flex;
    flex-direction: row !important;
    align-items: center;
    gap: var(--space-2);
    cursor: pointer;
    user-select: none;
}

.checkbox input[type="checkbox"] {
    width: 18px;
    height: 18px;
    cursor: pointer;
    accent-color: var(--color-accent);
}

/* Tools Section - Prominent game controls */
.tools {
    background: var(--color-surface);
    border: 1px solid var(--color-border);
    border-radius: var(--radius-lg);
    padding: var(--space-3);
    display: flex;
    gap: var(--space-3);
}

.tool {
    flex: 1;
    font-family: var(--font-family);
    font-size: 15px;
    font-weight: 600;
    padding: var(--space-3) var(--space-4);
    background: var(--color-surface-raised);
    border: 2px solid var(--color-border);
    border-radius: var(--radius-md);
    color: var(--color-text-secondary);
    cursor: pointer;
    transition: all var(--transition-fast);
    position: relative;
}

.tool:hover {
    border-color: var(--color-border-heavy);
    transform: translateY(-1px);
}

.tool.active {
    background: var(--color-accent);
    border-color: var(--color-accent);
    color: white;
    box-shadow: 0 0 0 3px rgba(59, 130, 246, 0.1);
}

.tool:active {
    transform: translateY(0);
}

/* Puzzle Container - The Game Board */
.puzzle-shell {
    background: var(--color-surface);
    border: 2px solid var(--color-border);
    border-radius: var(--radius-lg);
    padding: var(--space-6);
    display: grid;
    grid-template-columns: auto 1fr;
    grid-template-rows: auto 1fr;
    gap: var(--space-4);
    align-items: center;
    justify-items: center;
}

/* Corner Info Panel */
.corner {
    grid-column: 1;
    grid-row: 1;
    padding: var(--space-3);
    background: var(--color-surface-raised);
    border: 1px solid var(--color-border);
    border-radius: var(--radius-md);
    font-size: 13px;
    line-height: 1.5;
    color: var(--color-text-muted);
    align-self: start;
    justify-self: stretch;
}

.corner p {
    margin: 0;
}

/* Hints Layout */
.column-hints {
    grid-column: 2;
    grid-row: 1;
    display: grid;
    grid-template-columns: repeat(var(--cols, 5), var(--cell-size));
    gap: 0;
    justify-self: start;
}

.row-hints {
    grid-column: 1;
    grid-row: 2;
    display: grid;
    grid-template-rows: repeat(var(--rows, 5), var(--cell-size));
    gap: 0;
    align-self: start;
}

.hint-line {
    display: flex;
    align-items: center;
    justify-content: flex-end;
    padding: var(--space-2);
    gap: var(--space-1);
    font-family: var(--font-mono);
    font-size: 14px;
    font-weight: 700;
    color: var(--color-text-secondary);
    min-height: var(--cell-size);
}

.column-hints .hint-line {
    flex-direction: column;
    justify-content: flex-end;
    align-items: center;
    min-width: var(--cell-size);
    min-height: auto;
}

.hint-line span {
    display: inline-block;
    min-width: 1.5ch;
    text-align: center;
}

.hint-line.complete {
    color: var(--color-complete);
}

.hint-line.contradiction {
    color: var(--color-contradiction);
    animation: shake 0.3s ease-in-out;
}

@keyframes shake {
    0%, 100% { transform: translateX(0); }
    25% { transform: translateX(-2px); }
    75% { transform: translateX(2px); }
}

/* Grid - The star of the show */
.grid {
    grid-column: 2;
    grid-row: 2;
    display: grid;
    grid-template-columns: repeat(var(--cols, 5), var(--cell-size));
    grid-template-rows: repeat(var(--rows, 5), var(--cell-size));
    background: var(--color-border-heavy);
    border: var(--grid-border-thick) solid var(--color-border-heavy);
    border-radius: var(--radius-md);
    overflow: hidden;
    gap: 0;
    touch-action: none;
    user-select: none;
    box-shadow: 0 4px 12px rgba(0, 0, 0, 0.3);
}

/* Grid Cells */
.cell {
    background: var(--color-empty);
    border: var(--grid-border-thin) solid var(--color-border);
    position: relative;
    cursor: pointer;
    transition: background var(--transition-fast);
}

/* Heavy borders every 5 cells for better visual grouping */
.cell[data-row="0"],
.cell[data-row="5"],
.cell[data-row="10"],
.cell[data-row="15"] {
    border-top-width: var(--grid-border-medium);
}

.cell[data-col="0"],
.cell[data-col="5"],
.cell[data-col="10"],
.cell[data-col="15"] {
    border-left-width: var(--grid-border-medium);
}

/* Cell States */
.cell.filled {
    background: var(--color-filled);
    border-color: var(--color-filled);
}

.cell.marked {
    background: var(--color-empty);
    position: relative;
}

.cell.marked::after {
    content: "×";
    position: absolute;
    inset: 0;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 24px;
    font-weight: 700;
    color: var(--color-marked);
    pointer-events: none;
}

.cell.contradiction {
    background: var(--color-contradiction);
    animation: pulse-contradiction 0.5s ease-out;
}

.cell.filled.contradiction {
    background: var(--color-contradiction);
    border-color: var(--color-contradiction);
}

@keyframes pulse-contradiction {
    0% {
        box-shadow: 0 0 0 0 var(--color-contradiction);
    }
    100% {
        box-shadow: 0 0 0 6px transparent;
    }
}

/* Hover states for interactivity */
.cell:hover {
    opacity: 0.8;
}

/* Legend */
.legend {
    background: var(--color-surface);
    border: 1px solid var(--color-border);
    border-radius: var(--radius-lg);
    padding: var(--space-4);
    display: flex;
    flex-wrap: wrap;
    justify-content: center;
    gap: var(--space-6);
}

.legend-item {
    display: flex;
    align-items: center;
    gap: var(--space-2);
    font-size: 13px;
    font-weight: 600;
    color: var(--color-text-secondary);
}

.legend-item::before {
    content: "";
    display: block;
    width: 20px;
    height: 20px;
    border-radius: var(--radius-sm);
    border: 2px solid var(--color-border);
}

.legend-item.filled::before {
    background: var(--color-filled);
    border-color: var(--color-filled);
}

.legend-item.marked::before {
    background: var(--color-empty);
    border-color: var(--color-border);
    position: relative;
}

.legend-item.marked::after {
    content: "×";
    position: absolute;
    margin-left: -18px;
    font-size: 16px;
    font-weight: 700;
    color: var(--color-marked);
}

.legend-item.contradiction::before {
    background: var(--color-contradiction);
    border-color: var(--color-contradiction);
}

/* Responsive Design */
@media (max-width: 900px) {
    :root {
        --cell-size: min(44px, 9vw);
    }

    .puzzle-shell {
        padding: var(--space-4);
        gap: var(--space-3);
    }
}

@media (max-width: 640px) {
    :root {
        --cell-size: min(36px, 11vw);
    }

    .app-shell {
        padding: var(--space-4);
        gap: var(--space-4);
    }

    .controls,
    .tools,
    .legend {
        flex-direction: column;
        align-items: stretch;
    }

    .controls label,
    .controls select,
    .controls button {
        width: 100%;
    }

    .hint-line {
        font-size: 12px;
    }

    .puzzle-shell {
        grid-template-columns: minmax(80px, auto) 1fr;
        grid-template-rows: minmax(80px, auto) 1fr;
    }
}

@media (max-width: 480px) {
    :root {
        --cell-size: min(32px, 12vw);
    }

    .hero h1 {
        font-size: 24px;
    }

    .hint-line {
        font-size: 11px;
    }

    .cell.marked::after {
        font-size: 18px;
    }
}

/* Print styles */
@media print {
    body {
        background: white;
    }

    .controls,
    .tools,
    .legend {
        display: none;
    }
}

/* NEW ENGAGEMENT FEATURES */

/* Difficulty filters */
.difficulty-filters {
    display: flex;
    gap: var(--space-2);
    flex-wrap: wrap;
    width: 100%;
    margin-bottom: var(--space-3);
}

.filter-btn {
    border: 2px solid var(--color-border);
    border-radius: var(--radius-md);
    padding: var(--space-2) var(--space-4);
    font-size: 14px;
    font-weight: 600;
    cursor: pointer;
    background: var(--color-surface);
    color: var(--color-text-muted);
    transition: all var(--transition-fast);
}

.filter-btn.active {
    background: var(--color-accent);
    color: white;
    border-color: var(--color-accent);
}

.filter-btn:hover:not(.active) {
    border-color: var(--color-accent);
    color: var(--color-accent);
}

/* Stats bar */
.stats-bar {
    background: var(--color-surface);
    border: 1px solid var(--color-border);
    border-radius: var(--radius-lg);
    padding: var(--space-4);
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(120px, 1fr));
    gap: var(--space-5);
}

.stat-item {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: var(--space-1);
}

.stat-label {
    font-size: 12px;
    font-weight: 600;
    color: var(--color-text-muted);
    text-transform: uppercase;
    letter-spacing: 0.05em;
}

.stat-value {
    font-size: 24px;
    font-weight: 700;
    color: var(--color-text);
}

/* Hint button */
.hint-btn {
    background: linear-gradient(135deg, #fbbf24, #f59e0b);
    color: white;
    box-shadow: 0 6px 16px rgba(251, 191, 36, 0.3);
}

.hint-btn:hover {
    transform: translateY(-2px);
    box-shadow: 0 8px 20px rgba(251, 191, 36, 0.4);
}

.hint-btn:active {
    transform: translateY(0);
}

.hint-icon {
    display: inline-block;
    animation: pulse-glow 2s ease-in-out infinite;
}

@keyframes pulse-glow {
    0%, 100% {
        opacity: 1;
        transform: scale(1);
    }
    50% {
        opacity: 0.8;
        transform: scale(1.1);
    }
}

/* Progress summary */
.progress-summary {
    background: var(--color-surface);
    border: 1px solid var(--color-border);
    border-radius: var(--radius-lg);
    padding: var(--space-5);
}

.progress-summary h3 {
    margin: 0 0 var(--space-4) 0;
    font-size: 20px;
    color: var(--color-text);
}

.progress-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(140px, 1fr));
    gap: var(--space-4);
    margin-bottom: var(--space-5);
}

.progress-item {
    display: flex;
    flex-direction: column;
    align-items: center;
    padding: var(--space-4);
    background: rgba(148, 163, 184, 0.1);
    border-radius: var(--radius-md);
    gap: var(--space-2);
}

.progress-label {
    font-size: 12px;
    font-weight: 600;
    color: var(--color-text-muted);
    text-transform: uppercase;
    letter-spacing: 0.05em;
}

.progress-value {
    font-size: 28px;
    font-weight: 700;
    color: var(--color-accent);
}

.daily-puzzle-btn {
    width: 100%;
    border: none;
    border-radius: var(--radius-md);
    padding: var(--space-4);
    font-size: 18px;
    font-weight: 700;
    cursor: pointer;
    background: linear-gradient(135deg, #8b5cf6, #6366f1);
    color: white;
    transition: all var(--transition-base);
    box-shadow: 0 8px 20px rgba(139, 92, 246, 0.3);
}

.daily-puzzle-btn:hover {
    transform: translateY(-2px);
    box-shadow: 0 10px 25px rgba(139, 92, 246, 0.4);
}

/* Achievements panel */
.achievements-panel {
    background: linear-gradient(135deg, #06d6a0, #118ab2);
    border-radius: var(--radius-lg);
    padding: var(--space-5);
    box-shadow: 0 15px 50px rgba(6, 214, 160, 0.3);
    color: white;
    animation: slideIn 0.5s ease-out;
}

.achievements-panel h3 {
    margin: 0 0 var(--space-4) 0;
    font-size: 24px;
}

#achievementsList {
    display: flex;
    flex-direction: column;
    gap: var(--space-3);
}

.achievement-item {
    background: rgba(255, 255, 255, 0.2);
    border-radius: var(--radius-md);
    padding: var(--space-3) var(--space-4);
    backdrop-filter: blur(10px);
    animation: achievementPop 0.5s cubic-bezier(0.68, -0.55, 0.265, 1.55);
}

.achievement-item strong {
    display: block;
    font-size: 18px;
    margin-bottom: var(--space-1);
}

@keyframes slideIn {
    from {
        opacity: 0;
        transform: translateY(-20px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

@keyframes achievementPop {
    0% {
        opacity: 0;
        transform: scale(0.8);
    }
    100% {
        opacity: 1;
        transform: scale(1);
    }
}

/* Celebration overlay */
.celebration-overlay {
    position: fixed;
    inset: 0;
    background: rgba(15, 23, 42, 0.9);
    backdrop-filter: blur(10px);
    display: flex;
    align-items: center;
    justify-content: center;
    z-index: 1000;
    animation: fadeIn 0.3s ease-out;
}

.celebration-content {
    background: var(--color-surface);
    border-radius: var(--radius-xl);
    padding: var(--space-8);
    max-width: 500px;
    width: 90%;
    box-shadow: 0 25px 80px rgba(6, 214, 160, 0.4);
    animation: celebrationBounce 0.6s cubic-bezier(0.68, -0.55, 0.265, 1.55);
    text-align: center;
}

.celebration-content h2 {
    font-size: 40px;
    margin: 0 0 var(--space-4) 0;
    color: var(--color-complete);
    text-shadow: 0 2px 10px rgba(6, 214, 160, 0.3);
}

#celebrationStats {
    margin: var(--space-5) 0;
    padding: var(--space-4);
    background: rgba(148, 163, 184, 0.1);
    border-radius: var(--radius-md);
    font-size: 18px;
    line-height: 1.8;
}

#celebrationAchievements {
    margin: var(--space-4) 0;
}

.celebration-btn {
    border: none;
    border-radius: var(--radius-md);
    padding: var(--space-4) var(--space-6);
    font-size: 18px;
    font-weight: 700;
    cursor: pointer;
    margin: var(--space-2);
    transition: all var(--transition-base);
}

.celebration-btn:not(.secondary) {
    background: var(--color-accent);
    color: white;
    box-shadow: 0 8px 20px rgba(17, 138, 178, 0.3);
}

.celebration-btn.secondary {
    background: var(--color-border);
    color: var(--color-text);
}

.celebration-btn:hover {
    transform: translateY(-2px);
}

@keyframes fadeIn {
    from {
        opacity: 0;
    }
    to {
        opacity: 1;
    }
}

@keyframes celebrationBounce {
    0% {
        opacity: 0;
        transform: scale(0.5) rotate(-5deg);
    }
    100% {
        opacity: 1;
        transform: scale(1) rotate(0deg);
    }
}

/* Hint reveal effect */
.cell.hint-reveal {
    animation: hintPulse 0.8s ease-in-out;
    box-shadow: 0 0 0 3px #fbbf24;
}

@keyframes hintPulse {
    0%, 100% {
        transform: scale(1);
    }
    50% {
        transform: scale(1.15);
    }
}

/* Completed puzzle marker in dropdown */
.puzzle-completed {
    color: var(--color-complete);
}

@media (max-width: 900px) {
    .stats-bar {
        grid-template-columns: repeat(2, 1fr);
    }

    .progress-grid {
        grid-template-columns: repeat(2, 1fr);
    }
}

@media (max-width: 640px) {
    .difficulty-filters {
        justify-content: center;
    }

    .filter-btn {
        flex: 1;
        min-width: 60px;
    }

    .celebration-content {
        padding: var(--space-5);
    }

    .celebration-content h2 {
        font-size: 28px;
    }
}