/**
 * Sudoku Training - Hauptstyles
 * Barrierefreies Design für Schlaganfall-Rehabilitation
 * KEIN ROT/GRÜN wegen Farbenblindheit!
 */

/* === RESET & BASE === */

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

:root {
    /* Farben (KEIN Rot/Grün!) */
    --color-primary: #1e3a8a;        /* Dunkelblau */
    --color-primary-light: #3b82f6;  /* Blau */
    --color-secondary: #fbbf24;       /* Gold/Gelb */
    --color-warning: #f97316;         /* Orange (statt Rot!) */
    --color-success: #3b82f6;         /* Blau (statt Grün!) */
    --color-bg: #ffffff;
    --color-bg-secondary: #f3f4f6;
    --color-bg-tertiary: #e5e7eb;
    --color-text: #000000;
    --color-text-secondary: #4b5563;
    --color-text-light: #6b7280;
    --color-border: #d1d5db;
    --color-border-thick: #9ca3af;

    /* Abstände */
    --spacing-xs: 0.25rem;    /* 4px */
    --spacing-sm: 0.5rem;     /* 8px */
    --spacing-md: 1rem;       /* 16px */
    --spacing-lg: 1.5rem;     /* 24px */
    --spacing-xl: 2rem;       /* 32px */
    --spacing-2xl: 3rem;      /* 48px */

    /* Typografie */
    --font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Oxygen, Ubuntu, Cantarell, sans-serif;
    --font-size-xs: 0.75rem;  /* 12px */
    --font-size-sm: 0.875rem; /* 14px */
    --font-size-md: 1rem;     /* 16px */
    --font-size-lg: 1.125rem; /* 18px */
    --font-size-xl: 1.5rem;   /* 24px */
    --font-size-2xl: 2rem;    /* 32px */

    /* Sudoku-Zellen */
    --cell-size-4x4: 80px;
    --cell-size-6x6: 60px;
    --cell-size-9x9: 45px;
    --cell-font-size: 24px;

    /* Touch-Targets (mindestens 48px für Accessibility) */
    --touch-target-min: 48px;
    --button-large: 80px;

    /* Animationen */
    --transition-fast: 150ms ease;
    --transition-normal: 300ms ease;

    /* Schatten */
    --shadow-sm: 0 1px 2px 0 rgba(0, 0, 0, 0.05);
    --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.1);
    --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.1);

    /* Border Radius */
    --radius-sm: 0.375rem;  /* 6px */
    --radius-md: 0.5rem;    /* 8px */
    --radius-lg: 0.75rem;   /* 12px */
    --radius-xl: 1rem;      /* 16px */
}

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

body {
    font-family: var(--font-family);
    font-size: var(--font-size-md);
    line-height: 1.6;
    color: var(--color-text);
    background-color: var(--color-bg);
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
    overflow-x: hidden;
    touch-action: manipulation; /* Verhindert doppelten Tap-Zoom */
}

/* === LAYOUT === */

.app {
    min-height: 100vh;
    display: flex;
    flex-direction: column;
}

.screen {
    display: none;
    flex: 1;
    flex-direction: column;
}

.screen.active {
    display: flex;
}

.container {
    width: 100%;
    max-width: 800px;
    margin: 0 auto;
    padding: var(--spacing-lg);
}

/* === HEADER === */

.app-header {
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: var(--spacing-md) var(--spacing-lg);
    background-color: var(--color-primary);
    color: white;
    box-shadow: var(--shadow-md);
}

.app-logo {
    font-size: var(--font-size-xl);
    font-weight: 700;
    color: white;
}

.user-greeting {
    font-size: var(--font-size-lg);
    font-weight: 500;
}

.icon-btn {
    min-width: var(--touch-target-min);
    min-height: var(--touch-target-min);
    padding: var(--spacing-sm);
    background: rgba(255, 255, 255, 0.1);
    border: none;
    border-radius: var(--radius-md);
    color: white;
    font-size: var(--font-size-xl);
    cursor: pointer;
    transition: background var(--transition-fast);
}

.icon-btn:hover {
    background: rgba(255, 255, 255, 0.2);
}

.icon-btn:active {
    transform: scale(0.95);
}

/* === MAIN CONTENT === */

.main-content {
    flex: 1;
    overflow-y: auto;
    overflow-x: hidden;
}

.view {
    display: none;
}

.view.active {
    display: block;
}

/* === TYPOGRAPHY === */

h1, h2, h3, h4 {
    font-weight: 700;
    line-height: 1.2;
    margin-bottom: var(--spacing-md);
}

h1 { font-size: var(--font-size-2xl); }
h2 { font-size: var(--font-size-xl); }
h3 { font-size: var(--font-size-lg); }
h4 { font-size: var(--font-size-md); }

p {
    margin-bottom: var(--spacing-md);
}

.subtitle {
    font-size: var(--font-size-lg);
    color: var(--color-text-secondary);
    text-align: center;
}

.text-center {
    text-align: center;
}

/* === BUTTONS === */

.btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: var(--spacing-sm);
    min-height: var(--touch-target-min);
    padding: var(--spacing-md) var(--spacing-lg);
    font-size: var(--font-size-lg);
    font-weight: 600;
    text-align: center;
    text-decoration: none;
    border: none;
    border-radius: var(--radius-lg);
    cursor: pointer;
    transition: all var(--transition-fast);
    user-select: none;
    -webkit-tap-highlight-color: transparent;
}

.btn:active {
    transform: scale(0.97);
}

.btn-primary {
    background-color: var(--color-primary);
    color: white;
}

.btn-primary:hover {
    background-color: #1e40af;
}

.btn-secondary {
    background-color: var(--color-bg-secondary);
    color: var(--color-text);
    border: 2px solid var(--color-border);
}

.btn-secondary:hover {
    background-color: var(--color-bg-tertiary);
}

.btn-small {
    min-height: var(--touch-target-min);
    padding: var(--spacing-sm) var(--spacing-md);
    font-size: var(--font-size-md);
}

.btn-large {
    min-height: 64px;
    padding: var(--spacing-lg) var(--spacing-xl);
    font-size: var(--font-size-xl);
    width: 100%;
    margin-bottom: var(--spacing-md);
}

.btn-block {
    width: 100%;
}

.btn-icon {
    font-size: 1.2em;
}

/* === CARDS === */

.welcome-card {
    /* Fallback mit hohem Kontrast, falls Theme nicht lädt */
    background: #1e3a8a;
    background: linear-gradient(135deg, var(--color-primary, #1e3a8a), var(--color-primary-light, #3b82f6));
    color: white !important;
    padding: var(--spacing-xl);
    border-radius: var(--radius-xl);
    margin-bottom: var(--spacing-xl);
    box-shadow: var(--shadow-lg);
}

.welcome-card h2 {
    margin-bottom: var(--spacing-sm);
    color: white !important;
    font-weight: 700;
}

.welcome-card p {
    font-size: var(--font-size-lg);
    margin-bottom: 0;
    color: white !important;
}

/* === STATS === */

.stats-overview {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: var(--spacing-md);
    margin-bottom: var(--spacing-xl);
}

.stat-card {
    background: white;
    border: 2px solid var(--color-border);
    border-radius: var(--radius-lg);
    padding: var(--spacing-lg);
    text-align: center;
    transition: transform var(--transition-fast);
}

.stat-card:hover {
    transform: translateY(-2px);
    box-shadow: var(--shadow-md);
}

.stat-icon {
    font-size: 2.5rem;
    margin-bottom: var(--spacing-sm);
}

.stat-value {
    font-size: var(--font-size-2xl);
    font-weight: 700;
    color: var(--color-primary);
    margin-bottom: var(--spacing-xs);
}

.stat-label {
    font-size: var(--font-size-sm);
    color: var(--color-text-secondary);
}

/* === USER SELECT === */

.app-title {
    text-align: center;
    color: var(--color-primary);
    margin: var(--spacing-2xl) 0 var(--spacing-lg);
}

.user-select-list {
    display: flex;
    flex-direction: column;
    gap: var(--spacing-md);
    margin: var(--spacing-xl) 0;
}

.user-select-btn {
    display: flex;
    align-items: center;
    gap: var(--spacing-lg);
    min-height: var(--button-large);
    padding: var(--spacing-lg) var(--spacing-xl);
    background: white;
    border: 3px solid var(--color-primary);
    border-radius: var(--radius-xl);
    font-size: var(--font-size-xl);
    font-weight: 600;
    color: var(--color-primary);
    cursor: pointer;
    transition: all var(--transition-fast);
}

.user-select-btn:hover {
    background: var(--color-primary);
    color: white;
    transform: translateX(8px);
}

.user-select-btn:active {
    transform: translateX(8px) scale(0.98);
}

.user-icon {
    font-size: 2.5rem;
}

.user-name {
    flex: 1;
    text-align: left;
}

/* === SIZE SELECTOR === */

.size-selector {
    margin-bottom: var(--spacing-xl);
}

.size-selector h3 {
    text-align: center;
    margin-bottom: var(--spacing-lg);
}

.size-buttons {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(150px, 1fr));
    gap: var(--spacing-md);
}

.size-btn {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: var(--spacing-md);
    min-height: 120px;
    padding: var(--spacing-lg);
    background: white;
    border: 3px solid var(--color-primary);
    border-radius: var(--radius-lg);
    font-size: var(--font-size-lg);
    font-weight: 600;
    color: var(--color-primary);
    cursor: pointer;
    transition: all var(--transition-fast);
}

.size-btn:hover,
.size-btn.selected {
    background: var(--color-primary);
    color: white;
    transform: scale(1.05);
}

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

.size-grid {
    font-size: 3rem;
}

/* Grid Icons (vereinfacht) */
.grid-icon::before {
    content: '▦';
}

/* === DIFFICULTY SLIDER === */

.difficulty-selector {
    margin-bottom: var(--spacing-xl);
}

.difficulty-selector h3 {
    text-align: center;
    margin-bottom: var(--spacing-lg);
}

.difficulty-slider {
    padding: 0 var(--spacing-md);
}

#difficulty-slider {
    -webkit-appearance: none;
    appearance: none;
    width: 100%;
    height: 12px;
    background: linear-gradient(to right, var(--color-success), var(--color-secondary), var(--color-warning));
    border-radius: var(--radius-md);
    outline: none;
    margin-bottom: var(--spacing-md);
}

#difficulty-slider::-webkit-slider-thumb {
    -webkit-appearance: none;
    appearance: none;
    width: 32px;
    height: 32px;
    background: white;
    border: 3px solid var(--color-primary);
    border-radius: 50%;
    cursor: pointer;
    box-shadow: var(--shadow-md);
}

#difficulty-slider::-moz-range-thumb {
    width: 32px;
    height: 32px;
    background: white;
    border: 3px solid var(--color-primary);
    border-radius: 50%;
    cursor: pointer;
    box-shadow: var(--shadow-md);
}

.difficulty-labels {
    display: flex;
    justify-content: space-between;
    align-items: center;
    font-size: var(--font-size-md);
    color: var(--color-text-secondary);
}

.difficulty-value {
    font-size: var(--font-size-2xl);
    font-weight: 700;
    color: var(--color-primary);
}

/* === GAME HEADER === */

.game-header {
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: var(--spacing-md) var(--spacing-lg);
    border-bottom: 2px solid var(--color-border);
}

.game-info {
    display: flex;
    align-items: center;
    gap: var(--spacing-sm);
    font-size: var(--font-size-lg);
    font-weight: 600;
}

.separator {
    color: var(--color-text-light);
}

/* === PROGRESS BAR === */

.progress-bar {
    position: relative;
    height: 48px;
    background: var(--color-bg-secondary);
    border-radius: var(--radius-md);
    margin: var(--spacing-lg);
    overflow: hidden;
}

.progress-fill {
    height: 100%;
    background: linear-gradient(90deg, var(--color-primary), var(--color-primary-light));
    transition: width var(--transition-normal);
}

.progress-text {
    position: absolute;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
    font-weight: 600;
    color: var(--color-text);
    text-shadow: 0 0 4px white;
}

/* === INSTRUCTIONS BOX === */

.instructions-box {
    background: var(--color-bg-secondary);
    border: 2px solid var(--color-border);
    border-radius: var(--radius-lg);
    margin: var(--spacing-lg);
    overflow: hidden;
}

.instructions-toggle {
    width: 100%;
    display: flex;
    align-items: center;
    gap: var(--spacing-md);
    min-height: var(--touch-target-min);
    padding: var(--spacing-md) var(--spacing-lg);
    background: white;
    border: none;
    font-size: var(--font-size-lg);
    font-weight: 600;
    cursor: pointer;
    transition: background var(--transition-fast);
}

.instructions-toggle:hover {
    background: var(--color-bg-secondary);
}

.toggle-icon {
    font-size: 1.5em;
}

.toggle-text {
    flex: 1;
    text-align: left;
}

.toggle-arrow {
    transition: transform var(--transition-normal);
}

.instructions-toggle[aria-expanded="false"] .toggle-arrow {
    transform: rotate(-90deg);
}

.instructions-content {
    padding: var(--spacing-lg);
    max-height: 600px;
    overflow-y: auto;
    transition: max-height var(--transition-normal);
}

.instructions-content.collapsed {
    max-height: 0;
    padding: 0;
    overflow: hidden;
}

.instructions-content h4 {
    color: var(--color-primary);
    margin-top: var(--spacing-lg);
    margin-bottom: var(--spacing-sm);
}

.instructions-content h4:first-child {
    margin-top: 0;
}

.instructions-content ol {
    margin-left: var(--spacing-lg);
    margin-bottom: var(--spacing-md);
}

.instructions-content li {
    margin-bottom: var(--spacing-sm);
}

.instructions-content small {
    color: var(--color-text-secondary);
}

/* === SUDOKU GRID === */

.sudoku-container {
    display: flex;
    justify-content: center;
    padding: var(--spacing-lg);
}

.sudoku-grid {
    display: inline-grid;
    background-color: var(--color-border-thick);
    border: 3px solid var(--color-primary);
    gap: 0;
}

/* Grid Layouts */
.sudoku-grid.size-4 {
    grid-template-columns: repeat(4, var(--cell-size-4x4));
    grid-template-rows: repeat(4, var(--cell-size-4x4));
}

.sudoku-grid.size-6 {
    grid-template-columns: repeat(6, var(--cell-size-6x6));
    grid-template-rows: repeat(6, var(--cell-size-6x6));
}

.sudoku-grid.size-9 {
    grid-template-columns: repeat(9, var(--cell-size-9x9));
    grid-template-rows: repeat(9, var(--cell-size-9x9));
}

/* Sudoku Cell */
.sudoku-cell {
    display: flex;
    align-items: center;
    justify-content: center;
    background: white;
    border: 1px solid var(--color-border);
    font-size: var(--cell-font-size);
    font-weight: 600;
    cursor: pointer;
    user-select: none;
    transition: all var(--transition-fast);
    position: relative;
}

/* Vorgegeben (nicht editierbar) */
.sudoku-cell.given {
    background-color: var(--color-bg-tertiary);
    color: var(--color-text);
    font-weight: 700;
    cursor: default;
}

/* Eigene Eingabe */
.sudoku-cell.user {
    color: var(--color-primary);
}

/* Gewählte Zelle */
.sudoku-cell.selected {
    border: 5px solid var(--color-secondary) !important;
    z-index: 10;
}

/* Gleiche Zahlen highlighten */
.sudoku-cell.highlight {
    background-color: rgba(219, 234, 254, 0.5); /* Hellblau 50% */
}

/* Fehlerhafte Zelle */
.sudoku-cell.error {
    border: 3px solid var(--color-warning) !important;
    position: relative;
}

.sudoku-cell.error::after {
    content: '⚠';
    position: absolute;
    top: 2px;
    right: 2px;
    font-size: 12px;
    color: var(--color-warning);
}

/* Richtige Zelle (temporär) */
.sudoku-cell.correct {
    border: 3px solid var(--color-success) !important;
    position: relative;
}

.sudoku-cell.correct::after {
    content: '✓';
    position: absolute;
    top: 2px;
    right: 2px;
    font-size: 12px;
    color: var(--color-success);
}

/* Hint Zelle */
.sudoku-cell.hint {
    border: 5px solid var(--color-secondary) !important;
    animation: pulse 0.5s ease;
}

/* Mögliche Zahlen (kleine Punkte) */
.sudoku-cell .candidates {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 2px;
    position: absolute;
    inset: 4px;
    font-size: 8px;
    color: var(--color-primary-light);
}

/* Dicke Linien für Boxen */
.sudoku-grid.size-4 .sudoku-cell:nth-child(4n+2),
.sudoku-grid.size-4 .sudoku-cell:nth-child(4n+3) {
    border-right-width: 1px;
}

.sudoku-grid.size-4 .sudoku-cell:nth-child(n+5):nth-child(-n+8),
.sudoku-grid.size-4 .sudoku-cell:nth-child(n+9):nth-child(-n+12) {
    border-bottom-width: 1px;
}

.sudoku-grid.size-4 .sudoku-cell:nth-child(2),
.sudoku-grid.size-4 .sudoku-cell:nth-child(6),
.sudoku-grid.size-4 .sudoku-cell:nth-child(10),
.sudoku-grid.size-4 .sudoku-cell:nth-child(14) {
    border-right: 3px solid var(--color-primary);
}

.sudoku-grid.size-4 .sudoku-cell:nth-child(n+9) {
    border-top: 3px solid var(--color-primary);
}

/* === NUMBER PAD === */

.number-pad {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(70px, 1fr));
    gap: var(--spacing-md);
    padding: var(--spacing-lg);
    max-width: 500px;
    margin: 0 auto;
}

.number-btn {
    min-height: var(--button-large);
    min-width: var(--button-large);
    font-size: var(--font-size-2xl);
    font-weight: 700;
    background: white;
    border: 3px solid var(--color-primary);
    border-radius: var(--radius-lg);
    color: var(--color-primary);
    cursor: pointer;
    transition: all var(--transition-fast);
    user-select: none;
}

.number-btn:hover {
    background: var(--color-primary);
    color: white;
    transform: scale(1.05);
}

.number-btn:active {
    transform: scale(0.95);
}

.number-btn.erase {
    background: var(--color-warning);
    border-color: var(--color-warning);
    color: white;
}

.number-btn.erase:hover {
    background: #ea580c;
}

/* === HELP BUTTONS === */

.help-buttons {
    display: grid;
    grid-template-columns: repeat(2, 1fr);
    gap: var(--spacing-md);
    padding: var(--spacing-lg);
    background: var(--color-bg-secondary);
    border-top: 2px solid var(--color-border);
}

.help-btn {
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    gap: var(--spacing-xs);
    min-height: var(--button-large);
    padding: var(--spacing-md);
    background: white;
    border: 2px solid var(--color-primary);
    border-radius: var(--radius-lg);
    font-size: var(--font-size-sm);
    font-weight: 600;
    color: var(--color-primary);
    cursor: pointer;
    transition: all var(--transition-fast);
    position: relative;
}

.help-btn:hover {
    background: var(--color-primary);
    color: white;
    transform: translateY(-2px);
    box-shadow: var(--shadow-md);
}

.help-btn:active {
    transform: translateY(0) scale(0.98);
}

.help-icon {
    font-size: 1.8em;
}

.help-text {
    text-align: center;
    line-height: 1.2;
}

.help-counter {
    position: absolute;
    top: 4px;
    right: 4px;
    min-width: 24px;
    height: 24px;
    display: flex;
    align-items: center;
    justify-content: center;
    background: var(--color-warning);
    color: white;
    border-radius: 50%;
    font-size: var(--font-size-xs);
    font-weight: 700;
}

/* === FEEDBACK BOX === */

.feedback-box {
    min-height: 60px;
    margin: var(--spacing-md) var(--spacing-lg);
    padding: var(--spacing-md);
    background: var(--color-bg-secondary);
    border-radius: var(--radius-lg);
    text-align: center;
    font-size: var(--font-size-lg);
    font-weight: 600;
    display: flex;
    align-items: center;
    justify-content: center;
    opacity: 0;
    transition: opacity var(--transition-normal);
}

.feedback-box.visible {
    opacity: 1;
}

.feedback-box.success {
    background: rgba(59, 130, 246, 0.1);
    color: var(--color-success);
    border: 2px solid var(--color-success);
}

.feedback-box.error {
    background: rgba(249, 115, 22, 0.1);
    color: var(--color-warning);
    border: 2px solid var(--color-warning);
}

.feedback-box.hint {
    background: rgba(251, 191, 36, 0.1);
    color: #d97706;
    border: 2px solid var(--color-secondary);
}

/* === SUCCESS SCREEN === */

.success-animation {
    margin: var(--spacing-2xl) 0;
}

.success-icon {
    font-size: 5rem;
    margin-bottom: var(--spacing-lg);
    animation: bounce 0.6s ease;
}

.success-title {
    font-size: var(--font-size-2xl);
    color: var(--color-primary);
    margin-bottom: var(--spacing-md);
}

.success-message {
    font-size: var(--font-size-lg);
    color: var(--color-text-secondary);
}

.success-stats {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: var(--spacing-lg);
    margin: var(--spacing-2xl) 0;
    padding: var(--spacing-xl);
    background: var(--color-bg-secondary);
    border-radius: var(--radius-xl);
}

.success-stat {
    text-align: center;
}

.success-stat .stat-label {
    font-size: var(--font-size-sm);
    color: var(--color-text-secondary);
    margin-bottom: var(--spacing-xs);
}

.success-stat .stat-value {
    font-size: var(--font-size-2xl);
    font-weight: 700;
    color: var(--color-primary);
}

.success-actions {
    margin-top: var(--spacing-2xl);
}

/* === MODALS === */

.modal-overlay {
    position: fixed;
    inset: 0;
    background: rgba(0, 0, 0, 0.5);
    z-index: 100;
    display: flex;
    align-items: center;
    justify-content: center;
    opacity: 0;
    pointer-events: none;
    transition: opacity var(--transition-normal);
}

.modal-overlay.visible {
    opacity: 1;
    pointer-events: auto;
}

.modal {
    position: fixed;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%) scale(0.9);
    width: 90%;
    max-width: 500px;
    background: white;
    border-radius: var(--radius-xl);
    box-shadow: var(--shadow-lg);
    z-index: 101;
    opacity: 0;
    pointer-events: none;
    transition: all var(--transition-normal);
}

.modal.visible {
    opacity: 1;
    transform: translate(-50%, -50%) scale(1);
    pointer-events: auto;
}

.modal-content {
    padding: var(--spacing-xl);
}

.modal-close {
    position: absolute;
    top: var(--spacing-md);
    right: var(--spacing-md);
    width: 40px;
    height: 40px;
    background: var(--color-bg-secondary);
    border: none;
    border-radius: 50%;
    font-size: var(--font-size-xl);
    font-weight: 700;
    color: var(--color-text);
    cursor: pointer;
    transition: all var(--transition-fast);
}

.modal-close:hover {
    background: var(--color-bg-tertiary);
    transform: rotate(90deg);
}

.modal h3 {
    margin-bottom: var(--spacing-lg);
    padding-right: var(--spacing-2xl); /* Platz für Close-Button */
}

.modal-body {
    margin-bottom: var(--spacing-lg);
}

.modal-actions {
    display: flex;
    gap: var(--spacing-md);
    margin-top: var(--spacing-lg);
}

.modal-actions .btn {
    flex: 1;
}

/* === ANIMATIONS === */

@keyframes pulse {
    0%, 100% {
        transform: scale(1);
    }
    50% {
        transform: scale(1.05);
    }
}

@keyframes bounce {
    0%, 100% {
        transform: translateY(0);
    }
    50% {
        transform: translateY(-20px);
    }
}

@keyframes shake {
    0%, 100% {
        transform: translateX(0);
    }
    25% {
        transform: translateX(-10px);
    }
    75% {
        transform: translateX(10px);
    }
}

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

.shake {
    animation: shake 0.3s ease;
}

.pulse {
    animation: pulse 0.3s ease;
}

/* === UTILITY CLASSES === */

.hidden {
    display: none !important;
}

.invisible {
    opacity: 0;
    pointer-events: none;
}

.disabled {
    opacity: 0.5;
    cursor: not-allowed;
    pointer-events: none;
}

/* === RESPONSIVE === */

@media (max-width: 768px) {
    :root {
        --cell-size-4x4: 70px;
        --cell-size-6x6: 50px;
        --cell-size-9x9: 35px;
    }

    .container {
        padding: var(--spacing-md);
    }

    .stats-overview {
        grid-template-columns: 1fr;
    }

    .help-buttons {
        grid-template-columns: 1fr;
    }

    .success-stats {
        grid-template-columns: 1fr;
    }
}

@media (max-width: 480px) {
    :root {
        --cell-size-4x4: 60px;
        --cell-size-6x6: 45px;
        --cell-size-9x9: 30px;
        --cell-font-size: 20px;
    }

    .app-header {
        padding: var(--spacing-sm) var(--spacing-md);
    }

    .user-greeting {
        font-size: var(--font-size-md);
    }
}

/* === PRINT === */

@media print {
    .app-header,
    .help-buttons,
    .number-pad,
    .btn {
        display: none !important;
    }
}

/* === ACCESSIBILITY === */

/* Fokus-Indikator */
*:focus {
    outline: 3px solid var(--color-secondary);
    outline-offset: 2px;
}

/* Reduzierte Animationen für Nutzer mit Präferenz */
@media (prefers-reduced-motion: reduce) {
    *,
    *::before,
    *::after {
        animation-duration: 0.01ms !important;
        animation-iteration-count: 1 !important;
        transition-duration: 0.01ms !important;
    }
}

/* High Contrast Mode Support */
@media (prefers-contrast: high) {
    :root {
        --color-border: #000000;
        --color-border-thick: #000000;
    }

    .btn,
    .sudoku-cell,
    .help-btn {
        border-width: 3px;
    }
}