/* ===========================
   Variables CSS
   =========================== */
:root {
    /* Couleurs */
    --charcoal: #1a1a1a;
    --cream: #faf8f5;
    --accent-red: #d32f2f;
    --gray-light: #e0e0e0;
    --gray-mid: #9e9e9e;
    --gray-dark: #424242;
    --shadow: rgba(0, 0, 0, 0.1);
    --shadow-strong: rgba(0, 0, 0, 0.2);
    
    /* Typographie */
    --font-display: 'Noto Serif JP', serif;
    --font-mono: 'IBM Plex Mono', monospace;
    
    /* Espacements */
    --spacing-xs: 0.5rem;
    --spacing-sm: 1rem;
    --spacing-md: 1.5rem;
    --spacing-lg: 2rem;
    --spacing-xl: 3rem;
    
    /* Transitions */
    --transition-fast: 150ms ease;
    --transition-normal: 300ms ease;
    --transition-slow: 500ms ease;
    
    /* Grille */
    --cell-size: 3.5rem;
    --cell-size-mobile: 2.5rem;
}

/* ===========================
   Reset & Base
   =========================== */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

body {
    font-family: var(--font-mono);
    background: var(--cream);
    color: var(--charcoal);
    line-height: 1.6;
    overflow-x: hidden;
    min-height: 100vh;
}

button {
    font-family: inherit;
    cursor: pointer;
    border: none;
    background: none;
}

button:focus-visible {
    outline: 2px solid var(--accent-red);
    outline-offset: 2px;
}

/* ===========================
   Écrans & Navigation
   =========================== */
.screen {
    display: none;
    min-height: 100vh;
    padding: var(--spacing-md);
}

.screen.active {
    display: flex;
    animation: fadeIn var(--transition-normal);
}

@keyframes fadeIn {
    from {
        opacity: 0;
        transform: translateY(10px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

/* ===========================
   Écran d'accueil
   =========================== */
#homeScreen {
    justify-content: center;
    align-items: center;
}

.home-container {
    max-width: 600px;
    width: 100%;
}

.home-header {
    text-align: center;
    margin-bottom: var(--spacing-xl);
}

.title {
    display: flex;
    flex-direction: column;
    gap: var(--spacing-xs);
}

.title-jp {
    font-family: var(--font-display);
    font-size: 4rem;
    font-weight: 700;
    color: var(--charcoal);
    letter-spacing: 0.1em;
    animation: slideDown 0.6s ease;
}

.title-latin {
    font-size: 1.5rem;
    font-weight: 500;
    letter-spacing: 0.2em;
    text-transform: uppercase;
    color: var(--gray-mid);
    animation: slideDown 0.6s ease 0.1s backwards;
}

.subtitle {
    margin-top: var(--spacing-sm);
    font-size: 0.9rem;
    color: var(--gray-mid);
    animation: slideDown 0.6s ease 0.2s backwards;
}

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

.section-title {
    font-size: 0.75rem;
    font-weight: 600;
    letter-spacing: 0.15em;
    text-transform: uppercase;
    color: var(--gray-mid);
    margin-bottom: var(--spacing-sm);
}

/* Mode Selector */
.mode-selector {
    margin-bottom: var(--spacing-lg);
}

.mode-options {
    display: grid;
    grid-template-columns: repeat(2, 1fr);
    gap: var(--spacing-sm);
}

.mode-btn {
    display: flex;
    flex-direction: column;
    align-items: center;
    padding: var(--spacing-md);
    background: white;
    border: 2px solid var(--gray-light);
    border-radius: 8px;
    transition: all var(--transition-normal);
}

.mode-btn:hover {
    border-color: var(--gray-mid);
    transform: translateY(-2px);
    box-shadow: 0 4px 12px var(--shadow);
}

.mode-btn.active {
    border-color: var(--accent-red);
    background: var(--charcoal);
    color: var(--cream);
}

.mode-icon {
    font-size: 2rem;
    font-weight: 600;
    margin-bottom: var(--spacing-xs);
}

.mode-label {
    font-weight: 600;
    margin-bottom: 0.25rem;
}

.mode-desc {
    font-size: 0.75rem;
    opacity: 0.7;
}

/* Difficulty Selector */
.difficulty-selector {
    margin-bottom: var(--spacing-xl);
}

/* Custom Options */
.custom-options {
    margin-bottom: var(--spacing-lg);
    padding: var(--spacing-md);
    background: white;
    border-radius: 8px;
    border: 2px solid var(--gray-light);
}

.custom-options.hidden {
    display: none;
}

.option-label {
    display: block;
    font-size: 0.85rem;
    font-weight: 600;
    color: var(--charcoal);
    margin-bottom: var(--spacing-sm);
}

.alphabet-selector {
    margin-bottom: var(--spacing-md);
}

.alphabet-grid {
    display: grid;
    grid-template-columns: repeat(2, 1fr);
    gap: var(--spacing-xs);
}

.alphabet-btn {
    display: flex;
    flex-direction: column;
    align-items: center;
    padding: var(--spacing-sm);
    background: var(--cream);
    border: 2px solid var(--gray-light);
    border-radius: 6px;
    transition: all var(--transition-fast);
}

.alphabet-btn:hover {
    border-color: var(--gray-mid);
    transform: translateY(-1px);
}

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

.alphabet-sample {
    font-size: 1.5rem;
    font-weight: 600;
    margin-bottom: 0.25rem;
}

.alphabet-name {
    font-size: 0.75rem;
}

.symbol-selector {
    margin-bottom: var(--spacing-sm);
}

.symbol-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(50px, 1fr));
    gap: var(--spacing-xs);
    margin-bottom: var(--spacing-sm);
    max-height: 300px;
    overflow-y: auto;
    padding: var(--spacing-xs);
    background: var(--cream);
    border-radius: 4px;
}

.symbol-btn {
    aspect-ratio: 1;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 1.2rem;
    font-weight: 600;
    background: white;
    border: 2px solid var(--gray-light);
    border-radius: 6px;
    transition: all var(--transition-fast);
    cursor: pointer;
}

.symbol-btn:hover {
    border-color: var(--gray-mid);
    transform: scale(1.05);
}

.symbol-btn.selected {
    border-color: var(--accent-red);
    background: var(--accent-red);
    color: white;
}

.symbol-btn.disabled {
    opacity: 0.3;
    cursor: not-allowed;
}

.symbol-counter {
    text-align: center;
    font-size: 0.85rem;
    color: var(--gray-mid);
    padding: var(--spacing-xs);
}

.symbol-counter #selectedCount {
    font-weight: 700;
    color: var(--accent-red);
    font-size: 1.1rem;
}

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

.difficulty-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(100px, 1fr));
    gap: var(--spacing-xs);
}

.diff-btn {
    display: flex;
    flex-direction: column;
    align-items: center;
    padding: var(--spacing-sm);
    background: white;
    border: 2px solid var(--gray-light);
    border-radius: 6px;
    transition: all var(--transition-normal);
}

.diff-btn:hover {
    border-color: var(--gray-mid);
    transform: translateY(-2px);
}

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

.diff-label {
    font-size: 0.85rem;
    font-weight: 600;
    margin-bottom: 0.25rem;
}

.diff-level {
    font-size: 0.7rem;
    letter-spacing: 0.1em;
}

/* Start Button */
.start-btn {
    width: 100%;
    display: flex;
    align-items: center;
    justify-content: center;
    gap: var(--spacing-sm);
    padding: var(--spacing-md) var(--spacing-lg);
    background: var(--charcoal);
    color: var(--cream);
    font-size: 1rem;
    font-weight: 600;
    letter-spacing: 0.05em;
    border-radius: 8px;
    transition: all var(--transition-normal);
    box-shadow: 0 4px 12px var(--shadow);
}

.start-btn:hover {
    background: var(--accent-red);
    transform: translateY(-2px);
    box-shadow: 0 6px 20px var(--shadow-strong);
}

.btn-arrow {
    font-size: 1.2rem;
    transition: transform var(--transition-normal);
}

.start-btn:hover .btn-arrow {
    transform: translateX(4px);
}

/* ===========================
   Écran de jeu
   =========================== */
#gameScreen {
    flex-direction: column;
    padding: var(--spacing-sm);
}

.game-container {
    max-width: 600px;
    width: 100%;
    margin: 0 auto;
}

/* Game Header */
.game-header {
    display: flex;
    align-items: center;
    justify-content: space-between;
    margin-bottom: var(--spacing-md);
    padding: var(--spacing-sm) 0;
}

.back-btn {
    font-size: 1.5rem;
    color: var(--charcoal);
    transition: all var(--transition-fast);
    padding: var(--spacing-xs);
}

.back-btn:hover {
    color: var(--accent-red);
    transform: translateX(-2px);
}

.game-info {
    display: flex;
    gap: var(--spacing-xs);
}

.game-mode-badge,
.game-diff-badge {
    font-size: 0.7rem;
    font-weight: 600;
    padding: 0.25rem 0.75rem;
    border-radius: 20px;
    background: var(--charcoal);
    color: var(--cream);
}

.game-diff-badge {
    background: var(--accent-red);
}

.timer {
    font-size: 1.2rem;
    font-weight: 600;
    font-family: var(--font-mono);
    color: var(--charcoal);
}

/* Sudoku Grid */
.sudoku-container {
    position: relative;
    margin-bottom: var(--spacing-md);
}

.sudoku-grid {
    display: grid;
    grid-template-columns: repeat(9, 1fr);
    gap: 0;
    background: var(--charcoal);
    border: 3px solid var(--charcoal);
    border-radius: 4px;
    box-shadow: 0 8px 24px var(--shadow-strong);
    aspect-ratio: 1;
    max-width: 100%;
    margin: 0 auto;
}

.cell {
    aspect-ratio: 1;
    background: white;
    border: 1px solid var(--gray-light);
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 1.5rem;
    font-weight: 600;
    font-family: var(--font-mono);
    cursor: pointer;
    transition: all var(--transition-fast);
    position: relative;
}

/* Bordures épaisses 3x3 */
.cell:nth-child(3n) {
    border-right: 2px solid var(--charcoal);
}

.cell:nth-child(n+19):nth-child(-n+27),
.cell:nth-child(n+46):nth-child(-n+54) {
    border-bottom: 2px solid var(--charcoal);
}

.cell.fixed {
    background: var(--cream);
    color: var(--charcoal);
    font-weight: 700;
    cursor: default;
}

.cell.selected {
    background: #fff3e0;
    border: 2px solid var(--accent-red);
    z-index: 1;
}

.cell.highlighted {
    background: #f5f5f5;
}

.cell.same-value {
    background: #bbdefb;
    font-weight: 700;
}

.cell.error {
    background: #ffebee;
    color: var(--accent-red);
    animation: shake 0.3s ease;
}

@keyframes shake {
    0%, 100% { transform: translateX(0); }
    25% { transform: translateX(-4px); }
    75% { transform: translateX(4px); }
}

.cell:not(.fixed):hover {
    background: #fafafa;
}

/* Notes */
.cell .notes {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    grid-template-rows: repeat(3, 1fr);
    gap: 1px;
    width: 100%;
    height: 100%;
    font-size: 0.5rem;
    color: var(--gray-mid);
    position: absolute;
    padding: 2px;
}

.cell .note {
    display: flex;
    align-items: center;
    justify-content: center;
}

/* Loading Overlay */
.loading-overlay {
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: rgba(250, 248, 245, 0.95);
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    gap: var(--spacing-sm);
    border-radius: 4px;
    z-index: 10;
}

.loading-overlay.hidden {
    display: none;
}

.loading-spinner {
    width: 40px;
    height: 40px;
    border: 3px solid var(--gray-light);
    border-top-color: var(--accent-red);
    border-radius: 50%;
    animation: spin 0.8s linear infinite;
}

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

/* Clavier virtuel */
.keyboard {
    display: grid;
    grid-template-columns: repeat(5, 1fr);
    gap: var(--spacing-xs);
    margin-bottom: var(--spacing-md);
}

.key-btn {
    aspect-ratio: 1;
    font-size: 1.2rem;
    font-weight: 600;
    background: white;
    border: 2px solid var(--gray-light);
    border-radius: 6px;
    transition: all var(--transition-fast);
}

.key-btn:hover {
    border-color: var(--gray-mid);
    transform: translateY(-2px);
}

.key-btn:active {
    transform: translateY(0) scale(0.95);
}

/* Contrôles */
.controls {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: var(--spacing-xs);
    margin-bottom: var(--spacing-md);
}

.control-btn {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 0.25rem;
    padding: var(--spacing-sm);
    background: white;
    border: 2px solid var(--gray-light);
    border-radius: 6px;
    transition: all var(--transition-fast);
}

.control-btn:hover {
    border-color: var(--gray-mid);
}

.control-btn.toggle-btn.active {
    background: var(--charcoal);
    border-color: var(--charcoal);
    color: var(--cream);
}

.control-btn .icon {
    font-size: 1.2rem;
}

.control-btn .label {
    font-size: 0.7rem;
    font-weight: 600;
}

/* Actions */
.actions {
    display: grid;
    grid-template-columns: repeat(2, 1fr);
    gap: var(--spacing-xs);
}

.action-btn {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: var(--spacing-xs);
    padding: var(--spacing-sm);
    background: var(--charcoal);
    color: var(--cream);
    border-radius: 6px;
    font-weight: 600;
    font-size: 0.85rem;
    transition: all var(--transition-fast);
}

.action-btn:hover {
    background: var(--accent-red);
    transform: translateY(-1px);
}

.action-btn.secondary {
    background: white;
    color: var(--charcoal);
    border: 2px solid var(--gray-light);
}

.action-btn.secondary:hover {
    border-color: var(--gray-mid);
    background: white;
}

.action-btn.toggle-btn.active {
    background: var(--accent-red);
}

.action-btn .icon {
    font-size: 1rem;
}

/* ===========================
   Modals
   =========================== */
.modal {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: rgba(26, 26, 26, 0.8);
    display: flex;
    align-items: center;
    justify-content: center;
    z-index: 100;
    padding: var(--spacing-md);
}

.modal.hidden {
    display: none;
}

.modal-content {
    background: var(--cream);
    padding: var(--spacing-xl);
    border-radius: 8px;
    max-width: 400px;
    width: 100%;
    text-align: center;
    animation: modalIn var(--transition-normal);
}

@keyframes modalIn {
    from {
        opacity: 0;
        transform: scale(0.9);
    }
    to {
        opacity: 1;
        transform: scale(1);
    }
}

.modal h2 {
    font-family: var(--font-display);
    font-size: 2rem;
    margin-bottom: var(--spacing-md);
    color: var(--charcoal);
}

.modal-btn {
    width: 100%;
    padding: var(--spacing-md);
    margin-top: var(--spacing-sm);
    background: var(--charcoal);
    color: var(--cream);
    font-weight: 600;
    border-radius: 6px;
    transition: all var(--transition-fast);
}

.modal-btn:hover {
    background: var(--accent-red);
}

.modal-btn.secondary {
    background: white;
    color: var(--charcoal);
    border: 2px solid var(--gray-light);
}

.modal-btn.secondary:hover {
    border-color: var(--gray-mid);
    background: white;
}

.win-time {
    font-size: 1.5rem;
    font-weight: 600;
    color: var(--accent-red);
    margin-bottom: var(--spacing-sm);
}

.win-message {
    color: var(--gray-mid);
    margin-bottom: var(--spacing-md);
}

/* ===========================
   Responsive
   =========================== */
@media (max-width: 640px) {
    :root {
        --cell-size: 2.5rem;
    }
    
    .title-jp {
        font-size: 3rem;
    }
    
    .title-latin {
        font-size: 1.2rem;
    }
    
    .difficulty-grid {
        grid-template-columns: repeat(2, 1fr);
    }
    
    .mode-options {
        grid-template-columns: 1fr;
    }
    
    .alphabet-grid {
        grid-template-columns: repeat(2, 1fr);
    }
    
    .symbol-grid {
        grid-template-columns: repeat(auto-fill, minmax(45px, 1fr));
    }
    
    .cell {
        font-size: 1.2rem;
    }
    
    .cell .notes {
        font-size: 0.4rem;
    }
    
    .keyboard {
        grid-template-columns: repeat(5, 1fr);
    }
    
    .controls {
        grid-template-columns: repeat(2, 1fr);
    }
    
    .control-btn .label {
        display: none;
    }
}

@media (max-width: 400px) {
    .cell {
        font-size: 1rem;
    }
    
    .key-btn {
        font-size: 1rem;
    }
}

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

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