/* ============================================
   RESET E CONFIGURAZIONE BASE
   ============================================ */

/* Reset margini e padding, box-sizing uniforme */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

/* Variabili CSS per colori del tema */
:root {
    --primary-color: #808080;  /* Grigio principale */
    --dark-color: #4d4d4d;     /* Grigio scuro */
}

/* ============================================
   STILI BODY E LAYOUT GENERALE
   ============================================ */

/* Body con sfondo fisso e layout centrato */
body {
    font-family: 'Arial';
    background-image: url('../img/sfondo3.jpg');
    background-size: cover;
    background-position: center;
    background-attachment: fixed;
    background-repeat: no-repeat;
    min-height: 100vh;
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    padding: 20px;
}

/* ============================================
   MENU DI NAVIGAZIONE
   ============================================ */

/* Stile del menu di navigazione superiore */
body > div:first-child {
    background: rgba(0, 0, 0, 0.5);
    border-radius: 10px;
    padding: 15px 30px;
    margin-bottom: 20px;
    box-shadow: 0 4px 6px rgba(0, 0, 0, 0.3);
}

body > div:first-child table {
    border-collapse: collapse;
}

body > div:first-child td {
    padding: 10px 20px;
}

body > div:first-child a {
    text-decoration: none;
    color: white;
    font-weight: bold;
    font-size: 18px;
    transition: color 0.3s;
}

body > div:first-child a:hover {
    color: var(--primary-color);
}

/* ============================================
   CONTAINER PRINCIPALE E TITOLO
   ============================================ */

/* Container principale con sfondo semi-trasparente */
.container {
    background: rgba(0, 0, 0, 0.5);
    border-radius: 20px;
    padding: 30px;
    box-shadow: 0 10px 30px rgba(0, 0, 0, 0.5);
    max-width: 950px;
    width: 100%;
}

h1 {
    text-align: center;
    color: white;
    margin-bottom: 20px;
    font-size: 2.5em;
    text-shadow: 2px 2px 4px rgba(0, 0, 0, 0.5);
}

/* ============================================
   CONTROLLI E PULSANTI DI DIFFICOLTÀ
   ============================================ */

/* Area controlli */
.controls {
    margin-bottom: 20px;
}

.left-section {
    display: flex;
    flex-direction: column;
    gap: 15px;
}

.difficulty {
    display: flex;
    gap: 10px;
    justify-content: flex-start;
}

.difficulty label {
    font-weight: bold;
    color: white;
    margin-right: 10px;
}

.btn-difficulty {
    background: transparent;
    border: none;
    padding: 8px 0px;
    margin: 0 5px;
    border-radius: 5px;
    cursor: pointer;
    font-weight: bold;
    color: white;
    transition: all 0.3s;
}

.btn-difficulty:hover {
    color: var(--primary-color);
    text-shadow: 0 0 10px var(--primary-color);
}

.btn-difficulty.active {
    color: var(--primary-color);
    text-shadow: 0 0 10px var(--primary-color);
}

.game-controls {
    display: none;
}

.btn {
    background: var(--primary-color);
    color: white;
    border: none;
    padding: 10px 20px;
    border-radius: 8px;
    cursor: pointer;
    font-weight: bold;
    font-size: 14px;
    transition: all 0.3s;
    box-shadow: 0 2px 5px rgba(0, 0, 0, 0.2);
}

.btn:hover {
    background: var(--dark-color);
    transform: translateY(-2px);
    box-shadow: 0 4px 8px rgba(0, 0, 0, 0.3);
}

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

.btn.active {
    background: #28a745;
    box-shadow: 0 0 10px rgba(40, 167, 69, 0.5);
}

.message {
    position: fixed;
    top: -100px;
    left: 50%;
    transform: translateX(-50%);
    padding: 15px 30px;
    border-radius: 20px;
    font-weight: bold;
    font-size: 16px;
    box-shadow: 0 8px 20px rgba(0, 0, 0, 0.3);
    z-index: 1000;
    opacity: 0;
    transition: all 0.5s ease;
    min-width: 200px;
    text-align: center;
}

.message::after {
    content: '';
    position: absolute;
    bottom: -10px;
    left: 50%;
    transform: translateX(-50%);
    width: 0;
    height: 0;
    border-left: 10px solid transparent;
    border-right: 10px solid transparent;
    border-top: 10px solid inherit;
}

.message.show {
    top: 80px;
    opacity: 1;
    animation: slideDown 0.5s ease forwards;
}

@keyframes slideDown {
    0% {
        top: -100px;
        opacity: 0;
    }
    100% {
        top: 80px;
        opacity: 1;
    }
}

.message.success {
    background: #d4edda;
    color: #155724;
    border: 2px solid #155724;
}

.message.success::after {
    border-top-color: #d4edda;
}

.message.error {
    background: #f8d7da;
    color: #721c24;
    border: 2px solid #721c24;
}

.message.error::after {
    border-top-color: #f8d7da;
}

.message.info {
    background: #d1ecf1;
    color: #0c5460;
    border: 2px solid #0c5460;
}

.message.info::after {
    border-top-color: #d1ecf1;
}

/* ============================================
   GRIGLIA SUDOKU E CELLE
   ============================================ */

/* Layout principale dell'area di gioco */
.game-area {
    display: flex;
    gap: 30px;
    justify-content: center;
    align-items: center;
    flex-wrap: nowrap;
}

.sudoku-board {
    display: grid;
    grid-template-columns: repeat(9, 1fr);
    gap: 0;
    width: 100%;
    max-width: 450px;
    min-width: 300px;
    margin: 0;
    background: #000;
    border: 3px solid #000;
    border-radius: 5px;
    flex-shrink: 0;
}

/* Singola cella della griglia Sudoku */
.cell {
    aspect-ratio: 1;
    display: flex;
    align-items: center;
    justify-content: center;
    background: white;
    border: 1px solid #ccc;
    font-size: 24px;
    font-weight: bold;
    cursor: pointer;
    transition: all 0.2s;
}

.cell input {
    width: 100%;
    height: 100%;
    border: none;
    text-align: center;
    font-size: 24px;
    font-weight: bold;
    background: transparent;
    outline: none;
    color: #333;
}

.cell-wrapper {
    width: 100%;
    height: 100%;
    position: relative;
}

.cell-input {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    border: none;
    text-align: center;
    font-size: 24px;
    font-weight: bold;
    background: transparent;
    outline: none;
    color: transparent;
    caret-color: transparent;
    z-index: 1;
}

/* Container griglia 3x3 per visualizzare note multiple */
.notes-container {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    grid-template-rows: repeat(3, 1fr);
    padding: 2px;
    gap: 1px;
    pointer-events: none;
}

.note {
    font-size: 10px;
    color: #666;
    display: flex;
    align-items: center;
    justify-content: center;
    font-weight: normal;
}

/* Cella con numero fisso (non modificabile dal giocatore) */
.cell.fixed {
    background: #f0f0f0;
    cursor: default;
}

.cell.fixed input {
    color: #000;
    font-weight: bold;
    cursor: default;
}

.cell.selected {
    background: #bbdefb;
}

.cell.error {
    background: #ffcdd2;
}

.cell.correct {
    background: #c8e6c9;
}

/* ============================================
   BORDI SPESSI PER BLOCCHI 3x3
   ============================================ */

/* Bordi verticali tra blocchi (colonne 3 e 6) */
.cell:nth-child(9n+3),
.cell:nth-child(9n+6) {
    border-right: 2px solid #000;
}

.cell:nth-child(n+19):nth-child(-n+27),
.cell:nth-child(n+46):nth-child(-n+54) {
    border-bottom: 2px solid #000;
}

/* ============================================
   PALETTE NUMERI E PANNELLO DESTRO
   ============================================ */

/* Pannello destro con controlli e palette */
.right-panel {
    display: flex;
    flex-direction: column;
    gap: 15px;
}

.palette-controls {
    display: flex;
    flex-direction: row;
    gap: 10px;
    justify-content: space-between;
    align-items: center;
    margin-right: 20px;
}

.control-buttons {
    display: flex;
    gap: 10px;
}

.number-palette {
    background: transparent;
    padding: 20px;
    border-radius: 10px;
    min-width: 250px;
    flex-shrink: 0;
    display: flex;
    flex-direction: column;
}

.btn-palette {
    background: transparent;
    color: white;
    border: none;
    padding: 0;
    border-radius: 5px;
    cursor: pointer;
    font-weight: bold;
    font-size: 16px;
    transition: all 0.3s;
    box-shadow: 0 2px 5px rgba(0, 0, 0, 0.2);
    width: 32px;
    height: 32px;
    display: flex;
    align-items: center;
    justify-content: center;
}

.btn-palette .icon {
    font-size: 24px;
    line-height: 1;
}

.btn-palette .label {
    font-size: 11px;
    line-height: 1;
}

.btn-palette:hover {
    background: transparent;
    transform: translateY(-2px);
    box-shadow: 0 4px 8px rgba(0, 0, 0, 0.3);
}

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

.btn-palette.active {
    background: transparent;
    box-shadow: 0 0 10px rgba(40, 167, 69, 0.5);
}

.number-palette h3 {
    color: white;
    text-align: center;
    margin-bottom: 15px;
    font-size: 1.3em;
}

/* Griglia 3x3 per i pulsanti numerici 1-9 */
.numbers-grid {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 10px;
}

/* Singolo pulsante numerico (1-9) */
.number-btn {
    aspect-ratio: 1;
    display: flex;
    align-items: center;
    justify-content: center;
    background: transparent;
    border: 2px solid var(--primary-color);
    border-radius: 8px;
    font-size: 64px;
    font-weight: bold;
    cursor: pointer;
    transition: all 0.3s;
    position: relative;
    color: white;
    text-shadow: 2px 2px 4px rgba(0, 0, 0, 0.8);
    min-height: 100px;
}

.number-btn:hover {
    background: rgba(255, 255, 255, 0.2);
    color: white;
    transform: scale(1.1);
    border-color: var(--primary-color);
}

.number-btn.selected {
    background: rgba(255, 255, 255, 0.3);
    color: white;
    border-color: var(--primary-color);
    box-shadow: 0 0 15px var(--primary-color);
}

/* Indicatore di completamento (tutte e 9 le occorrenze inserite) */
.number-btn.completed::after {
    content: '✓';
    position: absolute;
    top: -5px;
    right: -5px;
    background: #28a745;
    color: white;
    width: 20px;
    height: 20px;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 14px;
    border: 2px solid white;
}

/* ============================================
   TIMER E STATISTICHE
   ============================================ */

/* Timer con pulsante pausa */
.timer {
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: 2px;
    margin-top: 10px;
    margin-left: 20px;
    margin-right: 20px;
    font-size: 18px;
    font-weight: bold;
    color: white;
    max-width: 210px;
}

.timer #pause-btn {
    padding: 6px;
    font-size: 16px;
    flex-shrink: 0;
    display: flex;
    align-items: center;
    justify-content: center;
    line-height: 1;
}

/* ============================================
   STATISTICHE DI GIOCO
   ============================================ */

/* Area statistiche errori e suggerimenti */
.game-stats {
    display: flex;
    justify-content: space-around;
    margin-top: 15px;
    padding: 15px;
    background: rgba(0, 0, 0, 0.4);
    border-radius: 10px;
}

.game-stats .stat {
    font-size: 16px;
    font-weight: bold;
}

.game-stats .stat span:first-child {
    color: white;
}

.game-stats .stat span:last-child {
    color: #ff6b6b;
}

/* ============================================
   RESPONSIVE DESIGN
   ============================================ */

/* Ottimizzazione per schermi piccoli */
@media (max-width: 600px) {
    .container {
        padding: 15px;
    }
    
    h1 {
        font-size: 2em;
    }
    
    .game-area {
        flex-direction: column;
        align-items: center;
    }
    
    .left-section {
        width: 100%;
        align-items: center;
    }
    
    .difficulty {
        justify-content: center;
    }
    
    .number-palette {
        width: 100%;
        max-width: 300px;
    }
    
    .cell input {
        font-size: 18px;
    }
    
    .btn {
        padding: 8px 12px;
        font-size: 12px;
    }
    
    .btn-difficulty {
        padding: 6px 10px;
        font-size: 12px;
    }
}