/* ============================================
   RESET E CONFIGURAZIONE BASE
   Stili per la pagina delle regole del Sudoku
   ============================================ */

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

/* Variabili colore tema */
:root {
    --primary-color: #808080;  /* Grigio tema */
    --dark-color: #4d4d4d;     /* Grigio scuro */
}

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

/* Body con sfondo fisso */
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;
    padding: 20px;
}

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

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

body > div:first-child table {
    border-collapse: collapse;
    margin: 0 auto;
}

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

/* Container principale pagina regole */
.container {
    max-width: 1200px;
    margin: 0 auto;
    background: rgba(0, 0, 0, 0.7);
    border-radius: 20px;
    padding: 40px;
    box-shadow: 0 10px 30px rgba(0, 0, 0, 0.5);
}

h1 {
    text-align: center;
    color: white;
    margin-bottom: 40px;
    font-size: 3em;
    text-shadow: 2px 2px 4px rgba(0, 0, 0, 0.5);
    letter-spacing: 2px;
}

.content {
    line-height: 1.8;
    color: white;
}

/* ============================================
   SEZIONE INTRODUTTIVA
   ============================================ */

/* Sezione obiettivo del gioco */
.intro-section {
    text-align: center;
    margin-bottom: 50px;
    padding: 30px;
    background: rgba(255, 255, 255, 0.05);
    border-radius: 15px;
    border: 2px solid rgba(255, 255, 255, 0.1);
}

.intro-section h2 {
    color: white;
    margin-bottom: 20px;
    font-size: 2em;
}

.intro-section p {
    font-size: 1.2em;
    line-height: 1.8;
}

/* ============================================
   GRIGLIA REGOLE FONDAMENTALI
   ============================================ */

/* Sezione con le tre regole del Sudoku */
.rules-grid {
    margin-bottom: 50px;
}

.rules-grid h2 {
    text-align: center;
    color: white;
    margin-bottom: 30px;
    font-size: 2em;
    border-bottom: 3px solid var(--primary-color);
    padding-bottom: 15px;
}

.rules-container {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: 25px;
    margin-bottom: 20px;
}

/* ============================================
   CARD DELLE REGOLE
   ============================================ */

/* Singola card regola con effetti hover */
.rule-card {
    background: linear-gradient(135deg, rgba(255, 255, 255, 0.1) 0%, rgba(255, 255, 255, 0.05) 100%);
    padding: 30px;
    border-radius: 15px;
    border: 2px solid rgba(255, 255, 255, 0.1);
    transition: all 0.3s ease;
    position: relative;
    overflow: hidden;
}

.rule-card::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    width: 5px;
    height: 100%;
    background: var(--primary-color);
    transition: width 0.3s ease;
}

.rule-card:hover {
    transform: translateY(-10px);
    box-shadow: 0 15px 30px rgba(0, 0, 0, 0.3);
    border-color: var(--primary-color);
}

.rule-card:hover::before {
    width: 100%;
    opacity: 0.1;
}

/* Numero identificativo della regola (1, 2, 3) */
.rule-number {
    width: 50px;
    height: 50px;
    background: var(--primary-color);
    color: white;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 1.8em;
    font-weight: bold;
    margin-bottom: 15px;
    box-shadow: 0 5px 15px rgba(0, 0, 0, 0.3);
}

.rule-card h3 {
    color: white;
    margin-bottom: 15px;
    font-size: 1.4em;
}

.rule-card p {
    margin: 0;
    font-size: 1.05em;
    line-height: 1.6;
}

/* ============================================
   SEZIONE A DUE COLONNE (COME GIOCARE E STRATEGIE)
   ============================================ */

/* Layout a due colonne responsive */
.two-column-section {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(450px, 1fr));
    gap: 30px;
    margin-bottom: 50px;
}

.column {
    background: rgba(255, 255, 255, 0.05);
    padding: 30px;
    border-radius: 15px;
    border: 2px solid rgba(255, 255, 255, 0.1);
}

.column h2 {
    color: white;
    margin-bottom: 25px;
    font-size: 1.8em;
    border-bottom: 3px solid var(--primary-color);
    padding-bottom: 10px;
}

/* ============================================
   LISTE ORDINATE E NON ORDINATE
   ============================================ */

/* Lista passi numerati (Come si Gioca) */
.steps {
    list-style: none;
    counter-reset: step-counter;
    padding-left: 0;
}

.steps li {
    counter-increment: step-counter;
    margin: 15px 0;
    padding: 15px 15px 15px 60px;
    background: rgba(255, 255, 255, 0.08);
    border-radius: 10px;
    position: relative;
    transition: all 0.3s ease;
}

.steps li:hover {
    background: rgba(255, 255, 255, 0.12);
    transform: translateX(5px);
}

.steps li::before {
    content: counter(step-counter);
    position: absolute;
    left: 15px;
    top: 50%;
    transform: translateY(-50%);
    background: var(--primary-color);
    color: white;
    width: 35px;
    height: 35px;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    font-weight: bold;
    font-size: 1.2em;
}

/* Lista consigli con icona lampadina */
.tips {
    list-style: none;
    padding-left: 0;
}

.tips li {
    padding: 15px 15px 15px 50px;
    margin: 12px 0;
    background: rgba(255, 243, 205, 0.15);
    border-radius: 10px;
    position: relative;
    border-left: 4px solid var(--primary-color);
    transition: all 0.3s ease;
}

.tips li:hover {
    background: rgba(255, 243, 205, 0.25);
    transform: translateX(5px);
}

.tips li::before {
    content: "💡";
    position: absolute;
    left: 15px;
    font-size: 1.3em;
    top: 50%;
    transform: translateY(-50%);
}

/* ============================================
   SEZIONE FUNZIONALITÀ DEL GIOCO
   ============================================ */

/* Sezione con griglia delle funzioni disponibili */
.features-section {
    margin-bottom: 50px;
}

.features-section h2 {
    text-align: center;
    color: white;
    margin-bottom: 30px;
    font-size: 2em;
    border-bottom: 3px solid var(--primary-color);
    padding-bottom: 15px;
}

.features-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 20px;
}

.feature-card {
    background: rgba(255, 255, 255, 0.08);
    padding: 25px;
    border-radius: 15px;
    text-align: center;
    border: 2px solid rgba(255, 255, 255, 0.1);
    transition: all 0.3s ease;
}

.feature-card:hover {
    transform: translateY(-5px);
    background: rgba(255, 255, 255, 0.12);
    border-color: var(--primary-color);
    box-shadow: 0 10px 25px rgba(0, 0, 0, 0.3);
}

.feature-icon {
    font-size: 3em;
    margin-bottom: 15px;
}

.feature-card h3 {
    color: white;
    margin-bottom: 10px;
    font-size: 1.3em;
}

.feature-card p {
    color: rgba(255, 255, 255, 0.9);
    font-size: 0.95em;
    line-height: 1.5;
}

/* ============================================
   CALL TO ACTION
   ============================================ */

/* Sezione con pulsante "Inizia a Giocare" */
.cta {
    text-align: center;
    margin-top: 40px;
    padding-top: 30px;
    border-top: 2px solid #ddd;
}

.play-button {
    display: inline-block;
    background: linear-gradient(135deg, var(--primary-color) 0%, var(--dark-color) 100%);
    color: white;
    text-decoration: none;
    padding: 15px 40px;
    border-radius: 50px;
    font-weight: bold;
    font-size: 1.3em;
    transition: all 0.3s;
    box-shadow: 0 5px 15px rgba(0, 0, 0, 0.3);
}

.play-button:hover {
    transform: translateY(-3px);
    box-shadow: 0 8px 20px rgba(0, 0, 0, 0.5);
}

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

/* Adattamenti per tablet e mobile */
@media (max-width: 768px) {
    .container {
        padding: 20px;
    }
    
    h1 {
        font-size: 2em;
    }
    
    .rule-section h2 {
        font-size: 1.5em;
    }
    
    .steps li {
        padding-left: 55px;
    }
    
    .steps li::before {
        width: 30px;
        height: 30px;
        font-size: 1em;
    }
    
    .difficulty-levels {
        grid-template-columns: 1fr;
    }
}