:root {
    --primary: #2563eb;
    --secondary: #0ea5e9;
    --dark: #1e293b;
    --light: #f1f5f9;
    --accent: #10b981;
    --text: #334155;
    --text-light: #475569;
    --white: #ffffff;
    --shadow: 0 2px 10px rgba(0,0,0,0.1);
    --shadow-hover: 0 6px 16px rgba(0,0,0,0.12);
    --transition: all 0.3s ease;
}

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

body {
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    background-color: #f8fafc;
    color: var(--text);
    line-height: 1.6;
    min-height: 100vh;
    display: flex;
    flex-direction: column;
}

header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 1rem 5%;
    background-color: var(--white);
    box-shadow: var(--shadow);
    position: sticky;
    top: 0;
    z-index: 100;
}

.logo {
    font-size: 1.8rem;
    font-weight: 700;
    color: var(--primary);
}

nav ul {
    display: flex;
    list-style: none;
    gap: 2rem;
}

nav a {
    text-decoration: none;
    color: var(--dark);
    font-weight: 500;
    transition: var(--transition);
}

nav a:hover,
nav a:focus {
    color: var(--primary);
    outline: none;
}

/* Contenedor para los botones de autenticación y Patreon */
.auth-buttons,
.patreon-buttons {
    display: flex;
    gap: 1rem;
    align-items: center;
}

/* Estilos comunes para los botones (ahora incluye #patreonBtn) */
#loginBtn,
#registerBtn,
#patreonBtn {
    background: var(--primary);
    color: var(--white);
    border: none;
    padding: 0.6rem 1.5rem;
    border-radius: 6px;
    cursor: pointer;
    font-weight: 500;
    font-size: 0.95rem;
    transition: var(--transition);
    text-decoration: none;
    display: inline-block;
    text-align: center;
    min-width: 120px;
}

/* Efectos hover/focus (ahora incluye #patreonBtn) */
#loginBtn:hover,
#loginBtn:focus,
#registerBtn:hover,
#registerBtn:focus,
#patreonBtn:hover,
#patreonBtn:focus {
    background: #1d4ed8;
    transform: translateY(-1px);
    box-shadow: 0 4px 12px rgba(37, 99, 235, 0.3);
    outline: none;
}

/* Variación sutil para diferenciación */
#registerBtn {
    background: linear-gradient(135deg, var(--primary) 0%, #1d4ed8 100%);
    font-weight: 600;
}

#registerBtn:hover,
#registerBtn:focus {
    background: linear-gradient(135deg, #1d4ed8 0%, #1e40af 100%);
}

.hero {
    min-height: 70vh;
    background: linear-gradient(120deg, #e0f2fe 0%, #bae6fd 100%);
    display: flex;
    align-items: center;
    padding: 2rem 5%;
    text-align: center;
    flex-direction: column;
    justify-content: center;
}

.hero-content {
    max-width: 800px;
}

.hero h1 {
    font-size: clamp(1.8rem, 5vw, 2.8rem);
    margin-bottom: 1.5rem;
    color: var(--dark);
}

.hero p {
    font-size: clamp(1rem, 2.5vw, 1.2rem);
    margin-bottom: 2.5rem;
    color: var(--text-light);
    max-width: 600px;
    margin-left: auto;
    margin-right: auto;
}

.cta-button {
    background: var(--accent);
    color: var(--white);
    font-size: 1.1rem;
    padding: 0.8rem 2.5rem;
    border: none;
    border-radius: 6px;
    cursor: pointer;
    transition: var(--transition);
    font-weight: 600;
}

.cta-button:hover,
.cta-button:focus {
    transform: translateY(-3px);
    background: #0da271;
    outline: none;
}

.simulations {
    padding: 4rem 5%;
    background-color: #f8fafc;
    flex-grow: 1;
}

.simulations h2 {
    text-align: center;
    font-size: clamp(1.5rem, 4vw, 2.2rem);
    margin-bottom: 2.5rem;
    color: var(--dark);
}

.cases-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: 1.8rem;
    max-width: 1200px;
    margin: 0 auto;
}

.case-card {
    background: var(--white);
    border-radius: 12px;
    padding: 1.8rem;
    box-shadow: 0 4px 12px rgba(0,0,0,0.08);
    transition: var(--transition);
    display: flex;
    flex-direction: column;
}

.case-card:hover {
    transform: translateY(-5px);
    box-shadow: var(--shadow-hover);
}

.case-card h3 {
    font-size: 1.4rem;
    margin-bottom: 0.8rem;
    color: var(--primary);
}

.case-card p {
    color: var(--text-light);
    margin-bottom: 1.2rem;
    flex-grow: 1;
}

.difficulty {
    display: inline-block;
    padding: 0.3rem 0.8rem;
    border-radius: 20px;
    font-size: 0.85rem;
    margin-bottom: 1.2rem;
    align-self: flex-start;
}

.difficulty-basic {
    background-color: #dcfce7;
    color: #166534;
}

.difficulty-intermediate {
    background-color: #dbeafe;
    color: #1e40af;
}

.difficulty-moderate {
    background-color: #fef3c7;
    color: #92400e;
}

.difficulty-advanced {
    background-color: #fee2e2;
    color: #b91c1c;
}

.case-btn {
    background: var(--primary);
    color: var(--white);
    border: none;
    padding: 0.7rem 1.5rem;
    border-radius: 6px;
    cursor: pointer;
    font-weight: 500;
    width: 100%;
    transition: var(--transition);
}

.case-btn:hover,
.case-btn:focus {
    background: #1d4ed8;
    outline: none;
}

footer {
    background: var(--dark);
    color: var(--white);
    text-align: center;
    padding: 1.5rem;
    margin-top: 2rem;
}

footer a {
    color: var(--secondary);
    text-decoration: none;
}

footer a:hover,
footer a:focus {
    text-decoration: underline;
    outline: none;
}

.skip-link {
    position: absolute;
    top: -40px;
    left: 0;
    background: var(--primary);
    color: white;
    padding: 8px;
    z-index: 1000;
    transition: top 0.3s;
}

.skip-link:focus {
    top: 0;
}

.mobile-menu-btn {
    display: none;
}

/* Media queries para pantallas grandes (13+ pulgadas) */
@media (min-width: 1024px) {
    header {
        display: grid;
        grid-template-columns: auto 1fr auto;
        align-items: center;
        gap: 2rem;
    }
    
    nav {
        justify-self: center;
    }
    
    .auth-buttons,
    .patreon-buttons {
        justify-self: end;
        gap: 1.2rem;
    }
    
    #loginBtn,
    #registerBtn,
    #patreonBtn {
        padding: 0.7rem 1.8rem;
        font-size: 1rem;
        min-width: 130px;
    }
}

@media (max-width: 1023px) {
    header {
        flex-wrap: wrap;
        gap: 1rem;
    }
    
    .auth-buttons,
    .patreon-buttons {
        order: 3;
        flex-basis: 100%;
        justify-content: center;
        gap: 1rem;
    }
    
    .mobile-menu-btn {
        display: block;
        background: none;
        border: none;
        font-size: 1.5rem;
        cursor: pointer;
        color: var(--dark);
    }
    
    nav ul {
        display: none;
        flex-direction: column;
        width: 100%;
        text-align: center;
        order: 4;
        flex-basis: 100%;
    }
    
    nav ul.show {
        display: flex;
    }
}

@media (max-width: 768px) {
    .hero {
        padding: 3rem 5%;
    }
    
    .cases-grid {
        grid-template-columns: 1fr;
    }
    
    nav ul {
        gap: 1rem;
    }
}

@media (max-width: 480px) {
    .hero {
        padding: 2rem 5%;
    }
    
    .simulations {
        padding: 2rem 5%;
    }
    
    .case-card {
        padding: 1.2rem;
    }
    
    .auth-buttons,
    .patreon-buttons {
        flex-direction: column;
        gap: 0.8rem;
    }
    
    #loginBtn,
    #registerBtn,
    #patreonBtn {
        width: 100%;
        min-width: auto;
    }
}