:root {
    --accent: #3b82f6;
    --indigo: #6366f1;
    --bg-dark: #0f172a;
    --glass: rgba(255, 255, 255, 0.05);
    --glass-border: rgba(255, 255, 255, 0.15);
}

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

body {
    font-family: 'Outfit', sans-serif;
    background-color: var(--bg-dark);
    color: white;
    overflow-x: hidden;
    scroll-behavior: smooth;
}

.liquid-background {
    position: fixed;
    top: 0;
    left: 0;
    width: 100vw;
    height: 100vh;
    z-index: -1;
    background: linear-gradient(135deg, #1e1b4b 0%, #1e3a8a 50%, #312e81 100%);
    filter: blur(80px);
    opacity: 0.6;
}

.glass-nav {
    position: sticky;
    top: 0;
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 1.5rem 10%;
    background: rgba(15, 23, 42, 0.8);
    backdrop-filter: blur(12px);
    z-index: 100;
    border-bottom: 1px solid var(--glass-border);
}

.logo {
    font-size: 1.8rem;
    font-weight: 800;
    background: linear-gradient(to right, #60a5fa, #a78bfa);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
}

.nav-links a {
    color: rgba(255, 255, 255, 0.7);
    text-decoration: none;
    margin-left: 2rem;
    font-weight: 600;
    transition: color 0.3s;
}

.nav-links a:hover {
    color: white;
}

.hero {
    height: 80vh;
    display: flex;
    flex-direction: column;
    justify-content: center;
    align-items: center;
    text-align: center;
    padding: 0 10%;
}

h1 {
    font-size: 5rem;
    font-weight: 800;
    margin-bottom: 1rem;
    letter-spacing: -2px;
}

.tagline {
    font-size: 1.5rem;
    color: rgba(255, 255, 255, 0.6);
    max-width: 600px;
    margin-bottom: 2rem;
}

.app-badges {
    margin-top: 2rem;
}

.app-store-badge {
    display: inline-block;
    transition: transform 0.3s, opacity 0.3s;
}

.app-store-badge:hover {
    transform: scale(1.05);
    opacity: 0.9;
}

.section {
    padding: 4rem 10%;
}

.glass-card {
    background: var(--glass);
    backdrop-filter: blur(16px);
    border: 1px solid var(--glass-border);
    border-radius: 2rem;
    padding: 3rem;
    box-shadow: 0 25px 50px -12px rgba(0, 0, 0, 0.5);
}

h2 {
    font-size: 2.5rem;
    margin-bottom: 2rem;
    text-align: center;
}

.features-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 2rem;
}

.feature {
    text-align: center;
    padding: 1.5rem;
}

.feature .icon {
    font-size: 3rem;
    margin-bottom: 1rem;
}

.guide-content {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 3rem;
}

.device-guide h3 {
    margin-bottom: 1.5rem;
    color: var(--accent);
}

.device-guide ul {
    list-style: none;
}

.device-guide li {
    margin-bottom: 1rem;
    padding-left: 1.5rem;
    position: relative;
}

.device-guide li::before {
    content: "→";
    position: absolute;
    left: 0;
    color: var(--accent);
}

/* Sudoku Game Styling */
.sudoku-grid {
    display: grid;
    grid-template-columns: repeat(9, 1fr);
    width: 100%;
    max-width: 450px;
    margin: 2rem auto;
    background: rgba(255, 255, 255, 0.1);
    border: 3px solid rgba(255, 255, 255, 0.4);
    gap: 1px;
}

.cell {
    aspect-ratio: 1;
    background: rgba(15, 23, 42, 0.6);
    display: flex;
    justify-content: center;
    align-items: center;
    font-size: 1.2rem;
    font-weight: 600;
    cursor: pointer;
    transition: background 0.2s;
    border-right: 1px solid rgba(255, 255, 255, 0.1);
    border-bottom: 1px solid rgba(255, 255, 255, 0.1);
}

/* Bordes gruesos entre bloques de 3x3 */
.cell:nth-child(9n+3) {
    border-right: 3px solid rgba(255, 255, 255, 0.4);
}

.cell:nth-child(9n+6) {
    border-right: 3px solid rgba(255, 255, 255, 0.4);
}

/* Filas 3 y 6 (índices 2 y 5) necesitan borde inferior grueso */
.cell[data-row="2"],
.cell[data-row="5"] {
    border-bottom: 3px solid rgba(255, 255, 255, 0.4);
}

.cell:hover {
    background: rgba(59, 130, 246, 0.2);
}

.cell.selected {
    background: rgba(59, 130, 246, 0.4);
    outline: 2px solid var(--accent);
    z-index: 1;
}

.cell.highlighted {
    background: rgba(255, 255, 255, 0.08);
}

.cell.fixed {
    color: rgba(255, 255, 255, 0.4);
    cursor: default;
}

.num-pad {
    display: flex;
    justify-content: center;
    gap: 0.5rem;
    margin-top: 2rem;
}

.num-pad button {
    width: 40px;
    height: 40px;
    border-radius: 8px;
    border: 1px solid var(--glass-border);
    background: var(--glass);
    color: white;
    font-weight: bold;
    cursor: pointer;
}

.num-pad button:hover {
    background: var(--accent);
}

/* Support Form Styling */
.support-form {
    display: flex;
    flex-direction: column;
    gap: 1.5rem;
    max-width: 500px;
    margin: 2rem auto;
}

.form-group {
    display: flex;
    flex-direction: column;
    gap: 0.5rem;
}

.form-group label {
    font-weight: 600;
    color: rgba(255, 255, 255, 0.8);
    font-size: 0.9rem;
}

.form-group input,
.form-group textarea {
    padding: 1rem;
    border-radius: 0.8rem;
    border: 1px solid var(--glass-border);
    background: rgba(255, 255, 255, 0.05);
    color: white;
    font-family: 'Outfit', sans-serif;
    font-size: 1rem;
    transition: border-color 0.3s, box-shadow 0.3s;
}

.form-group input:focus,
.form-group textarea:focus {
    outline: none;
    border-color: var(--accent);
    box-shadow: 0 0 0 3px rgba(59, 130, 246, 0.2);
}

.form-group textarea {
    resize: vertical;
    min-height: 120px;
}

.form-status {
    text-align: center;
    padding: 1rem;
    border-radius: 0.8rem;
    font-weight: 600;
    display: none;
}

.form-status.success {
    display: block;
    background: rgba(34, 197, 94, 0.2);
    color: #4ade80;
    border: 1px solid rgba(34, 197, 94, 0.3);
}

.form-status.error {
    display: block;
    background: rgba(239, 68, 68, 0.2);
    color: #f87171;
    border: 1px solid rgba(239, 68, 68, 0.3);
}

.cta-button {
    display: inline-block;
    background: var(--accent);
    color: white;
    padding: 1rem 2rem;
    border-radius: 1rem;
    text-decoration: none;
    font-weight: 700;
    margin-top: 1rem;
    transition: transform 0.2s;
}

.cta-button:hover {
    transform: scale(1.05);
}

footer {
    padding: 4rem 10%;
    text-align: center;
    border-top: 1px solid var(--glass-border);
    color: rgba(255, 255, 255, 0.4);
}

.footer-links a {
    color: rgba(255, 255, 255, 0.4);
    margin: 0 1rem;
    text-decoration: none;
}

@keyframes drop {
    from { transform: translateY(-50px); opacity: 0; }
    to { transform: translateY(0); opacity: 1; }
}

.animate-drop { animation: drop 1s ease-out; }

/* Responsive Mobile */
@media (max-width: 768px) {
    .glass-nav {
        flex-direction: column;
        gap: 1rem;
        padding: 1rem 5%;
    }

    .nav-links {
        display: flex;
        flex-wrap: wrap;
        justify-content: center;
        gap: 0.5rem;
    }

    .nav-links a {
        margin-left: 0;
        font-size: 0.85rem;
        padding: 0.4rem 0.8rem;
        background: rgba(255, 255, 255, 0.05);
        border-radius: 8px;
        border: 1px solid var(--glass-border);
    }

    .hero {
        height: auto;
        min-height: 60vh;
        padding: 4rem 5%;
    }

    h1 {
        font-size: 2.8rem;
        letter-spacing: -1px;
    }

    h2 {
        font-size: 1.8rem;
    }

    .tagline {
        font-size: 1.1rem;
    }

    .section {
        padding: 2rem 5%;
    }

    .glass-card {
        padding: 1.5rem;
        border-radius: 1.25rem;
    }

    .guide-content {
        grid-template-columns: 1fr;
        gap: 1.5rem;
    }

    .sudoku-grid {
        max-width: 320px;
    }

    .cell {
        font-size: 1rem;
    }

    .num-pad button {
        width: 34px;
        height: 34px;
        font-size: 0.85rem;
    }

    .support-form {
        max-width: 100%;
    }

    footer {
        padding: 2rem 5%;
    }

    .footer-links {
        display: flex;
        flex-wrap: wrap;
        justify-content: center;
        gap: 0.5rem;
    }
}

@media (max-width: 480px) {
    h1 {
        font-size: 2.2rem;
    }

    .features-grid {
        grid-template-columns: 1fr;
    }

    .num-pad {
        flex-wrap: wrap;
    }
}