:root {
    /* Palette: Deep Black, Dark Gray, and Vibrant Green */
    --bg-base: #0d0d0d;
    --bg-pattern-line: #1a1a1a; 
    
    --main-card-bg: #141414;
    --inner-card-bg: #1e1e1e;
    --inner-card-hover: #262626;
    
    --text-main: #ffffff;
    --text-muted: #94a3b8;
    --accent: #4ade80; 
    --border-muted: #2a2a2a;
    --border-radius-lg: 24px;
    --border-radius-md: 16px;
}

* {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
}

body {
    display: flex;
    justify-content: center;
    align-items: center;
    min-height: 100vh;
    padding: 2rem;
    color: var(--text-main);
    
    /* --- The CSS Check-Cross Pattern --- */
    background-color: var(--bg-base);
    background-image:
        linear-gradient(90deg, var(--bg-pattern-line) 1px, transparent 1px),
        linear-gradient(0deg, var(--bg-pattern-line) 1px, transparent 1px),
        linear-gradient(45deg, var(--bg-pattern-line) 25%, transparent 25%, transparent 75%, var(--bg-pattern-line) 75%),
        linear-gradient(45deg, var(--bg-pattern-line) 25%, transparent 25%, transparent 75%, var(--bg-pattern-line) 75%);
    background-size: 20px 20px, 20px 20px, 10px 10px, 10px 10px;
    background-position: 0 0, 0 0, 0 0, 5px 5px;
}

/* --- The Main Layout Card --- */
.main-wrapper-card {
    background-color: var(--main-card-bg);
    border: 1px solid var(--border-muted);
    border-radius: var(--border-radius-lg);
    width: 100%;
    max-width: 1100px;
    padding: 4rem;
    box-shadow: 0 25px 50px -12px rgba(0, 0, 0, 0.5);
    display: flex;
    flex-direction: column;
}

header {
    text-align: center;
    margin-bottom: 3.5rem;
}

header h1 {
    font-size: 3rem;
    letter-spacing: -1.5px;
    font-weight: 800;
    margin-bottom: 0.5rem;
}

header p {
    color: var(--text-muted);
    font-size: 1.1rem;
}

/* --- Navigation & Links --- */
.back-link {
    color: var(--accent);
    text-decoration: none;
    font-size: 0.95rem;
    font-weight: 600;
    transition: opacity 0.2s;
    display: inline-block;
    margin-bottom: 1rem;
}

.back-link:hover {
    opacity: 0.7;
}

.play-button-container {
    display: flex;
    justify-content: center;
    margin: 2rem 0;
}

.play-button {
    background-color: var(--accent);
    color: var(--bg-base);
    text-decoration: none;
    font-weight: 800;
    font-size: 1.25rem;
    padding: 1rem 3rem;
    border-radius: var(--border-radius-md);
    transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
    border: 2px solid var(--accent);
    box-shadow: 0 10px 15px -3px rgba(74, 222, 128, 0.3);
}

.play-button:hover {
    background-color: transparent;
    color: var(--accent);
    box-shadow: 0 20px 25px -5px rgba(74, 222, 128, 0.2);
}

/* --- Game/Battle Area --- */
.container {
    display: flex;
    gap: 2.5rem;
    width: 100%;
    justify-content: center;
    flex-wrap: wrap;
}

.game-area {
    display: flex;
    align-items: center;
    gap: 1.5rem;
    flex: 2;
    min-width: 350px;
}

.card {
    background-color: var(--inner-card-bg);
    border: 1px solid var(--border-muted);
    border-radius: var(--border-radius-md);
    padding: 3rem 1.5rem;
    text-align: center;
    cursor: pointer;
    flex: 1;
    display: flex;
    flex-direction: column;
    justify-content: center;
    align-items: center;
    min-height: 320px;
    transition: all 0.2s ease;
}

.card:hover {
    background-color: var(--inner-card-hover);
    border-color: var(--accent);
    box-shadow: 0 0 20px rgba(74, 222, 128, 0.1);
}

.card h2 {
    font-size: 2.2rem;
    margin-bottom: 1rem;
    letter-spacing: -0.5px;
}

.card p {
    color: var(--text-muted);
    line-height: 1.5;
    margin-bottom: 1.5rem;
}

.vs-badge {
    color: var(--border-muted);
    font-weight: 900;
    font-size: 0.9rem;
    background: var(--bg-base);
    width: 50px;
    height: 50px;
    border-radius: 50%;
    display: flex;
    justify-content: center;
    align-items: center;
    border: 1px solid var(--border-muted);
    flex-shrink: 0;
}

.category-tag {
    padding: 0.3rem 0.8rem;
    background: rgba(255, 255, 255, 0.05);
    border-radius: 20px;
    font-size: 0.7rem;
    color: var(--accent);
    text-transform: uppercase;
    letter-spacing: 1px;
    font-weight: bold;
}


/* --- Mobile Responsiveness --- */
@media (max-width: 768px) {
    .main-wrapper-card { padding: 2rem 1.5rem; }
    header h1 { font-size: 2.2rem; }
    .game-area { flex-direction: column; }
    .vs-badge { margin: -1rem 0; z-index: 10; }
    .card { width: 100%; min-height: 250px; }
}