:root {
    --primary-color: #3498db;
    --danger-color: #e74c3c;
    --success-color: #2ecc71;
    --text-color: #2c3e50;
    --bg-color: #ecf0f1;
}

body {
    margin: 0;
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif; /* Familiar for Windows users */
    overflow: hidden;
    background-color: var(--bg-color);
    user-select: none; /* Prevent text selection during clicking */
}

#app {
    position: relative;
    width: 100vw;
    height: 100vh;
}

.screen {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    display: flex;
    flex-direction: column;
    justify-content: center;
    align-items: center;
    background: rgba(255, 255, 255, 0.9);
    z-index: 10;
}

/* Margin for buttons in screens */
.screen button {
    margin: 10px;
    min-width: 150px;
}

.hidden {
    display: none !important;
}

/* Canvas fills the screen behind UI */
canvas {
    display: block;
    cursor: crosshair;
    transition: background 1s ease;
}

canvas.level-1 { background: linear-gradient(to bottom, #87CEEB 0%, #E0F6FF 100%); } /* Day */
canvas.level-2 { background: linear-gradient(to bottom, #FF7F50 0%, #FFD700 100%); } /* Sunset */
canvas.level-3 { background: linear-gradient(to bottom, #2c3e50 0%, #3498db 100%); } /* Night */
canvas.level-4 { background: linear-gradient(to bottom, #1a2a6c 0%, #b21f1f 100%, #fdbb2d 100%); } /* Dusk */
canvas.level-5 { background: linear-gradient(to bottom, #000000 0%, #434343 100%); } /* Space */
canvas.level-6 { background: linear-gradient(to bottom, #87CEEB 0%, #E0F6FF 100%); } /* Day */
canvas.level-7 { background: linear-gradient(to bottom, #FF7F50 0%, #FFD700 100%); } /* Sunset */
canvas.level-8 { background: linear-gradient(to bottom, #2c3e50 0%, #3498db 100%); } /* Night */
canvas.level-9 { background: linear-gradient(to bottom, #1a2a6c 0%, #b21f1f 100%, #fdbb2d 100%); } /* Dusk */
canvas.level-10 { background: linear-gradient(to bottom, #000000 0%, #434343 100%); } /* Space */

/* HUD (Heads Up Display) */
.hud {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    padding: 10px 20px;
    display: flex;
    justify-content: space-between;
    font-size: 1.5rem;
    font-weight: bold;
    color: white;
    text-shadow: 2px 2px 4px rgba(0,0,0,0.5);
    background: rgba(0,0,0,0.1);
    box-sizing: border-box;
    pointer-events: none; /* Let clicks pass through to canvas */
}

#ammo-display {
    position: absolute;
    bottom: 20px;
    right: 20px;
    font-size: 3rem;
    font-weight: bold;
    color: white;
    opacity: 0.5;
    pointer-events: none;
    text-shadow: 2px 2px 4px rgba(0,0,0,0.8);
    font-family: 'Consolas', 'Courier New', monospace; /* Monospace for numbers */
}

/* Leaderboard */
#leaderboard-container {
    position: absolute;
    top: 60px;
    right: 20px;
    width: 200px;
    /* Default game state: translucent */
    background: rgba(255, 255, 255, 0.4); 
    border-radius: 8px;
    padding: 10px;
    box-shadow: 0 4px 6px rgba(0,0,0,0.1);
    transition: opacity 0.5s, background-color 0.5s;
    pointer-events: none; /* Let clicks pass */
}

/* Solid state for initial screen */
#leaderboard-container.solid-mode {
    background: rgba(255, 255, 255, 1.0);
    top: 50%;
    border: 2px solid #ccc;
    transform: translateY(-50%);
    z-index: 20; /* Above login screen */
    pointer-events: auto;
}

/* Machine Gun Cursor */
canvas.machine-gun-active {
    cursor: url('data:image/svg+xml;utf8,<svg xmlns="http://www.w3.org/2000/svg" width="32" height="32" viewBox="0 0 32 32"><circle cx="16" cy="16" r="14" fill="none" stroke="red" stroke-width="2"/><line x1="16" y1="4" x2="16" y2="28" stroke="red" stroke-width="2"/><line x1="4" y1="16" x2="28" y2="16" stroke="red" stroke-width="2"/></svg>') 16 16, crosshair !important;
}

#initial-leaderboard {
    margin-top: 20px;
    background: rgba(255, 255, 255, 0.9);
    padding: 15px;
    border-radius: 8px;
    width: 300px;
    max-height: 200px;
    overflow-y: auto;
    border: 1px solid #ccc;
}
#initial-leaderboard ul {
    list-style: none;
    padding: 0;
}
#initial-leaderboard li {
    display: flex;
    justify-content: space-between;
    border-bottom: 1px solid #eee;
    padding: 5px 0;
}

#leaderboard-list {
    list-style: none;
    padding: 0;
    margin: 0;
}

#leaderboard-list li {
    display: flex;
    justify-content: space-between;
    border-bottom: 1px solid #ccc;
    padding: 4px 0;
}

/* Controls */
button {
    padding: 10px 20px;
    font-size: 1.2rem;
    background-color: var(--primary-color);
    color: white;
    border: none;
    border-radius: 5px;
    cursor: pointer;
    transition: transform 0.1s;
}

button:active {
    transform: scale(0.95);
}

input {
    padding: 10px;
    font-size: 1.2rem;
    margin-right: 10px;
}