:root {
    --building-color-1: #5d6d7e;
    --building-color-2: #34495e;
    --building-color-3: #2c3e50;
}

body {
    margin: 0;
    padding: 0;
    display: flex;
    justify-content: center;
    align-items: center;
    height: 100vh;
    font-family: "Arial", sans-serif;
    overflow: hidden;
}

#game-container {
    position: relative;
    width: 400px;
    height: 700px;
    overflow: hidden;
    border: 3px solid #333;
    border-radius: 10px;
    box-shadow: 0 0 20px rgba(0, 0, 0, 0.3);
}

#game-bg {
    position: absolute;
    width: 100%;
    height: 100%;
    background: url("assets/images/bg-normal.png") center/cover;
    transition: opacity 5s;
    z-index: 1;
}

#bird {
    position: absolute;
    width: 50px;
    height: 50px;
    background: url("assets/images/bird-normal.png") center/contain no-repeat;
    left: 80px;
    z-index: 10;
    image-rendering: pixelated;
}

.building {
    position: absolute;
    background: var(--building-color-1);
    right: -150px;
    bottom: 30px;
    width: 100px;
    box-shadow: inset 0 -10px 0 rgba(0, 0, 0, 0.2);
    z-index: 5;
}

.building::after {
    content: "";
    position: absolute;
    width: 100%;
    height: 20px;
    background: #7f8c8d;
    bottom: -20px;
}

.window {
    position: absolute;
    background: #f9e79f;
    width: 8px;
    height: 8px;
    border-radius: 2px;
}

#ground {
    position: absolute;
    width: 100%;
    height: 30px;
    background: #7f8c8d;
    bottom: 0;
    z-index: 20;
    background-image: linear-gradient(45deg, #95a5a6 25%, transparent 25%),
        linear-gradient(-45deg, #95a5a6 25%, transparent 25%),
        linear-gradient(45deg, transparent 75%, #95a5a6 75%),
        linear-gradient(-45deg, transparent 75%, #95a5a6 75%);
    background-size: 20px 20px;
}

#score {
    position: absolute;
    top: 20px;
    left: 20px;
    font-size: 24px;
    font-weight: bold;
    color: white;
    text-shadow: 2px 2px 4px rgba(0, 0, 0, 0.5);
    z-index: 30;
}

#start-screen {
    position: absolute;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
    background-color: rgba(0, 0, 0, 0.8);
    color: white;
    padding: 20px;
    border-radius: 10px;
    text-align: center;
    z-index: 40;
    width: 80%;
}

#game-over {
    position: absolute;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
    background-color: rgba(0, 0, 0, 0.8);
    color: white;
    padding: 20px;
    border-radius: 10px;
    text-align: center;
    display: none;
    z-index: 40;
    width: 80%;
}

#start-btn,
#restart-btn,
#change-name-btn {
    margin-top: 15px;
    padding: 10px 20px;
    background-color: #3498db;
    border: none;
    border-radius: 5px;
    color: white;
    font-weight: bold;
    cursor: pointer;
}

#player-name {
    padding: 8px;
    margin: 10px 0;
    border-radius: 5px;
    border: none;
    width: 80%;
    font-size: 16px;
}

#leaderboard {
    margin-top: 20px;
    text-align: left;
}

#leaderboard h3 {
    margin-bottom: 10px;
}

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

#leaderboard li {
    margin: 5px 0;
    font-size: 14px;
}

.cloud {
    position: absolute;
    background: white;
    border-radius: 50%;
    opacity: 0.8;
    z-index: 2;
}

#sun-moon {
    position: absolute;
    width: 40px;
    height: 40px;
    border-radius: 50%;
    top: 50px;
    right: 50px;
    z-index: 3;
    transition: all 5s;
}