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

body {
    background: #000;
    color: #fff;
    font-family: 'Arial', sans-serif;
    overflow: hidden;
    position: relative;
}

canvas {
    display: block;
    background: url('data:image/svg+xml;base64,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');
}

#startBtn {
    position: absolute;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
    padding: 15px 30px;
    font-size: 28px;
    cursor: pointer;
    z-index: 10;
    background: linear-gradient(145deg, #23a6d5, #23d5ab);
    color: white;
    border: none;
    border-radius: 15px;
    box-shadow: 0 5px 15px rgba(35, 197, 184, 0.4);
    text-shadow: 0 2px 4px rgba(0, 0, 0, 0.2);
    transition: all 0.3s ease;
}

#startBtn:hover {
    transform: translate(-50%, -52%);
    box-shadow: 0 8px 25px rgba(35, 197, 184, 0.6);
}

/* --- GIAO DIỆN PAUSE & RESUME --- */
#pause-overlay {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: rgba(0, 5, 15, 0.85);
    /* Nền tối mờ ám xanh */
    backdrop-filter: blur(5px);
    display: none;
    /* Mặc định ẩn */
    flex-direction: column;
    justify-content: center;
    align-items: center;
    z-index: 100;
}

#pause-title {
    color: #00ffff;
    font-size: 50px;
    letter-spacing: 5px;
    text-shadow: 0 0 20px #00ffff;
    margin-bottom: 10px;
}

#pause-subtitle {
    color: #cbd5e1;
    font-size: 20px;
    margin-bottom: 40px;
    font-family: 'Courier New', Courier, monospace;
}

#resume-btn {
    padding: 15px 40px;
    font-size: 24px;
    font-weight: bold;
    cursor: pointer;
    background: transparent;
    color: #fff;
    border: 2px solid #00ffff;
    border-radius: 5px;
    box-shadow: 0 0 15px rgba(0, 255, 255, 0.3), inset 0 0 15px rgba(0, 255, 255, 0.2);
    transition: all 0.2s ease;
    text-transform: uppercase;
    letter-spacing: 2px;
}

#resume-btn:hover {
    background: rgba(0, 255, 255, 0.2);
    box-shadow: 0 0 25px rgba(0, 255, 255, 0.6), inset 0 0 20px rgba(0, 255, 255, 0.4);
    transform: scale(1.05);
}

/* Thanh Loading */
#resume-progress-container {
    width: 400px;
    height: 10px;
    background: #1e293b;
    border: 1px solid #334155;
    border-radius: 5px;
    margin-top: 30px;
    display: none;
    /* Mặc định ẩn */
    overflow: hidden;
    position: relative;
    box-shadow: 0 0 10px rgba(0, 0, 0, 0.5);
}

#resume-progress-bar {
    width: 0%;
    height: 100%;
    background: linear-gradient(90deg, #0ea5e9, #00ffff);
    box-shadow: 0 0 10px #00ffff;
}