body {
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
    background-color: #f4f7f6;
    display: flex;
    justify-content: center;
    align-items: center;
    height: 100vh;
    margin: 0;
}

.stopwatch-container {
    background-color: #ffffff;
    padding: 2rem 3rem;
    border-radius: 20px;
    box-shadow: 0 10px 25px rgba(0, 0, 0, 0.1);
    text-align: center;
    width: 320px;
}

h1 {
    color: #333;
    margin-bottom: 1.5rem;
    font-weight: 600;
}

#display {
    font-family: "Courier New", Courier, monospace;
    font-size: 3rem;
    font-weight: bold;
    color: #222;
    margin-bottom: 2rem;
    padding: 1rem;
    background: #f8f9fa;
    border-radius: 12px;
}

.controls {
    display: flex;
    gap: 10px;
    justify-content: center;
}

button {
    padding: 0.8rem 1.2rem;
    font-size: 1rem;
    border: none;
    border-radius: 8px;
    cursor: pointer;
    transition: all 0.2s ease;
    font-weight: 500;
}

#startBtn {
    background-color: #4caf50;
    color: white;
}

#startBtn:hover {
    background-color: #43a047;
}

#stopBtn {
    background-color: #f44336;
    color: white;
}

#stopBtn:hover {
    background-color: #d32f2f;
}

#resetBtn {
    background-color: #757575;
    color: white;
}

#resetBtn:hover {
    background-color: #616161;
}

button:disabled {
    background-color: #ccc;
    cursor: not-allowed;
    opacity: 0.6;
}