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

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Oxygen, Ubuntu, Cantarell, 'Open Sans', 'Helvetica Neue', sans-serif;
    display: flex;
    justify-content: center;
    align-items: center;
    min-height: 100vh;
    background-color: #f5f5f7;
}

.container {
    background: rgba(255, 255, 255, 0.9);
    padding: 2rem;
    border-radius: 20px;
    box-shadow: 0 8px 30px rgba(0, 0, 0, 0.1);
    backdrop-filter: blur(20px);
}

.timer {
    font-size: 4rem;
    font-weight: 300;
    color: #1d1d1f;
    text-align: center;
    font-variant-numeric: tabular-nums;
    margin-bottom: 1.5rem;
}

.buttons {
    display: flex;
    gap: 1rem;
    justify-content: center;
}

.btn {
    width: 60px;
    height: 60px;
    border: none;
    border-radius: 50%;
    cursor: pointer;
    transition: all 0.3s ease;
    display: flex;
    align-items: center;
    justify-content: center;
}

#startBtn {
    background-color: #007AFF;
}

#startBtn:hover {
    background-color: #0066d6;
}

#resetBtn {
    background-color: #ff3b30;
}

#resetBtn:hover {
    background-color: #d63429;
}

.icon {
    width: 24px;
    height: 24px;
    fill: white;
}

/* 暂停状态的按钮样式 */
#startBtn.paused .icon {
    width: 20px;
    height: 20px;
}