* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Oxygen, Ubuntu, Cantarell, 'Open Sans', 'Helvetica Neue', sans-serif;
}

body {
    background-color: #f5f5f7;
    display: flex;
    justify-content: center;
    align-items: center;
    min-height: 100vh;
}

.container {
    background-color: white;
    border-radius: 20px;
    box-shadow: 0 8px 30px rgba(0, 0, 0, 0.12);
    padding: 40px;
    text-align: center;
    width: 340px;
}

.timer-display {
    font-size: 48px;
    font-weight: 300;
    color: #1d1d1f;
    margin-bottom: 40px;
    letter-spacing: 2px;
}

.colon {
    display: inline-block;
    width: 12px;
}

.controls {
    display: flex;
    justify-content: space-between;
}

.btn {
    flex: 1;
    margin: 0 8px;
    padding: 12px 0;
    border: none;
    border-radius: 12px;
    font-size: 16px;
    font-weight: 500;
    cursor: pointer;
    transition: all 0.3s ease;
    color: white;
}

#start-btn {
    background-color: #007aff;
}

#pause-btn {
    background-color: #ff9500;
}

#reset-btn {
    background-color: #ff3b30;
}

.btn:hover {
    opacity: 0.9;
    transform: translateY(-2px);
}

.btn:active {
    transform: translateY(1px);
}