body {
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
    display: flex;
    flex-direction: column;
    justify-content: center;
    align-items: center;
    min-height: 100vh;
    background-color: #2c3e50;
    color: #ecf0f1;
    margin: 0;
}

.tabs {
    margin-bottom: 2rem;
}

.tab-link {
    background: none;
    border: none;
    color: #bdc3c7;
    padding: 1rem 1.5rem;
    cursor: pointer;
    font-size: 1.2rem;
    transition: color 0.3s ease, border-bottom 0.3s ease;
    border-bottom: 2px solid transparent;
}

.tab-link.active {
    color: #3498db;
    border-bottom: 2px solid #3498db;
}

.tab-content {
    display: none;
    text-align: center;
}

.tab-content.active {
    display: block;
}

.breathing-container {
    position: relative;
    width: 300px;
    height: 300px;
    margin: 2rem auto;
}

.circle {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background-color: #3498db;
    border-radius: 50%;
    transform: scale(0.4);
}

.countdown {
    position: absolute;
    top: 49%;
    left: 50%;
    transform: translate(-50%, -50%);
    font-size: 80px;
    color: white;
}


.instructions {
    font-size: 1.5rem;
    color: #fff;
    margin-top: 2rem;
}


.toggle-container {
    display: flex;
    align-items: center;
    justify-content: center;
    margin-top: 2rem;
}

.switch {
    position: relative;
    display: inline-block;
    width: 60px;
    height: 34px;
    margin-right: 10px;
}

.switch input {
    opacity: 0;
    width: 0;
    height: 0;
}

.slider {
    position: absolute;
    cursor: pointer;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background-color: #ccc;
    transition: .4s;
    border-radius: 34px;
}

.slider:before {
    position: absolute;
    content: "";
    height: 26px;
    width: 26px;
    left: 4px;
    bottom: 4px;
    background-color: white;
    transition: .4s;
    border-radius: 50%;
}

input:checked + .slider {
    background-color: #3498db;
}

input:checked + .slider:before {
    transform: translateX(26px);
}