body {
    display: flex;
    justify-content: center;
    align-items: center;
    height: 100vh;
    margin: 0;
    font-family: Arial, sans-serif;
    background-color: #f5f5f5;
}

.countdown {
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    text-align: center;
    background-color: rgba(255,255,255, 0.55);
    padding: 20px;
    border-radius: 10px;
    margin: 0 auto;
    max-width: 80vw;
}

#target-date, #countdown-name {
    font-family: 'Segoe UI', sans-serif;
    font-size: 16px;
    padding: 10px;
    border: 1px solid #ccc;
    border-radius: 5px;
    width: 80%;
    margin-bottom: 10px;
}

#timer, #countdown-name-display {
    font-size: 24px;
    margin: 10px;
}

#start-button {
    background-color: #0074D9;
    color: #ffffff;
    font-size: 16px;
    padding: 10px 20px;
    border: none;
    border-radius: 5px;
    cursor: pointer;
    transition: background-color 0.3s ease;
}

#start-button:hover {
    background-color: #005ea3;
}

#fullscreen-button {
    display: none;
    position: absolute;
    bottom: 20px;
    right: 20px;
    width: 50px;
    height: 50px;
    background: rgba(255, 255, 255, 0.25); /* semi-transparent white */
    backdrop-filter: blur(10px); /* frosted glass effect */
    -webkit-backdrop-filter: blur(10px); /* Safari support */
    border-radius: 50%; /* circle button */
    border: 1px solid rgba(255, 255, 255, 0.4); /* subtle border */
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center; /* center the icon */
    transition: all 0.3s ease;
    box-shadow: 0 4px 15px rgba(0,0,0,0.1);
}

#fullscreen-button:hover {
    background: rgba(255, 255, 255, 0.4);
    transform: scale(1.1);
}


#countdown-name-display {
    font-size: 24px; /* Decrease the font size for the countdown name */
    font-weight: bold;
    margin: 5px; /* Decrease the margin between the timer and the countdown name */
}

input:invalid {
    border: 2px solid red;
}

input:focus:invalid {
    border: 2px solid red;
}