body {
    font-family: sans-serif;
    background-color: #f4f4f4;
    margin: 0;
    display: flex;
    justify-content: center;
    align-items: center;
    height: 100vh;
}

.container {
    display: flex;
    width: 800px;
    height: 600px;
    background-color: #fff;
    box-shadow: 0 0 10px rgba(0, 0, 0, 0.1);
    border-radius: 10px;
    overflow: hidden;
}

.calendar-container {
    flex: 1;
    background-color: #2c3e50;
    color: #fff;
    display: flex;
    justify-content: center;
    align-items: center;
    flex-direction: column;
}

.calendar {
    text-align: center;
}

.month {
    font-size: 24px;
    font-weight: bold;
}

.day-of-week {
    font-size: 18px;
    margin-top: 10px;
}

.day {
    font-size: 80px;
    font-weight: bold;
}

.year {
    font-size: 24px;
}

.time {
    font-size: 18px;
    margin-top: 20px;
}

.todo-container {
    flex: 1;
    padding: 20px;
    overflow-y: auto;
}

h1 {
    margin-top: 0;
}

#todo-form {
    display: flex;
    margin-bottom: 20px;
}

#todo-input {
    flex: 1;
    padding: 10px;
    border: 1px solid #ccc;
    border-radius: 5px;
}

#todo-form button {
    padding: 10px;
    background-color: #2c3e50;
    color: #fff;
    border: none;
    border-radius: 5px;
    margin-left: 10px;
    cursor: pointer;
}

#todo-list {
    list-style: none;
    padding: 0;
    margin: 0;
}

#todo-list li {
    display: flex;
    align-items: center;
    padding: 10px;
    border-bottom: 1px solid #ccc;
}

#todo-list li.completed {
    text-decoration: line-through;
    color: #aaa;
}

#todo-list li input[type="checkbox"] {
    margin-right: 10px;
}

#remove-completed {
    margin-top: 20px;
    padding: 10px;
    background-color: #e74c3c;
    color: #fff;
    border: none;
    border-radius: 5px;
    cursor: pointer;
}