style.css

@import url('https://fonts.googleapis.com/css2?family=Poppins:wght@200;400;600&display=swap');

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

body {
    font-family: 'Poppins', sans-serif;
    background-color: #75a9ee;
    display: flex;
    flex-wrap: wrap;
    padding-top: 3rem;
}

button {
    cursor: pointer;
}

.notes {
    background-color: #ffffff;
    margin: 20px;
    height: 400px;
    width: 400px;
    box-shadow: 0 0 10px 4px rgba(0, 0, 0, 0.1);
}

.notes .tools {
    background-color: #98ecbe;
    display: flex;
    justify-content: flex-end;
    padding: 0.5rem;
}

.notes .tools button {
    background-color: transparent;
    border: none;
    color: #ffffff;
    font-size: 1rem;
    margin-left: 0.5rem;
}

.notes .main {
    height: 100%;
    width: 100%;
    padding: 0.5rem;
    overflow: hidden;
    /* background-color: #f1f1f1; */
}

.notes textarea {
    outline: none; 
    border: none;
    height: calc(100% - 40px);
    width: 100%;
    font-size: 1.2rem;
    overflow: hidden;
    padding: 0.5rem;
}

.notes .hidden {
    display: none;
}

.add {
    background-color: #39ca93;
    border-radius: 3px;
    border: none;
    color: #ffffff;
    padding: 0.5rem 1rem;
    position: fixed;
    top: 1rem;
    right: 1rem;
    /* outline: none; */
}

span {
    position: absolute;
    top: 1rem;
    left: 1rem;;
    color: #ffffff;
    background-color: #4a92f0;
    width: 100%;
    margin: -1rem;
    padding: 1rem;
    text-align: center;
}