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

body, input, button {
    font-family: 'Open Sans', sans-serif;
    font-size: 16px;
}

.head_bar {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 10px 20px;
    background-color: #232F34;
    color: white;
}

.head_bar__title {
    margin: 0;
}

main {
    padding: 16px;
}

.input_section {
    max-width: 800px;
    width: 100%;
    margin: 0 auto;
    padding: 16px;
    border-radius: 10px;
}

.input_section > h2 {
    text-align: center;
    color: #232F34;
}

.input_section > form > .input {
    margin: 8px 0;
}

.input_section > form > #cancelEdit {
    background-color: #F44336ed;
    color: white;
    border: 0;
    border-radius: 5px;
    display: block;
    margin-bottom: 8px;
    width: 100%;
    padding: 8px;
    cursor: pointer;
}

.input_section > form > #bookSubmit {
    background-color: #F9AA33;
    color: #232F34;
    border: 0;
    border-radius: 5px;
    display: block;
    width: 100%;
    padding: 8px;
    cursor: pointer;
}

.input_section > form > button > span {
    font-weight: bold;
}

.input_section > form > .input > input {
    display: block;
    width: 100%;
    padding: 8px;
    border-radius: 5px;
}

.input_section > form > .input > label {
    color: #232F34;
    font-weight: bold;
}

.input_section > form > .input_inline {
    margin: 12px 0;
    display: flex;
    align-items: center;
}

.input_section > form > .input_inline > label {
    color: #232F34;
    font-weight: bold;
    margin-right: 10px;
}

.search_bar {
    display: flex;
    align-items: center;
    width: 100%;
    max-width: 200px;
    border-bottom: 1px solid #FFFFFF;
    overflow: hidden;
}

.search_bar input[type="search"] {
    flex: 1;
    padding: 10px;
    border: none;
    outline: none;
    font-size: 16px;
    background-color: #232F34;
    color: #FFFFFF;
}

.search_bar input[type="search"]::placeholder {
    color: #999;
}

.empty_book {
    margin-top: 32px;
    text-align: center;
}

.book_shelf_container {
    display: flex;
    flex-wrap: wrap;
    justify-content: space-between;
    margin-top: 16px;
}

.book_shelf {
    flex: 1;
    width: calc(50% - 20px);
    margin-bottom: 20px;
    padding: 16px;
    border-radius: 10px;
}

.book_shelf > h2 {
    color: #232F34;
    padding-bottom: 8px;
    border-bottom: 1px solid #4A6572;
}

.book_shelf > .book_list {
    padding: 16px 0;
}

.book_shelf > .book_list > .book_item {
    padding: 8px 16px 16px 16px;
    border: 1px solid black;
    border-radius: 5px;
    margin: 10px 0;
}

.book_shelf > .book_list > .book_item > h3, p {
    margin: 8px 0;
}

.book_shelf > .book_list > .book_item > .action > button {
    border: 0;
    padding: 5px;
    margin: 5px 5px 0 0;
    border-radius: 5px;
    cursor: pointer;
}

.book_shelf > .book_list > .book_item > .action > .green {
    background-color: #4CAF50;
    color: white;
}

.book_shelf > .book_list > .book_item > .action > .grey {
    background-color: #9E9E9E;
    color: white;
}

.book_shelf > .book_list > .book_item > .action > .red {
    background-color: #F44336;
    color: white;
}

.floating_action_button {
    position: fixed;
    bottom: 20px;
    right: 20px;
    background-color: #F9AA33;
    color: #232F34;
    width: 60px;
    height: 60px;
    border-radius: 50%;
    font-size: 24px;
    text-align: center;
    line-height: 60px;
    cursor: pointer;
    box-shadow: 0 4px 6px rgba(0, 0, 0, 0.1), 0 1px 3px rgba(0, 0, 0, 0.08);
}

.modal {
    display: none;
    position: fixed;
    z-index: 1;
    left: 0;
    top: 0;
    width: 100%;
    height: 100%;
    overflow: auto;
    background-color: rgba(0,0,0,0.4);
}

.modal-content {
    position: relative;
    background-color: #fefefe;
    margin: 15% auto;
    padding: 20px;
    border: 1px solid #888;
    border-radius: 8px;
    width: 50%;
}

.close {
    position: absolute;
    top: 10px;
    right: 10px;
    cursor: pointer;
    font-size: 24px;
    color: #757575;
}

.close:hover {
    color: #212121;
}

@media only screen and (max-width: 768px) {
    .book_shelf {
        width: calc(100% - 20px);
    }
}

@media only screen and (max-width: 600px) {
    .head_bar__title {
        font-size: 24px;
    }

    .search_bar {
        max-width: 30%;
    }

    .book_shelf_container {
        flex-direction: column;
    }

    .book_shelf {
        width: calc(100% - 20px);
        margin-bottom: 10px;
    }
    
    .modal-content {
        margin: 15% auto;
        width: 80% !important;
    }
}