index.css

body {
    font-family: helvetica, arial, sans-serif;
    background: #efefef;
    margin: 0px;
}

#wrapper {
    max-width: 500px;
    width: 90%;
    margin: 0 auto 20px;
    position: relative;
}

header {
    position: relative;
    height: 40px;
    margin: 1px 0;
    background: #fff;
    border-radius: 20px 20px 0px 0px;
    box-shadow: 0 12px 8px -9px #555;
    padding: 1px;
}

#cards-main span {
    position: absolute;
    font-family:"Source Sans Pro", helvetica, sans-serif;
    width: 2.3em;
    padding:.25em .3em;
    font-weight:600;
    text-align: center;
    height: 30px;
    top: 3px;
}
#cards-main header span:first-child {
    border-top-left-radius:10px;
    left: 10px;background:#4eb8ea;}
#cards-main header span:nth-child(3) {
    border-bottom-right-radius:10px;
    right: 10px;background:#f88c21;}

#cards-main span:hover {
    color: #555;
    border-color: #fff;
    border: 0;
    cursor: pointer;
    opacity:1; visibility:visible; /*两个属性都会产生过渡动画*/
}
header h2 {
    padding: 0;
    font-family: 'Lato', helvetica, sans-serif;
    font-weight: 900;
    font-size: 1.5em;
    line-height: 1;
    color: #4eb8ea;
    text-align: center;
    margin: 10px auto;
}

#cards-main article {
    margin: 1px 0 0;
    padding: 0;
}

#cards-main nav {
    position: relative;
    height: 40px;
    margin: 1px 0;
    background: #fff;
    box-shadow: 0 12px 8px -9px #555;
    padding: 1px;
}

#cards-main nav span:first-child {
    border-top-left-radius:10px;
    left: 0;background:#d6e636;}
#cards-main nav span:nth-child(2) {
    border-bottom-right-radius:10px;
    left: 15%;background:#ee4c98;}
#cards-main nav span:nth-child(7) {
    border-bottom-right-radius:10px;
    border: 2px solid;
    top: 1px;
    right: 13px;}

#cards-main nav span:nth-child(7).btn-marker {
    color: red;
    background-color: #9fa4a8;}

#cards-main nav form {
    margin: 10px auto;
    padding: 2px 100px;
    width: 100px;
}

#cards-main nav form input {
    width: 70px;
    text-align: center;
    font-size: 15px;
    border: none;
}

#cards-main nav i {
    position: absolute;
    display: block;
    top: 13px;
}

#cards-main nav i:nth-child(3) {left: 32%;}
#cards-main nav i:nth-child(5) {right: 38%;}
#cards-main nav i:nth-child(6) {right: 30%;}

i:hover {cursor: pointer;}

#cards-main aside {
    position: relative;
    height: 50px;
    margin: 10px 0;
    background: #fff;
    border-radius: 0px 0px 20px 20px;
    box-shadow: 0 12px 8px -9px #555;
    padding: 1px;
}

#cards-main aside span:first-child {
    border-top-left-radius:10px;
    width: 5.7em;
    left: 0;background:#f00f2f;}
#cards-main aside span:nth-child(2) {
    width: 6.3em;
    left: 32%;background:#554050;}
#cards-main aside span:nth-child(3) {
    border-bottom-right-radius:10px;
    width: 6.5em;
    right: 0px;background:#00e636;}

#cards-main article {
    perspective: 1000px;
    position: relative;
    height: 450px;
    overflow: hidden;
}

.card {
    position: absolute;
    opacity: 0;
    font-size: 1.5em;
    top: 0px;
    left: 0px;
    height: 100%;
    width: 100%;
    touch-action: none;
    transform: translateX(50%) rotateY(-10deg);
    transition: transform 0.4s ease, opacity 0.4s ease;
}

.card.active {
    cursor: pointer;
    opacity: 1;
    z-index: 10;
    transform: translateX(0) rotateY(0deg);
}

.card.left {
    transform: translateX(-50%) rotateY(10deg);
}

.inner-card {
    box-shadow: 0 1px 10px rgba(0, 0, 0, 0.3);
    border-radius: 4px;
    margin: 10px;
    height: 430px;
    max-width: 480px;
    width: 96%;
    position: relative;
    transform-style: preserve-3d;
    transition: transform 0.4s ease;
}

.card.show-answer .inner-card {
    transform: rotateX(180deg);
}

.inner-card-front,
.inner-card-back {
    backface-visibility: hidden;
    position: absolute;
    top: 0;
    left: 0;
    display: flex;
    align-items: center;
    justify-content: center;
    height: 100%;
    width: 100%;
    background: #fff;
}

.inner-card-front {
    transform: rotateX(0deg);
    z-index: 2;
}

.inner-card-back {
    transform: rotateX(180deg);
}

.inner-card-front::after,
.inner-card-back::after {
    content: '\f021  Flip';
    font-family: 'Font Awesome 5 Free', Lato, sans-serif;
    position: absolute;
    top: 10px;
    right: 10px;
    font-weight: bold;
    font-size: 16px;
    color: #ddd;
}

#card-create {
    opacity: 0;
    z-index: -1;
    display: none;
    background-color: #f0f0f0;
    border-top: 2px solid #eee;
    padding: 10px 0;
    position: absolute;
    width: 100%;
    height: 100%;
    top: 0;
    transition: 0.3s ease;
}
#card-create.show {
    opacity: 1;
    z-index: 2;
    display: block;
}

#card-create header i {
    position: absolute;
    text-align: center;
    top: 15px;
    right: 30px;
}

#card-create article {
    margin:16px 0 0;
    padding:15px;
    background:#fff;
    border-radius:20px 0;
    box-shadow:0 12px 8px -9px #555;
}

#card-create article label{
    display: block;
    margin: 0 0 10px;
}

#card-create article textarea {
    border: 1px solid #aaa;
    border-radius: 3px;
    font-size: 16px;
    padding: 5px;
    /* width: 350px; */
    width: 95%;
    /* max-width: 100%; */
}

#card-create article input {
    margin:5px auto;
    padding:3px 10px 2px; /*输入文本与控件的间距*/
    color:#555;
    font-size:.8em;
    outline:none; /*去掉默认的轮廓线*/
    border-radius:10px 0 10px 0;
}

#card-create article input:hover {
    color: #555;
    border-color: #000;
    border: 3;
    cursor: pointer;
}

#cards-all {
    opacity: 0;
    z-index: -1;
    display: none;
    background-color: #f0f0f0;
    border-top: 2px solid #eee;
    padding: 10px 0;
    position: absolute;
    width: 100%;
    height: 100%;
    top: 0;
    transition: 0.3s ease;
}
#cards-all.show {
    opacity: 1;
    z-index: 2;
    display: block;
}
#cards-all header span {
    position: absolute;
    font-family:"Source Sans Pro", helvetica, sans-serif;
    width: 90px;
    padding:.25em .3em;
    font-weight:600;
    text-align: center;
    height: 30px;
    top: 3px;
    border-top-left-radius:10px;
    left: 10px;
    background:hsl(300, 50%, 50%);
}

#cards-all span:hover {
    color: #555;
    border-color: #fff;
    border: 0;
    cursor: pointer;
    opacity:1; visibility:visible; /*两个属性都会产生过渡动画*/
}

#cards-all header i {
    position: absolute;
    top: 15px;
    right: 30px;
}

#cards-all nav {
    position: relative;
    height: 30px;
    margin: 5px 0;
    background: #fff;
    box-shadow: 0 12px 8px -9px #555;
    padding: 1px;
}

#cards-all nav input {
    width: 100px;
    padding:2px 0 3px 5px;
    border-radius:0px 0px 10px 0px;
    font-family:"Source Sans Pro", helvetica, sans-serif;
    font-weight: 400; font-size:1em;
    color:#888;
    outline:none; /*去掉默认的轮廓线*/
    transition:.3s width; /*搜索框过渡动画*/
    position: absolute;
    left: 85px;
}

#cards-all nav select {
    width: 75px;
    padding:2px 0 3px 5px;
    border-radius:10px 0px 0px 0px;
    font-family:"Source Sans Pro", helvetica, sans-serif;
    font-weight: 400; font-size:1em;
    color:black;
    position: absolute;
    left: 10px;
}

#cards-all nav input:focus { width:150px;}/*在获得焦点时扩展到这么宽*/

#cards-all nav button {
    width: 60px;
    padding: 2px 0 3px 5px;
    position: absolute;
    border-radius:10px 0 10px 0;
    right: 10%;
}

#cards-all nav button:hover {
    color: #555;
    border-color: #000;
    border: 3;
    cursor: pointer;
}

.etyma {
    background-color: transparent;
    border: 1px solid #9fa4a8;
    border-radius: 10px;
    margin: 5px auto;
    padding: 30px;
    width: 84%;
    position: relative;
    overflow: hidden;
    transition: 0.3s ease;
}

.etyma span {
    position: absolute;
    border-bottom-right-radius:10px;
    border: 2px solid;
    top: 10px;
    right: 50%;
}

.etyma span.btn-marker {
    color: red;
    background-color: #9fa4a8;
}

.etyma.active {
    background-color: #fff;
    box-shadow: 0 3px 6px rgba(0, 0, 0, 0.1), 0 3px 6px rgba(0, 0, 0, 0.1);
}

.etyma-text {
    display: none;
    margin: 30px 0 0;
}

.etyma.active .etyma-text {
    display: block;
}

.etyma-toggle {
    border: 0;
    border-radius: 50%;
    cursor: pointer;
    font-size: 16px;
    padding: 0;
    position: absolute;
    top: 30px;
    right: 30px;
    height: 30px;
    width: 30px;
}


.etyma-toggle i:nth-child(2) {
    display: none;
}

.etyma.active .etyma-toggle i:nth-child(2) {
    color: #fff;
    display: block;
}

.etyma.active .etyma-toggle i:nth-child(1) {
    display: none;
}