a {
    text-decoration: none;
    color:black;
}
html, body {
    height: 100%;
    font-weight: 1;
    background-color: rgb(244,245,247);
}
body {
    display: flex;
    flex-direction: column;
}
.container {
    display: flex;
    height: 90%;
    flex-direction: row;
}
.side-bar {
    flex: 0 0 10%;
    display: flex;
    flex-direction: column;
    align-items: center;
    background-color: white;
    z-index: 1;
}
.tasks-content {
    width: 100%;
    height: auto;
    display: flex;
    flex-direction: column;
    align-items: center;
}
.top-bar {
    display: flex;
    flex-direction: row;
    height: 10%;
    align-items: flex-end;
    background-color: white;
    z-index: 2;
    box-shadow: 0px 5px 5px -5px rgba(0, 0, 0, 0.5);
}
.side-bar-button {
    display: block;
    width: 80%;
    padding: 10px;
    margin: 5px 0;
    text-align: center;
    color: black;
    text-decoration: none;
    background-color: white;
}
.side-bar-button:hover {
    background-color: #087DCE;
    color: white;
    transition: 0.3s ease;
}
div {
    /*border: 2px solid black;*/
}
#logo {
    height: 100%;
}
#logo-text {
    font-size: 30px;
    position: relative;
    bottom: 35%;
    color:black;
}

#logo-text span {
    font-size: 20px;
}
.top-bar-btn {
    flex-direction: row;
    height: 50%;
    align-items: flex-end;
    margin-left: 30px;
}
.top-bar-tag:hover {
    color:#087DCE;
    border-bottom: 1px solid #087DCE;
    transition: 0.5s ease;
}
.top-bar-tag {
    width:10%;
    height: 100%;
    color:black;
    margin-right: 20px;
    font-size: 26px;
}
.top-bar-logo {
    height: 100%;
}
#empty-logo {
    width: 25%;
}
.task-area {
    width:80%;
    height: 200px;
    margin-left: 10px;
    margin-top: 50px;
    display: flex;
    flex-direction: row;
    background-color: white;
    border-radius: 8px;
    box-shadow: 0 0 5px 0 rgba(0, 0, 0, 0.5);
    transition: 0.3s ease;
}
.task-area:hover {
    transform: translateY(-5px); /* 鼠标悬停时向上浮动 */
}
.task-cover img {
    height: 100%;
    box-shadow: 0 0 10px rgba(187, 186, 186, 0.3); /* 这里的 rgba() 中的最后一个参数表示透明度 */
}
.task-description {
    flex:1;
    width: auto;
    display: flex;
    flex-direction: column;
    margin-left: 10px;
}
a.task-button {
    width: 10%;
    padding: 10px;
    border-radius: 8px;
    float: right;
    text-decoration: none;
    color:black;
    background-color: rgb(255, 245, 247);
    text-align: center;
    margin-right: 10px;
    box-shadow: 0 0 5px rgb(0, 0, 0);
}
a.task-button:hover {
    background-color:#087DCE;
    color: white;
    transition: 0.3s ease;
}
.progress {
    width: 60%;
    height: 20px;
    background-color: #dadada;
    border-radius: 4px;
    box-shadow: inset 0 1px 2px rgba(0, 0, 0, 0.1);
    margin-top: 20px;
    margin-left: auto;
    margin-right: 20px;
}

.progress-bar {
    height: 100%;
    line-height: 20px;
    color: #fff;
    text-align: center;
    background-color: #087DCE;
    border-radius: 4px;
    transition: width 0.3s ease-in-out;
    box-shadow: inset 0 1px 2px rgba(0, 0, 0, 0.2);
    position: relative;

}

.progress-text {
    position: absolute;
    top: 0;
    left: 50%;
    transform: translateX(-50%);
}

.task-top-bar {
    display: flex;
    flex-direction: row;
}
.top-bar-right {
    display: flex;
    flex:1;
    height: 100%;
}
.top-bar-account {
    display: flex;
    margin-left:auto;
    margin-right: 40px;
    height: 100%;
    align-items: center;
}
.drop-menu {
    width: 130px;
    color:black;
    border-bottom: 1px solid darkgray;
    margin-top: auto;
    margin-left: auto;
    margin-right: 50px;
}
.top-bar-account{
    width: 100%;
    height: 45px;
    line-height: 45px;
    text-align: center;
    position: relative;
    overflow: hidden;
    display: flex;
    flex-direction: column;
}
.top-bar-account:hover{
    overflow: visible;
    background-color: #087DCE;
    color: white;
    z-index: 999;
    cursor: pointer;
    transition: 0.5s ease;
}
.drop{
    background-color: white;
    text-align: center;
    width: 100%;
    height: 45px;
    line-height: 45px;
}
.drop a {
    color:black;
}
.drop:hover{
    background: #087DCE;
    cursor: pointer;
}
.drop:hover a {
    color:white;
}
.up-area {
    width: 80%;
    display: flex;
    justify-content: center;
    align-items: center;
    flex-direction: column;
}
#teach-video {
    margin-top: 10px;
}
.video-title {
    margin-top: 20px;
}
.video-title-text {
    font-size:22px;
    font-weight: 2;
}
.down-area {
    width: 80%;
    height: auto;
    display: flex;
    justify-content: center;
}
.illustrate-text {
    margin: 20px;
    padding: 10px;
    width: 60%;
    box-shadow: 0 0 5px rgba(0, 0, 0, 0.5);
}
.illustrate-text p {
    margin-left: 30px;
    margin-right: 30px;
}