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

:root {
    --primary: #ff0066;
    --bg-00: #fff;
    --bg-01: #000;
    --bg-02: #ddd;
    --bg-03: rgba(255, 255, 255, 0.6);
    --ff: system-ui, -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Oxygen, Ubuntu, Cantarell, 'Open Sans', 'Helvetica Neue', sans-serif;
}

@media (prefers-color-scheme: dark) {
    :root {
        --bg-00: #000;
        --bg-01: #fff;
        --bg-02: #333;
        --bg-03: rgba(0, 0, 0, 0.4);
    }
}

::selection {
    background: var(--bg-01);
    color: var(--bg-00);
}

::-webkit-scrollbar {
    display: none;
}

body {
    background: var(--bg-00);
    font-size: 16px;
    font-family: var(--ff);
    color: var(--bg-01);
}

a {
    text-decoration: none;
}

svg {
    fill: var(--bg-01);
}


/* header */
header {
    position: sticky;
    position: -webkit-sticky;
    top: 0;
    left: 0;
    border-bottom: 1px solid var(--bg-02);
    z-index: 4;
    backdrop-filter: blur(50px);
    background: var(--bg-00);
}

header .container {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 0.7rem 1rem;
}

header .container .menu-btn {
    position: relative;
    cursor: pointer;
}

header .container .left {
    display: flex;
    align-items: center;
    gap: 0.7rem;
}

header .container .right {
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

header .account-img {
    display: flex;
    align-items: center;
    justify-content: center;
}

header .account-img img {
    width: 36px;
    border-radius: 50%;
}

.btn-0 {
    padding: 0.5rem 1rem 0.5rem 0.5rem;
    border-radius: 50px;
    border: 1px solid var(--bg-01);
    background: var(--bg-01);
    font-size: 1em;
    color: var(--bg-00);
    display: flex;
    gap: 0.3rem;
    height: 40px;
    align-items: center;
    justify-content: center;
}

.btn-0 svg {
    fill: var(--bg-00) !important;
    scale: 0.9;
}

header .btn-1 {
    padding: 0.5rem;
    border-radius: 50%;
    background: var(--bg-02);
    width: 36px;
    height: 36px;
}

header .btn-2 {
    padding: 0.5rem 1rem 0.5rem 1rem;
    border-radius: 50px;
    border: 1px solid var(--bg-01);
    background: var(--bg-01);
    font-size: 0.9em;
    color: var(--bg-00);
    display: flex;
    gap: 0.3rem;
    height: 36px;
}

header .logo {
    font-size: 1.6em;
    color: var(--bg-01);
    font-weight: bolder;
}

.btn-3 {
    padding: 0.5rem;
    border-radius: 50px;
    border: 1px solid var(--bg-01);
    background: var(--bg-01);
    font-size: 1em;
    color: var(--bg-00);
    display: flex;
    gap: 0.3rem;
    height: 36px;
    font-size: 0.9em;
}


/* section */
.classes-section {
    background: var(--bg-00);
}

.classes-section .container {
    padding: 1rem;
    max-width: 800px;
    margin: 1rem auto;
    display: grid;
    grid-template-columns: repeat(2, 1fr);
    flex-wrap: wrap;
    gap: 1rem;
    border: 1px solid var(--bg-02);
    border-radius: 1rem;
}

.classes-section .container:nth-child(2) {
    border: 1px solid var(--bg-02);
}

.classes-section .container .item {
    background: linear-gradient(135deg, #ff9e30, #ff3557);
    width: 100%;
    height: 200px;
    border-radius: 1rem;
    color: var(--bg-01);
    padding: 2rem;
    display: flex;
    flex-direction: column;
    gap: 0.5rem;
    align-items: center;
    justify-content: center;
}

/* create-class-section */
.create-class-section {
    background: var(--bg-00);
}

form {
    padding: 1rem;
    margin: 0 auto;
    max-width: 800px;
    margin-top: 1rem;
    display: flex;
    flex-direction: column;
    gap: 0.5rem;
    align-items: flex-start;
    border: 1px solid var(--bg-02);
    border-radius: 1rem;
}

form .form-group {
    display: flex;
    flex-direction: column;
    gap: 0.3rem;
    width: 100%;
}

form input[type="text"],
form input[type="time"],
form select {
    width: 100%;
    padding: 0.5rem;
    border-radius: 5px;
    background: var(--bg-02);
    color: var(--bg-01);
    border: none;
}

form select {
    appearance: none;
}

form input[type="submit"] {
    padding: 0.5rem 1rem;
    border-radius: 50px;
    background: var(--bg-01);
    color: var(--bg-00);
    border: none;
    outline: none;
    font-size: 1em;
    font-family: var(--ff);
    margin-top: 1rem;
    font-weight: 400;
    cursor: pointer;
}

form .buttons {
    display: flex;
    gap: 0.5rem;
}

form .btn-2 {
    cursor: pointer;
    font-weight: 400;
    padding: 0.5rem 1rem;
    border-radius: 50px;
    background: #ff0066;
    color: var(--bg-00);
    border: none;
    outline: none;
    font-size: 1em;
    font-family: var(--ff);
    margin-top: 1rem;
}

form .files {
    display: flex;
    flex-direction: column;
    gap: 0.5rem;
    border-top: 1px solid var(--bg-02);
    width: 100%;
    padding-top: 1rem;
}

form .files a {
    color: #00bcc9;
}

form .files a:hover {
    text-decoration: underline;
}

form #formContent {
    width: 100%;
}

form .banner {
    background: linear-gradient(135deg, #309bff, #d035ff);
    width: 100%;
    padding: 1rem;
    border-radius: 1rem 1rem 0 0;
    text-align: center;
    font-weight: bold;
    font-size: 1.2em;
}

form .banner h2 {
    font-size: 2em;
    margin-bottom: 0.5rem;
}

form .error-msg {
    padding: 0.5rem;
    display: none;
    color: #ff0066;
    font-size: 0.9em;
}

form .upload-files {
    padding: 1rem;
    border-radius: 1rem;
    border: 2px dashed #808080;
    margin: 0.5rem 0;
}

form input[type="file"] {
    cursor: pointer;
}

form textarea {
    font-family: var(--ff);
    font-size: 1em;
    width: 100%;
    padding: 0.5rem;
    border-radius: 5px;
    background: var(--bg-02);
    color: var(--bg-01);
    border: none;
    resize: none;
    height: 100px;
}

/* tags */
.tags-container {
    overflow-x: auto;
}

.tags {
    display: flex;
    gap: 0.5rem;
    max-width: 800px;
    margin: 0 auto;
    padding: 1rem;
    width: 800px;
}

.tags .tag {
    color: var(--bg-01);
    background: var(--bg-02);
    padding: 0.5rem 1rem;
    border-radius: 5px;
    font-size: 0.8em;
    font-weight: 500;
}

.tags .tag.active {
    background: var(--bg-01);
    color: var(--bg-00);
}

/* login-section */
.login-section {
    background: var(--bg-00);
    max-width: 360px !important;
    margin: 1rem auto;
    margin-top: 8rem;
}

.login-section .teacher {
    border: 1px solid var(--bg-02);
    border-radius: 1rem;
}

.login-section form {
    align-items: center;
}

.login-section form a {
    font-size: 0.9em;
    color: var(--bg-01);
}

.show-study-resources .file-name a {
    color: #00acac;
}

/* notification-section */
.notification-section {
    margin: 1rem auto;
    max-width: 800px;
    border-radius: 1rem;
    border: 1px solid var(--bg-02);
}

.notification-section .container {
    padding: 1rem;
    display: flex;
    flex-direction: column;
}

.notice-content {
    font-size: 1rem;
    border-left: 2px solid #00a048;
    padding-left: 1rem;
}

.notification-section .container p {
    border-bottom: 1px solid var(--bg-02);
    padding: 1rem 0;
}

/* sidebar */
.sidebar {
    position: fixed;
    top: 3.6rem;
    left: 0;
    background: var(--bg-00);
    height: 100%;
    overflow: auto;
    width: 240px;
    transition: 200ms ease-in-out;
    z-index: 4;
    border-right: 1px solid var(--bg-02);
}

.sidebar.active {
    left: -100%;
}

.sidebar .container {
    display: flex;
    flex-direction: column;
    gap: 1rem;
}

.sidebar .container .item {
    display: flex;
    flex-direction: column;
    padding: 0.5rem;
    border-bottom: 1px solid var(--bg-02);
}

.sidebar .container .item:last-child {
    border-bottom: none;
}

.sidebar .container .item a {
    text-decoration: none;
    padding: 0.5rem;
    display: flex;
    align-items: center;
    cursor: pointer;
    color: var(--bg-01);
}

.sidebar .container .item p {
    padding-left: 1rem;
    font-size: 0.8em;
}

.sidebar .container .item svg {
    margin-right: 0.7rem;
}

/* teacher */
.sidebar .subject {
    width: 100%;
    background: transparent;
    padding: 0.9rem 1rem 0 1rem;
}

.sidebar .subject-title {
    background: var(--bg-02);
    color: var(--bg-01);
    border-radius: 50px;
    padding: 0.5rem;
    font-size: 1em;
    text-align: center;
}

.sidebar .teacher {
    padding: 1rem;
    border-bottom: none;
    display: flex;
    gap: 0.7rem;
    align-items: center;
}

.sidebar .teacher .info .title {
    background: transparent;
    color: var(--bg-01);
    border-radius: 50px;
    font-size: 0.7em;
    padding: 0;
    padding-left: 0;
}

.sidebar .teacher .info .name {
    font-size: 1em;
    font-weight: bold;
    color: var(--bg-01);
    padding-left: 0;
}

.sidebar .teacher img {
    width: 50px;
    height: 50px;
    border-radius: 50%;

}

.owner-info {
    display: flex;
    font-size: 0.8em;
    gap: 0 1rem;
    flex-wrap: wrap;
    padding: 0 0.5rem 0 1rem;
}

.owner-info a {
    padding: 0 !important;
    color: #808080 !important;
}

.copyright-text {
    color: #868686 !important;
}

/* teacher */
.subject {
    width: 100%;
    background: linear-gradient(-35deg, rgba(48, 155, 255, 0.3), rgba(208, 53, 255, 0.3));
    padding: 2rem 0;
}

.subject-title {
    max-width: 800px;
    margin: 0 auto;
    padding: 1rem;
    font-size: 3em;
}

.teacher {
    padding: 2rem 1rem 1rem 1rem;
    border-bottom: none;
    display: flex;
    gap: 1rem;
    max-width: 800px;
    margin: 0 auto;
    align-items: center;
}

.teacher .info {
    display: flex;
    flex-direction: column;
}

.teacher .info p {
    font-size: 0.9em;
}

.teacher .info .title {
    background: var(--bg-01);
    color: var(--bg-00);
    padding: 0.3rem 0.7rem;
    border-radius: 50px;
    font-size: 0.7em;
    width: fit-content;
    margin-bottom: 0.2rem;
    font-weight: 500;
}

.teacher .info .name {
    font-size: 1.6em;
    font-weight: bold;
}

.teacher img {
    width: 80px;
    height: 80px;
    border-radius: 50%;

}

/* MEDIA */
@media screen and (max-width: 1280px) {
    .sidebar {
        left: -100%;
        transition: 200ms ease-in-out;
    }

    .sidebar.active {
        left: 0;
    }
}

@media screen and (max-width: 540px) {
    .classes-section .container {
        grid-template-columns: repeat(1, 1fr);
    }
}