@font-face {
    font-family: "roboto";
    src: url(./fonts/Roboto-Regular.ttf);
    font-weight: 400;
}

@font-face {
    font-family: "roboto";
    src: url(./fonts/Roboto-Medium.ttf);
    font-weight: 500;
}

@font-face {
    font-family: "roboto";
    src: url(./fonts/Roboto-Bold.ttf);
    font-weight: 700;
}

@font-face {
    font-family: "nunito";
    src: url(./fonts/Nunito-Regular.ttf);
    font-weight: 400;
}

@font-face {
    font-family: "nunito";
    src: url(./fonts/Nunito-Medium.ttf);
    font-weight: 500;
}

@font-face {
    font-family: "nunito";
    src: url(./fonts/Nunito-Bold.ttf);
    font-weight: 700;
}

:root {
    --font-main: "roboto";
    --text-title: #101010;
    --text-describe: #646764;
    --color-button: #962428;
    --color-hover: #ff551d;
    --mauchinh: #171f32;
}

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

body {
    margin: 0;
    padding: 0;
    font-style: normal;
    font-size: 16px;
    text-align: left !important;
    font-family: var(--font-main);
    font-weight: 400;
    color: var(--text-title);
}

.wrap-banner.teach-banner.banner-problem {
    min-height: 250px;
}

.title-problem {
    margin-top: 20px;
    margin-bottom: 10px;
    font-family: 'nunito';
    color: #471a04;
}

.page-title {
    font-size: 2em;
    font-weight: 700;
    line-height: 1.4;
}

.time-date {
    display: flex;
    justify-content: flex-start;
    gap: 20px;
    margin-bottom: 20px;
    color: #7f8c8d;
    font-size: 0.8em;
    font-weight: 400;
}

.icon-celendar,
.admin-us,
.comment-stt {
    display: flex;
    align-items: center;
    gap: 8px;
}

.icon-celendar i,
.admin-us i,
.comment-stt i {
    color: #471a04;
    font-size: 0.9em;
}

.ngay-thang h3,
.ten-use .name-us,
.comment-stt .number-cm {
    margin: 0;
}


.noi-dung {
    position: relative;
    padding-left: 20px;
    box-shadow: 0 8px 20px rgba(0, 0, 0, 0.1);
    background-color: #ffffff;
    overflow: hidden;
    color: #666;
}

.line-stand-left {
    position: absolute;
    top: 0;
    left: 0;
    width: 3px;
    height: 60px;
    background-color: #972428;
    transition: height 0.3s ease;
}

.noi-dung:hover .line-stand-left {
    height: 15%;
}

.nd-courses {
    overflow: hidden;

}

.nhay-home {
    float: left;
    color: rgba(109, 101, 101, 0.92);
    font-size: 1.125em;
    padding: 34px 40px 25px;
    display: flex;
    flex-direction: row;
    gap: 10px;
}

.nhay-home i {
    font-size: 0.7em;
    padding-top: 15px;
}

.style2 {
    background-color: #fff !important;
    margin-bottom: 10px !important;
}

blockquote:before {
    content: "\f129" !important;
    font-size: 35px;
    color: #972428;
    padding-bottom: 0px;
    display: inline-block;
    font-family: 'Flaticon';
    font-weight: 400;
    text-align: center;
    top: 0px;
    background: transparent !important;
    transform: rotate(180deg);
}

.title-noidung {
    clear: both;
    padding: 40px;
    font-family: var(--font-main) !important;
}

.title-noidung img {
    width: 100%;
    height: auto;
    object-fit: cover;
}

.title-noidung h1 {
    font-size: 40px;
    color: #1e73be;
    word-wrap: break-word;
    overflow-wrap: break-word;
    white-space: normal;
    max-width: 100%;
}

.title-noidung p,
.title-noidung span,
.title-noidung a,
.title-noidung code,
.title-noidung pre {
    word-wrap: break-word;
    overflow-wrap: break-word;
    white-space: normal;
    max-width: 100%;
    font-family: var(--font-main) !important;
}

.title-noidung #toc {
    padding: 2em !important;
    margin: 20px;
}

.title-noidung #toc li a {
    color: #972428;
}

.title-noidung #toc .toc_list li {
    margin: 10px 0;
}

.title-noidung p {
    margin-bottom: 10px;
    line-height: 1.6;
    color: #2c3e50;
}

.title-noidung strong {
    color: black;
    font-style: italic;
}

.title-noidung em {
    color: #34495e;
    font-size: 1.2em;
}

.source-courses {
    padding: 16px 20px;
    margin: 20px 0;
}

.content-source {
    display: flex;
    flex-direction: column;
    gap: 8px;
}

.title-source {
    font-size: 1.1em;
    font-weight: 700;
    color: #f42800;
    font-family: 'nunito';
    margin: 0;
}

.phu-sr {
    padding-top: 20px;
    padding-bottom: 20px;
    font-size: 1em;
    color: #7a7a7a;
    margin: 0;
}

.link-sr {
    font-size: 1em;
    color: #972428;
    text-decoration: none;
    word-break: break-all;

}

.link-sr:hover {
    text-decoration: underline;
}

.next-presr {
    display: flex;
    justify-content: space-between;
    flex-wrap: wrap;
    margin: 40px 0;
    gap: 10px;
}

.prev-sr,
.nex-sr {
    flex: 1 1 40%;
    background-color: #ffffff;
    padding: 20px;
    box-shadow: 0 2px 6px rgba(0, 0, 0, 0.05);
    transition: transform 0.3s ease;
    font-family: 'Tahoma', Geneva, sans-serif;
    font-weight: 400;
}

.container_k {
    display: flex;
    max-width: 1000px;
    margin: auto;
}

.menu {
    width: 200px;
    background: #e0f5f5;
    padding: 10px;
}

.menu-item {
    background: #c0eaff;
    padding: 10px;
    margin-bottom: 5px;
    cursor: pointer;
}

.menu-item:hover {
    background: #a0ddff;
}

.content-menu {
    border: 1px solid #777777;
}

.link-pr {
    text-decoration: none;
    color: inherit;
    display: flex;
    flex-direction: column;
    gap: 8px;
}

.prev-link,
.next-link {
    font-size: 1em;
    color: #777777;
    display: flex;
    align-items: center;
    gap: 6px;
}

.link-pre,
.link-nex {
    font-size: 1em;
    color: #333;
    line-height: 1.4;
    display: none;
}

.next-link {
    padding-left: 70%;
}

.link-nex {
    text-align: end;
}

.dropdown-group {
    border: 1px solid #d5d8dc;
    font-family: 'roboto';
}

.bai-st {
    padding-top: 60px;
}

.dropdown-toggle {
    display: block;
    width: 100%;
    padding: 12px;
    color: #6ec1e4;
    text-align: left;
    font-size: 1em;
    cursor: pointer;
    font-weight: 700;
    padding: 20px 25px;
    background-color: white;
    border-bottom: 1px solid #7a7a7a;
}

.dropdown-content {
    display: none;
    padding: 15px;
    background: white;
    color: #7A7A7A;
}

.dropdown-content.active {
    display: block;
}

.dropdown-toggle.active {
    color: #61ce70;
}

.dropdown-content h4 strong {
    font-family: 'nunito';
    font-weight: 700;
    color: #36007c;
}

.dropdown-content p {
    color: #7a7a7a;
    font-weight: 400;
    font-size: 1em;
    margin: 0 0 26px;
}

.dropdown-content ol {
    counter-reset: item;
    list-style: none;
}

.dropdown-content ol li {
    position: relative;
    padding-left: 40px;
}

.dropdown-content ol li::before {
    content: counter(item) ".";
    counter-increment: item;
    position: absolute;
    left: 0;
    top: 0;
    color: #646764;
    width: 30px;
    text-align: right;
}

.dropdown-content ul {
    list-style: none;
    padding-left: 0;
}

.dropdown-content ul li {
    position: relative;
    padding-left: 30px;
}

.dropdown-content ul li::before {
    content: "•";
    position: absolute;
    left: 0;
    top: 0;
    font-size: 1.3em;
}

.pc {
    display: none;
    display: inline-block;
    width: 60%;
    padding-left: 5px;
    vertical-align: top;
    display: none;
}

.pc h4 strong {
    font-family: 'nunito';
    font-weight: 700;
    color: #36007c;
}

.pc p {
    color: #7a7a7a;
    font-weight: 400;
    font-size: 1em;
    margin: 0px 0px 26px;
}

.pc ol {
    counter-reset: item;
    list-style: none;
}

.pc ol li {
    position: relative;
    padding-left: 40px;
}

.pc ol li::before {
    content: counter(item) ".";
    counter-increment: item;
    position: absolute;
    left: 0;
    top: 0;
    color: #646764;
    width: 30px;
    text-align: right;
}

.pc ul {
    list-style: none;
    padding-left: 0;
}

.pc ul li {
    position: relative;
    padding-left: 30px;
}

.pc ul li::before {
    content: "•";
    position: absolute;
    left: 0;
    top: 0;
    color: #646764;
    font-size: 1.3em;
}

.reading-tips {
    margin: 0 auto;
}

.reading-tips h3 {
    font-size: 16px;
    color: #666;
    text-transform: uppercase;
    margin-bottom: 15px;
    border-bottom: 1px solid #eee;
    padding-bottom: 5px;
}

.reading-tips h3.reading-title {
    border: none;
    font-size: 46px;
    color: #6ec1e4;
    margin: 15px 0;
}

.tip-item {
    border-top: 1px solid #ddd;
}

.tip-title {
    cursor: pointer;
    padding: 12px 15px;
    background: #fff;
    color: #6ec1e4;
    position: relative;
    font-weight: 700;
    transition: background 0.3s;
}

.tip-title:hover {
    background: #f9f9f9;
}

.tip-title::before {
    content: "▶";
    display: inline-block;
    margin-right: 8px;
    transition: transform 0.3s;
}

.tip-title.active::before {
    transform: rotate(90deg);
}

.tip-content {
    display: none;
    padding: 12px 15px;
    background: #fdfdfd;
    font-size: 14px;
    color: #333;
    border-top: 1px solid #eee;
}

@media(min-width:576px) {

    .link-pre,
    .link-nex {
        display: block;
    }
}

@media (min-width: 996px) {
    .pc {
        display: inline-block;
    }

    .dropdown-group {
        display: inline-block;
        width: 30%;
        border: unset;
    }

    .dropdown-toggle {
        border-bottom: unset;
    }

    .dropdown-content {
        display: none !important;
    }
}