* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
}

body {
    background-color: #f5f7fa;
    color: #333;
    line-height: 1.6;
}

.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 5px;
}
a {
    text-decoration: none;
    color: inherit;
}

.header {
    background-color: #4e7fd1;
    color: white;
    text-align: center;
    padding: 1.5rem 1rem;
    box-shadow: 0 2px 5px rgba(0,0,0,0.1);
    border-radius: 10px;
    margin-bottom: 10px;
}

.header h1 {
    font-size: 2rem;
    margin-bottom: 0.5rem;
    font-weight: 600;
}

.header p {
    font-size: 1rem;
    margin-bottom: 1.5rem;
    opacity: 0.9;
}

.nav-container {
    display: flex;
    justify-content: center;
    flex-wrap: wrap;
    gap: 0.75rem;
    max-width: 960px;
    margin: 0 auto;
}

.nav-button {
    background-color: rgba(255, 255, 255, 0.9);
    color: #333;
    padding: 0.5rem 1rem;
    border-radius: 20px;
    text-decoration: none;
    display: flex;
    align-items: center;
    gap: 0.5rem;
    transition: all 0.2s ease;
    font-size: 0.9rem;
    white-space: nowrap;
}

.nav-button:hover {
    background-color: white;
    transform: translateY(-2px);
    box-shadow: 0 3px 8px rgba(0,0,0,0.1);
}

.nav-icon {
    font-size: 1.1rem;
}

.breadcrumb-container {
    background-color: #e2e8f0;
    border-radius: 0.5rem;
    padding: 0.75rem 1rem;
    margin-bottom: 1rem;
}

h1 {
    font-size: 2rem;
    margin-bottom: 0px;
}

.header-box {
    background: linear-gradient(135deg, #8197c2, #9bade1);
    color: white;
    padding: 15px 5px;
    text-align: center;
    border-radius: 10px;
    margin-bottom: 20px;
    box-shadow: 0 4px 12px rgba(0, 0, 0, 0.1);
}

.header-box p {
    margin-bottom: 0px;
    /*font-size: 1.2rem;*/
}

.subtitle {
    font-size: 1.2rem;
    opacity: 0.9;
}

/*.search-bar {*/
/*    display: flex;*/
/*    margin: 0 auto;*/
/*    margin-top: 10px !important;*/
/*    max-width: 600px;*/
/*    padding: 0 5px;*/
/*}*/

/*.search-bar input {*/
/*    !*flex: 1;*!*/
/*    padding: 12px 15px;*/
/*    border: none;*/
/*    border-radius: 30px 0 0 30px;*/
/*    font-size: 16px;*/
/*    box-shadow: inset 0 2px 5px rgba(0, 0, 0, 0.1);*/
/*}*/

/*.search-bar select {*/
/*    !* flex: 1; *!*/
/*    padding: 12px 15px;*/
/*    border: none;*/
/*    box-shadow: inset 0 2px 5px rgba(0, 0, 0, 0.1);*/
/*}*/

/*.search-bar button {*/
/*    background-color: #ff6b6b;*/
/*    color: white;*/
/*    border: none;*/
/*    padding: 5px 20px;*/
/*    border-radius: 0 30px 30px 0;*/
/*    cursor: pointer;*/
/*    font-weight: bold;*/
/*    transition: background-color 0.3s;*/
/*}*/

/*.search-bar button:hover {*/
/*    background-color: #ff5252;*/
/*}*/

/* Search bar base style */
.search-bar {
  display: flex;
  flex-direction: row;
  flex-wrap: wrap;
  justify-content: center;
  align-items: center;
  gap: 10px;
    /*max-width: 600px;*/
  /* background: white; */
  border-radius: 50px;
  padding: 8px;
}

/* Inputs and Select */
.search-bar input[type="text"],
.search-bar select {
  flex: 1 1 auto;
  font-size: 14px;
  padding: 10px 14px;
  border: none;
  border-radius: 30px;
  outline: none;
  min-width: 120px;
    max-width: 500px;
}

/* Button style */
.search-bar button {
  background-color: #fc5c7d;
  color: white;
  border: none;
  padding: 10px 20px;
  font-size: 14px;
  font-weight: bold;
  border-radius: 30px;
  cursor: pointer;
  transition: background-color 0.3s ease;
}

.search-bar button:hover {
  background-color: #e14b6c;
}


.categories {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(350px, 1fr));
    gap: 25px;
    margin-top: 40px;
}

.category {
    background-color: white;
    border-radius: 10px;
    padding: 25px;
    box-shadow: 0 4px 10px rgba(0, 0, 0, 0.05);
    transition: transform 0.3s ease, box-shadow 0.3s ease;
}

.category:hover {
    transform: translateY(-5px);
    box-shadow: 0 6px 15px rgba(0, 0, 0, 0.1);
}

.category-header {
    display: flex;
    align-items: center;
    margin-bottom: 20px;
}

.category-icon {
    font-size: 26px;
    margin-right: 15px;
    width: 50px;
    height: 50px;
    display: flex;
    align-items: center;
    justify-content: center;
    border-radius: 50%;
}

.category-title {
    font-size: 1.4rem;
    font-weight: bold;
    color: #333;
}

.category-list {
    list-style: none;
}

.category-list li {
    padding: 8px 0;
    border-bottom: 1px dashed #eee;
    display: flex;
    align-items: center;
}

.category-list li:last-child {
    border-bottom: none;
}

.category-list li:before {
    content: "•";
    color: #ff6b6b;
    font-weight: bold;
    margin-right: 10px;
}

.category-list a {
    text-decoration: none;
    color: inherit;
}

.category-list a:hover {
    color: #ff6b6b;
}

.icon-academic {
    background-color: #e9f5ff;
    color: #3a86ff;
}

.icon-skills {
    background-color: #eefbf5;
    color: #06d6a0;
}

.icon-tech {
    background-color: #f0f5ff;
    color: #7b61ff;
}

.icon-exam {
    background-color: #fff4e5;
    color: #ff9e43;
}

.icon-entertainment {
    background-color: #ffeeee;
    color: #ff6b6b;
}

footer {
    margin-top: 50px;
    text-align: center;
    padding: 20px;
    color: #666;
    font-size: 0.9rem;
}

.footer-links a {
    margin: 0 0.5rem;
    color: #1e3a8a;
    text-decoration: none;
}
.footer-links a:hover {
    text-decoration: underline;
}

.popular-tags {
    display: flex;
    flex-wrap: wrap;
    justify-content: center;
    margin: 20px 0;
    gap: 10px;
}

.popular-tags a {
    text-decoration: none;
}

.tag {
    background-color: #eee;
    padding: 8px 15px;
    border-radius: 20px;
    font-size: 1rem;
    color: #383838;
    /* color: #5278ff; */
    transition: background-color 0.3s;
}

.tag:hover {
    background-color: #ddd;
    cursor: pointer;
}

@media (max-width: 768px) {
    .container {
        padding: 5px;
    }
    .categories {
        grid-template-columns: 1fr;
    }

    .header {
        padding: 0.75rem 0.5rem;
    }

    .header h1 {
        font-size: 1.2rem;
        margin-bottom: 0.3rem;
    }

    .header p {
        font-size: 0.75rem;
        margin-bottom: 0.75rem;
    }

    .nav-container {
        flex-direction: row;
        flex-wrap: wrap;
        gap: 0.4rem;
        padding: 0 0.5rem;
    }

    .nav-button {
        flex: 0 0 calc(50% - 0.2rem);
        justify-content: center;
        padding: 0.4rem 0.5rem;
        font-size: 0.75rem;
    }

    .nav-icon {
        font-size: 0.9rem;
    }
}

@media (max-width: 500px) {
    .search-bar {
        max-width: 400px;
    }
    /*header {*/
    /*    padding: 5px 0;*/
    /*    text-align: center;*/
    /*    border-radius: 10px;*/
    /*    box-shadow: 0 4px 12px rgba(0, 0, 0, 0.1);*/
    /*}*/
    
    /*.title-header {*/
    /*    font-size: 2rem;*/
    /*}*/
    /*.subtitle {*/
    /*    font-size: 1rem;*/
    /*}*/

    .header-box {
        padding: 10px 0;
    }
    .header-box h1 {
        font-size: 1.5rem;
    }
    .header-box p {
        font-size: 1rem;
    }
}

@media (min-width: 769px) and (max-width: 1024px) {
    .nav-container {
        flex-wrap: wrap;
        justify-content: center;
    }

    .nav-button {
        flex: 0 0 calc(50% - 0.5rem);
        justify-content: flex-start;
    }
}


.app-box {
    border-left: 5px solid #3b82f6;
    padding-left: 1rem;
    margin-top: 1.5rem;
}

.app-box h3 {
    font-size: 1.25rem;
    font-weight: 600;
    color: #1e40af;
    margin-bottom: 0.75rem;
}

.content-section {
    background-color: white;
    padding: 10px;
    border-radius: 0.75rem;
    box-shadow: 0 6px 20px rgba(0, 0, 0, 0.06);
    margin-bottom: 2rem;
    line-height: 1.75;
}

code {
    background-color: #f3f4f6;
    padding: 0.2rem 0.4rem;
    border-radius: 0.25rem;
    color: #d97706;
}

blockquote {
    font-style: italic;
    color: #4b5563;
    border-left: 4px solid #93c5fd;
    padding-left: 1rem;
    margin: 1.5rem 0;
    background-color: #f1f5f9;
    border-radius: 0.5rem;
}


.course-list {
    display: flex;
    flex-direction: column;
    gap: 2rem;
    margin-top: 2rem;
}

.course-list a {
    text-decoration: none;
}

.course-card {
    background-color: white;
    border-radius: 1rem;
    padding: 15px;
    box-shadow: 0 8px 24px rgba(0,0,0,0.06);
    transition: 0.3s;
}
.course-card:hover {
    transform: translateY(-4px);
    box-shadow: 0 12px 32px rgba(0,0,0,0.1);
}
.course-card h3 {
    color: #1d4ed8;
    font-size: 1.5rem;
    font-weight: 600;
}
.course-card p {
    color: #475569;
    font-size: 1rem;
    margin-bottom: 0.5rem;
}
.course-card ul {
    padding-left: 1.2rem;
    color: #334155;
    margin-bottom: 0;
}


/*chi tiet khoa hoc*/
.detail-section {
    background-color: white;
    padding: 20px;
    border-radius: 1rem;
    margin-top: 2rem;
    box-shadow: 0 8px 24px rgba(0, 0, 0, 0.06);
}
.detail-section h2 {
    color: #1d4ed8;
    font-weight: 700;
    margin-top: 0rem;
}
.detail-section p, .detail-section ul {
    font-size: 1.1rem;
    color: #334155;
    line-height: 1.8;
}
.detail-section ul {
    padding-left: 1.2rem;
    color: #475569;
}
.lecture-nav {
    display: flex;
    flex-direction: column;
    gap: 0.5rem;
    margin-top: 1.5rem;
}
.lecture-nav button {
    background-color: #e2e8f0;
    border: none;
    padding: 0.75rem 1rem;
    text-align: left;
    border-radius: 0.5rem;
    font-weight: 500;
    color: #1e3a8a;
}
.lecture-nav button:hover {
    background-color: #cbd5e1;
}
.lecture-nav button.active-lecture {
    background-color: #1d4ed8;
    color: white;
}
.video-container iframe {
    width: 100%;
    height: 360px;
    border-radius: 0.5rem;
    border: none;
    margin-bottom: 1rem;
}
.lecture-title {
    font-size: 1.25rem;
    font-weight: 600;
    color: #1e40af;
    margin-top: 2rem;
}
.lecture-desc {
    font-size: 1rem;
    color: #475569;
    margin-bottom: 1rem;
}
.cta {
    margin-top: 2.5rem;
    text-align: center;
}
.cta a {
    font-weight: 600;
    font-size: 1rem;
}

.toc-list li::before {
    content: "" !important;
}

.custom-list li::before {
    content: "" !important;
}

@media (max-width: 393px) {
    .header h1 {
        font-size: 1rem;
    }

    .header p {
        font-size: 0.8rem;
        margin-bottom: 0.3rem;
    }

    .nav-button {
        height: 1.5rem;
        font-size: 0.6rem;
        padding: 0.2rem;
    }

    .nav-icon {
        font-size: 0.65rem;
        margin-right: 0.15rem;
    }
}

/*.figure {*/
/*    flex-direction: column !important;*/
/*}*/