body {
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    margin: 0;
    padding: 0;
    display: flex;
    flex-direction: column;
    height: 100vh;
}

header {
    background-color: #333;
    color: white;
    padding: 1rem;
    display: flex;
    justify-content: space-between;
    align-items: center;
}

header a {
    color: white;
    text-decoration: none;
    margin-left: 1rem;
}

.container {
    display: flex;
    flex: 1;
    overflow: hidden;
}

/* Sidebar */
.sidebar {
    width: 20%;
    background-color: #f4f4f4;
    border-right: 1px solid #ddd;
    display: flex;
    flex-direction: column;
    padding: 1rem;
    box-sizing: border-box;
}

.lesson-list {
    flex: 1;
    overflow-y: auto;
}

.lesson-item {
    padding: 0.5rem;
    border-bottom: 1px solid #eee;
    cursor: pointer;
}

.lesson-item:hover {
    background-color: #e0e0e0;
}

.language-filter {
    border-top: 1px solid #ccc;
    padding-top: 1rem;
    margin-top: 1rem;
}

.language-tag {
    display: inline-block;
    background: #ddd;
    padding: 2px 6px;
    border-radius: 4px;
    margin: 2px;
    font-size: 0.8rem;
    cursor: pointer;
}

.language-tag.active {
    background: #007bff;
    color: white;
}

/* Main Content */
.main-content {
    width: 80%;
    padding: 2rem;
    box-sizing: border-box;
    overflow-y: auto;
}

/* Forms */
.form-group {
    margin-bottom: 1rem;
}

.form-group label {
    display: block;
    margin-bottom: 0.5rem;
}

.form-group input,
.form-group select {
    width: 100%;
    padding: 0.5rem;
    box-sizing: border-box;
}

/* Editor */
#editor {
    width: 100%;
    height: 60vh;
    font-family: monospace;
    padding: 1rem;
    box-sizing: border-box;
}

.login-container {
    display: flex;
    justify-content: center;
    align-items: center;
    height: 100vh;
}

.btn {
    padding: 0.5rem 1rem;
    background-color: #007bff;
    color: white;
    border: none;
    border-radius: 4px;
    cursor: pointer;
    text-decoration: none;
}

/* Tabs */
.tab-container {
    margin-top: 1rem;
}

.tabs {
    display: flex;
    border-bottom: 1px solid #ccc;
    margin-bottom: 1rem;
}

.tab {
    padding: 0.5rem 1rem;
    cursor: pointer;
    border: 1px solid transparent;
    border-bottom: none;
    margin-right: 0.2rem;
}

.tab:hover {
    background-color: #f8f9fa;
}

.tab.active {
    background-color: #fff;
    border-color: #ccc;
    border-bottom-color: #fff;
    font-weight: bold;
    margin-bottom: -1px;
}

.tab-content {
    display: none;
    padding: 1rem;
    border: 1px solid #ccc;
    /* Optional enclosure */
    border-top: none;
}

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

/* Markdown Content Display */
.content-display {
    line-height: 1.6;
    color: #333;
}

.content-display h2 {
    margin-top: 1.5rem;
}

.content-display p {
    margin-bottom: 1rem;
}

.content-display img {
    max-width: 100%;
}

/* Language Badges */
.lang-badge {
    background: #e9ecef;
    color: #495057;
    font-size: 0.75rem;
    padding: 2px 6px;
    border-radius: 4px;
    text-transform: uppercase;
}

.lesson-item {
    display: flex;
    justify-content: space-between;
    align-items: center;
}

/* Lesson Header & Meta */
.lesson-header {
    display: flex;
    justify-content: space-between;
    align-items: flex-start;
    flex-wrap: nowrap;
    /* Prevent stacking */
}

.lesson-meta {
    font-size: 0.85rem;
    color: #666;
    margin-top: 0.5rem;
}

.lesson-meta a {
    color: #007bff;
    text-decoration: none;
}

.meta-dates {
    margin-top: 0.25rem;
    font-size: 0.8rem;
    color: #888;
}

.btn-danger {
    background-color: #dc3545;
}

.btn-primary {
    background-color: #007bff;
}

.btn {
    white-space: nowrap;
    /* Prevent button text wrap */
}