css
/* ==========================================================================
   1. VARIABLES Y TEMA
   ========================================================================== */
:root {
    --primary-color: #007bff;
    --secondary-color: #6c757d;
    --success-color: #28a745;
    --danger-color: #dc3545;
    --warning-color: #ffc107;
    --info-color: #17a2b8;
    
    --text-color-light: #333;
    --bg-color-light: #f4f7fc;
    --card-bg-light: #ffffff;
    --border-color-light: #dee2e6;

    --text-color-dark: #e0e0e0;
    --bg-color-dark: #121212;
    --card-bg-dark: #1e1e1e;
    --border-color-dark: #444;

    --font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    --sidebar-width: 260px;
    --sidebar-width-collapsed: 80px;
    --header-height: 70px;
    --border-radius: 8px;
    --box-shadow: 0 4px 8px rgba(0,0,0,0.05);
    --transition-speed: 0.3s ease;
}

[data-theme="dark"] {
    --primary-color: #3b82f6;
    --text-color: var(--text-color-dark);
    --bg-color: var(--bg-color-dark);
    --card-bg: var(--card-bg-dark);
    --border-color: var(--border-color-dark);
}

[data-theme="light"] {
    --text-color: var(--text-color-light);
    --bg-color: var(--bg-color-light);
    --card-bg: var(--card-bg-light);
    --border-color: var(--border-color-light);
}

/* ==========================================================================
   2. ESTILOS GLOBALES Y RESET
   ========================================================================== */
* {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
}

body {
    font-family: var(--font-family);
    background-color: var(--bg-color);
    color: var(--text-color);
    transition: background-color var(--transition-speed), color var(--transition-speed);
}

a {
    color: var(--primary-color);
    text-decoration: none;
}

ul {
    list-style: none;
}

.hidden {
    display: none !important;
}

/* ==========================================================================
   3. LOADER
   ========================================================================== */
#loader {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: var(--bg-color-light);
    display: flex;
    justify-content: center;
    align-items: center;
    flex-direction: column;
    z-index: 9999;
    transition: opacity 0.5s ease;
}
.spinner {
    border: 8px solid #f3f3f3;
    border-top: 8px solid var(--primary-color);
    border-radius: 50%;
    width: 60px;
    height: 60px;
    animation: spin 1s linear infinite;
}
#loader p {
    margin-top: 20px;
    font-size: 1.2rem;
    color: var(--text-color-light);
}
@keyframes spin {
    0% { transform: rotate(0deg); }
    100% { transform: rotate(360deg); }
}

/* ==========================================================================
   4. LAYOUT PRINCIPAL
   ========================================================================== */
.app-container {
    display: flex;
}

.sidebar {
    width: var(--sidebar-width);
    height: 100vh;
    background-color: var(--card-bg);
    border-right: 1px solid var(--border-color);
    display: flex;
    flex-direction: column;
    position: fixed;
    top: 0;
    left: 0;
    transition: width var(--transition-speed);
    z-index: 100;
}

.main-content {
    flex-grow: 1;
    margin-left: var(--sidebar-width);
    display: flex;
    flex-direction: column;
    transition: margin-left var(--transition-speed);
}

/* Sidebar colapsado */
body.sidebar-collapsed .sidebar {
    width: var(--sidebar-width-collapsed);
}
body.sidebar-collapsed .main-content {
    margin-left: var(--sidebar-width-collapsed);
}
body.sidebar-collapsed .sidebar .sidebar-brand,
body.sidebar-collapsed .sidebar .nav-link span {
    display: none;
}
body.sidebar-collapsed .sidebar-header,
body.sidebar-collapsed .sidebar-menu li a {
    justify-content: center;
}
body.sidebar-collapsed .sidebar-footer {
    justify-content: center;
}
body.sidebar-collapsed .sidebar .theme-switcher i {
    display: none;
}

/* ==========================================================================
   5. SIDEBAR
   ========================================================================== */
.sidebar-header {
    display: flex;
    align-items: center;
    padding: 20px;
    height: var(--header-height);
    font-size: 1.5rem;
    font-weight: bold;
    color: var(--primary-color);
}
.sidebar-header i {
    margin-right: 15px;
    font-size: 1.8rem;
}
.sidebar-menu {
    flex-grow: 1;
    padding-top: 20px;
}
.sidebar-menu li a {
    display: flex;
    align-items: center;
    padding: 15px 20px;
    color: var(--text-color);
    transition: background-color var(--transition-speed), color var(--transition-speed);
    white-space: nowrap;
}
.sidebar-menu li a:hover, .sidebar-menu li a.active {
    background-color: var(--primary-color);
    color: white;
}
.sidebar-menu li a i {
    font-size: 1.2rem;
    width: 30px;
    text-align: center;
    margin-right: 15px;
}
.sidebar-footer {
    padding: 20px;
    border-top: 1px solid var(--border-color);
}

/* ==========================================================================
   6. HEADER PRINCIPAL
   ========================================================================== */
.main-header {
    height: var(--header-height);
    background: var(--card-bg);
    display: flex;
    align-items: center;
    padding: 0 20px;
    border-bottom: 1px solid var(--border-color);
    position: sticky;
    top: 0;
    z-index: 99;
}
.hamburger-menu {
    display: none;
    background: none;
    border: none;
    font-size: 1.5rem;
    cursor: pointer;
    color: var(--text-color);
}
.main-header h1 {
    font-size: 1.8rem;
    font-weight: 600;
}
.header-actions {
    margin-left: auto;
    display: flex;
    align-items: center;
    gap: 20px;
}
.search-container {
    position: relative;
}
.search-container i {
    position: absolute;
    left: 15px;
    top: 50%;
    transform: translateY(-50%);
    color: var(--secondary-color);
}
#global-search {
    padding: 10px 15px 10px 40px;
    border: 1px solid var(--border-color);
    border-radius: 20px;
    background-color: var(--bg-color);
    color: var(--text-color);
    width: 250px;
    transition: all var(--transition-speed);
}
#global-search:focus {
    outline: none;
    border-color: var(--primary-color);
    box-shadow: 0 0 0 3px rgba(0, 123, 255, 0.25);
}
.user-profile {
    display: flex;
    align-items: center;
    gap: 10px;
}
.user-profile img {
    width: 40px;
    height: 40px;
    border-radius: 50%;
    object-fit: cover;
}

/* ==========================================================================
   7. CONTENIDO DE PÁGINA
   ========================================================================== */
.page-content {
    padding: 20px;
    flex-grow: 1;
}
.page {
    display: none;
}
.page.active {
    display: block;
    animation: fadeIn 0.5s ease-in-out;
}
@keyframes fadeIn {
    from { opacity: 0; transform: translateY(10px); }
    to { opacity: 1; transform: translateY(0); }
}

.card {
    background-color: var(--card-bg);
    border: 1px solid var(--border-color);
    border-radius: var(--border-radius);
    padding: 20px;
    margin-bottom: 20px;
    box-shadow: var(--box-shadow);
    transition: all var(--transition-speed);
}
.card:hover {
    transform: translateY(-5px);
    box-shadow: 0 8px 16px rgba(0,0,0,0.1);
}
.card h3 {
    margin-bottom: 15px;
    font-size: 1.2rem;
}
.card h4 {
    margin-bottom: 10px;
    font-size: 1.1rem;
    color: var(--primary-color);
}

/* ==========================================================================
   8. COMPONENTES: BOTONES, FORMULARIOS, ETC.
   ========================================================================== */
.btn {
    padding: 10px 20px;
    border: none;
    border-radius: var(--border-radius);
    cursor: pointer;
    font-size: 1rem;
    font-weight: 500;
    transition: all var(--transition-speed);
    display: inline-flex;
    align-items: center;
    gap: 8px;
}
.btn i { line-height: 1; }
.btn-primary { background-color: var(--primary-color); color: white; }
.btn-primary:hover { background-color: #0056b3; }
.btn-secondary { background-color: var(--secondary-color); color: white; }
.btn-secondary:hover { background-color: #5a6268; }
.btn-success { background-color: var(--success-color); color: white; }
.btn-danger { background-color: var(--danger-color); color: white; }
.btn-sm { padding: 5px 10px; font-size: 0.8rem; }
.btn-icon { background: transparent; border: none; padding: 5px; font-size: 1.1rem; color: var(--text-color); }
.btn-icon:hover { color: var(--primary-color); }

form label {
    display: block;
    margin-bottom: 5px;
    font-weight: 500;
}
form input[type="text"],
form input[type="number"],
form input[type="date"],
form select {
    width: 100%;
    padding: 10px;
    margin-bottom: 15px;
    border: 1px solid var(--border-color);
    border-radius: var(--border-radius);
    background-color: var(--bg-color);
    color: var(--text-color);
}
form button[type="submit"] {
    margin-top: 10px;
}

/* Theme Switcher */
.theme-switcher { display: flex; align-items: center; justify-content: space-between; }
.switch { position: relative; display: inline-block; width: 50px; height: 26px; }
.switch input { opacity: 0; width: 0; height: 0; }
.slider { position: absolute; cursor: pointer; top: 0; left: 0; right: 0; bottom: 0; background-color: #ccc; transition: .4s; }
.slider:before { position: absolute; content: ""; height: 20px; width: 20px; left: 3px; bottom: 3px; background-color: white; transition: .4s; }
input:checked + .slider { background-color: var(--primary-color); }
input:checked + .slider:before { transform: translateX(24px); }
.slider.round { border-radius: 34px; }
.slider.round:before { border-radius: 50%; }

/* ==========================================================================
   9. ESTILOS DE SECCIONES ESPECÍFICAS
   ========================================================================== */

/* Dashboard */
.stats-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
    gap: 20px;
}
.stats-grid .card {
    display: flex;
    align-items: center;
    gap: 20px;
}
.stats-grid .card i {
    font-size: 2.5rem;
    color: var(--primary-color);
}
.stats-grid .card h3 {
    margin: 0;
    font-size: 2rem;
}
.stats-grid .card p {
    margin: 0;
    color: var(--secondary-color);
}
.charts-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 20px;
    margin-top: 20px;
}
#notifications-list li {
    padding: 10px;
    border-bottom: 1px solid var(--border-color);
}
#notifications-list li:last-child {
    border-bottom: none;
}
.notification-danger { color: var(--danger-color); font-weight: 500; }

/* Placeholder */
.placeholder {
    text-align: center;
    padding: 50px;
    color: var(--secondary-color);
}
.placeholder i {
    font-size: 4rem;
    margin-bottom: 20px;
}
.placeholder h2 {
    color: var(--text-color);
    margin-bottom: 10px;
}
.inline-link {
    font-weight: 600;
    cursor: pointer;
}

/* Gestión Académica */
.tabs-container {
    display: flex;
    border-bottom: 1px solid var(--border-color);
    margin-bottom: 20px;
}
.tab {
    padding: 10px 20px;
    cursor: pointer;
    border: none;
    background: transparent;
    color: var(--text-color);
    border-bottom: 3px solid transparent;
    transition: all var(--transition-speed);
}
.tab:hover {
    background-color: rgba(0,0,0,0.05);
}
.tab.active {
    border-bottom-color: var(--primary-color);
    font-weight: 600;
}
.course-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 20px;
}
.course-selector {
    padding: 8px;
    border-radius: var(--border-radius);
    border-color: var(--border-color);
}
.table-container {
    overflow-x: auto;
}
.grades-table {
    width: 100%;
    border-collapse: collapse;
    white-space: nowrap;
}
.grades-table th, .grades-table td {
    padding: 12px 15px;
    text-align: left;
    border: 1px solid var(--border-color);
}
.grades-table thead {
    background-color: var(--bg-color);
}
.grades-table th {
    font-weight: 600;
}
.grades-table .col-fixed {
    position: sticky;
    left: 0;
    background-color: var(--card-bg);
    z-index: 1;
}
.grades-table .col-actions {
    text-align: center;
}
.grades-table input.grade-input {
    width: 60px;
    padding: 5px;
    text-align: center;
    border: 1px solid transparent;
    border-radius: 4px;
}
.grades-table input.grade-input:focus {
    border-color: var(--primary-color);
    outline: none;
    background-color: var(--bg-color);
}

.grade-approved { background-color: rgba(40, 167, 69, 0.1); }
.grade-failed { background-color: rgba(220, 53, 69, 0.1); }

/* Configuración */
.config-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(350px, 1fr));
    gap: 20px;
}
.institucion-card, .curso-card {
    border: 1px solid var(--border-color);
    border-radius: var(--border-radius);
    padding: 15px;
    margin-bottom: 15px;
    background-color: var(--bg-color);
}
.institucion-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 10px;
}
.curso-item {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 8px;
    border-radius: 4px;
}
.curso-item:hover {
    background-color: var(--bg-color-light);
}
[data-theme="dark"] .curso-item:hover {
    background-color: var(--bg-color-dark);
}

/* Reportes y Ayuda */
.report-controls, .backup-controls {
    display: flex;
    flex-wrap: wrap;
    gap: 15px;
    margin-top: 15px;
}
.faq-item {
    margin-bottom: 15px;
    border-left: 3px solid var(--primary-color);
    padding-left: 15px;
}

/* ==========================================================================
   10. MODAL
   ========================================================================== */
.modal-container {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background-color: rgba(0,0,0,0.6);
    display: flex;
    justify-content: center;
    align-items: center;
    z-index: 1000;
    opacity: 0;
    visibility: hidden;
    transition: opacity 0.3s, visibility 0.3s;
}
.modal-container.visible {
    opacity: 1;
    visibility: visible;
}
.modal-content {
    background: var(--card-bg);
    padding: 30px;
    border-radius: var(--border-radius);
    width: 90%;
    max-width: 600px;
    position: relative;
    transform: scale(0.9);
    transition: transform 0.3s;
}
.modal-container.visible .modal-content {
    transform: scale(1);
}
.modal-close-btn {
    position: absolute;
    top: 15px;
    right: 15px;
    background: none;
    border: none;
    font-size: 1.8rem;
    cursor: pointer;
    color: var(--text-color);
}
#modal-body h3 {
    margin-top: 0;
    margin-bottom: 20px;
}

/* ==========================================================================
   11. RESPONSIVE DESIGN
   ========================================================================== */
@media (max-width: 1024px) {
    body {
        --sidebar-width: var(--sidebar-width-collapsed);
    }
    .main-content {
        margin-left: var(--sidebar-width-collapsed);
    }
    .sidebar .sidebar-brand, .sidebar .nav-link span { display: none; }
    .sidebar-header, .sidebar-menu li a { justify-content: center; }
    .sidebar-footer { justify-content: center; }
    .sidebar .theme-switcher i { display: none; }
}

@media (max-width: 768px) {
    .main-content { margin-left: 0; }
    .sidebar {
        transform: translateX(-100%);
        transition: transform var(--transition-speed);
    }
    .sidebar.open {
        transform: translateX(0);
        width: 260px; /* Ancho completo al abrir */
    }
    .sidebar.open .sidebar-brand, 
    .sidebar.open .nav-link span,
    .sidebar.open .theme-switcher i {
        display: inline-block;
    }
    .sidebar.open .sidebar-header, 
    .sidebar.open .sidebar-menu li a {
        justify-content: flex-start;
    }
    .hamburger-menu { display: block; }
    .header-actions {
        gap: 10px;
    }
    #global-search {
        width: 150px;
    }
    .main-header h1 {
        font-size: 1.4rem;
        margin-left: 10px;
    }
    .stats-grid, .charts-grid, .config-grid {
        grid-template-columns: 1fr;
    }
}

@media (max-width: 480px) {
    .header-actions {
        flex-direction: column-reverse;
        align-items: flex-end;
        gap: 5px;
    }
    .main-header {
        height: auto;
        padding-top: 10px;
        padding-bottom: 10px;
    }
    .search-container, #global-search {
        width: 100%;
    }
    .page-content {
        padding: 10px;
    }
    .card {
        padding: 15px;
    }
    .course-header {
        flex-direction: column;
        align-items: stretch;
        gap: 10px;
    }
}