/* =============================================================================
   CSS Variables - Customize your theme here
   ============================================================================= */
:root {
    --primary-color: #3498db;
    --primary-hover: #2980b9;
    --secondary-color: #2c3e50;
    --background-color: #ecf0f1;
    --card-background: #ffffff;
    --text-color: #2c3e50;
    --text-muted: #7f8c8d;
    --border-color: #bdc3c7;
    --success-color: #27ae60;
    --warning-color: #f39c12;
    --danger-color: #e74c3c;
    --sidebar-width: 220px;
    --header-height: 60px;
    --footer-height: 40px;
}

/* =============================================================================
   Reset & Base Styles
   ============================================================================= */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Oxygen, Ubuntu, sans-serif;
    background-color: var(--background-color);
    color: var(--text-color);
    line-height: 1.6;
}

/* =============================================================================
   App Layout
   ============================================================================= */
#app-container {
    display: grid;
    grid-template-areas:
        "header header"
        "nav main"
        "footer footer";
    grid-template-columns: var(--sidebar-width) 1fr;
    grid-template-rows: var(--header-height) 1fr var(--footer-height);
    min-height: 100vh;
}

/* Header */
#app-header {
    grid-area: header;
    background-color: var(--secondary-color);
    color: white;
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: 0 20px;
    box-shadow: 0 2px 4px rgba(0, 0, 0, 0.1);
    z-index: 100;
}

#logo h1 {
    font-size: 1.5rem;
    font-weight: 600;
}

#header-actions {
    display: flex;
    align-items: center;
    gap: 15px;
}

#current-time {
    font-size: 0.9rem;
    opacity: 0.9;
}

/* Navigation Sidebar */
#main-nav {
    grid-area: nav;
    background-color: var(--card-background);
    border-right: 1px solid var(--border-color);
    padding: 20px 0;
}

#nav-menu {
    list-style: none;
}

#nav-menu li {
    margin: 5px 10px;
}

.nav-link {
    display: flex;
    align-items: center;
    gap: 12px;
    padding: 12px 15px;
    text-decoration: none;
    color: var(--text-color);
    border-radius: 8px;
    transition: all 0.2s ease;
}

.nav-link:hover {
    background-color: var(--background-color);
}

.nav-link.active {
    background-color: var(--primary-color);
    color: white;
}

.nav-icon {
    font-size: 1.2rem;
}

.nav-text {
    font-weight: 500;
}

/* Main Content */
#content-container {
    grid-area: main;
    padding: 20px;
    overflow-y: auto;
}

#content-container.loading #loading-indicator {
    display: flex;
}

#loading-indicator {
    display: none;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    padding: 60px;
    color: var(--text-muted);
}

.spinner {
    width: 40px;
    height: 40px;
    border: 4px solid var(--border-color);
    border-top-color: var(--primary-color);
    border-radius: 50%;
    animation: spin 1s linear infinite;
    margin-bottom: 15px;
}

@keyframes spin {
    to { transform: rotate(360deg); }
}

/* Footer */
#app-footer {
    grid-area: footer;
    background-color: var(--card-background);
    border-top: 1px solid var(--border-color);
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 0.85rem;
    color: var(--text-muted);
}

/* =============================================================================
   Common Components
   ============================================================================= */

/* Cards */
.card {
    background-color: var(--card-background);
    border-radius: 8px;
    box-shadow: 0 2px 4px rgba(0, 0, 0, 0.05);
    padding: 20px;
    margin-bottom: 20px;
}

.card-header {
    font-size: 1.1rem;
    font-weight: 600;
    margin-bottom: 15px;
    padding-bottom: 10px;
    border-bottom: 1px solid var(--border-color);
}

/* Stats Cards */
.stats-container {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
    gap: 20px;
    margin-bottom: 20px;
}

.stat-card {
    background-color: var(--card-background);
    border-radius: 8px;
    box-shadow: 0 2px 4px rgba(0, 0, 0, 0.05);
    padding: 20px;
    text-align: center;
}

.stat-value {
    display: block;
    font-size: 2rem;
    font-weight: 700;
    color: var(--primary-color);
    margin-bottom: 5px;
}

.stat-label {
    font-size: 0.9rem;
    color: var(--text-muted);
    text-transform: uppercase;
    letter-spacing: 0.5px;
}

/* Buttons */
.btn {
    display: inline-flex;
    align-items: center;
    gap: 8px;
    padding: 10px 20px;
    border: none;
    border-radius: 6px;
    font-size: 0.95rem;
    font-weight: 500;
    cursor: pointer;
    transition: all 0.2s ease;
}

.btn-primary {
    background-color: var(--primary-color);
    color: white;
}

.btn-primary:hover {
    background-color: var(--primary-hover);
}

.btn-secondary {
    background-color: var(--background-color);
    color: var(--text-color);
    border: 1px solid var(--border-color);
}

.btn-secondary:hover {
    background-color: var(--border-color);
}

.btn-success {
    background-color: var(--success-color);
    color: white;
}

.btn-danger {
    background-color: var(--danger-color);
    color: white;
}

/* Forms */
.form-group {
    margin-bottom: 20px;
}

.form-label {
    display: block;
    font-weight: 500;
    margin-bottom: 8px;
}

.form-control {
    width: 100%;
    padding: 10px 12px;
    border: 1px solid var(--border-color);
    border-radius: 6px;
    font-size: 1rem;
    transition: border-color 0.2s ease;
}

.form-control:focus {
    outline: none;
    border-color: var(--primary-color);
}

select.form-control {
    cursor: pointer;
}

/* Checkbox / Toggle */
.form-check {
    display: flex;
    align-items: center;
    gap: 10px;
}

.form-check input[type="checkbox"] {
    width: 18px;
    height: 18px;
    cursor: pointer;
}

/* Tables */
.table-container {
    background-color: var(--card-background);
    border-radius: 8px;
    box-shadow: 0 2px 4px rgba(0, 0, 0, 0.05);
    padding: 20px;
    overflow-x: auto;
}

/* Modal */
.modal {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background-color: rgba(0, 0, 0, 0.5);
    display: flex;
    align-items: center;
    justify-content: center;
    z-index: 1000;
}

.modal-content {
    background-color: var(--card-background);
    border-radius: 8px;
    padding: 25px;
    min-width: 400px;
    max-width: 90%;
    max-height: 90vh;
    overflow-y: auto;
    position: relative;
}

.modal-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 20px;
    padding-bottom: 15px;
    border-bottom: 1px solid var(--border-color);
}

.modal-title {
    font-size: 1.25rem;
    font-weight: 600;
}

.modal-close {
    background: none;
    border: none;
    font-size: 1.5rem;
    cursor: pointer;
    color: var(--text-muted);
    line-height: 1;
}

.modal-close:hover {
    color: var(--text-color);
}

.modal-body {
    margin-bottom: 20px;
}

.modal-footer {
    display: flex;
    justify-content: flex-end;
    gap: 10px;
    padding-top: 15px;
    border-top: 1px solid var(--border-color);
}

/* Alerts */
.alert {
    padding: 15px 20px;
    border-radius: 6px;
    margin-bottom: 20px;
}

.alert-success {
    background-color: rgba(39, 174, 96, 0.1);
    border: 1px solid var(--success-color);
    color: var(--success-color);
}

.alert-warning {
    background-color: rgba(243, 156, 18, 0.1);
    border: 1px solid var(--warning-color);
    color: var(--warning-color);
}

.alert-danger {
    background-color: rgba(231, 76, 60, 0.1);
    border: 1px solid var(--danger-color);
    color: var(--danger-color);
}

/* Status Badges */
.badge {
    display: inline-block;
    padding: 4px 10px;
    border-radius: 12px;
    font-size: 0.8rem;
    font-weight: 500;
}

.badge-success {
    background-color: rgba(39, 174, 96, 0.1);
    color: var(--success-color);
}

.badge-warning {
    background-color: rgba(243, 156, 18, 0.1);
    color: var(--warning-color);
}

.badge-danger {
    background-color: rgba(231, 76, 60, 0.1);
    color: var(--danger-color);
}

/* Page Titles */
.page-title {
    font-size: 1.5rem;
    font-weight: 600;
    margin-bottom: 20px;
    color: var(--secondary-color);
}

/* Error Container */
#error-container {
    text-align: center;
    padding: 60px 20px;
}

#error-container h2 {
    color: var(--danger-color);
    margin-bottom: 10px;
}

/* =============================================================================
   Responsive Design
   ============================================================================= */
@media (max-width: 768px) {
    #app-container {
        grid-template-areas:
            "header"
            "main"
            "footer";
        grid-template-columns: 1fr;
        grid-template-rows: var(--header-height) 1fr var(--footer-height);
    }
    
    #main-nav {
        display: none;
    }
    
    .stats-container {
        grid-template-columns: 1fr;
    }
    
    .modal-content {
        min-width: auto;
        margin: 20px;
    }
}