/* --- Design Tokens --- */
:root {
    --bg-main: #0c0f14; /* Muted Arctic Night */
    --bg-card: rgba(22, 29, 38, 0.75); /* Frost Slate */
    --bg-card-hover: rgba(28, 37, 49, 0.9);
    --border-color: rgba(255, 255, 255, 0.06);
    --border-glow: rgba(212, 128, 82, 0.12); /* Soft Copper glow */
    
    --text-primary: #f2f4f7;
    --text-secondary: #a1aab8;
    --text-muted: #6b7787;
    
    /* Accents (Muted Nordic Palette: Copper, Sage, Earth) */
    --accent-purple: #d48052; /* Warm Copper */
    --accent-purple-glow: rgba(212, 128, 82, 0.25);
    --accent-cyan: #7fa492; /* Soft Pine/Sage */
    --accent-cyan-glow: rgba(127, 164, 146, 0.25);
    --accent-rose: #d66868; /* Muted Red-Clay */
    
    --font-heading: 'Outfit', sans-serif;
    --font-body: 'Inter', sans-serif;
    
    --shadow-sm: 0 4px 6px -1px rgba(0, 0, 0, 0.1), 0 2px 4px -1px rgba(0, 0, 0, 0.06);
    --shadow-lg: 0 10px 20px -3px rgba(0, 0, 0, 0.4), 0 4px 10px -2px rgba(0, 0, 0, 0.1);
    --shadow-glow: 0 0 20px 0 rgba(212, 128, 82, 0.05);
    
    --transition-smooth: all 0.25s cubic-bezier(0.4, 0, 0.2, 1);
    --transition-fast: all 0.12s cubic-bezier(0.4, 0, 0.2, 1);

    /* Theme Dynamic Colors (Dark Mode Defaults) */
    --bg-header: rgba(15, 23, 42, 0.4);
    --bg-search-bar: rgba(15, 23, 42, 0.6);
    --bg-dropdown: #111827;
    --bg-toolbar: rgba(22, 29, 38, 0.4);
    --bg-toolbar-btn: rgba(255, 255, 255, 0.04);
    --bg-toolbar-btn-hover: rgba(255, 255, 255, 0.08);
    --bg-item-hover: rgba(255, 255, 255, 0.03);
    --shadow-popover: 0 10px 25px rgba(0, 0, 0, 0.5), 0 0 0 1px var(--border-glow);
    --logo-gradient: linear-gradient(135deg, #FFFFFF 0%, #A78BFA 100%);
    --bg-gradient-alpha-1: 0.03;
    --bg-gradient-alpha-2: 0.03;
    --skeleton-gradient: linear-gradient(90deg, rgba(255,255,255,0.03) 25%, rgba(255,255,255,0.08) 50%, rgba(255,255,255,0.03) 75%);
    --bg-calendar-other-day: rgba(0,0,0,0.15);
    --event-border-color: rgba(255, 255, 255, 0.08);
    --common-event-bg: rgba(22, 29, 38, 0.4);
    --bg-lecture-event: #161c28;
    --bg-lecture-event-hover: #1f293d;
}

body.light-mode {
    --bg-main: #f3f5f8;
    --bg-card: rgba(255, 255, 255, 0.85);
    --bg-card-hover: rgba(255, 255, 255, 0.95);
    --border-color: rgba(0, 0, 0, 0.08);
    --border-glow: rgba(212, 128, 82, 0.08);
    
    --text-primary: #1e293b;
    --text-secondary: #475569;
    --text-muted: #94a3b8;
    
    --bg-header: rgba(255, 255, 255, 0.75);
    --bg-search-bar: rgba(255, 255, 255, 0.9);
    --bg-dropdown: #ffffff;
    --bg-toolbar: rgba(255, 255, 255, 0.8);
    --bg-toolbar-btn: rgba(0, 0, 0, 0.03);
    --bg-toolbar-btn-hover: rgba(0, 0, 0, 0.06);
    --bg-item-hover: rgba(0, 0, 0, 0.02);
    --shadow-popover: 0 10px 25px rgba(0, 0, 0, 0.06);
    --logo-gradient: linear-gradient(135deg, #0f172a 0%, #6d28d9 100%);
    --bg-gradient-alpha-1: 0.02;
    --bg-gradient-alpha-2: 0.02;
    --skeleton-gradient: linear-gradient(90deg, rgba(0,0,0,0.03) 25%, rgba(0,0,0,0.08) 50%, rgba(0,0,0,0.03) 75%);
    --bg-calendar-other-day: rgba(0,0,0,0.03);
    --event-border-color: rgba(0, 0, 0, 0.08);
    --common-event-bg: rgba(0, 0, 0, 0.03);
    --bg-lecture-event: #ffffff;
    --bg-lecture-event-hover: #f8fafc;
}

/* --- Base Resets & Typography --- */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

body {
    background-color: var(--bg-main);
    color: var(--text-primary);
    font-family: var(--font-body);
    font-size: 15px;
    line-height: 1.6;
    background-image: 
        radial-gradient(circle at 10% 20%, rgba(212, 128, 82, var(--bg-gradient-alpha-1)) 0%, transparent 40%),
        radial-gradient(circle at 90% 80%, rgba(127, 164, 146, var(--bg-gradient-alpha-2)) 0%, transparent 40%);
    background-attachment: fixed;
    min-height: 100vh;
    transition: background-color 0.3s ease, color 0.3s ease, border-color 0.3s ease;
}

h1, h2, h3, h4 {
    font-family: var(--font-heading);
    font-weight: 600;
}

/* --- Layout --- */
.app-container {
    max-width: 1600px;
    margin: 0 auto;
    padding: 24px;
    display: flex;
    flex-direction: column;
    gap: 24px;
    min-height: 100vh;
}

/* --- Glassmorphic Card Styling --- */
.card {
    background: var(--bg-card);
    backdrop-filter: blur(12px);
    -webkit-backdrop-filter: blur(12px);
    border: 1px solid var(--border-color);
    border-radius: 16px;
    box-shadow: var(--shadow-lg);
    transition: var(--transition-smooth);
}

.card:hover {
    border-color: rgba(139, 92, 246, 0.2);
    box-shadow: var(--shadow-lg), var(--shadow-glow);
}

/* --- Main Header --- */
.main-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    gap: 32px;
    flex-wrap: wrap;
    background: var(--bg-header);
    backdrop-filter: blur(8px);
    border: 1px solid var(--border-color);
    border-radius: 16px;
    padding: 16px 24px;
    position: relative;
    z-index: 1000;
}

.logo-area {
    display: flex;
    align-items: center;
    gap: 16px;
}

.logo-icon {
    font-size: 32px;
    filter: drop-shadow(0 0 8px var(--accent-purple-glow));
}

.logo-text h1 {
    font-size: 24px;
    background: var(--logo-gradient);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    letter-spacing: -0.5px;
}

.logo-text p {
    font-size: 12px;
    color: var(--text-secondary);
}

/* --- Search Bar & Autocomplete --- */
.search-wrapper {
    position: relative;
    width: 100%;
    max-width: 600px;
    margin: 0 auto;
}

.search-bar-container {
    display: flex;
    align-items: center;
    background: var(--bg-search-bar);
    border: 1px solid var(--border-color);
    border-radius: 12px;
    padding: 4px 16px;
    transition: var(--transition-smooth);
}

.search-bar-container:focus-within {
    border-color: var(--accent-purple);
    box-shadow: 0 0 0 3px var(--accent-purple-glow);
}

.search-icon {
    font-size: 16px;
    margin-right: 12px;
    color: var(--text-muted);
}

#course-search-input {
    width: 100%;
    background: transparent;
    border: none;
    outline: none;
    color: var(--text-primary);
    font-family: var(--font-body);
    font-size: 14px;
    padding: 12px 0;
}

#course-search-input::placeholder {
    color: var(--text-muted);
}

#clear-search-btn {
    background: transparent;
    border: none;
    color: var(--text-secondary);
    font-size: 20px;
    cursor: pointer;
    padding: 0 8px;
    transition: var(--transition-fast);
}

#clear-search-btn:hover {
    color: var(--text-primary);
}

.hidden {
    display: none !important;
}

.search-results-dropdown {
    position: absolute;
    top: calc(100% + 8px);
    left: 0;
    right: 0;
    background: var(--bg-dropdown);
    border: 1px solid var(--border-color);
    border-radius: 12px;
    box-shadow: var(--shadow-lg), 0 10px 30px rgba(0, 0, 0, 0.5);
    max-height: 400px;
    overflow-y: auto;
    z-index: 10000;
    padding: 8px;
}

.search-item {
    padding: 12px 16px;
    border-radius: 8px;
    cursor: pointer;
    transition: var(--transition-fast);
    display: flex;
    flex-direction: column;
    gap: 4px;
}

.search-item:hover {
    background: rgba(139, 92, 246, 0.1);
}

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

.search-item-code {
    font-family: var(--font-heading);
    font-weight: 700;
    color: var(--accent-cyan);
    font-size: 13px;
    letter-spacing: 0.5px;
}

.search-item-name {
    font-weight: 500;
    color: var(--text-primary);
    font-size: 14px;
}

.search-item-meta {
    font-size: 12px;
    color: var(--text-secondary);
    display: flex;
    gap: 16px;
}

.no-results {
    padding: 24px;
    text-align: center;
    color: var(--text-muted);
}

/* --- Main Layout Grid --- */
.main-content {
    display: grid;
    grid-template-columns: 1fr; /* Single column layout */
    gap: 16px;
    flex: 1;
}

/* --- Workspace Toolbar (Option 2) --- */
.workspace-toolbar {
    display: flex;
    gap: 12px;
    align-items: center;
    position: relative;
    margin-bottom: 12px;
    background: var(--bg-toolbar);
    border: 1px solid var(--border-color);
    padding: 8px 16px;
    border-radius: 12px;
    backdrop-filter: blur(8px);
    z-index: 900;
}

.toolbar-dropdown-wrapper {
    position: relative;
}

.toolbar-btn {
    background: var(--bg-toolbar-btn);
    border: 1px solid var(--border-color);
    color: var(--text-primary);
    padding: 8px 16px;
    border-radius: 8px;
    font-family: var(--font-heading);
    font-weight: 600;
    font-size: 13px;
    cursor: pointer;
    transition: var(--transition-fast);
    display: flex;
    align-items: center;
    gap: 8px;
}

.toolbar-btn:hover:not(:disabled) {
    background: var(--bg-toolbar-btn-hover);
    border-color: rgba(255, 255, 255, 0.2);
}

.toolbar-btn:disabled {
    opacity: 0.4;
    cursor: not-allowed;
}

.toolbar-btn .badge {
    background: var(--accent-purple);
    color: #ffffff;
    padding: 2px 6px;
    border-radius: 10px;
    font-size: 10px;
    font-weight: 700;
}

/* Popover cards floating directly underneath buttons */
.toolbar-popover-card {
    position: absolute;
    top: calc(100% + 8px);
    left: 0;
    width: 320px;
    max-height: 480px;
    overflow-y: auto;
    background: var(--bg-dropdown);
    border: 1px solid var(--border-color);
    border-radius: 12px;
    box-shadow: var(--shadow-popover);
    padding: 16px;
    z-index: 1000;
    display: flex;
    flex-direction: column;
    gap: 12px;
}

.toolbar-popover-card.hidden {
    display: none !important;
}

.toolbar-popover-card h3 {
    margin: 0;
    font-size: 14px;
    font-weight: 700;
    color: var(--text-primary);
    font-family: var(--font-heading);
}

.popover-desc {
    font-size: 11px;
    color: var(--text-secondary);
    margin: 0;
    line-height: 1.4;
}

.section-desc {
    font-size: 11px;
    color: var(--text-secondary);
    margin-bottom: 8px;
}

#course-info-section, .course-info-section {
    display: flex;
    flex-direction: column;
    gap: 8px;
}

.course-badge-code {
    display: inline-block;
    align-self: flex-start;
    background: var(--accent-cyan-glow);
    color: var(--accent-cyan);
    border: 1px solid rgba(6, 182, 212, 0.3);
    padding: 2px 8px;
    border-radius: 6px;
    font-family: var(--font-heading);
    font-weight: 700;
    font-size: 12px;
    letter-spacing: 0.5px;
}

.course-info-title {
    font-size: 20px;
    line-height: 1.3;
}

.course-info-impl {
    font-size: 13px;
    color: var(--text-secondary);
}

.course-info-dates {
    font-size: 12px;
    color: var(--text-muted);
    display: flex;
    align-items: center;
    gap: 6px;
    margin-top: 4px;
}

/* Skeletons */
.skeleton {
    background: var(--skeleton-gradient);
    background-size: 200% 100%;
    animation: loading-pulse 1.5s infinite;
    border-radius: 8px;
}

.skeleton-title {
    height: 24px;
    width: 80%;
    margin-bottom: 8px;
}

.skeleton-text {
    height: 14px;
    width: 95%;
    margin-bottom: 6px;
}

.skeleton-text.short {
    width: 60%;
}

@keyframes loading-pulse {
    0% { background-position: 200% 0; }
    100% { background-position: -200% 0; }
}

/* Sidebar - Group Filters */
.filter-section h2, .sharing-section h2 {
    font-size: 16px;
    margin-bottom: 4px;
}

#group-filters-container, .group-filters-container {
    display: flex;
    flex-direction: column;
    gap: 12px;
}

.no-filters-msg {
    font-size: 13px;
    color: var(--text-muted);
    font-style: italic;
    text-align: center;
    padding: 16px 0;
}

.group-set-filter-card {
    background: rgba(255, 255, 255, 0.02);
    border: 1px solid var(--border-color);
    border-radius: 10px;
    padding: 12px;
}

.group-set-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    font-family: var(--font-heading);
    font-weight: 600;
    font-size: 13px;
    margin-bottom: 10px;
    color: var(--text-primary);
}

.group-set-toggle-all {
    background: transparent;
    border: none;
    color: var(--accent-cyan);
    font-size: 11px;
    cursor: pointer;
}

.subgroup-list {
    display: flex;
    flex-direction: column;
    gap: 8px;
}

.subgroup-item {
    display: flex;
    align-items: center;
    gap: 8px;
    font-size: 12px;
    color: var(--text-secondary);
    cursor: pointer;
}

.subgroup-item input[type="checkbox"] {
    accent-color: var(--accent-purple);
    cursor: pointer;
    width: 14px;
    height: 14px;
}

/* Sidebar - Sharing Tools */
.share-actions {
    display: flex;
    flex-direction: column;
    gap: 12px;
}

.share-url-container {
    display: flex;
    gap: 8px;
}

#ics-feed-url {
    flex: 1;
    background: rgba(0,0,0,0.3);
    border: 1px solid var(--border-color);
    border-radius: 8px;
    padding: 8px 12px;
    color: var(--text-secondary);
    font-family: var(--font-body);
    font-size: 12px;
    outline: none;
}

#ics-feed-url:focus {
    border-color: var(--accent-purple);
}

.btn {
    font-family: var(--font-heading);
    font-weight: 600;
    font-size: 13px;
    padding: 10px 16px;
    border-radius: 8px;
    cursor: pointer;
    border: none;
    text-align: center;
    transition: var(--transition-fast);
    text-decoration: none;
}

.btn-primary {
    background: var(--accent-purple);
    color: #FFFFFF;
    box-shadow: 0 4px 10px var(--accent-purple-glow);
}

.btn-primary:hover:not(:disabled) {
    background: #7C3AED;
    transform: translateY(-1px);
    box-shadow: 0 6px 14px var(--accent-purple-glow);
}

.btn-primary:disabled {
    opacity: 0.5;
    cursor: not-allowed;
    box-shadow: none;
}

.btn-secondary {
    background: rgba(255,255,255,0.05);
    border: 1px solid var(--border-color);
    color: var(--text-primary);
}

.btn-secondary:hover:not(.disabled) {
    background: rgba(255,255,255,0.1);
    border-color: var(--text-secondary);
}

.btn-secondary.disabled {
    opacity: 0.5;
    cursor: not-allowed;
    pointer-events: none;
}

.instructions-card {
    background: rgba(139, 92, 246, 0.03);
    border: 1px dashed rgba(139, 92, 246, 0.2);
    border-radius: 10px;
    padding: 12px;
    margin-top: 8px;
}

.instructions-card h3 {
    font-size: 12px;
    font-weight: 600;
    margin-bottom: 6px;
    color: var(--text-primary);
}

.instructions-card ul {
    list-style: none;
    display: flex;
    flex-direction: column;
    gap: 4px;
}

.instructions-card li {
    font-size: 11px;
    color: var(--text-secondary);
}

.instructions-card li strong {
    color: var(--accent-cyan);
}

/* --- Calendar Area --- */
.calendar-area {
    padding: 24px;
    position: relative;
    min-height: 600px;
    height: calc(100vh - 150px);
    display: flex;
    flex-direction: column;
}

/* Calendar Loading Overlay */
.loading-overlay {
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: rgba(11, 15, 25, 0.8);
    backdrop-filter: blur(4px);
    z-index: 10;
    display: flex;
    flex-direction: column;
    justify-content: center;
    align-items: center;
    gap: 16px;
    border-radius: 16px;
}

.spinner {
    width: 48px;
    height: 48px;
    border: 4px solid var(--border-color);
    border-top: 4px solid var(--accent-purple);
    border-radius: 50%;
    animation: spin 1s linear infinite;
}

@keyframes spin {
    0% { transform: rotate(0deg); }
    100% { transform: rotate(360deg); }
}

/* Calendar Placeholder Content */
.calendar-placeholder {
    display: flex;
    justify-content: center;
    align-items: center;
    height: 100%;
    width: 100%;
    color: var(--text-muted);
}

.placeholder-content {
    text-align: center;
    max-width: 400px;
    display: flex;
    flex-direction: column;
    gap: 12px;
}

.placeholder-icon {
    font-size: 64px;
    opacity: 0.3;
}

.placeholder-content h2 {
    color: var(--text-secondary);
}

.placeholder-content p {
    font-size: 13px;
}

/* --- FullCalendar Theme Customization --- */
#calendar {
    height: 100%;
    width: 100%;
}

/* Header toolbar override */
.fc .fc-toolbar {
    margin-bottom: 20px !important;
}

.fc .fc-toolbar-title {
    font-family: var(--font-heading) !important;
    font-weight: 600 !important;
    font-size: 20px !important;
    color: var(--text-primary);
}

/* Button override */
.fc .fc-button-primary {
    background-color: var(--bg-toolbar-btn) !important;
    border-color: var(--border-color) !important;
    color: var(--text-primary) !important;
    font-family: var(--font-heading) !important;
    font-weight: 500 !important;
    font-size: 13px !important;
    transition: var(--transition-fast) !important;
    text-transform: capitalize !important;
}

.fc .fc-button-primary:hover {
    background-color: var(--bg-toolbar-btn-hover) !important;
    border-color: var(--text-secondary) !important;
}

.fc .fc-button-primary:disabled {
    opacity: 0.3 !important;
}

.fc .fc-button-active {
    background-color: var(--accent-purple) !important;
    border-color: var(--accent-purple) !important;
    color: #FFFFFF !important;
    box-shadow: 0 0 10px var(--accent-purple-glow) !important;
}

/* Grid Override */
.fc td, .fc th {
    border-color: var(--border-color) !important;
}

.fc .fc-col-header-cell-cushion {
    font-family: var(--font-heading);
    font-weight: 600;
    font-size: 13px;
    color: var(--text-secondary);
    padding: 8px 0 !important;
}

.fc .fc-day-other {
    background: var(--bg-calendar-other-day) !important;
    opacity: 0.4;
}

.fc .fc-day-today {
    background: rgba(139, 92, 246, 0.03) !important;
}

.fc .fc-daygrid-day-number {
    font-family: var(--font-heading);
    font-size: 13px;
    font-weight: 500;
    color: var(--text-secondary);
    padding: 8px 12px !important;
}

/* Custom style for calendar events */
.fc-event {
    border-radius: 6px !important;
    border: 1px solid var(--event-border-color) !important; /* Subtle boundary border */
    padding: 4px 6px !important;
    font-size: 11px !important;
    font-family: var(--font-body);
    font-weight: 500 !important;
    box-shadow: var(--shadow-sm);
    cursor: pointer;
    transition: var(--transition-fast);
}

.fc-event:hover {
    transform: scale(1.02);
    box-shadow: 0 4px 12px rgba(0,0,0,0.3);
    filter: brightness(1.1);
}

.fc-event-title-container {
    overflow: hidden;
    text-overflow: ellipsis;
}

/* Prevent text clipping in short vertical events (e.g. 45 min) */
.fc-timegrid-event {
    padding: 2px 4px !important;
}

.fc-timegrid-event .fc-event-time {
    font-size: 9.5px !important;
    line-height: 1 !important;
    margin-bottom: 2px !important;
    opacity: 0.85;
}

.fc-timegrid-event .fc-event-title {
    font-size: 10.5px !important;
    line-height: 1.15 !important;
    font-weight: 500;
}

/* Event popover custom styles */
.fc-popover {
    background: var(--bg-dropdown) !important;
    border: 1px solid var(--border-color) !important;
    border-radius: 10px !important;
    box-shadow: var(--shadow-lg) !important;
}

.fc-popover-header {
    background: var(--bg-toolbar-btn) !important;
    border-bottom: 1px solid var(--border-color) !important;
    padding: 8px 12px !important;
    font-family: var(--font-heading) !important;
    font-weight: 600 !important;
    color: var(--text-primary) !important;
}

.fc-popover-title {
    color: var(--text-primary) !important;
}

.fc-popover-close {
    color: var(--text-secondary) !important;
}

/* Custom details styling on event hover / click tooltip */
.event-tooltip {
    position: absolute;
    background: var(--bg-dropdown);
    border: 1px solid var(--border-color);
    border-radius: 8px;
    padding: 12px;
    box-shadow: var(--shadow-lg);
    z-index: 1000;
    font-size: 12px;
    max-width: 320px;
    pointer-events: auto;
    display: flex;
    flex-direction: column;
    gap: 4px;
}

.event-tooltip-title {
    font-weight: 600;
    color: var(--text-primary);
    margin-bottom: 4px;
}

.event-tooltip-meta {
    color: var(--text-secondary);
}

/* --- Toast notification --- */
.toast {
    position: fixed;
    bottom: 24px;
    right: 24px;
    background: #10B981;
    color: #FFFFFF;
    padding: 12px 24px;
    border-radius: 8px;
    font-family: var(--font-heading);
    font-weight: 600;
    font-size: 14px;
    box-shadow: 0 10px 15px -3px rgba(16, 185, 129, 0.3);
    z-index: 1000;
    animation: slide-in 0.3s ease-out forwards;
}

@keyframes slide-in {
    from {
        transform: translateY(100px);
        opacity: 0;
    }
    to {
        transform: translateY(0);
        opacity: 1;
    }
}

/* --- Scrollbar Styling --- */
::-webkit-scrollbar {
    width: 6px;
    height: 6px;
}

::-webkit-scrollbar-track {
    background: transparent;
}

::-webkit-scrollbar-thumb {
    background: rgba(255, 255, 255, 0.1);
    border-radius: 10px;
}

::-webkit-scrollbar-thumb:hover {
    background: rgba(139, 92, 246, 0.3);
}


/* Mobile bottom utility bar hidden on desktop */
.mobile-utils-container {
    display: none !important;
}

/* Narrow Desktop Header Adjustments */
@media (min-width: 769px) and (max-width: 1100px) {
    .main-header {
        display: grid;
        grid-template-columns: 1fr;
        gap: 16px;
        justify-items: center;
    }
    
    .logo-area {
        grid-column: 1;
        grid-row: 1;
    }
    
    .search-wrapper {
        grid-column: 1;
        grid-row: 2;
        width: 100%;
        max-width: none;
    }
}

/* --- Responsive Adjustments --- */
.mobile-tabs-container {
    display: none;
}

@media (max-width: 768px) {
    .mobile-tabs-container {
        display: flex;
        background: var(--bg-toolbar);
        border: 1px solid var(--border-color);
        border-radius: 12px;
        padding: 4px;
        gap: 4px;
        margin-bottom: 8px;
    }
    
    .mobile-tab-btn {
        flex: 1;
        background: transparent;
        border: none;
        color: var(--text-secondary);
        padding: 10px;
        font-family: var(--font-heading);
        font-weight: 600;
        font-size: 13px;
        border-radius: 8px;
        cursor: pointer;
        transition: var(--transition-fast);
        display: flex;
        justify-content: center;
        align-items: center;
        gap: 6px;
    }
    
    .mobile-tab-btn.active {
        background: var(--accent-purple); /* Warm Copper */
        color: #ffffff;
    }
    
    .mobile-tab-btn .badge {
        background: rgba(255, 255, 255, 0.15);
        color: var(--text-secondary);
        padding: 2px 6px;
        border-radius: 10px;
        font-size: 10px;
        font-weight: 700;
    }
    
    .mobile-tab-btn.active .badge {
        background: rgba(255, 255, 255, 0.25);
        color: #ffffff;
    }

    body.light-mode .mobile-tab-btn:not(.active) .badge {
        background: rgba(0, 0, 0, 0.08);
        color: var(--text-secondary);
    }
    
    /* Hide/Show views on mobile based on active tab */
    .workspace-toolbar, .calendar-area {
        display: none !important;
    }
    
    .workspace-toolbar.mobile-active {
        display: flex !important;
        flex-direction: column !important;
    }
    
    .calendar-area.mobile-active {
        display: block !important;
        height: calc(100vh - 200px); /* Fill most of vertical viewport */
    }
    
    .main-content {
        grid-template-columns: 1fr !important;
        gap: 12px !important;
    }
    
    .app-container {
        padding: 12px !important;
        gap: 12px !important;
    }

    /* Mobile workspace toolbar structure */
    .workspace-toolbar {
        display: none !important;
        flex-direction: column !important;
        gap: 16px !important;
        width: 100% !important;
        background: transparent !important;
        border: none !important;
        padding: 0 !important;
        backdrop-filter: none !important;
        margin-bottom: 0 !important;
    }
    
    .toolbar-dropdown-wrapper {
        width: 100% !important;
    }
    
    /* Hide desktop toggle buttons on mobile */
    .toolbar-btn {
        display: none !important;
    }
    
    /* Format absolute popovers as static inline cards */
    .toolbar-popover-card {
        position: static !important;
        display: flex !important;
        opacity: 1 !important;
        visibility: visible !important;
        width: 100% !important;
        box-shadow: var(--shadow-sm) !important;
        border: 1px solid var(--border-color) !important;
        background: var(--bg-card) !important;
        border-radius: 16px !important;
        padding: 16px !important;
        box-sizing: border-box !important;
        gap: 12px !important;
        max-height: none !important;
        overflow-y: visible !important;
    }
    
    .toolbar-popover-card.hidden {
        display: flex !important;
    }

    /* Hide share popover on mobile if display: none is injected by JS */
    #dropdown-share-sync[style*="display: none"] {
        display: none !important;
    }

    /* Style search bar input font-size to 16px to prevent iOS Safari auto-zoom-on-focus */
    #course-search-input {
        font-size: 16px !important;
    }

    /* Style bottom utility bar layout */
    .mobile-utils-container {
        display: flex !important;
        background: var(--bg-toolbar);
        border: 1px solid var(--border-color);
        border-radius: 12px;
        padding: 4px;
        gap: 4px;
        margin-top: 12px;
        width: 100%;
        box-sizing: border-box;
    }
    
    .mobile-util-btn {
        flex: 1;
        background: transparent;
        border: none;
        color: var(--text-secondary);
        padding: 10px;
        font-family: var(--font-heading);
        font-weight: 600;
        font-size: 13px;
        border-radius: 8px;
        cursor: pointer;
        transition: var(--transition-fast);
        display: flex;
        justify-content: center;
        align-items: center;
        gap: 6px;
    }
    
    .mobile-util-btn:hover:not(:disabled) {
        background: var(--bg-toolbar-btn-hover);
        color: var(--text-primary);
    }
    
    .mobile-util-btn:disabled {
        opacity: 0.4;
        cursor: not-allowed;
    }

    /* Mobile Header Layout Optimization */
    .search-wrapper {
        width: 100% !important;
        max-width: none !important;
        margin-bottom: 12px !important;
    }

    /* FullCalendar mobile font scaling & text wrap containment */
    .fc-event-time,
    .fc-event-title,
    .fc-event-title-container {
        font-size: 10.5px !important;
        line-height: 1.15 !important;
    }
    
    .fc-event-main {
        padding: 2px 4px !important;
    }
}

/* --- Active Course Items --- */
.active-course-item {
    display: flex;
    justify-content: space-between;
    align-items: center;
    background: rgba(255, 255, 255, 0.03);
    border: 1px solid var(--border-color);
    border-radius: 8px;
    padding: 8px 12px;
    margin-bottom: 8px;
    font-size: 13px;
    transition: var(--transition-fast);
}

.active-course-item:hover {
    background: rgba(255, 255, 255, 0.06);
    border-color: rgba(255, 255, 255, 0.15);
}

.active-course-details {
    display: flex;
    flex-direction: column;
    gap: 2px;
    flex: 1;
    overflow: hidden;
    padding-right: 8px;
}

.active-course-header {
    display: flex;
    align-items: center;
    gap: 8px;
}

.active-course-color-dot {
    width: 8px;
    height: 8px;
    border-radius: 50%;
    flex-shrink: 0;
}

.active-course-code {
    font-weight: 700;
    color: var(--text-primary);
    font-family: var(--font-heading);
}

.active-course-name {
    color: var(--text-secondary);
    font-size: 12px;
    white-space: nowrap;
    overflow: hidden;
    text-overflow: ellipsis;
}

.remove-course-btn {
    background: transparent;
    border: none;
    color: var(--text-muted);
    font-size: 18px;
    cursor: pointer;
    line-height: 1;
    padding: 2px 6px;
    border-radius: 4px;
    transition: var(--transition-fast);
}

.remove-course-btn:hover {
    color: var(--accent-rose);
    background: rgba(244, 63, 94, 0.1);
}

.sync-course-btn {
    background: transparent;
    border: none;
    color: var(--text-muted);
    font-size: 13px;
    cursor: pointer;
    line-height: 1;
    padding: 4px 6px;
    border-radius: 4px;
    transition: var(--transition-fast);
}

.sync-course-btn:hover {
    color: var(--accent-cyan);
    background: rgba(6, 182, 212, 0.1);
}

@media (max-width: 480px) {
    .event-tooltip {
        max-width: calc(100vw - 16px) !important;
    }
}

/* Custom styling for Lectures (Option 2: Left Accent Bar vs. Solid Card) */
.fc-timegrid-event.lecture-event,
.fc-daygrid-event.lecture-event {
    background-color: var(--bg-lecture-event) !important; /* Solid card background */
    border: 1px solid var(--lecture-border-color) !important;
    border-left-width: 4px !important;
    border-radius: 6px !important;
    box-shadow: 0 2px 4px rgba(0,0,0,0.15);
}

.fc-timegrid-event.lecture-event:hover,
.fc-daygrid-event.lecture-event:hover {
    background-color: var(--bg-lecture-event-hover) !important; /* Slightly lighter on hover */
}

/* Make sure text elements inside the card use the course color for high contrast readability */
.lecture-event .fc-event-main,
.lecture-event .fc-event-title,
.lecture-event .fc-event-time,
.lecture-event .fc-event-title-container {
    color: var(--lecture-text-color) !important;
    font-weight: 500;
}

/* --- App Footer --- */
.app-footer {
    margin-top: 32px;
    border-top: 1px solid var(--border-color);
    padding: 24px 0 8px 0;
    font-size: 11px;
    color: var(--text-muted);
    line-height: 1.5;
    text-align: center;
}

.app-footer p {
    margin: 0;
}

.app-footer a {
    color: var(--accent-purple);
    text-decoration: none;
    border-bottom: 1px dashed rgba(212, 128, 82, 0.4);
    padding-bottom: 1px;
}

/* Collapsible Course Filter Cards */
.course-filter-card {
    border: 1px solid rgba(255, 255, 255, 0.05);
    border-radius: 8px;
    background: rgba(255, 255, 255, 0.01);
    margin-bottom: 8px;
    overflow: hidden;
}

.course-filter-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 8px 12px;
    background: rgba(255, 255, 255, 0.03);
    cursor: pointer;
    user-select: none;
    transition: background var(--transition-fast);
}

.course-filter-header:hover {
    background: rgba(255, 255, 255, 0.06);
}

.course-filter-header .chevron {
    transition: transform var(--transition-fast);
}

.course-filter-content {
    display: none;
    padding: 12px;
    flex-direction: column;
    gap: 8px;
    border-top: 1px solid rgba(255, 255, 255, 0.05);
}

.course-filter-card.active .course-filter-content {
    display: flex;
}

/* --- Theme Toggle Button --- */
.theme-toggle-btn {
    background: var(--bg-toolbar-btn);
    border: 1px solid var(--border-color);
    color: var(--text-primary);
    font-size: 16px;
    cursor: pointer;
    padding: 8px;
    border-radius: 50%;
    width: 36px;
    height: 36px;
    display: flex;
    align-items: center;
    justify-content: center;
    transition: var(--transition-smooth);
    outline: none;
    user-select: none;
    align-self: center;
}

.theme-toggle-btn:hover {
    background: var(--bg-toolbar-btn-hover);
    transform: scale(1.05);
}

/* --- Course External Link --- */
.course-external-link svg {
    transition: color 0.15s ease, opacity 0.15s ease, transform 0.15s ease;
}

.course-external-link:hover svg {
    color: var(--accent-cyan) !important;
    opacity: 1 !important;
    transform: scale(1.1);
}