:root {
    --bg-app: #ffffff;
    --bg-sidebar: #f5f5f7;
    --bg-content: #ffffff;
    --bg-hover: rgba(0, 0, 0, 0.05);
    --bg-active: rgba(0, 0, 0, 0.08);
    --border: #e1e1e6;
    --text-primary: #1d1d1f;
    --text-secondary: #86868b;
    --accent: #007aff;
    --accent-hover: #0062cc;
    --danger: #ff3b30;
    --success: #34c759;
    --radius: 10px;
    --shadow-sm: 0 1px 2px rgba(0,0,0,0.04);
    --font-stack: 'Inter', -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
}

:root:not(.light) {
    --bg-app: #1e1e1e;
    --bg-sidebar: #171717;
    --bg-content: #1e1e1e;
    --bg-hover: rgba(255, 255, 255, 0.08);
    --bg-active: rgba(255, 255, 255, 0.12);
    --border: #333333;
    --text-primary: #f5f5f7;
    --text-secondary: #86868b;
    --accent: #0a84ff;
    --accent-hover: #409cff;
}

/* Reset & Base */
* { box-sizing: border-box; margin: 0; padding: 0; outline: none; }
body {
    font-family: var(--font-stack);
    background: var(--bg-app);
    color: var(--text-primary);
    height: 100vh;
    overflow: hidden;
    font-size: 14px;
    -webkit-font-smoothing: antialiased;
    transition: background 0.3s ease, color 0.3s ease;
}

/* Role Badge */
.role-badge {
    font-size: 11px;
    font-weight: 600;
    letter-spacing: 0.2px;
    padding: 4px 8px;
    border-radius: 999px;
    border: 1px solid var(--border);
    color: var(--text-secondary);
    background: var(--bg-app);
    white-space: nowrap;
}

/* Auth Page */
.auth-page {
    height: 100vh;
    width: 100vw;
    display: flex;
    flex-direction: column;
    background:
        radial-gradient(1200px 600px at 10% -10%, rgba(0, 122, 255, 0.18), transparent 60%),
        radial-gradient(900px 500px at 90% 0%, rgba(52, 199, 89, 0.14), transparent 55%),
        var(--bg-app);
}

.auth-topbar {
    height: 64px;
    padding: 0 20px;
    display: flex;
    align-items: center;
    justify-content: space-between;
}

.auth-shell {
    flex: 1;
    display: flex;
    align-items: center;
    justify-content: center;
    padding: 24px;
}

.auth-card {
    width: 100%;
    max-width: 420px;
    border: 1px solid var(--border);
    border-radius: 14px;
    background: var(--bg-content);
    box-shadow: 0 10px 30px rgba(0,0,0,0.08);
    padding: 18px;
}

.auth-card-header h1 {
    font-size: 18px;
    font-weight: 600;
    letter-spacing: -0.2px;
}

.auth-card-header p {
    margin-top: 6px;
    color: var(--text-secondary);
    font-size: 13px;
}

.auth-form {
    margin-top: 14px;
    display: flex;
    flex-direction: column;
    gap: 10px;
}

.auth-label {
    font-size: 12px;
    font-weight: 600;
    color: var(--text-secondary);
}

.auth-alert {
    margin-top: 12px;
    border: 1px solid rgba(255, 59, 48, 0.35);
    background: rgba(255, 59, 48, 0.10);
    color: var(--text-primary);
    border-radius: 10px;
    padding: 10px 12px;
    font-size: 13px;
}

.auth-footnote {
    margin-top: 12px;
    color: var(--text-secondary);
    font-size: 12px;
    text-align: center;
}

/* Layout */
.app-root {
    display: flex;
    height: 100vh;
    width: 100vw;
}

/* Sidebar */
.sidebar {
    width: 260px;
    background: var(--bg-sidebar);
    border-right: 1px solid var(--border);
    display: flex;
    flex-direction: column;
    flex-shrink: 0;
    transition: background 0.3s ease, border-color 0.3s ease;
}

.sidebar-header {
    height: 52px;
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: 0 16px;
    border-bottom: 1px solid transparent;
}

.app-brand {
    font-weight: 600;
    font-size: 15px;
    display: flex;
    align-items: center;
    gap: 8px;
    color: var(--text-primary);
}

.icon-btn {
    background: none;
    border: none;
    color: var(--text-secondary);
    cursor: pointer;
    padding: 4px;
    border-radius: 6px;
    display: flex;
    align-items: center;
    justify-content: center;
    transition: color 0.2s, background 0.2s;
}
.icon-btn:hover { color: var(--text-primary); background: var(--bg-hover); }

/* Theme Toggle Icons */
.icon-sun { display: none; }
:root:not(.light) .icon-moon { display: none; }
:root:not(.light) .icon-sun { display: block; }

.sidebar-content {
    flex: 1;
    overflow-y: auto;
    padding: 16px 12px;
    display: flex;
    flex-direction: column;
    gap: 16px;
}

.section-label {
    font-size: 11px;
    font-weight: 600;
    text-transform: uppercase;
    color: var(--text-secondary);
    letter-spacing: 0.5px;
    padding: 0 8px;
    margin-bottom: 4px;
}

.nav-list {
    display: flex;
    flex-direction: column;
    gap: 2px;
}

.nav-item {
    padding: 8px 12px;
    border-radius: 6px;
    cursor: pointer;
    font-size: 13px;
    color: var(--text-primary);
    transition: background 0.15s ease;
    display: flex;
    justify-content: space-between;
    align-items: center;
}
.nav-item:hover { background: var(--bg-hover); }
.nav-item.active { background: var(--bg-active); font-weight: 500; }
.nav-item .meta { font-size: 11px; color: var(--text-secondary); }

.sidebar-form {
    display: flex;
    gap: 6px;
    margin-top: auto;
    padding-top: 12px;
    border-top: 1px solid var(--border);
}
.sidebar-form .input-group {
    display: flex;
    flex: 1;
    gap: 6px;
}
.sidebar-form input { flex: 1; min-width: 0; }
.sidebar-form select { width: 60px; }

.sidebar-footer {
    padding: 16px;
    border-top: 1px solid var(--border);
}
.week-picker {
    display: flex;
    flex-direction: column;
    gap: 6px;
}
.week-picker label { font-size: 11px; color: var(--text-secondary); font-weight: 500; }

/* Main Content */
.main-content {
    flex: 1;
    display: flex;
    flex-direction: column;
    background: var(--bg-content);
    min-width: 0;
}

.content-header {
    height: 64px;
    padding: 0 32px;
    display: flex;
    align-items: center;
    justify-content: space-between;
    border-bottom: 1px solid var(--border);
}
.content-header h2 {
    font-size: 20px;
    font-weight: 600;
    letter-spacing: -0.5px;
}

.header-actions { display: flex; gap: 12px; }
.header-form { display: flex; gap: 8px; }

.content-body {
    flex: 1;
    overflow: auto;
    padding: 0;
    position: relative;
}

.register-container {
    min-width: 100%;
    display: inline-block;
}

.empty-state {
    padding: 40px;
    text-align: center;
    color: var(--text-secondary);
    font-size: 14px;
}

/* Table */
.students-table {
    width: 100%;
    border-collapse: collapse;
    font-size: 13px;
}
.students-table th, .students-table td {
    padding: 10px 16px;
    text-align: left;
    border-bottom: 1px solid var(--border);
}
.students-table th {
    font-weight: 500;
    color: var(--text-secondary);
    background: var(--bg-content);
    position: sticky;
    top: 0;
    z-index: 10;
    white-space: nowrap;
    backdrop-filter: blur(8px);
    background: rgba(var(--bg-content), 0.9);
    background: var(--bg-content);
}
.students-table td {
    color: var(--text-primary);
    vertical-align: middle;
}
.student-row { transition: background 0.1s; }
.student-row:hover { background: var(--bg-hover); }
.student-row.focused { background: var(--bg-active); }

/* Inputs & Buttons */
input, select {
    background: var(--bg-app);
    border: 1px solid var(--border);
    color: var(--text-primary);
    padding: 6px 10px;
    border-radius: 6px;
    font-size: 13px;
    transition: border-color 0.2s, box-shadow 0.2s;
}
input:focus, select:focus {
    border-color: var(--accent);
    box-shadow: 0 0 0 3px rgba(0, 122, 255, 0.15);
}

.btn-primary {
    background: var(--accent);
    color: white;
    border: none;
    padding: 8px 16px;
    border-radius: 8px;
    font-size: 13px;
    font-weight: 600;
    cursor: pointer;
    transition: all 0.2s ease;
    box-shadow: 0 2px 4px rgba(0,0,0,0.1);
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: 6px;
}
.btn-primary:hover {
    background: var(--accent-hover);
    transform: translateY(-1px);
    box-shadow: 0 4px 8px rgba(0,0,0,0.15);
}
.btn-primary:active {
    transform: translateY(0);
    box-shadow: none;
}

.btn-sm {
    background: var(--bg-hover);
    border: 1px solid transparent;
    color: var(--text-primary);
    padding: 6px;
    border-radius: 6px;
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
}
.btn-sm:hover { background: var(--bg-active); }

/* Custom Checkbox */
input[type="checkbox"] {
    appearance: none;
    -webkit-appearance: none;
    width: 22px;
    height: 22px;
    border: 1.5px solid var(--border);
    border-radius: 6px;
    background: var(--bg-hover);
    cursor: pointer;
    position: relative;
    transition: all 0.2s cubic-bezier(0.2, 0.8, 0.2, 1);
    vertical-align: middle;
}
input[type="checkbox"]:hover {
    border-color: var(--accent);
    background: var(--bg-active);
}
input[type="checkbox"]:checked {
    background: var(--accent);
    border-color: var(--accent);
    transform: scale(1.05);
    box-shadow: 0 2px 4px rgba(0,0,0,0.1);
}
input[type="checkbox"]:focus {
    box-shadow: 0 0 0 3px rgba(0, 122, 255, 0.2);
    border-color: var(--accent);
}

/* Sidebar Action Button */
.btn-sidebar-action {
    margin-top: auto;
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 8px;
    width: 100%;
    padding: 10px;
    background: var(--bg-app);
    border: 1px solid var(--border);
    border-radius: 8px;
    color: var(--text-primary);
    font-weight: 500;
    font-size: 13px;
    cursor: pointer;
    transition: all 0.2s ease;
    margin-top: 12px;
}
.btn-sidebar-action:hover {
    background: var(--bg-hover);
    border-color: var(--text-secondary);
}
.btn-sidebar-action:active {
    transform: scale(0.98);
}

/* Footer */
.content-footer {
    padding: 12px 32px;
    border-top: 1px solid var(--border);
    background: var(--bg-content);
    font-size: 12px;
    color: var(--text-secondary);
    display: flex;
    justify-content: space-between;
}
.shortcuts { display: flex; gap: 16px; }
kbd {
    background: var(--bg-active);
    border: 1px solid var(--border);
    border-radius: 4px;
    padding: 2px 6px;
    font-family: inherit;
    font-size: 11px;
    min-width: 20px;
    display: inline-block;
    text-align: center;
}

/* Scrollbars */
::-webkit-scrollbar { width: 10px; height: 10px; }
::-webkit-scrollbar-track { background: transparent; }
::-webkit-scrollbar-thumb { background: var(--border); border-radius: 5px; border: 2px solid var(--bg-app); }
::-webkit-scrollbar-thumb:hover { background: var(--text-secondary); }

@media (max-width: 768px) {
    .app-root { flex-direction: column; }
    .sidebar { width: 100%; height: auto; border-right: none; border-bottom: 1px solid var(--border); }
    .sidebar-content { display: none; }
    .sidebar-header { border-bottom: 1px solid var(--border); }
}

/* Modal */
.modal-overlay {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: rgba(0, 0, 0, 0.4);
    backdrop-filter: blur(4px);
    display: flex;
    align-items: center;
    justify-content: center;
    z-index: 100;
    opacity: 0;
    visibility: hidden;
    transition: all 0.2s ease;
}
.modal-overlay.active {
    opacity: 1;
    visibility: visible;
}

.modal {
    background: var(--bg-content);
    width: 100%;
    max-width: 400px;
    max-height: 85vh;
    display: flex;
    flex-direction: column;
    border-radius: 12px;
    box-shadow: 0 20px 40px rgba(0,0,0,0.2);
    transform: scale(0.95);
    transition: transform 0.2s cubic-bezier(0.16, 1, 0.3, 1);
    border: 1px solid var(--border);
}
.modal-overlay.active .modal {
    transform: scale(1);
}

.modal-header {
    padding: 16px 20px;
    border-bottom: 1px solid var(--border);
    display: flex;
    align-items: center;
    justify-content: space-between;
}
.modal-header h3 {
    font-size: 16px;
    font-weight: 600;
    margin: 0;
}

.modal-body {
    padding: 20px;
    display: flex;
    flex-direction: column;
    gap: 16px;
    overflow-y: auto;
}

.form-group {
    display: flex;
    flex-direction: column;
    gap: 6px;
}
.form-group label {
    font-size: 12px;
    font-weight: 500;
    color: var(--text-secondary);
}
.form-group input {
    width: 100%;
    padding: 8px 12px;
    font-size: 14px;
    border: 1px solid var(--border);
    border-radius: 6px;
    background: var(--bg-app);
    color: var(--text-primary);
}

.form-group textarea {
    width: 100%;
    padding: 8px 12px;
    font-size: 14px;
    resize: vertical;
    min-height: 80px;
    border: 1px solid var(--border);
    border-radius: 6px;
    background: var(--bg-app);
    color: var(--text-primary);
    font-family: inherit;
}

.form-group select {
    width: 100%;
    padding: 8px 12px;
    font-size: 14px;
    border: 1px solid var(--border);
    border-radius: 6px;
    background: var(--bg-app);
    color: var(--text-primary);
}

input[type="checkbox"] {
    accent-color: var(--accent);
}

.activity-only {
    display: none;
}

.modal-footer {
    padding: 16px 20px;
    background: var(--bg-sidebar);
    border-top: 1px solid var(--border);
    border-radius: 0 0 12px 12px;
    display: flex;
    justify-content: flex-end;
    gap: 10px;
}

.btn-secondary {
    background: var(--bg-app);
    border: 1px solid var(--border);
    color: var(--text-primary);
    padding: 6px 14px;
    border-radius: 6px;
    font-size: 13px;
    font-weight: 500;
    cursor: pointer;
    transition: background 0.2s;
}
.btn-secondary:hover {
    background: var(--bg-hover);
}

/* Flatpickr Overrides */
.flatpickr-calendar {
    background: var(--bg-sidebar) !important;
    box-shadow: 0 10px 40px rgba(0,0,0,0.4) !important;
    border: 1px solid var(--border) !important;
    border-radius: 12px !important;
    font-family: var(--font-stack) !important;
    width: 300px !important;
    overflow: hidden;
}
.flatpickr-calendar.arrowTop:before, .flatpickr-calendar.arrowTop:after {
    border-bottom-color: var(--bg-sidebar) !important;
}
.flatpickr-months {
    background: var(--bg-sidebar) !important;
    border-bottom: 1px solid var(--border);
    padding: 10px 0;
}
.flatpickr-months .flatpickr-month {
    background: transparent !important;
    color: var(--text-primary) !important;
    fill: var(--text-primary) !important;
    height: 34px;
}
.flatpickr-current-month .flatpickr-monthDropdown-months,
.flatpickr-current-month input.cur-year {
    color: var(--text-primary) !important;
    font-weight: 600 !important;
    font-size: 15px !important;
}
.flatpickr-current-month .flatpickr-monthDropdown-months:hover,
.flatpickr-current-month input.cur-year:hover {
    background: var(--bg-hover) !important;
}
.flatpickr-current-month .flatpickr-monthDropdown-months .flatpickr-monthDropdown-month {
    background-color: var(--bg-sidebar) !important;
    color: var(--text-primary) !important;
}

.flatpickr-weekdays {
    background: var(--bg-sidebar) !important;
    height: 28px;
    align-items: center;
    border-bottom: 1px solid var(--border);
}
.flatpickr-weekday {
    color: var(--text-secondary) !important;
    font-weight: 600 !important;
    font-size: 11px !important;
    text-transform: uppercase;
    letter-spacing: 0.5px;
}
.flatpickr-days {
    padding: 5px;
    background: var(--bg-content) !important;
}
.flatpickr-day {
    color: var(--text-primary) !important;
    border-radius: 4px !important;
    height: 36px;
    line-height: 36px;
    margin-top: 2px;
    border: 1px solid transparent !important;
}
.flatpickr-day.today {
    border-color: var(--accent) !important;
    font-weight: 600;
}
.flatpickr-day.nextMonthDay:hover{
    background-color: red !important;
}
.flatpickr-day.nextMonthDay.inRange{
    background-color: white !important;
}

.flatpickr-day.inRange {
    box-shadow: none !important;
    -webkit-box-shadow: none !important;
}

.flatpickr-day.inRange,
.flatpickr-day.prevMonthDay.inRange,
.flatpickr-day.nextMonthDay.inRange,
.flatpickr-day.today.inRange,
.flatpickr-day.prevMonthDay.today.inRange,
.flatpickr-day.nextMonthDay.today.inRange,
.flatpickr-day:hover,
.flatpickr-day.prevMonthDay:hover,
.flatpickr-day.nextMonthDay:hover,
.flatpickr-day:focus,
.flatpickr-day.prevMonthDay:focus,
.flatpickr-day.nextMonthDay:focus{
    background-color: #ffffff1f !important;
    /* color: black !important; */
}


/* Selected State - Solid Blue Bar */
.flatpickr-day.selected, 
.flatpickr-day.startRange, 
.flatpickr-day.endRange, 
.flatpickr-day.selected.inRange, 
.flatpickr-day.startRange.inRange, 
.flatpickr-day.endRange.inRange, 
.flatpickr-day.selected:focus, 
.flatpickr-day.startRange:focus, 
.flatpickr-day.endRange:focus, 
.flatpickr-day.selected:hover, 
.flatpickr-day.startRange:hover, 
.flatpickr-day.endRange:hover, 
.flatpickr-day.selected.prevMonthDay, 
.flatpickr-day.startRange.prevMonthDay, 
.flatpickr-day.endRange.prevMonthDay, 
.flatpickr-day.selected.nextMonthDay, 
.flatpickr-day.startRange.nextMonthDay, 
.flatpickr-day.endRange.nextMonthDay {
    background: var(--accent) !important;
    border-color: var(--accent) !important;
    color: white !important;
    box-shadow: none !important;
}

/* Muted days */
.flatpickr-day.flatpickr-disabled, 
.flatpickr-day.flatpickr-disabled:hover,
.flatpickr-day.prevMonthDay, 
.flatpickr-day.nextMonthDay {
    color: var(--text-secondary) !important;
    opacity: 0.5;
    background: transparent !important;
}

/* Navigation Arrows */
.flatpickr-prev-month, .flatpickr-next-month {
    fill: var(--text-primary) !important;
    padding: 10px;
    height: 34px;
}
.flatpickr-prev-month:hover, .flatpickr-next-month:hover {
    fill: var(--accent) !important;
    background: transparent !important;
}
.flatpickr-prev-month svg, .flatpickr-next-month svg {
    width: 14px;
    height: 14px;
}

/* Tag Input & Student Picker */
.tags-input-container {
    display: flex;
    flex-wrap: wrap;
    gap: 6px;
    padding: 6px;
    border: 1px solid var(--border);
    border-radius: 6px;
    background: var(--bg-app);
    min-height: 38px;
    align-items: center;
}

.tag-chip {
    background: var(--bg-active);
    color: var(--text-primary);
    font-size: 12px;
    padding: 2px 8px;
    border-radius: 12px;
    display: flex;
    align-items: center;
    gap: 4px;
    border: 1px solid var(--border);
}

.tag-remove {
    cursor: pointer;
    opacity: 0.5;
    display: flex;
    align-items: center;
}
.tag-remove:hover { opacity: 1; color: var(--danger); }

.btn-tag-add {
    background: none;
    border: 1px dashed var(--border);
    color: var(--text-secondary);
    padding: 2px 8px;
    border-radius: 12px;
    font-size: 11px;
    cursor: pointer;
    display: flex;
    align-items: center;
    gap: 4px;
    transition: all 0.2s;
}
.btn-tag-add:hover {
    border-color: var(--accent);
    color: var(--accent);
    background: var(--bg-hover);
}

.student-picker-dropdown {
    position: absolute;
    background: var(--bg-content);
    border: 1px solid var(--border);
    border-radius: 8px;
    box-shadow: 0 4px 12px rgba(0,0,0,0.15);
    width: 250px;
    z-index: 1000;
    margin-top: 4px;
    overflow: hidden;
    display: flex;
    flex-direction: column;
}

#studentPickerSearch {
    border: none;
    border-bottom: 1px solid var(--border);
    border-radius: 0;
    padding: 8px 12px;
    font-size: 13px;
    background: var(--bg-content);
}
#studentPickerSearch:focus { box-shadow: none; }

.student-picker-list {
    max-height: 200px;
    overflow-y: auto;
}

.picker-item {
    padding: 8px 12px;
    font-size: 13px;
    cursor: pointer;
    color: var(--text-primary);
    transition: background 0.1s;
}
.picker-item:hover { background: var(--bg-hover); }
.picker-item.selected { opacity: 0.5; pointer-events: none; }

/* Stats Dashboard */
.stats-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
    gap: 20px;
    margin-bottom: 24px;
}

.stat-card {
    background: var(--bg-app);
    border: 1px solid var(--border);
    border-radius: 12px;
    padding: 20px;
    box-shadow: var(--shadow-sm);
}

.stat-card h3 {
    font-size: 13px;
    color: var(--text-secondary);
    font-weight: 500;
    margin-bottom: 8px;
}

.stat-value {
    font-size: 28px;
    font-weight: 600;
    color: var(--text-primary);
}

.charts-row {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(400px, 1fr));
    gap: 20px;
    margin-bottom: 24px;
}

.chart-card {
    background: var(--bg-app);
    border: 1px solid var(--border);
    border-radius: 12px;
    padding: 20px;
    box-shadow: var(--shadow-sm);
}

.chart-card h3 {
    font-size: 15px;
    font-weight: 600;
    margin-bottom: 16px;
}

.stats-table-container {
    background: var(--bg-app);
    border: 1px solid var(--border);
    border-radius: 12px;
    padding: 20px;
    box-shadow: var(--shadow-sm);
}