:root {
    --et-primary: #5b5ce2;
    --et-primary-dark: #4546c7;
    --et-primary-soft: #eeeeff;
    --et-accent: #14b8a6;
    --et-bg: #f4f6fb;
    --et-surface: #ffffff;
    --et-surface-2: #f9fafc;
    --et-text: #172033;
    --et-muted: #718096;
    --et-border: #e7eaf1;
    --et-danger: #ef4444;
    --et-warning: #f59e0b;
    --et-success: #10b981;
    --et-sidebar: #101426;
    --et-sidebar-muted: #929bb5;
    --et-radius: 18px;
    --et-shadow: 0 12px 35px rgba(24, 32, 60, .08);
}

* { box-sizing: border-box; }
html { scroll-behavior: smooth; }
body {
    min-height: 100vh;
    margin: 0;
    background: var(--et-bg);
    color: var(--et-text);
    font-family: Inter, ui-sans-serif, system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
    -webkit-font-smoothing: antialiased;
}
a { text-decoration: none; }
button, input, select, textarea { font: inherit; }

.app-shell {
    min-height: 100vh;
    display: flex;
}
.app-sidebar {
    position: fixed;
    inset: 0 auto 0 0;
    z-index: 1040;
    width: 272px;
    padding: 22px 16px;
    background:
        radial-gradient(circle at 5% 0%, rgba(91,92,226,.32), transparent 38%),
        var(--et-sidebar);
    color: white;
    display: flex;
    flex-direction: column;
    transition: transform .25s ease;
}
.app-main {
    width: calc(100% - 272px);
    margin-left: 272px;
    min-height: 100vh;
}
.app-topbar {
    position: sticky;
    top: 0;
    z-index: 1020;
    min-height: 76px;
    padding: 14px 28px;
    background: rgba(244,246,251,.88);
    border-bottom: 1px solid rgba(231,234,241,.9);
    backdrop-filter: blur(18px);
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: 18px;
}
.app-content {
    width: 100%;
    max-width: 1640px;
    margin-inline: auto;
    padding: 28px;
}
.brand-lockup {
    display: flex;
    align-items: center;
    gap: 12px;
    padding: 2px 6px 24px;
}
.brand-mark {
    width: 44px;
    height: 44px;
    border-radius: 14px;
    display: grid;
    place-items: center;
    background: linear-gradient(145deg, #7778ff, #4b4ccc);
    box-shadow: 0 12px 25px rgba(91,92,226,.35);
    color: white;
    font-weight: 900;
    font-size: 1.15rem;
}
.brand-title { color: white; font-weight: 800; letter-spacing: -.035em; line-height: 1.05; }
.brand-subtitle { color: var(--et-sidebar-muted); font-size: .76rem; margin-top: 4px; }

.nav-section-label {
    margin: 18px 12px 8px;
    color: #69738f;
    font-size: .66rem;
    font-weight: 800;
    letter-spacing: .14em;
    text-transform: uppercase;
}
.app-nav { display: grid; gap: 4px; }
.app-nav .nav-link {
    display: flex;
    align-items: center;
    gap: 12px;
    min-height: 46px;
    padding: 10px 13px;
    border-radius: 13px;
    color: var(--et-sidebar-muted);
    font-weight: 650;
    transition: .18s ease;
}
.app-nav .nav-link i {
    width: 22px;
    font-size: 1.05rem;
    text-align: center;
}
.app-nav .nav-link:hover {
    color: white;
    background: rgba(255,255,255,.07);
    transform: translateX(2px);
}
.app-nav .nav-link.active {
    color: white;
    background: linear-gradient(135deg, rgba(100,101,239,.96), rgba(75,76,204,.96));
    box-shadow: 0 12px 25px rgba(61,62,181,.24);
}
.sidebar-profile {
    margin-top: auto;
    padding: 14px;
    border: 1px solid rgba(255,255,255,.08);
    border-radius: 16px;
    background: rgba(255,255,255,.045);
}
.avatar {
    width: 44px;
    height: 44px;
    border-radius: 14px;
    object-fit: cover;
    display: grid;
    place-items: center;
    background: linear-gradient(145deg, #e9eaff, #c9cbff);
    color: var(--et-primary-dark);
    font-weight: 850;
}
.page-eyebrow {
    color: var(--et-primary);
    font-size: .72rem;
    font-weight: 800;
    letter-spacing: .12em;
    text-transform: uppercase;
}
.page-title {
    margin: 3px 0 4px;
    font-size: clamp(1.65rem, 3vw, 2.25rem);
    font-weight: 820;
    letter-spacing: -.045em;
}
.page-subtitle { color: var(--et-muted); margin: 0; }
.page-header {
    display: flex;
    align-items: flex-end;
    justify-content: space-between;
    gap: 20px;
    margin-bottom: 24px;
}
.modern-card {
    background: var(--et-surface);
    border: 1px solid var(--et-border);
    border-radius: var(--et-radius);
    box-shadow: 0 2px 5px rgba(24,32,60,.02);
}
.modern-card.hoverable { transition: transform .2s ease, box-shadow .2s ease; }
.modern-card.hoverable:hover { transform: translateY(-2px); box-shadow: var(--et-shadow); }

.metric-card {
    position: relative;
    overflow: hidden;
    padding: 22px;
}
.metric-card::after {
    content: "";
    position: absolute;
    right: -26px;
    top: -32px;
    width: 112px;
    height: 112px;
    border-radius: 50%;
    background: var(--metric-soft, var(--et-primary-soft));
}
.metric-icon {
    position: relative;
    z-index: 1;
    width: 46px;
    height: 46px;
    border-radius: 14px;
    display: grid;
    place-items: center;
    background: var(--metric-soft, var(--et-primary-soft));
    color: var(--metric-color, var(--et-primary));
    font-size: 1.25rem;
}
.metric-value {
    margin-top: 22px;
    font-size: 2rem;
    font-weight: 850;
    letter-spacing: -.04em;
}
.metric-label { color: var(--et-muted); font-size: .86rem; font-weight: 650; }
.metric-trend { font-size: .76rem; font-weight: 700; color: var(--et-success); }

.card-header-modern {
    padding: 20px 22px;
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: 14px;
    border-bottom: 1px solid var(--et-border);
}
.card-title-modern { margin: 0; font-size: 1rem; font-weight: 780; letter-spacing: -.02em; }
.card-body-modern { padding: 22px; }

.btn {
    border-radius: 12px;
    font-weight: 700;
    padding: .68rem 1rem;
    border-width: 1px;
}
.btn-sm { padding: .45rem .72rem; border-radius: 10px; }
.btn-primary {
    background: linear-gradient(135deg, #6566ec, #5152d2);
    border-color: #5556d5;
    box-shadow: 0 7px 16px rgba(81,82,210,.18);
}
.btn-primary:hover { background: linear-gradient(135deg, #5758dc, #4546c7); border-color: #4546c7; }
.btn-light { background: #f3f4f8; border-color: #e8eaf0; color: #394154; }
.btn-icon {
    width: 42px;
    height: 42px;
    padding: 0;
    display: grid;
    place-items: center;
}

.form-control, .form-select {
    min-height: 46px;
    border: 1px solid #dde1ea;
    border-radius: 12px;
    background-color: #fff;
    color: var(--et-text);
    box-shadow: none;
}
textarea.form-control { min-height: 110px; }
.form-control:focus, .form-select:focus {
    border-color: #8d8ef3;
    box-shadow: 0 0 0 .24rem rgba(91,92,226,.11);
}
.form-label {
    color: #424b61;
    font-size: .83rem;
    font-weight: 700;
    margin-bottom: .45rem;
}
.input-icon { position: relative; }
.input-icon i {
    position: absolute;
    left: 14px;
    top: 50%;
    transform: translateY(-50%);
    color: #98a2b3;
}
.input-icon .form-control { padding-left: 42px; }

.modern-table { margin: 0; }
.modern-table thead th {
    padding: 13px 18px;
    border-bottom: 1px solid var(--et-border);
    background: #fafbfe;
    color: #7b8498;
    font-size: .69rem;
    font-weight: 800;
    letter-spacing: .08em;
    text-transform: uppercase;
    white-space: nowrap;
}
.modern-table tbody td {
    padding: 16px 18px;
    border-color: #edf0f5;
    vertical-align: middle;
}
.modern-table tbody tr { transition: background .16s ease; }
.modern-table tbody tr:hover { background: #fafaff; }

.status-pill {
    display: inline-flex;
    align-items: center;
    gap: 6px;
    padding: .36rem .62rem;
    border-radius: 999px;
    font-size: .73rem;
    font-weight: 780;
    text-transform: capitalize;
}
.status-pill::before {
    content: "";
    width: 7px;
    height: 7px;
    border-radius: 50%;
    background: currentColor;
}
.status-success { background: #e9fbf3; color: #07845e; }
.status-warning { background: #fff7df; color: #a76a00; }
.status-danger { background: #ffeded; color: #cf3232; }
.status-info { background: #eceeff; color: #5152d2; }
.status-neutral { background: #f1f3f7; color: #697386; }

.student-cell { display: flex; align-items: center; gap: 12px; min-width: 210px; }
.student-avatar {
    width: 43px;
    height: 43px;
    flex: 0 0 43px;
    border-radius: 13px;
    object-fit: cover;
    display: grid;
    place-items: center;
    background: linear-gradient(145deg, #edf0ff, #dfe3ff);
    color: var(--et-primary);
    font-weight: 850;
}
.student-name { font-weight: 760; color: var(--et-text); }
.student-meta { color: var(--et-muted); font-size: .78rem; margin-top: 2px; }

.search-panel { padding: 16px; margin-bottom: 18px; }
.empty-state {
    padding: 58px 24px;
    text-align: center;
    color: var(--et-muted);
}
.empty-icon {
    width: 68px;
    height: 68px;
    margin: 0 auto 16px;
    border-radius: 20px;
    display: grid;
    place-items: center;
    background: var(--et-primary-soft);
    color: var(--et-primary);
    font-size: 1.6rem;
}
.section-title { font-size: 1.02rem; font-weight: 800; letter-spacing: -.02em; }
.section-caption { color: var(--et-muted); font-size: .84rem; }

.auth-page {
    min-height: 100vh;
    background:
        radial-gradient(circle at 10% 10%, rgba(91,92,226,.18), transparent 30%),
        radial-gradient(circle at 90% 80%, rgba(20,184,166,.13), transparent 34%),
        #f6f7fb;
    display: grid;
    grid-template-columns: minmax(0, 1.12fr) minmax(420px, .88fr);
}
.auth-showcase {
    padding: clamp(36px, 6vw, 92px);
    display: flex;
    flex-direction: column;
    justify-content: space-between;
    background:
        linear-gradient(150deg, rgba(16,20,38,.94), rgba(28,33,67,.97)),
        radial-gradient(circle at top left, #5b5ce2, transparent 55%);
    color: white;
}
.auth-showcase h1 {
    max-width: 760px;
    font-size: clamp(2.5rem, 6vw, 5.4rem);
    font-weight: 900;
    letter-spacing: -.07em;
    line-height: .97;
}
.auth-panel { display: grid; place-items: center; padding: 30px; }
.auth-card {
    width: min(460px, 100%);
    padding: clamp(25px, 4vw, 40px);
}
.auth-logo { display: flex; align-items: center; gap: 12px; margin-bottom: 34px; }
.auth-logo .brand-mark { width: 48px; height: 48px; }
.auth-title { font-size: 1.85rem; font-weight: 850; letter-spacing: -.045em; }
.auth-hint { color: var(--et-muted); }

.welcome-shell {
    min-height: 100vh;
    background:
        radial-gradient(circle at 15% 20%, rgba(91,92,226,.24), transparent 33%),
        radial-gradient(circle at 80% 70%, rgba(20,184,166,.16), transparent 32%),
        #0d1020;
    color: white;
}
.welcome-nav { padding: 22px 0; }
.hero-title {
    max-width: 950px;
    font-size: clamp(3rem, 7vw, 6.4rem);
    font-weight: 920;
    letter-spacing: -.075em;
    line-height: .92;
}
.hero-copy { max-width: 720px; color: #b9c0d1; font-size: 1.15rem; line-height: 1.75; }
.glass-card {
    border: 1px solid rgba(255,255,255,.12);
    border-radius: 24px;
    background: rgba(255,255,255,.075);
    backdrop-filter: blur(18px);
    box-shadow: 0 24px 80px rgba(0,0,0,.2);
}

.mobile-sidebar-button { display: none; }
.table-action-menu .dropdown-toggle::after { display: none; }

[data-bs-theme="dark"] {
    --et-bg: #0e1220;
    --et-surface: #171c2d;
    --et-surface-2: #1c2235;
    --et-text: #edf1fb;
    --et-muted: #9ca7bf;
    --et-border: #293149;
}
[data-bs-theme="dark"] .app-topbar { background: rgba(14,18,32,.88); }
[data-bs-theme="dark"] .modern-table thead th { background: #1c2235; }
[data-bs-theme="dark"] .modern-table tbody tr:hover { background: #1b2134; }
[data-bs-theme="dark"] .form-control,
[data-bs-theme="dark"] .form-select { background-color: #181e30; border-color: #303950; color: #edf1fb; }
[data-bs-theme="dark"] .btn-light { background: #252c40; border-color: #343d55; color: white; }

@media (max-width: 991.98px) {
    .app-sidebar { transform: translateX(-100%); }
    .app-sidebar.show { transform: translateX(0); box-shadow: 24px 0 60px rgba(0,0,0,.3); }
    .app-main { width: 100%; margin-left: 0; }
    .mobile-sidebar-button { display: grid; }
    .app-content { padding: 22px 16px; }
    .app-topbar { padding: 12px 16px; }
    .page-header { align-items: flex-start; flex-direction: column; }
    .auth-page { grid-template-columns: 1fr; }
    .auth-showcase { display: none; }
}
@media (max-width: 575.98px) {
    .app-topbar .topbar-title { display: none; }
    .metric-card { padding: 18px; }
    .page-title { font-size: 1.6rem; }
    .auth-panel { padding: 16px; }
}