:root {
    --bg: #0d111f;
    --panel: #18223a;
    --panel-alt: #223050;
    --line: rgba(129, 161, 255, 0.18);
    --text: #eef4ff;
    --muted: #9fb0d6;
    --accent: #5d8dff;
    --accent-2: #6ce5c2;
    --danger: #dc3545;
}

* {
    box-sizing: border-box;
}

body {
    margin: 0;
    min-height: 100vh;
    font-family: "Segoe UI", Tahoma, Geneva, Verdana, sans-serif;
    background:
        radial-gradient(circle at top left, rgba(93, 141, 255, 0.18), transparent 35%),
        radial-gradient(circle at bottom right, rgba(108, 229, 194, 0.14), transparent 30%),
        linear-gradient(180deg, #0a1020 0%, #121a31 100%);
    color: var(--text);
}

.page-shell {
    display: grid;
    grid-template-columns: 280px 1fr;
    min-height: 100vh;
}

.sidebar {
    border-right: 1px solid var(--line);
    background: rgba(7, 12, 26, 0.88);
    backdrop-filter: blur(14px);
    padding: 24px 18px;
    position: sticky;
    top: 0;
    height: 100vh;
}

.brand {
    display: flex;
    align-items: center;
    gap: 12px;
    color: var(--text);
    text-decoration: none;
    font-size: 1.2rem;
    font-weight: 700;
    margin-bottom: 28px;
}

.brand img,
.hero-title img {
    width: 44px;
    height: 44px;
}

.nav-link {
    color: var(--muted);
    border-radius: 12px;
    padding: 10px 12px;
    margin-bottom: 6px;
}

.nav-link:hover,
.nav-link:focus {
    color: var(--text);
    background: rgba(93, 141, 255, 0.12);
}

.content {
    padding: 32px;
}

.hero-card,
.panel,
.metric-card {
    background: rgba(24, 34, 58, 0.84);
    border: 1px solid var(--line);
    border-radius: 24px;
    box-shadow: 0 24px 60px rgba(0, 0, 0, 0.28);
}

.hero-card {
    padding: 28px;
}

.hero-title {
    display: flex;
    align-items: center;
    gap: 16px;
}

.hero-title h1 {
    margin: 0;
    font-size: 2rem;
}

.hero-title p {
    margin: 6px 0 0;
    color: var(--muted);
}

.runtime-note {
    margin-top: 16px;
    padding: 12px 14px;
    border-radius: 14px;
    background: rgba(108, 229, 194, 0.1);
    color: #d8fff5;
}

.glow {
    box-shadow: 0 0 0 1px rgba(93, 141, 255, 0.12), 0 0 24px rgba(93, 141, 255, 0.18);
}

.grid-two {
    display: grid;
    grid-template-columns: repeat(2, minmax(0, 1fr));
    gap: 20px;
}

.panel {
    padding: 24px;
}

.panel h2 {
    margin-top: 0;
    margin-bottom: 18px;
}

.metric-grid {
    display: grid;
    grid-template-columns: repeat(3, minmax(0, 1fr));
    gap: 18px;
}

.metric-card {
    padding: 22px;
}

.metric-card span {
    display: block;
    color: var(--muted);
    margin-bottom: 8px;
}

.metric-card strong {
    font-size: 2rem;
}

.section-header {
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: 12px;
}

.student-grid,
.stack {
    display: grid;
    gap: 12px;
}

.student-item,
.attendance-mark,
.admin-student-card {
    background: rgba(255, 255, 255, 0.04);
    border: 1px solid rgba(255, 255, 255, 0.05);
    border-radius: 16px;
    padding: 14px 16px;
}

.student-item::before {
    content: "Student";
    display: inline-block;
    font-size: 0.75rem;
    color: var(--accent-2);
    margin-right: 10px;
    text-transform: uppercase;
    letter-spacing: 0.08em;
}

.attendance-mark {
    border-left: 4px solid #28a745;
}

.feature-list {
    list-style: none;
    padding: 0;
    margin: 0;
}

.feature-list li {
    background: rgba(93, 141, 255, 0.08);
    border-radius: 14px;
    padding: 12px 14px;
    margin-bottom: 10px;
}

.feature-list li::before {
    content: "✓";
    margin-right: 10px;
    color: var(--accent-2);
    font-weight: 700;
}

.form-panel .form-control,
.form-panel .form-select {
    background: rgba(7, 12, 26, 0.7);
    border-color: rgba(255, 255, 255, 0.12);
    color: var(--text);
}

.form-panel .form-control:focus,
.form-panel .form-select:focus {
    background: rgba(7, 12, 26, 0.9);
    color: var(--text);
    border-color: var(--accent);
    box-shadow: 0 0 0 0.2rem rgba(93, 141, 255, 0.2);
}

.inline-form {
    display: flex;
    align-items: end;
    gap: 12px;
    flex-wrap: wrap;
}

.empty-state,
.muted {
    color: var(--muted);
}

.instructions {
    margin: 0;
    padding-left: 18px;
    color: var(--muted);
}

.admin-student-list {
    display: grid;
    gap: 12px;
}

.admin-student-card {
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: 16px;
}

.checkbox-row {
    display: flex;
    align-items: center;
    gap: 10px;
    color: var(--muted);
}

.btn-primary {
    background: linear-gradient(135deg, var(--accent), #3b63d1);
    border: none;
}

.btn-outline-light {
    border-color: rgba(255, 255, 255, 0.2);
}

.table {
    --bs-table-bg: transparent;
    --bs-table-striped-bg: rgba(255, 255, 255, 0.03);
    --bs-table-color: var(--text);
}

@media (max-width: 960px) {
    .page-shell {
        grid-template-columns: 1fr;
    }

    .sidebar {
        position: static;
        height: auto;
        border-right: 0;
        border-bottom: 1px solid var(--line);
    }

    .grid-two,
    .metric-grid {
        grid-template-columns: 1fr;
    }

    .content {
        padding: 20px;
    }

    .hero-title {
        align-items: flex-start;
        flex-direction: column;
    }
}