*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }

:root {
    --bg: var(--ui-bg);
    --surface: var(--ui-surface);
    --surface2: var(--ui-surface2);
    --surface3: var(--ui-surface3);
    --text: var(--ui-text);
    --border: var(--ui-border);
    --accent: var(--ui-accent);
    --success: var(--ui-success);
    --warning: var(--ui-warning);
    --danger: var(--ui-danger);
    --info: var(--ui-info);
    --accent2: var(--ui-accent-soft);
    --text-muted: var(--ui-muted);
    --input-bg: var(--ui-surface);
    --on-accent: var(--ui-on-accent);
    --accent-hover: var(--ui-accent-hover);
    --accent-soft: var(--ui-accent-soft);
    --success-bg: var(--ui-success-bg);
    --warning-bg: var(--ui-warning-bg);
    --danger-bg: var(--ui-danger-bg);
    --info-bg: var(--ui-info-bg);
    --radius: 10px;
    --shadow: none;
}

html { font-size: 16px; }

body {
    font-family: Inter, ui-sans-serif, system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
    background: var(--bg);
    color: var(--text);
    min-height: 100vh;
    display: flex;
    line-height: 1.5;
}

nav {
    width: 256px;
    min-height: 100vh;
    background: var(--surface);
    border-right: 1px solid var(--border);
    display: flex;
    flex-direction: column;
    padding: 1.5rem;
    position: fixed;
    top: 0; left: 0; bottom: 0;
    gap: 1.25rem;
}

.nav-logo {
    display: flex;
    align-items: center;
    gap: .65rem;
    font-size: 1.15rem;
    font-weight: 650;
    color: var(--text);
    margin-bottom: .75rem;
    letter-spacing: 0;
}
.nav-logo .brand-icon {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    width: 2rem;
    height: 2rem;
    color: var(--accent);
}
.nav-logo .brand-icon svg {
    width: 2rem;
    height: 2rem;
    stroke: currentColor;
    stroke-width: 2;
    stroke-linecap: round;
    stroke-linejoin: round;
    fill: none;
}
.nav-logo span { color: inherit; }

.nav-section {
    font-size: .75rem;
    font-weight: 650;
    color: var(--text-muted);
    margin: 1.25rem 0 .45rem;
}

nav a, .nav-button {
    display: flex;
    align-items: center;
    gap: .75rem;
    padding: .55rem .75rem;
    border-radius: 10px;
    color: var(--text);
    text-decoration: none;
    font-size: .9rem;
    font-weight: 450;
    transition: background .15s, color .15s;
}
nav a:hover, .nav-button:hover { background: var(--surface2); color: var(--text); }
nav a.active {
    background: var(--accent-soft);
    color: var(--accent);
    font-weight: 650;
}
nav a .icon, .nav-button .icon {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    width: 1rem;
    height: 1rem;
    min-width: 1rem;
    color: var(--text-muted);
}
nav a .icon svg, .nav-button .icon svg {
    width: 1rem;
    height: 1rem;
    stroke: currentColor;
    stroke-width: 2;
    stroke-linecap: round;
    stroke-linejoin: round;
    fill: none;
}
nav a.active .icon { color: var(--accent); }
.nav-button {
    width: 100%;
    border: 0;
    background: transparent;
    font: inherit;
    cursor: pointer;
    text-align: left;
}

.nav-bottom { margin-top: auto; }

main {
    margin-left: 256px;
    padding: 2rem;
    flex: 1;
    max-width: calc(100vw - 256px);
}

h1 {
    font-size: 1.875rem;
    font-weight: 700;
    line-height: 1.25;
    margin-bottom: 1.35rem;
    letter-spacing: 0;
}
h2 {
    font-size: 1.18rem;
    font-weight: 650;
    line-height: 1.35;
    margin-bottom: .85rem;
}

.card {
    background: var(--surface);
    border: 1px solid var(--border);
    border-radius: var(--radius);
    padding: 1.5rem;
    margin-bottom: 1.5rem;
    box-shadow: var(--shadow);
}

.btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: .4rem;
    min-height: 2.35rem;
    padding: .5rem .95rem;
    border: 1px solid transparent;
    border-radius: 10px;
    font-size: .88rem;
    font-weight: 500;
    cursor: pointer;
    text-decoration: none;
    transition: background .15s, border-color .15s, color .15s, transform .1s;
}
.btn:hover { transform: translateY(-1px); }
.btn:active { transform: translateY(0); }
.btn-primary { background: var(--accent); color: var(--on-accent); border-color: var(--accent); }
.btn-primary:hover { background: var(--accent-hover); border-color: var(--accent-hover); }
.btn-secondary { background: transparent; color: var(--text); border-color: var(--border); }
.btn-secondary:hover, .btn-ghost:hover { background: var(--surface2); }
.btn-ghost { background: transparent; border-color: var(--border); color: var(--text); }
.btn-danger { background: transparent; color: var(--danger); border-color: rgba(239,68,68,.35); }
.btn-danger:hover { background: rgba(239,68,68,.10); }
.btn-success { background: rgba(34,197,94,.15); color: var(--success); border-color: rgba(34,197,94,.35); }
.btn-sm { min-height: 2rem; padding: .3rem .65rem; font-size: .8rem; }
.btn[disabled], button[disabled] { opacity: .45; cursor: not-allowed; transform: none; }

.form-group { margin-bottom: 1.2rem; }
label {
    display: block;
    font-size: .9rem;
    color: var(--text);
    font-weight: 500;
    margin-bottom: .4rem;
}
input[type=text], input[type=date], input[type=password],
input[type=email], input[type=number], input[type=file],
textarea, select {
    width: 100%;
    background: var(--input-bg);
    border: 1px solid var(--border);
    border-radius: 10px;
    color: var(--text);
    padding: .55rem .75rem;
    font-size: .92rem;
    transition: border-color .2s, box-shadow .2s;
}
input[type=file] { padding: .45rem .75rem; }
input:focus, textarea:focus, select:focus {
    outline: none;
    border-color: var(--accent);
    box-shadow: 0 0 0 3px var(--accent-soft);
}
textarea { resize: vertical; }
input[type=checkbox], input[type=radio] { accent-color: var(--accent); }

table { width: 100%; border-collapse: collapse; }
th, td {
    padding: .75rem 1rem;
    text-align: left;
    border-bottom: 1px solid var(--border);
    vertical-align: middle;
}
th {
    font-size: .82rem;
    font-weight: 500;
    color: var(--text-muted);
}
tr:hover td { background: var(--surface3); }
tbody tr:last-child td { border-bottom: 0; }

.badge {
    display: inline-block;
    padding: .18rem .55rem;
    border-radius: 10px;
    font-size: .75rem;
    font-weight: 500;
    border: 1px solid transparent;
}
.badge-1 { background: rgba(34,197,94,.12); color: var(--success); border-color: rgba(34,197,94,.22); }
.badge-2 { background: rgba(132,204,22,.12); color: var(--success); border-color: rgba(132,204,22,.22); }
.badge-3 { background: rgba(245,158,11,.12); color: var(--warning); border-color: rgba(245,158,11,.22); }
.badge-4 { background: rgba(249,115,22,.12); color: var(--warning); border-color: rgba(249,115,22,.22); }
.badge-5 { background: rgba(239,68,68,.12); color: var(--danger); border-color: rgba(239,68,68,.22); }
.badge-cat { background: transparent; color: var(--text); border-color: var(--border); }

.messages { list-style: none; margin-bottom: 1rem; }
.messages li {
    padding: .75rem 1rem;
    border-radius: 8px;
    margin-bottom: .5rem;
    font-size: .9rem;
    border: 1px solid var(--border);
}
.messages .success { background: rgba(34,197,94,.10); border-color: rgba(34,197,94,.25); color: var(--success); }
.messages .error   { background: rgba(239,68,68,.10); border-color: rgba(239,68,68,.25); color: var(--danger); }
.messages .warning { background: rgba(245,158,11,.10); border-color: rgba(245,158,11,.25); color: var(--warning); }

.stats-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(220px, 1fr));
    gap: 1rem;
    margin-bottom: 1.5rem;
}
.stat-card {
    background: var(--surface);
    border: 1px solid var(--border);
    border-radius: var(--radius);
    padding: 1.25rem;
    box-shadow: var(--shadow);
}
.stat-number { font-size: 1.75rem; font-weight: 700; color: var(--text); line-height: 1.15; }
.stat-label { font-size: .875rem; color: var(--text-muted); margin-top: .35rem; }

.filter-bar {
    display: flex;
    flex-wrap: wrap;
    gap: .8rem;
    align-items: flex-end;
    background: var(--surface);
    border: 1px solid var(--border);
    border-radius: var(--radius);
    padding: 1rem 1.2rem;
    margin-bottom: 1.5rem;
    box-shadow: var(--shadow);
}
.filter-bar .form-group { margin-bottom: 0; flex: 1; min-width: 140px; }
.filter-bar label { font-size: .82rem; color: var(--text-muted); }

.actions { display: flex; gap: .5rem; flex-wrap: wrap; margin-bottom: 1.5rem; }

.text-muted { color: var(--text-muted); font-size: .85rem; }
.mt-1 { margin-top: .5rem; }
.mt-2 { margin-top: 1rem; }

code {
    background: var(--surface2);
    border: 1px solid var(--border);
    border-radius: 5px;
    padding: .08rem .35rem;
    color: var(--text);
}

hr { border: 0; border-top: 1px solid var(--border); }

.nav-toggle { display: none; }
.nav-links { display: flex; flex-direction: column; gap: .3rem; flex: 1; }
.responsive-grid { display: grid; grid-template-columns: var(--columns); gap: 1.5rem; align-items: start; }
.responsive-grid > *, main, .card { min-width: 0; }
.table-scroll { max-width: 100%; overflow-x: auto; }
.table-scroll:focus-visible, .nav-toggle:focus-visible { outline: 2px solid var(--accent); outline-offset: 3px; }
.table-hint { display: none; }

@media (max-width: 900px) {
    body { display: block; }
    nav {
        position: static;
        width: 100%;
        min-height: auto;
        border-right: 0;
        border-bottom: 1px solid var(--border);
    }
    main {
        margin-left: 0;
        max-width: none;
        padding: 1.25rem;
    }
    nav { padding: .75rem 1rem; gap: .5rem; }
    .nav-header { display: flex; align-items: center; justify-content: space-between; gap: .5rem; }
    .nav-logo { margin: 0; font-size: 1rem; }
    .nav-ready .nav-toggle { display: inline-flex; }
    .nav-ready .nav-links:not(.is-open) { display: none; }
    .nav-links { gap: .25rem; }
    .nav-section { margin: .75rem 0 .25rem; }
    .responsive-grid { grid-template-columns: minmax(0, 1fr); }
    .difficulty-grid { grid-template-columns: repeat(5, minmax(0, 1fr)); }
    .table-scroll table { min-width: 900px; }
    .table-hint { display: block; padding: .5rem .75rem; color: var(--text-muted); font-size: .8rem; }
    .btn, .btn-sm, nav a, .nav-button { min-height: 44px; }
    input[type=text], input[type=date], input[type=password], input[type=email],
    input[type=number], input[type=file], textarea, select { font-size: 1rem; min-height: 44px; }
    input[type=checkbox], input[type=radio] { width: 20px; height: 20px; flex-shrink: 0; }
}
@media (max-width: 600px) {
    main { padding: 1rem .75rem; }
    h1 { font-size: 1.5rem; overflow-wrap: anywhere; }
    .card { padding: 1rem; }
    .stats-grid { grid-template-columns: minmax(0, 1fr); }
    .filter-bar { padding: .75rem; }
    .filter-bar .form-group { flex: 1 1 100% !important; min-width: 0; }
    .category-editor { grid-template-columns: minmax(0, 1fr) auto !important; }
    .category-editor > input[type=text] { grid-column: 1 / -1; }
    .difficulty-grid { grid-template-columns: repeat(3, minmax(0, 1fr)) !important; }
    #selected-list > div > div:first-child { flex-wrap: wrap; }
    .mc-option-row .mc-option-grid { grid-template-columns: 32px minmax(0, 1fr); }
    .mc-option-grid .mc-correct-label { grid-column: 2; }
    .mc-option-grid .mc-delete-label { grid-column: 2; }
}

/* Refined Violet: quieter surfaces and a compact, consistent working layout. */
body { font-family: ui-sans-serif, system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif; }
nav { padding: 1.5rem 1rem; overflow-y: auto; }
.nav-logo { padding: 0 .65rem; font-size: 1.3rem; font-weight: 750; letter-spacing: -.035em; }
.brand-name { display: grid; line-height: 1.15; }
.brand-name small { margin-top: .35rem; color: var(--text-muted); font-size: .62rem; font-weight: 600; letter-spacing: .2em; text-transform: uppercase; }
.nav-section { margin: .75rem .75rem .15rem; font-size: .67rem; letter-spacing: .08em; text-transform: uppercase; }
nav a, .nav-button { min-height: 44px; font-weight: 500; }
.nav-bottom { padding-top: 1rem; }
.nav-bottom .theme-control { justify-content: space-between; padding: 1rem .5rem 0; margin-top: .75rem; border-top: 1px solid var(--border); }
main { padding: 2.5rem clamp(1.25rem, 3vw, 3rem); }
h1 { letter-spacing: -.035em; }
h2 { letter-spacing: -.02em; }
a { color: var(--accent); }
.btn { min-height: 44px; font-weight: 600; }
.btn:hover { transform: none; }
.btn-sm { min-height: 36px; }
.btn-ghost { border-color: transparent; color: var(--text-muted); }
input[type=text], input[type=date], input[type=password], input[type=email], input[type=number], input[type=file], textarea, select { border-color: var(--ui-input-border); min-height: 44px; font-family: inherit; }
:where(a, button, input, select, textarea, summary):focus-visible { outline: 3px solid var(--accent); outline-offset: 3px; }
th { background: var(--surface3); font-size: .78rem; }
td { font-size: .9rem; }
.stat-card { border-color: transparent; }
.stat-number { font-variant-numeric: tabular-nums; letter-spacing: -.03em; }
.page-heading { display: flex; align-items: center; justify-content: space-between; flex-wrap: wrap; gap: 1rem; margin-bottom: 2rem; }
.page-heading h1 { margin-bottom: .3rem; }
.page-heading p { color: var(--text-muted); font-size: .95rem; }
.page-heading .actions { margin: 0; }
.quiz-secondary-actions { justify-content: flex-end; margin-bottom: 1rem; }
.quiz-section { margin-bottom: 2rem; }
.quiz-section h2 { font-size: 1rem; }
.quiz-table { min-width: 680px; }
.quiz-table td { padding-block: 1.2rem; }
.quiz-title { color: var(--text); font-weight: 650; text-decoration: none; }
.quiz-title:hover { color: var(--accent); }
.quiz-row-actions { white-space: nowrap; }
.status-pill { display: inline-block; padding: .3rem .65rem; border-radius: 8px; font-size: .75rem; font-weight: 600; }
.status-draft, .status-scheduled { background: var(--accent-soft); color: var(--ui-accent-text); }
.status-completed { background: var(--success-bg); color: var(--success); }
.status-archived { background: var(--surface2); color: var(--text-muted); }
@media (max-width: 900px) {
  nav { padding: .75rem 1rem; }
  main { padding: 1.5rem 1rem; }
  .nav-logo { padding: 0; }
  .nav-logo .brand-name { display: block; }
  .brand-name small { display: none; }
  .nav-bottom { padding-top: .25rem; }
  .nav-bottom .theme-control { justify-content: flex-start; }
  .btn-sm { min-height: 44px; }
}
@media (max-width: 600px) {
  .stats-grid { grid-template-columns: repeat(2, minmax(0, 1fr)); gap: .65rem; }
  .stat-card { padding: 1rem; }
  .stat-number { font-size: 1.45rem; }
  .stat-label { font-size: .8rem; }
  .page-heading { margin-bottom: 1.5rem; }
  .quiz-secondary-actions { justify-content: flex-start; }
}
@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after { transition: none !important; scroll-behavior: auto !important; }
}

.login-page { display: grid; place-items: center; min-height: 100dvh; padding: 1.5rem; }
.login-box { width: min(100%, 420px); }
.login-box h1 { margin-bottom: .5rem; }
.login-subtitle { margin-bottom: 2rem; color: var(--text-muted); }
.login-box input { margin-bottom: 1.25rem; }
.login-box .btn { width: 100%; margin-top: .5rem; }
.login-box .theme-control { margin-top: 2rem; justify-content: space-between; padding-top: 1.25rem; border-top: 1px solid var(--border); }
.login-box .error { margin-bottom: 1rem; border-radius: 10px; background: var(--danger-bg); color: var(--danger); padding: 1rem; }