:root {
  color-scheme: light;
  --bg: #f3efe6;
  --bg-elevated: #faf7f0;
  --panel: #fffdf8;
  --panel-strong: #ffffff;
  --ink: #1d2925;
  --muted: #68746f;
  --line: #d9d1c4;
  --line-strong: #c7bdae;
  --accent: #2f6f61;
  --accent-hover: #275f53;
  --accent-soft: #e3eee9;
  --accent-line: #c7ded4;
  --danger: #9d3f3f;
  --danger-soft: #f7e2e2;
  --warn: #8a641e;
  --warn-soft: #f8eed9;
  --good: #286245;
  --good-soft: #e3f1e9;
  --code-bg: #19231f;
  --code-ink: #dce9e3;
  --overlay: rgba(20, 28, 25, .58);
  --shadow-sm: 0 4px 14px rgba(41, 53, 49, .06);
  --shadow: 0 12px 34px rgba(41, 53, 49, .08);
  --radius-sm: 12px;
  --radius: 18px;
  --radius-lg: 24px;
  --focus: 0 0 0 3px rgba(47, 111, 97, .22);
}

:root[data-theme="dark"] {
  color-scheme: dark;
  --bg: #111714;
  --bg-elevated: #161e1a;
  --panel: #19231f;
  --panel-strong: #202c27;
  --ink: #eef5f1;
  --muted: #a7b5ae;
  --line: #34423c;
  --line-strong: #46564f;
  --accent: #79b7a5;
  --accent-hover: #91c7b7;
  --accent-soft: #243b34;
  --accent-line: #36584d;
  --danger: #ef9b9b;
  --danger-soft: #482a2a;
  --warn: #e9c47d;
  --warn-soft: #46391f;
  --good: #93d0ae;
  --good-soft: #243d30;
  --code-bg: #0d1210;
  --code-ink: #dce9e3;
  --overlay: rgba(3, 7, 5, .76);
  --shadow-sm: 0 4px 14px rgba(0, 0, 0, .15);
  --shadow: 0 14px 38px rgba(0, 0, 0, .22);
  --focus: 0 0 0 3px rgba(121, 183, 165, .26);
}

* { box-sizing: border-box; }
html { min-height: 100%; scroll-behavior: smooth; }
body {
  min-height: 100%;
  margin: 0;
  background: var(--bg);
  color: var(--ink);
  font-family: Inter, ui-sans-serif, system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", Arial, sans-serif;
  font-size: 16px;
  line-height: 1.58;
  text-rendering: optimizeLegibility;
  -webkit-font-smoothing: antialiased;
  transition: background-color .2s ease, color .2s ease;
}
body.learner-shell { padding-block-end: calc(84px + env(safe-area-inset-bottom)); }
img { max-width: 100%; }
a { color: var(--accent); text-underline-offset: .18em; }
a:hover { color: var(--accent-hover); }
button, input, textarea, select { font: inherit; }
button, .button-link {
  min-height: 44px;
  border: 0;
  border-radius: var(--radius-sm);
  padding: .72rem 1rem;
  background: var(--accent);
  color: #fff;
  cursor: pointer;
  font-weight: 700;
  line-height: 1.2;
  text-decoration: none;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: .45rem;
  transition: transform .15s ease, background-color .15s ease, border-color .15s ease, color .15s ease, opacity .15s ease;
  -webkit-tap-highlight-color: transparent;
}
button:hover, .button-link:hover { background: var(--accent-hover); color: #fff; }
button:active, .button-link:active { transform: translateY(1px); }
button:disabled { opacity: .5; cursor: not-allowed; transform: none; }
button.secondary { background: var(--accent-soft); color: var(--accent); border: 1px solid var(--accent-line); }
button.secondary:hover { background: var(--accent-line); color: var(--ink); }
button.ghost { background: transparent; color: var(--accent); border: 1px solid var(--line); }
button.ghost:hover { background: var(--bg-elevated); color: var(--accent-hover); border-color: var(--line-strong); }
button.danger { background: var(--danger); color: #fff; }
button:focus-visible, a:focus-visible, input:focus-visible, textarea:focus-visible, select:focus-visible { outline: none; box-shadow: var(--focus); }

input, textarea, select {
  width: 100%;
  min-height: 44px;
  border: 1px solid var(--line);
  border-radius: var(--radius-sm);
  padding: .72rem .82rem;
  background: var(--panel-strong);
  color: var(--ink);
  transition: border-color .15s ease, box-shadow .15s ease, background-color .2s ease;
}
input:hover, textarea:hover, select:hover { border-color: var(--line-strong); }
input:focus, textarea:focus, select:focus { border-color: var(--accent); }
input[type="checkbox"], input[type="radio"] { width: 20px; min-height: 20px; height: 20px; accent-color: var(--accent); flex: 0 0 auto; }
textarea { min-height: 108px; resize: vertical; }
label { display: grid; gap: .42rem; font-weight: 700; }
small, .muted { color: var(--muted); font-weight: 450; }

.skip-link { position: fixed; inset-block-start: 8px; inset-inline-start: 8px; transform: translateY(-160%); z-index: 100; background: var(--panel); padding: .6rem .8rem; border-radius: 10px; box-shadow: var(--shadow); }
.skip-link:focus { transform: translateY(0); }
.container { width: min(1120px, calc(100% - 24px)); margin-inline: auto; }
.main-content { padding-block: 18px 34px; }
.topbar {
  position: sticky;
  inset-block-start: 0;
  z-index: 30;
  background: color-mix(in srgb, var(--bg) 90%, transparent);
  backdrop-filter: blur(16px);
  -webkit-backdrop-filter: blur(16px);
  border-block-end: 1px solid color-mix(in srgb, var(--line) 82%, transparent);
}
.topbar-inner { min-height: 62px; display: flex; align-items: center; justify-content: space-between; gap: .75rem; }
.topbar-actions { display: flex; align-items: center; justify-content: flex-end; gap: .55rem; min-width: 0; }
.brand { font-weight: 850; letter-spacing: .005em; white-space: nowrap; }
.brand span { color: var(--accent); }
.user-name { max-width: 32vw; color: var(--muted); overflow: hidden; text-overflow: ellipsis; white-space: nowrap; font-size: .9rem; }
.theme-toggle { min-height: 40px; padding: .55rem .7rem; background: var(--panel); color: var(--ink); border: 1px solid var(--line); box-shadow: var(--shadow-sm); }
.theme-toggle:hover { background: var(--bg-elevated); color: var(--ink); }
.theme-toggle [data-theme-label] { display: none; }

.hero { padding-block: 48px; display: grid; gap: 20px; }
.hero h1 { max-width: 800px; margin: 0; font-size: clamp(2.2rem, 9vw, 4.5rem); line-height: 1.02; letter-spacing: -.045em; }
.hero p { max-width: 720px; font-size: 1.08rem; color: var(--muted); }
.compact-hero { max-width: 560px; margin-inline: auto; }
.form-submit { margin-block-start: 14px; }

.card {
  background: var(--panel);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  padding: 16px;
  box-shadow: var(--shadow-sm);
}
.card + .card { margin-block-start: 14px; }
.grid { display: grid; gap: 14px; }
.grid.two, .grid.three, .form-grid, .feedback-row { grid-template-columns: 1fr; }
.full { grid-column: 1 / -1; }

.nav-tabs {
  position: fixed;
  inset-inline: 0;
  inset-block-end: 0;
  z-index: 35;
  display: grid;
  grid-template-columns: repeat(5, minmax(0, 1fr));
  gap: 2px;
  padding: 7px max(8px, env(safe-area-inset-right)) calc(7px + env(safe-area-inset-bottom)) max(8px, env(safe-area-inset-left));
  background: color-mix(in srgb, var(--panel) 95%, transparent);
  backdrop-filter: blur(16px);
  -webkit-backdrop-filter: blur(16px);
  border-block-start: 1px solid var(--line);
  box-shadow: 0 -8px 24px rgba(20, 28, 25, .08);
}
.nav-tabs button {
  min-width: 0;
  min-height: 56px;
  padding: .35rem .2rem;
  flex-direction: column;
  gap: .12rem;
  background: transparent;
  color: var(--muted);
  border: 1px solid transparent;
  border-radius: 11px;
  font-size: .69rem;
  font-weight: 700;
  white-space: nowrap;
}
.nav-tabs button:hover { background: var(--bg-elevated); color: var(--ink); }
.nav-tabs button.active { color: var(--accent); background: var(--accent-soft); border-color: var(--accent-line); }
.nav-icon { font-size: .96rem; line-height: 1; }
.admin-shell .nav-tabs {
  position: sticky;
  inset-block-start: 62px;
  inset-inline: auto;
  inset-block-end: auto;
  display: flex;
  overflow-x: auto;
  justify-content: flex-start;
  padding: 10px 0;
  background: var(--bg);
  border: 0;
  box-shadow: none;
}
.admin-shell .nav-tabs button { min-height: 42px; flex: 0 0 auto; flex-direction: row; padding: .55rem .85rem; font-size: .84rem; }
.section { display: none; }
.section.active { display: block; animation: section-in .18s ease-out; }
@keyframes section-in { from { opacity: .65; transform: translateY(3px); } to { opacity: 1; transform: none; } }

.kicker { color: var(--accent); font-size: .74rem; font-weight: 850; letter-spacing: .13em; text-transform: uppercase; }
h1, h2, h3 { line-height: 1.18; text-wrap: balance; }
h1 { margin-block: 0 14px; }
h2 { margin-block: 0 14px; font-size: clamp(1.35rem, 5vw, 1.8rem); }
h3 { margin-block: 0 9px; }
p { margin-block: .55rem 1rem; }
.section-heading { display: flex; flex-wrap: wrap; align-items: flex-start; justify-content: space-between; gap: .8rem; margin-block-end: 14px; }
.section-heading > p { margin: 0; max-width: 560px; }
.form-section { padding-block: 4px 20px; border-block-end: 1px solid var(--line); }
.form-section + .form-section { padding-block-start: 20px; }
.form-section:last-of-type { border-block-end: 0; }
.profile-form { display: grid; gap: 0; }
.profile-editor-card { padding-block-end: 18px; }
.form-actions { display: flex; flex-direction: column; align-items: stretch; gap: .75rem; padding-block-start: 18px; }
.choice-grid { display: grid; gap: 10px; grid-template-columns: 1fr; }
.compact-choices { margin-block-start: 12px; }
.choice { display: flex; align-items: flex-start; gap: .75rem; padding: 13px; background: var(--panel-strong); border: 1px solid var(--line); border-radius: var(--radius-sm); cursor: pointer; }
.choice:hover { border-color: var(--accent); }
.choice span { display: grid; gap: .12rem; }
.choice small { line-height: 1.35; }

.lesson-article { overflow: hidden; }
.lesson-article h1 { font-size: clamp(1.75rem, 7vw, 2.7rem); }
.lesson-question { font-size: 1.08rem; font-weight: 750; color: var(--accent); }
.lesson-meta { display: flex; align-items: center; justify-content: space-between; flex-wrap: wrap; gap: .55rem; margin-block-end: 12px; }
.lesson-body { font-size: 1.02rem; }
.lesson-body section { padding-block: 17px; border-block-start: 1px solid var(--line); }
.lesson-body section:first-child { border-block-start: 0; }
.lesson-body ul, .lesson-body ol { padding-inline-start: 1.4rem; }
.lesson-body li + li { margin-block-start: .5rem; }
.lesson-card-image { display: block; width: 100%; border-radius: 15px; border: 1px solid var(--line); background: var(--panel-strong); margin-block: 15px; }
.lesson-actions, .card-footer { margin-block-start: 14px; }

.actions { display: flex; flex-wrap: wrap; gap: 8px; align-items: center; }
.badge { display: inline-flex; align-items: center; border-radius: 999px; padding: .28rem .65rem; background: var(--bg-elevated); border: 1px solid var(--line); color: var(--muted); font-size: .76rem; font-weight: 750; }
.badge.good { background: var(--good-soft); border-color: color-mix(in srgb, var(--good) 32%, transparent); color: var(--good); }
.badge.warn { background: var(--warn-soft); border-color: color-mix(in srgb, var(--warn) 32%, transparent); color: var(--warn); }
.badge.bad { background: var(--danger-soft); border-color: color-mix(in srgb, var(--danger) 32%, transparent); color: var(--danger); }
.metric-card { min-height: 120px; display: flex; flex-direction: column; justify-content: center; }
.metric { font-size: 2.15rem; font-weight: 850; line-height: 1; }
.metric-label { color: var(--muted); margin-block-start: .5rem; }
.list { display: grid; gap: 10px; }
.list-item { width: 100%; padding: 14px; border: 1px solid var(--line); border-radius: 14px; background: var(--panel-strong); color: var(--ink); text-align: start; box-shadow: none; }
button.list-item:hover { background: var(--bg-elevated); color: var(--ink); border-color: var(--accent-line); transform: translateY(-1px); }
.list-item h3 { font-size: 1.03rem; }
.table-wrap { overflow-x: auto; border: 1px solid var(--line); border-radius: 14px; }
table { width: 100%; border-collapse: collapse; font-size: .9rem; background: var(--panel-strong); }
th, td { text-align: start; padding: 11px; border-block-end: 1px solid var(--line); vertical-align: top; }
th { color: var(--muted); font-size: .73rem; text-transform: uppercase; letter-spacing: .06em; }

.notice { padding: 12px 14px; border-radius: var(--radius-sm); background: var(--accent-soft); border: 1px solid var(--accent-line); color: var(--ink); }
.notice.error { background: var(--danger-soft); border-color: color-mix(in srgb, var(--danger) 35%, transparent); color: var(--danger); }
.notice.warn { background: var(--warn-soft); border-color: color-mix(in srgb, var(--warn) 35%, transparent); color: var(--warn); }
.hidden { display: none !important; }
.loading { padding-block: 54px; text-align: center; color: var(--muted); }
.toast { position: fixed; inset-inline: 12px; inset-block-end: calc(86px + env(safe-area-inset-bottom)); z-index: 60; padding: 12px 15px; border-radius: 12px; background: var(--ink); color: var(--panel); box-shadow: var(--shadow); text-align: center; }
pre.code { white-space: pre-wrap; word-break: break-word; background: var(--code-bg); color: var(--code-ink); padding: 13px; border-radius: var(--radius-sm); font-size: .82rem; direction: ltr; text-align: left; }
.feedback-row { display: grid; gap: 11px; }

.dialog { position: fixed; inset: 0; background: var(--overlay); display: grid; place-items: center; padding: 14px; z-index: 70; }
.dialog .card { width: min(620px, 100%); max-height: min(90vh, 760px); overflow: auto; box-shadow: var(--shadow); }
.dialog-heading { display: flex; align-items: center; justify-content: space-between; gap: 1rem; }
.dialog-actions, .dialog-result { margin-block-start: 14px; }
.icon-button { width: 44px; min-width: 44px; padding: 0; font-size: 1.5rem; }
.empty-state { text-align: center; padding-block: 34px; }
.empty-state.compact { padding-block: 18px; }
.empty-state p { max-width: 560px; margin-inline: auto; }
.empty-icon { width: 48px; height: 48px; display: grid; place-items: center; margin-inline: auto; margin-block-end: 12px; border-radius: 50%; background: var(--accent-soft); color: var(--accent); font-size: 1.35rem; }
.rtl, [dir="rtl"] { text-align: start; }
[dir="auto"] { unicode-bidi: plaintext; }

@media (min-width: 560px) {
  .theme-toggle [data-theme-label] { display: inline; }
  .choice-grid { grid-template-columns: repeat(3, minmax(0, 1fr)); }
  .compact-choices { grid-template-columns: repeat(2, minmax(0, 1fr)); }
  .form-actions { flex-direction: row; align-items: center; }
}

@media (min-width: 760px) {
  body.learner-shell { padding-block-end: 0; }
  .container { width: min(1120px, calc(100% - 40px)); }
  .main-content { padding-block: 24px 60px; }
  .topbar-inner { min-height: 66px; }
  .user-name { max-width: 260px; }
  .card { border-radius: var(--radius-lg); padding: 21px; box-shadow: var(--shadow); }
  .grid.two, .form-grid, .feedback-row { grid-template-columns: repeat(2, minmax(0, 1fr)); }
  .grid.three { grid-template-columns: repeat(3, minmax(0, 1fr)); }
  .nav-tabs, .admin-shell .nav-tabs {
    position: sticky;
    inset-block-start: 66px;
    inset-inline: auto;
    inset-block-end: auto;
    z-index: 20;
    display: flex;
    justify-content: flex-start;
    gap: 7px;
    overflow-x: auto;
    margin-block-end: 14px;
    padding: 11px 0;
    background: color-mix(in srgb, var(--bg) 94%, transparent);
    border: 0;
    box-shadow: none;
    backdrop-filter: blur(10px);
  }
  .nav-tabs button, .admin-shell .nav-tabs button { min-height: 42px; flex: 0 0 auto; flex-direction: row; padding: .58rem .88rem; font-size: .84rem; }
  .nav-icon { font-size: .8rem; }
  .toast { inset-inline: auto 22px; inset-block-end: 22px; width: min(360px, calc(100% - 44px)); }
  .lesson-article { padding: 28px; }
}

@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after { scroll-behavior: auto !important; animation-duration: .01ms !important; animation-iteration-count: 1 !important; transition-duration: .01ms !important; }
}