:root {
  /* Neutral ramp (light theme baseline) */
  --neutral-0:  #ffffff;
  --neutral-50: #f7f7f5;
  --neutral-100: #efefec;
  --neutral-200: #e2e2dd;
  --neutral-300: #cfcfc9;
  --neutral-400: #a3a39d;
  --neutral-500: #6e6e68;
  --neutral-600: #4a4a45;
  --neutral-700: #2c2c28;
  --neutral-900: #141412;

  /* Brand */
  --accent: #2f60d8;
  --accent-strong: #1f47a3;
  --accent-soft: #ecf1fc;
  --accent-glow: rgba(47, 96, 216, .25);
  --accent-grad: linear-gradient(135deg, #3a6df0 0%, #6e8ff5 100%);
  --premium-grad: linear-gradient(135deg, #5b3ee0 0%, #2f60d8 100%);

  --green: #1f7a44;
  --green-bg: #e3f4ea;
  --red:   #c43025;
  --red-bg: #fce8e6;
  --amber: #b46900;
  --amber-bg: #fff3cd;

  /* Semantic surfaces (light) */
  --bg:            var(--neutral-50);
  --surface:       var(--neutral-0);
  --surface-raised: var(--neutral-0);
  --surface-sunken: var(--neutral-100);
  --border:        var(--neutral-200);
  --border-strong: var(--neutral-300);
  --text:          var(--neutral-900);
  --text-strong:   var(--neutral-900);
  --muted:         var(--neutral-500);
  --card:          var(--surface);
  --accent-bg:     var(--accent-soft);

  /* Spacing / radius / shadow / type scales */
  --space-1: .25rem;
  --space-2: .5rem;
  --space-3: .75rem;
  --space-4: 1rem;
  --space-5: 1.5rem;
  --space-6: 2rem;

  --radius-sm: .35rem;
  --radius-md: .5rem;
  --radius-lg: .75rem;
  --radius-xl: 1rem;
  --radius-pill: 999px;

  --shadow-sm: 0 1px 2px rgba(20,20,18,.04), 0 1px 1px rgba(20,20,18,.03);
  --shadow-md: 0 4px 12px rgba(20,20,18,.06), 0 1px 3px rgba(20,20,18,.04);
  --shadow-lg: 0 14px 32px rgba(20,20,18,.10), 0 4px 10px rgba(20,20,18,.06);
  --shadow-focus: 0 0 0 3px var(--accent-glow);

  --font-body: -apple-system, BlinkMacSystemFont, "Inter", "Segoe UI", system-ui, sans-serif;
  --font-display: "Inter", -apple-system, BlinkMacSystemFont, "Segoe UI", system-ui, sans-serif;

  --transition-fast: .12s ease;
  --transition-base: .18s ease;
}

[data-theme="dark"] {
  --neutral-0:  #15161a;
  --neutral-50: #1a1c20;
  --neutral-100: #20232a;
  --neutral-200: #2a2e37;
  --neutral-300: #3b414d;
  --neutral-400: #6c7280;
  --neutral-500: #9098a4;
  --neutral-600: #c1c6cf;
  --neutral-700: #e1e4ea;
  --neutral-900: #f3f5f8;

  --accent: #6e8ff5;
  --accent-strong: #94aef9;
  --accent-soft: rgba(110,143,245,.14);
  --accent-glow: rgba(110,143,245,.32);
  --accent-grad: linear-gradient(135deg, #6e8ff5 0%, #94aef9 100%);
  --premium-grad: linear-gradient(135deg, #8b6cff 0%, #6e8ff5 100%);

  --green: #4cc581;
  --green-bg: rgba(76,197,129,.14);
  --red:   #ef6b62;
  --red-bg: rgba(239,107,98,.14);
  --amber: #e9b35a;
  --amber-bg: rgba(233,179,90,.14);

  --bg:            #0f1115;
  --surface:       #181a20;
  --surface-raised: #1f222a;
  --surface-sunken: #14161b;
  --border:        #2a2e37;
  --border-strong: #3b414d;
  --text:          var(--neutral-900);
  --text-strong:   var(--neutral-900);
  --muted:         var(--neutral-500);
  --card:          var(--surface);
  --accent-bg:     var(--accent-soft);

  --shadow-sm: 0 1px 2px rgba(0,0,0,.4), 0 1px 1px rgba(0,0,0,.3);
  --shadow-md: 0 4px 14px rgba(0,0,0,.45), 0 1px 3px rgba(0,0,0,.35);
  --shadow-lg: 0 16px 36px rgba(0,0,0,.55), 0 4px 10px rgba(0,0,0,.4);
}

* { box-sizing: border-box; }
html, body { min-height: 100%; }
body {
  margin: 0;
  font-family: var(--font-body);
  background: var(--bg);
  color: var(--text);
  line-height: 1.55;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  transition: background-color .25s ease, color .25s ease;
}

/* Focus ring for keyboard users */
:where(button, a, input, select, textarea, [tabindex]):focus-visible {
  outline: none;
  box-shadow: var(--shadow-focus);
  border-radius: var(--radius-sm);
}

/* Particle background canvas */
#bg-canvas {
  position: fixed;
  inset: 0;
  width: 100%;
  height: 100%;
  z-index: -1;
  pointer-events: none;
  opacity: .55;
}
[data-theme="dark"] #bg-canvas { opacity: .42; }
@media (prefers-reduced-motion: reduce) {
  #bg-canvas { display: none; }
}

/* Shared spinner */
.spinner {
  display: inline-block;
  width: 1rem; height: 1rem;
  border: 2px solid var(--border);
  border-top-color: var(--accent);
  border-radius: 50%;
  animation: spin .7s linear infinite;
  vertical-align: -.2em;
}
@keyframes spin { to { transform: rotate(360deg); } }

/* Unified button base */
.btn {
  display: inline-flex; align-items: center; justify-content: center;
  gap: .4rem;
  padding: .55rem 1.1rem;
  border: 1px solid transparent;
  border-radius: var(--radius-md);
  background: var(--surface-sunken);
  color: var(--text);
  font: inherit; font-size: .92rem; font-weight: 500;
  cursor: pointer;
  transition: background var(--transition-fast), border-color var(--transition-fast),
              color var(--transition-fast), transform var(--transition-fast),
              box-shadow var(--transition-fast);
}
.btn:hover:not(:disabled) { border-color: var(--border-strong); }
.btn:active:not(:disabled) { transform: translateY(1px); }
.btn:disabled { opacity: .55; cursor: not-allowed; }
.btn--primary {
  background: var(--accent-grad);
  color: #fff;
  border-color: transparent;
  box-shadow: 0 1px 2px rgba(47,96,216,.25);
}
.btn--primary:hover:not(:disabled) {
  filter: brightness(1.06);
  box-shadow: 0 3px 10px rgba(47,96,216,.32);
}
.btn--ghost {
  background: transparent;
  border-color: var(--border);
  color: var(--text);
}
.btn--ghost:hover:not(:disabled) { border-color: var(--accent); color: var(--accent); }
.btn--sm { padding: .35rem .75rem; font-size: .82rem; }

/* ── Top bar ─────────────────────────────────────────────────────────────── */
#topbar {
  display: flex;
  align-items: center;
  gap: 1.25rem;
  padding: .7rem 1.25rem;
  background: var(--surface);
  border-bottom: 1px solid var(--border);
  backdrop-filter: saturate(180%) blur(6px);
  position: sticky; top: 0; z-index: 50;
}
#topbar h1 {
  margin: 0;
  font-size: 1.15rem;
  font-weight: 700;
  letter-spacing: -.01em;
  white-space: nowrap;
  font-family: var(--font-display);
  background: var(--accent-grad);
  -webkit-background-clip: text;
  background-clip: text;
  color: transparent;
}
#topbar h1 a { color: inherit; text-decoration: none; }
#main-tabs { display: flex; gap: .35rem; flex-wrap: wrap; }
.main-tab {
  padding: .45rem 1rem;
  border: 1px solid transparent;
  border-radius: var(--radius-md);
  background: transparent;
  font: inherit;
  font-size: .9rem;
  font-weight: 500;
  cursor: pointer;
  color: var(--muted);
  text-decoration: none;
  transition: background var(--transition-fast), color var(--transition-fast), border-color var(--transition-fast);
}
.main-tab:hover { color: var(--text); background: var(--surface-sunken); }
.main-tab.active {
  background: var(--accent-soft);
  color: var(--accent);
  font-weight: 600;
}

/* Hamburger button — visible on small screens only */
#nav-toggle {
  display: none;
  width: 2.4rem; height: 2.4rem;
  align-items: center; justify-content: center;
  background: transparent;
  border: 1px solid var(--border);
  border-radius: var(--radius-md);
  color: var(--text);
  cursor: pointer;
  margin-left: auto;
}
#nav-toggle:hover { border-color: var(--accent); color: var(--accent); }
#nav-toggle svg { width: 1.1rem; height: 1.1rem; }

/* Mini theme toggle in topbar (icon only) */
.theme-toggle {
  width: 2.2rem; height: 2.2rem;
  display: inline-flex; align-items: center; justify-content: center;
  background: transparent;
  border: 1px solid var(--border);
  border-radius: var(--radius-md);
  cursor: pointer;
  color: var(--muted);
  margin-left: auto;
  flex-shrink: 0;
  transition: border-color var(--transition-fast), color var(--transition-fast);
}
.theme-toggle:hover { border-color: var(--accent); color: var(--accent); }
.theme-toggle svg { width: 1rem; height: 1rem; }
.theme-toggle .sun  { display: none; }
.theme-toggle .moon { display: block; }
[data-theme="dark"] .theme-toggle .sun  { display: block; }
[data-theme="dark"] .theme-toggle .moon { display: none; }

/* ── Subject sub-tabs ────────────────────────────────────────────────────── */
#subject-tabs {
  display: flex;
  flex-wrap: wrap;
  gap: .375rem;
  padding: .75rem 1.25rem;
  background: var(--card);
  border-bottom: 1px solid var(--border);
}
.subject-tab {
  padding: .35rem .85rem;
  border: 1px solid var(--border);
  border-radius: 999px;
  background: var(--bg);
  font: inherit;
  font-size: .85rem;
  cursor: pointer;
  color: var(--muted);
  transition: background .15s, border-color .15s, color .15s;
}
.subject-tab:hover { border-color: var(--accent); color: var(--accent); }
.subject-tab.active {
  background: var(--accent-bg);
  border-color: var(--accent);
  color: var(--accent);
  font-weight: 600;
}

/* ── Guide content area ──────────────────────────────────────────────────── */
#guide-body {
  max-width: 820px;
  margin: 0 auto;
  padding: 1.5rem 1.25rem 3rem;
}
#guide-content {
  background: var(--card);
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  padding: 1.75rem 2rem;
  box-shadow: var(--shadow-sm);
}
/* Markdown rendered content */
#guide-content h1 { font-size: 1.5rem; margin-top: 0; border-bottom: 2px solid var(--border); padding-bottom: .5rem; }
#guide-content h2 { font-size: 1.15rem; margin-top: 2rem; color: var(--accent); }
#guide-content h3 { font-size: 1rem; margin-top: 1.25rem; }
#guide-content p  { margin: .5rem 0; }
#guide-content ul, #guide-content ol { padding-left: 1.5rem; margin: .5rem 0; }
#guide-content li { margin: .25rem 0; }
#guide-content table {
  border-collapse: collapse;
  width: 100%;
  margin: 1rem 0;
  font-size: .9rem;
}
#guide-content th, #guide-content td {
  border: 1px solid var(--border);
  padding: .4rem .75rem;
  text-align: left;
}
#guide-content th { background: var(--bg); font-weight: 600; }
#guide-content code {
  background: var(--bg);
  padding: .1rem .35rem;
  border-radius: .25rem;
  font-size: .9em;
}
#guide-content hr { border: none; border-top: 1px solid var(--border); margin: 1.5rem 0; }
#guide-content strong { color: var(--text); }
/* Anchor highlight flash */
.guide-highlight {
  outline: 2px solid var(--accent);
  border-radius: .25rem;
  background: var(--accent-bg) !important;
  transition: background .3s;
}
.guide-loading, .guide-error { color: var(--muted); padding: 1rem 0; }

/* ── Section review test ─────────────────────────────────────────────────── */
#guide-test {
  margin-top: 2rem;
  border-top: 2px solid var(--border);
  padding-top: 1.5rem;
}
.test-heading { margin: 0 0 .25rem; font-size: 1.2rem; }
.test-subhead  { margin: 0 0 1.5rem; font-size: .85rem; color: var(--muted); }
.sq-block {
  background: var(--card);
  border: 1px solid var(--border);
  border-radius: .75rem;
  padding: 1.25rem 1.5rem;
  margin-bottom: 1rem;
}
.sq-num      { margin: 0 0 .25rem; font-size: .78rem; color: var(--muted); font-weight: 600; text-transform: uppercase; letter-spacing: .05em; }
.sq-question { margin: 0 0 .9rem; font-size: 1rem; font-weight: 500; }
.sq-options  { list-style: none; padding: 0; margin: 0 0 .75rem; display: flex; flex-direction: column; gap: .4rem; }
.sq-btn {
  width: 100%;
  text-align: left;
  padding: .65rem .9rem;
  background: var(--card);
  border: 1px solid var(--border);
  border-radius: .45rem;
  font: inherit;
  font-size: .95rem;
  color: var(--text);
  cursor: pointer;
  transition: border-color .15s, background .15s;
}
.sq-btn:hover:not(:disabled) { border-color: var(--accent); background: var(--accent-bg); }
.sq-btn:disabled { cursor: default; }
.sq-btn.sq-correct   { background: var(--green-bg); border-color: var(--green); font-weight: 600; }
.sq-btn.sq-incorrect { background: var(--red-bg);   border-color: var(--red); }
.sq-explain {
  padding: .35rem .85rem;
  background: var(--accent-bg);
  border: 1px solid var(--accent);
  border-radius: .4rem;
  font: inherit;
  font-size: .82rem;
  color: var(--accent);
  cursor: pointer;
  font-weight: 600;
}
.sq-explain:hover { background: var(--accent); color: #fff; }
.hidden { display: none; }

/* ── Practice test header ────────────────────────────────────────────────── */
#practice-view header {
  padding: 1rem 1.25rem;
  border-bottom: 1px solid var(--border);
  background: var(--card);
}
fieldset {
  border: 1px solid var(--border);
  border-radius: .5rem;
  padding: .5rem .75rem .75rem;
}
legend { font-size: .8rem; color: var(--muted); padding: 0 .25rem; }
#source-filter  { margin-bottom: .75rem; }
#set-toggles    { display: flex; flex-wrap: wrap; gap: .5rem .75rem; margin-bottom: .5rem; }
#set-toggles label { display: inline-flex; align-items: center; gap: .35rem; font-size: .9rem; cursor: pointer; }
.set-note       { font-size: .8rem; color: var(--muted); }
#difficulty-filter {
  display: flex; align-items: center; flex-wrap: wrap; gap: .5rem .75rem; margin-top: .25rem;
}
.diff-label { font-size: .85rem; color: var(--muted); }
#difficulty-filter label { display: inline-flex; align-items: center; gap: .35rem; font-size: .9rem; cursor: pointer; }
.diff-badge {
  display: inline-block; font-size: .68rem; font-weight: 700;
  padding: .1rem .45rem; border-radius: 999px;
  text-transform: uppercase; letter-spacing: .04em; vertical-align: middle;
}
.diff-easy   { background: var(--green-bg); color: var(--green); }
.diff-medium { background: #fff3cd; color: #7a5c00; }
.diff-hard   { background: var(--red-bg); color: var(--red); }
#categories label {
  display: inline-flex; align-items: center; gap: .35rem;
  margin: .25rem .75rem .25rem 0; font-size: .9rem; cursor: pointer;
}

/* ── Quiz area ───────────────────────────────────────────────────────────── */
main {
  max-width: 720px;
  margin: 1.5rem auto;
  padding: 1.5rem;
  background: var(--card);
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow-sm);
}
#meta    { color: var(--muted); font-size: .85rem; margin-bottom: .75rem; }
#question { font-size: 1.1rem; margin-bottom: 1rem; white-space: pre-wrap; }
#options  { list-style: none; padding: 0; margin: 0 0 1rem; display: flex; flex-direction: column; gap: .5rem; }
#options button {
  width: 100%; text-align: left; padding: .75rem 1rem;
  background: var(--card); border: 1px solid var(--border); border-radius: .5rem;
  font: inherit; color: var(--text); cursor: pointer; transition: background .15s, border-color .15s;
}
#options button:hover:not(:disabled) { border-color: var(--accent); }
#options button:disabled { cursor: default; }
#options button.correct   { background: var(--green-bg); border-color: var(--green); }
#options button.incorrect { background: var(--red-bg);   border-color: var(--red); }
#feedback { font-weight: 600; margin-bottom: 1rem; min-height: 1.25rem; }
#feedback.correct   { color: var(--green); }
#feedback.incorrect { color: var(--red); }
#next {
  padding: .6rem 1.25rem;
  background: var(--accent); color: #fff;
  border: 0; border-radius: .5rem; font: inherit; cursor: pointer;
}
#next:hover { filter: brightness(1.05); }
#empty { color: var(--muted); }

/* ── AI Tutor ────────────────────────────────────────────────────────────── */
#tutor-view {
  max-width: 760px;
  margin: 0 auto;
  padding: 1.5rem 1.25rem 3rem;
}
#tutor-container {
  background: var(--card);
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  padding: 2rem;
  box-shadow: var(--shadow-md);
}
.tutor-heading { margin: 0 0 .4rem; font-size: 1.3rem; }
.tutor-subhead  { margin: 0 0 1.5rem; color: var(--text); font-size: .9rem; line-height: 1.5; }
.tutor-label  { display: block; font-size: .85rem; font-weight: 600; margin-bottom: .35rem; color: var(--text); }
.tutor-input, .tutor-select {
  width: 100%; padding: .6rem .8rem; margin-bottom: 1rem;
  border: 1px solid var(--border); border-radius: .45rem;
  font: inherit; font-size: .95rem; background: var(--bg);
  color: var(--text);
  transition: border-color .15s;
}
.tutor-select option { background: var(--surface); color: var(--text); }
.tutor-input:focus, .tutor-select:focus { outline: none; border-color: var(--accent); }
.tutor-hint { font-size: .8rem; color: var(--muted); margin: 0 0 .6rem; text-align: center; }
.tutor-hint a, .tutor-hint strong { color: var(--accent); font-weight: 600; }
.tutor-hint-above { margin: .25rem 0 .5rem; }
.tutor-btn-primary {
  padding: .6rem 1.4rem;
  background: var(--accent); color: #fff;
  border: 0; border-radius: .5rem; font: inherit; font-size: .95rem;
  cursor: pointer; transition: filter .15s;
  display: block; width: 100%; margin-top: .5rem;
}
.tutor-btn-primary:hover:not(:disabled) { filter: brightness(1.08); }
.tutor-btn-primary:disabled { opacity: .5; cursor: default; }
.tutor-btn-sm {
  padding: .3rem .75rem;
  background: var(--bg); color: var(--muted);
  border: 1px solid var(--border); border-radius: .4rem;
  font: inherit; font-size: .82rem; cursor: pointer;
}
.tutor-btn-sm:hover { border-color: var(--accent); color: var(--accent); }

/* Chat header */
#tutor-chat-header {
  display: flex; align-items: center; justify-content: space-between;
  margin-bottom: .75rem; padding-bottom: .75rem;
  border-bottom: 1px solid var(--border);
}
#tutor-session-label { font-weight: 600; font-size: .95rem; }

/* Chat box */
#tutor-chat {
  min-height: 200px;
  max-height: 480px;
  overflow-y: auto;
  display: flex;
  flex-direction: column;
  gap: .75rem;
  margin-bottom: 1rem;
  padding: .25rem 0;
}
.tutor-msg { display: flex; }
.tutor-msg-user    { justify-content: flex-end; }
.tutor-msg-assistant { justify-content: flex-start; }
.tutor-msg .msg-text {
  max-width: 85%;
  padding: .65rem .9rem;
  border-radius: .65rem;
  font-size: .95rem;
  line-height: 1.55;
  white-space: pre-wrap;
}
.tutor-msg-user .msg-text {
  background: var(--accent); color: #fff;
  border-bottom-right-radius: .15rem;
}
.tutor-msg-assistant .msg-text {
  background: var(--surface-sunken); border: 1px solid var(--border);
  border-bottom-left-radius: .15rem;
}

/* Thinking-bubble dots */
.tutor-thinking {
  display: inline-flex; gap: .25rem; align-items: center;
  padding: .15rem .2rem;
}
.tutor-thinking .dot {
  width: .42rem; height: .42rem; border-radius: 50%;
  background: var(--muted);
  animation: tutor-think 1.1s ease-in-out infinite;
}
.tutor-thinking .dot:nth-child(2) { animation-delay: .15s; }
.tutor-thinking .dot:nth-child(3) { animation-delay: .3s; }
@keyframes tutor-think {
  0%, 60%, 100% { opacity: .25; transform: translateY(0); }
  30% { opacity: 1; transform: translateY(-2px); }
}
@media (prefers-reduced-motion: reduce) {
  .tutor-thinking .dot { animation: none; opacity: .55; }
}

/* Input row */
#tutor-input-row {
  display: flex; gap: .5rem; align-items: flex-end;
}
.tutor-textarea {
  flex: 1; padding: .6rem .8rem; resize: none;
  border: 1px solid var(--border); border-radius: .45rem;
  font: inherit; font-size: .95rem; background: var(--bg);
  color: var(--text);
  transition: border-color .15s;
}
.tutor-textarea:focus { outline: none; border-color: var(--accent); }
#tutor-send {
  flex-shrink: 0; width: auto;
  padding: .6rem 1.2rem;
}

/* ── Tutor gate / premium prompt ─────────────────────────────────────────── */
#tutor-gate { margin-bottom: 1rem; }
.tutor-gate-msg {
  margin: 0;
  padding: .75rem 1rem;
  background: var(--accent-bg);
  border: 1px solid var(--accent);
  border-radius: .5rem;
  display: flex;
  align-items: center;
  gap: .75rem;
  flex-wrap: wrap;
  font-size: .9rem;
}
.tutor-gate-action {
  padding: .35rem .85rem;
  background: var(--accent); color: #fff;
  border: 0; border-radius: .4rem;
  font: inherit; font-size: .85rem;
  cursor: pointer; white-space: nowrap;
}
.tutor-gate-action:hover { filter: brightness(1.08); }

/* ── Session score overlay ───────────────────────────────────────────────── */
.score-overlay {
  position: absolute; inset: 0;
  background: rgba(255,255,255,.95);
  color: #1a1a1a;
  display: flex; align-items: flex-start; justify-content: center;
  padding: 2rem 1rem;
  border-radius: .75rem;
  overflow-y: auto;
}
#tutor-container { position: relative; }
.score-card { width: 100%; max-width: 480px; }
.score-title {
  margin: 0 0 .75rem; font-size: 1.15rem;
  border-bottom: 1px solid var(--border); padding-bottom: .5rem;
}
.score-overall { font-size: 1.05rem; margin-bottom: .75rem; }
.score-table {
  width: 100%; border-collapse: collapse;
  margin-bottom: .75rem; font-size: .9rem;
}
.score-table td { padding: .35rem .5rem; border-bottom: 1px solid var(--border); }
.score-icon { width: 1.5rem; text-align: center; }
.score-strong     { color: var(--green); font-weight: 600; }
.score-developing { color: #7a5c00; font-weight: 600; }
.score-weak       { color: var(--red); font-weight: 600; }
.score-summary { margin: .5rem 0; font-size: .9rem; }
.score-focus   { margin: .5rem 0 1rem; font-size: .9rem; }
.score-done-btn { margin-top: .5rem; }

/* ── Account top-bar button ──────────────────────────────────────────────── */
#account-btn-area { flex-shrink: 0; }
.acct-topbar-btn {
  padding: .38rem .9rem;
  border: 1px solid var(--border);
  border-radius: .5rem;
  background: var(--bg);
  font: inherit; font-size: .88rem;
  cursor: pointer; color: var(--text);
  transition: border-color .15s;
}
.acct-topbar-btn:hover { border-color: var(--accent); }
.acct-topbar-user { display: inline-flex; align-items: center; gap: .45rem; }
.acct-premium-badge {
  font-size: .72rem; font-weight: 700; text-transform: uppercase;
  letter-spacing: .04em; padding: .12rem .5rem;
  background: var(--premium-grad); color: #fff; border-radius: var(--radius-pill);
  box-shadow: 0 1px 3px rgba(91,62,224,.35);
}

/* ── Modal overlay ───────────────────────────────────────────────────────── */
#acct-overlay {
  position: fixed; inset: 0; z-index: 1000;
  background: rgba(0,0,0,.45);
  display: flex; align-items: flex-start; justify-content: center;
  padding: 3rem 1rem 2rem;
  overflow-y: auto;
}
#acct-overlay[hidden] { display: none; }
#acct-modal {
  position: relative;
  background: var(--card);
  border: 1px solid var(--border);
  border-radius: .85rem;
  padding: 2rem;
  width: 100%; max-width: 420px;
  box-shadow: 0 8px 32px rgba(0,0,0,.15);
}
.acct-close {
  position: absolute; top: .85rem; right: .85rem;
  width: 2rem; height: 2rem;
  background: none; border: none;
  font-size: 1.4rem; line-height: 1; color: var(--muted);
  cursor: pointer; border-radius: .3rem;
  display: flex; align-items: center; justify-content: center;
}
.acct-close:hover { background: var(--bg); color: var(--text); }
.acct-modal-title { margin: 0 0 1.25rem; font-size: 1.2rem; }

/* ── Form fields ─────────────────────────────────────────────────────────── */
.acct-field { margin-bottom: .85rem; }
.acct-field label {
  display: block; font-size: .83rem; font-weight: 600;
  margin-bottom: .3rem; color: var(--text);
}
.acct-optional { font-weight: 400; color: var(--muted); }
.acct-field input {
  width: 100%; padding: .55rem .75rem;
  border: 1px solid var(--border); border-radius: .45rem;
  font: inherit; font-size: .95rem; background: var(--bg);
  color: var(--text);
  transition: border-color .15s;
}
.acct-field input:focus { outline: none; border-color: var(--accent); }
.acct-error {
  margin-bottom: .75rem; padding: .5rem .75rem;
  background: var(--red-bg); color: var(--red);
  border-radius: .4rem; font-size: .85rem;
}
.acct-btn-primary {
  width: 100%; padding: .6rem;
  background: var(--accent); color: #fff;
  border: 0; border-radius: .5rem;
  font: inherit; font-size: .95rem; font-weight: 600;
  cursor: pointer; transition: filter .15s;
}
.acct-btn-primary:hover:not(:disabled) { filter: brightness(1.08); }
.acct-btn-primary:disabled { opacity: .55; cursor: default; }
.acct-btn-sm {
  padding: .3rem .7rem;
  background: var(--bg); color: var(--muted);
  border: 1px solid var(--border); border-radius: .4rem;
  font: inherit; font-size: .82rem; cursor: pointer; white-space: nowrap;
}
.acct-btn-sm:hover { border-color: var(--accent); color: var(--accent); }
.acct-btn-upgrade {
  padding: .45rem 1rem;
  background: var(--accent); color: #fff;
  border: 0; border-radius: .5rem;
  font: inherit; font-size: .88rem; font-weight: 600;
  cursor: pointer; transition: filter .15s; white-space: nowrap;
}
.acct-btn-upgrade:hover:not(:disabled) { filter: brightness(1.08); }
.acct-btn-upgrade:disabled { opacity: .55; cursor: default; }

/* ── Google button ───────────────────────────────────────────────────────── */
.acct-divider {
  display: flex; align-items: center; gap: .75rem;
  margin: .85rem 0; color: var(--muted); font-size: .82rem;
}
.acct-divider::before, .acct-divider::after {
  content: ''; flex: 1; height: 1px; background: var(--border);
}
.acct-google-btn {
  display: flex; align-items: center; justify-content: center; gap: .5rem;
  width: 100%; padding: .55rem;
  border: 1px solid var(--border); border-radius: .5rem;
  background: var(--card); color: var(--text);
  font: inherit; font-size: .9rem; text-decoration: none;
  transition: border-color .15s, background .15s;
}
.acct-google-btn:hover { border-color: var(--accent); background: var(--accent-bg); }
.acct-switch { margin: .85rem 0 0; font-size: .85rem; color: var(--muted); text-align: center; }
.acct-switch a { color: var(--accent); }

/* ── Profile panel ───────────────────────────────────────────────────────── */
.acct-profile-header {
  display: flex; align-items: flex-start; justify-content: space-between;
  gap: 1rem; margin-bottom: 1.25rem;
  padding-bottom: 1rem; border-bottom: 1px solid var(--border);
}
.acct-profile-email { margin: .2rem 0 0; font-size: .85rem; color: var(--muted); }
.acct-section { margin-bottom: 1.25rem; }
.acct-section-title {
  margin: 0 0 .6rem; font-weight: 600;
  text-transform: uppercase; letter-spacing: .04em;
  font-size: .78rem; color: var(--muted);
}
.acct-billing-row {
  display: flex; align-items: center; gap: .75rem; flex-wrap: wrap;
  padding: .75rem; background: var(--bg); border-radius: .5rem;
  margin-bottom: .5rem;
}
.acct-premium-badge-lg {
  font-size: .8rem; font-weight: 700; text-transform: uppercase;
  letter-spacing: .04em; padding: .22rem .65rem;
  background: var(--premium-grad); color: #fff; border-radius: var(--radius-pill);
  box-shadow: 0 1px 3px rgba(91,62,224,.35);
}
.acct-free-label { font-size: .9rem; color: var(--muted); }
.acct-upgrade-note { margin: 0; font-size: .82rem; color: var(--muted); }
.acct-overall { margin: 0 0 .5rem; font-size: .9rem; }
.acct-stats-table { width: 100%; border-collapse: collapse; font-size: .85rem; }
.acct-stats-table th, .acct-stats-table td {
  padding: .35rem .5rem; text-align: left;
  border-bottom: 1px solid var(--border);
}
.acct-stats-table th {
  font-size: .78rem; color: var(--muted);
  font-weight: 600; background: var(--bg);
}
.acct-session-item { padding: .65rem 0; border-bottom: 1px solid var(--border); }
.acct-session-item:last-child { border-bottom: none; }
.acct-session-meta { display: flex; align-items: baseline; gap: .5rem; flex-wrap: wrap; }
.acct-session-date { font-size: .82rem; color: var(--muted); }
.acct-session-summary { margin: .3rem 0 .4rem; font-size: .85rem; }
.acct-concepts { display: flex; flex-wrap: wrap; gap: .3rem; margin-top: .35rem; }
.acct-concept {
  font-size: .75rem; font-weight: 600;
  padding: .1rem .45rem; border-radius: 999px;
}
.acct-concept.score-strong    { background: var(--green-bg); color: var(--green); }
.acct-concept.score-developing { background: #fff3cd; color: #7a5c00; }
.acct-concept.score-weak      { background: var(--red-bg);  color: var(--red); }
.acct-empty, .acct-loading { margin: 0; font-size: .88rem; color: var(--muted); }

/* Theme picker (segmented control) */
.acct-theme-row {
  display: inline-flex;
  background: var(--surface-sunken);
  border: 1px solid var(--border);
  border-radius: var(--radius-md);
  padding: .2rem;
  gap: .15rem;
}
.acct-theme-opt {
  appearance: none;
  background: transparent;
  border: 0;
  padding: .45rem .9rem;
  font: inherit; font-size: .85rem; font-weight: 500;
  color: var(--muted);
  border-radius: var(--radius-sm);
  cursor: pointer;
  transition: background var(--transition-fast), color var(--transition-fast);
}
.acct-theme-opt:hover { color: var(--text); }
.acct-theme-opt.is-active {
  background: var(--surface);
  color: var(--accent);
  font-weight: 600;
  box-shadow: var(--shadow-sm);
}

/* ── Toast notifications ─────────────────────────────────────────────────── */
.acct-toast {
  position: fixed; bottom: 1.5rem; left: 50%;
  transform: translateX(-50%) translateY(1rem);
  padding: .75rem 1.25rem; border-radius: var(--radius-md);
  font-size: .92rem; font-weight: 500; z-index: 2000;
  opacity: 0; transition: opacity .3s, transform .3s;
  pointer-events: none;
  max-width: min(92vw, 480px);
  text-align: center;
  box-shadow: var(--shadow-lg);
}
.acct-toast-show { opacity: 1; transform: translateX(-50%) translateY(0); }
.acct-toast-success { background: var(--green); color: #fff; }
.acct-toast-error   { background: var(--red);   color: #fff; }
.acct-toast-info    { background: var(--accent); color: #fff; }

/* Crawlable study pages (server-rendered) */
.study-page-body { background: var(--bg); color: var(--text); }
.study-page-main { max-width: 820px; margin: 0 auto; padding: 1.5rem 1rem; }
.study-home-link { color: inherit; text-decoration: none; }
.study-breadcrumbs { color: var(--muted); font-size: .9rem; margin-bottom: 1rem; }
.study-breadcrumbs a { color: var(--accent); text-decoration: none; }
.study-breadcrumbs a:hover { text-decoration: underline; }
.study-body { line-height: 1.65; }
.study-body h2 { margin-top: 1.6rem; }
.study-body pre, .study-body code { background: var(--card); border: 1px solid var(--border); padding: .15rem .35rem; border-radius: .25rem; }
.study-body pre { padding: .6rem .8rem; overflow-x: auto; }
.study-ctas { display: flex; gap: .6rem; margin: 1.5rem 0; flex-wrap: wrap; }
.study-ctas a { text-decoration: none; }
.study-concept-heading { font-size: 1.1rem; margin-top: 1.5rem; }
.study-concept-list { padding-left: 1.2rem; line-height: 1.8; }
.study-concept-list a { color: var(--accent); text-decoration: none; }
.study-concept-list a:hover { text-decoration: underline; }

/* PiCAT simulation */
#sim-container { max-width: 820px; margin: 0 auto; padding: 1rem; }
.sim-heading { margin: 0 0 .5rem; }
.sim-subhead { color: var(--text); margin: 0 0 1rem; }
.sim-section-list { padding-left: 1.2rem; line-height: 1.7; }
.sim-note { color: var(--muted); font-size: .9rem; margin: .8rem 0 1.2rem; }
#sim-active-header {
  display: flex; align-items: center; gap: 1rem;
  padding: .6rem .8rem; margin-bottom: 1rem;
  background: var(--card); border: 1px solid var(--border); border-radius: .5rem;
}
#sim-active-header > span { font-weight: 600; }
.sim-timer { margin-left: auto; font-variant-numeric: tabular-nums; padding: .2rem .55rem; border-radius: var(--radius-sm); background: var(--accent-bg); color: var(--accent); font-weight: 600; }
.sim-timer-warning { background: var(--red-bg); color: var(--red); animation: sim-pulse 1s ease-in-out infinite; }
@keyframes sim-pulse {
  0%, 100% { transform: scale(1); box-shadow: 0 0 0 0 rgba(196,48,37,0); }
  50%      { transform: scale(1.04); box-shadow: 0 0 0 6px rgba(196,48,37,.12); }
}
@media (prefers-reduced-motion: reduce) {
  .sim-timer-warning { animation: none; }
}
#sim-question { font-size: 1.05rem; margin-bottom: .8rem; white-space: pre-wrap; }
#sim-options { list-style: none; padding: 0; margin: 0; }
#sim-options li { margin: .4rem 0; }
.sim-option {
  display: block; width: 100%; text-align: left;
  padding: .55rem .75rem; border: 1px solid var(--border);
  border-radius: .4rem; background: var(--bg); color: var(--text);
  font: inherit; cursor: pointer;
}
.sim-option:hover { border-color: var(--accent); }
.sim-option.selected { background: var(--accent-bg); border-color: var(--accent); color: var(--accent); }
#sim-controls { margin-top: 1rem; text-align: right; }
.sim-afqt { font-size: 1.1rem; margin: .8rem 0 1rem; }
.sim-afqt-note { color: var(--muted); font-weight: normal; font-size: .85rem; }
.sim-result-table { width: 100%; border-collapse: collapse; margin-bottom: 1rem; }
.sim-result-table th, .sim-result-table td { padding: .5rem .6rem; border-bottom: 1px solid var(--border); text-align: left; }
.sim-result-weak { background: var(--red-bg); }
.sim-result-actions { display: flex; gap: .6rem; }

/* Tutor multiple-choice question card */
.tutor-question-card {
  background: var(--card);
  border: 1px solid var(--border);
  border-radius: .5rem;
  padding: .8rem;
  margin: .4rem 0;
}
.tutor-question-prompt {
  font-weight: 600;
  margin-bottom: .6rem;
  white-space: pre-wrap;
}
.tutor-question-option {
  display: block;
  width: 100%;
  text-align: left;
  padding: .55rem .75rem;
  margin: .3rem 0;
  border: 1px solid var(--border);
  border-radius: .4rem;
  background: var(--bg);
  color: var(--text);
  font: inherit;
  cursor: pointer;
  white-space: pre-wrap;
}
.tutor-question-option:hover:not(:disabled) { border-color: var(--accent); }
.tutor-question-option:disabled { cursor: default; }
.tutor-question-option.chosen-correct {
  background: var(--green-bg); border-color: var(--green); color: var(--green);
}
.tutor-question-option.chosen-wrong {
  background: var(--red-bg); border-color: var(--red); color: var(--red);
}
.tutor-question-option.disabled-correct {
  background: var(--green-bg); border-color: var(--green);
}
.tutor-question-loading {
  font-style: italic;
  color: var(--muted);
  padding: .4rem 0;
}

/* ── Home view ────────────────────────────────────────────────────────── */
#home-view {
  max-width: 960px;
  margin: 0 auto;
  padding: 1.5rem 1.25rem 3rem;
}
.home-hero {
  position: relative;
  isolation: isolate;
  background: var(--card);
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  padding: 1.75rem 1.75rem 1.5rem;
  margin-bottom: 1.5rem;
  box-shadow: var(--shadow-md);
  overflow: hidden;
}
.home-hero > * { position: relative; z-index: 1; }
.home-hero::before, .home-hero::after { z-index: 0; }
.home-hero::before {
  content: '';
  position: absolute;
  inset: 0 auto 0 0;
  width: 5px;
  background: var(--accent-grad);
}
.home-hero::after {
  content: '';
  position: absolute;
  top: -40%; right: -20%;
  width: 360px; height: 360px;
  background: radial-gradient(circle at center, var(--accent-soft), transparent 65%);
  pointer-events: none;
}
.home-hero h2 {
  font-family: var(--font-display);
  letter-spacing: -.015em;
  font-weight: 700;
}
.home-hero h2 {
  margin: 0 0 .5rem;
  font-size: 1.75rem;
}
.home-lede {
  margin: 0 0 .75rem;
  font-size: 1.05rem;
  color: var(--text);
}
.home-free-note {
  margin: 0;
  padding: .75rem 1rem;
  background: var(--accent-bg);
  border-left: 3px solid var(--accent);
  border-radius: 4px;
  color: var(--text);
  font-size: .95rem;
}
.home-features {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
  gap: 1rem;
}
.home-card {
  background: var(--card);
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  padding: 1.35rem;
  display: flex;
  flex-direction: column;
  box-shadow: var(--shadow-sm);
  transition: transform var(--transition-base), box-shadow var(--transition-base), border-color var(--transition-base);
}
.home-card:hover {
  transform: translateY(-2px);
  box-shadow: var(--shadow-md);
  border-color: var(--border-strong);
}
.home-card h3 {
  margin: 0 0 .5rem;
  font-size: 1.2rem;
  display: flex;
  align-items: center;
  gap: .5rem;
}
.home-card-tag {
  font-size: .7rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: .04em;
  background: var(--premium-grad);
  color: #fff;
  padding: .15rem .5rem;
  border-radius: var(--radius-pill);
  box-shadow: 0 1px 3px rgba(91,62,224,.3);
}
.home-card p {
  margin: 0 0 1rem;
  color: var(--text);
  font-size: .95rem;
  line-height: 1.5;
  flex: 1;
}
.home-cta {
  align-self: flex-start;
  padding: .55rem 1rem;
  border: 1px solid var(--accent);
  border-radius: 6px;
  background: var(--accent);
  color: #fff;
  font-size: .95rem;
  font-weight: 500;
  cursor: pointer;
  transition: background .15s, color .15s;
}
.home-cta:hover {
  background: #1f47a3;
  border-color: #1f47a3;
}

/* ── Credit panel (inside profile modal) ─────────────────────────────── */
.acct-credit-row {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1rem;
}
.acct-credit-totals { display: flex; flex-direction: column; gap: .15rem; }
.acct-credit-total {
  font-size: 1.5rem;
  font-weight: 700;
  color: var(--text);
}
.acct-credit-split {
  display: flex;
  gap: .4rem;
  font-size: .8rem;
  color: var(--muted);
}
.acct-credit-note {
  margin: .5rem 0 0;
  font-size: .8rem;
  color: var(--muted);
}

/* ── Model picker ────────────────────────────────────────────────────── */
.tutor-model-note {
  margin: .25rem 0 1rem;
  font-size: .85rem;
  color: var(--text);
  font-style: italic;
}

/* ── Session-cost meter in chat header ───────────────────────────────── */
.tutor-session-cost {
  font-size: .8rem;
  color: var(--muted);
  margin-right: auto;
  margin-left: 1rem;
}
.tutor-session-cost-warn { color: #b46900; font-weight: 600; }
.tutor-session-cost-cap  { color: var(--red); font-weight: 700; }

.tutor-cap-note {
  margin: 1rem 0;
  padding: .75rem 1rem;
  background: var(--red-bg);
  border-left: 3px solid var(--red);
  border-radius: 4px;
  color: var(--red);
  font-weight: 500;
}

.tutor-gate-note {
  display: block;
  margin-top: .5rem;
  font-size: .8rem;
  color: var(--muted);
}

/* ── Top-up modal ─────────────────────────────────────────────────────── */
.modal {
  position: fixed;
  inset: 0;
  background: rgba(0,0,0,.45);
  display: flex;
  align-items: center;
  justify-content: center;
  z-index: 1100;
  padding: 1rem;
}
.modal[hidden] { display: none; }
.modal-card {
  background: var(--card);
  border-radius: 10px;
  max-width: 520px;
  width: 100%;
  padding: 1.75rem 1.5rem 1.5rem;
  position: relative;
  box-shadow: 0 12px 32px rgba(0,0,0,.2);
}
.modal-close {
  position: absolute;
  top: .5rem;
  right: .75rem;
  background: transparent;
  border: none;
  font-size: 1.6rem;
  line-height: 1;
  cursor: pointer;
  color: var(--muted);
}
.modal-close:hover { color: var(--text); }
.topup-title { margin: 0 0 .5rem; font-size: 1.25rem; }
.topup-subhead { margin: 0 0 1rem; color: var(--muted); font-size: .9rem; }
.topup-packs {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(140px, 1fr));
  gap: .75rem;
  margin-bottom: 1rem;
}
.topup-pack {
  background: var(--bg);
  border: 1px solid var(--border);
  border-radius: 8px;
  padding: 1rem .75rem;
  cursor: pointer;
  text-align: center;
  transition: border-color .15s, transform .1s;
}
.topup-pack:hover:not([disabled]) { border-color: var(--accent); transform: translateY(-1px); }
.topup-pack[disabled] { opacity: .5; cursor: not-allowed; }
.topup-pack-price { font-size: 1.4rem; font-weight: 700; color: var(--text); }
.topup-pack-credits { font-size: .85rem; color: var(--muted); margin-top: .25rem; }
.topup-bonus {
  display: inline-block;
  background: var(--green-bg);
  color: var(--green);
  font-weight: 600;
  font-size: .75rem;
  padding: 1px 5px;
  border-radius: 3px;
  margin-left: 4px;
}
.topup-unconfigured { display: block; margin-top: .3rem; color: var(--red); }
.topup-loading, .topup-error {
  text-align: center;
  color: var(--muted);
  padding: 1rem 0;
}
.topup-error { color: var(--red); }
.topup-fineprint {
  margin: 0;
  font-size: .8rem;
  color: var(--muted);
  text-align: center;
}

/* ── Mobile breakpoint (≤720px) ─────────────────────────────────────────── */
@media (max-width: 720px) {

  /* Topbar collapses, hamburger appears, nav becomes a slide-down drawer */
  #topbar {
    flex-wrap: wrap;
    gap: .75rem;
    padding: .65rem 1rem;
  }
  #topbar h1 { font-size: 1.05rem; }
  #nav-toggle { display: inline-flex; order: 0; margin-left: auto; }
  .theme-toggle { width: 2.2rem; height: 2.2rem; margin-left: 0; }
  #account-btn-area { margin-left: 0; }

  #main-tabs {
    order: 99;
    flex-basis: 100%;
    flex-direction: column;
    gap: .25rem;
    padding: 0;
    border-top: 0 solid var(--border);
    margin-top: 0;
    max-height: 0;
    overflow: hidden;
    transition: max-height .25s ease, padding .25s ease, margin-top .25s ease, border-top-width .25s ease;
  }
  body[data-nav-open] #main-tabs {
    max-height: 22rem;
    padding: .5rem 0 .35rem;
    margin-top: .5rem;
    border-top-width: 1px;
  }
  .main-tab {
    padding: .75rem .9rem;
    font-size: .95rem;
    text-align: left;
    border-radius: var(--radius-md);
    min-height: 44px;
  }

  /* Home view */
  #home-view { padding: 1rem .9rem 2rem; }
  .home-hero { padding: 1.25rem 1.1rem 1rem; }
  .home-hero h2 { font-size: 1.4rem; }
  .home-lede { font-size: .98rem; }
  .home-features { grid-template-columns: 1fr; gap: .75rem; }
  .home-card { padding: 1.1rem; }

  /* Practice filters stack */
  #practice-view header { padding: .75rem .9rem; }
  #set-toggles, #difficulty-filter { gap: .4rem .65rem; }
  #set-toggles label, #difficulty-filter label, #categories label { font-size: .92rem; min-height: 36px; }
  main { padding: 1.1rem; margin: 1rem .75rem; border-radius: var(--radius-md); }
  #options button { padding: .85rem .9rem; min-height: 44px; }

  /* Guide */
  #subject-tabs { padding: .55rem .85rem; }
  .subject-tab { padding: .55rem .95rem; font-size: .9rem; min-height: 38px; }
  #guide-body { padding: 1rem .85rem 2rem; }
  #guide-content { padding: 1.2rem 1.05rem; }
  #guide-content h1 { font-size: 1.3rem; }
  #guide-content h2 { font-size: 1.05rem; }

  /* Tutor */
  #tutor-view { padding: 1rem .85rem 2rem; }
  #tutor-container { padding: 1.25rem 1rem; }
  .tutor-heading { font-size: 1.15rem; }
  #tutor-chat-header { flex-wrap: wrap; gap: .35rem; }
  .tutor-session-cost { margin-left: 0; }
  #tutor-chat { max-height: 56vh; min-height: 220px; }
  .tutor-msg .msg-text { max-width: 92%; font-size: .94rem; }
  .tutor-question-card { padding: .7rem .65rem; }
  .tutor-question-option { padding: .7rem .75rem; min-height: 44px; }

  /* Simulation */
  #sim-container { padding: .9rem .85rem 2rem; }
  #sim-active-header { flex-wrap: wrap; gap: .5rem; padding: .55rem .7rem; }
  .sim-timer { margin-left: 0; }
  .sim-option { padding: .8rem .8rem; min-height: 44px; }

  /* Modals → bottom-sheet feel */
  #acct-overlay { padding: 0; align-items: flex-end; }
  #acct-modal {
    max-width: 100%;
    border-radius: var(--radius-xl) var(--radius-xl) 0 0;
    padding: 1.5rem 1.25rem 1.75rem;
    max-height: 92vh;
    overflow-y: auto;
  }
  .modal-card { padding: 1.4rem 1.1rem 1.25rem; }
  .topup-packs { grid-template-columns: 1fr 1fr; }

  /* Section-review */
  .sq-block { padding: 1rem 1rem; }
  .sq-btn { padding: .8rem .85rem; min-height: 44px; }

  /* Toasts */
  .acct-toast { bottom: 1rem; font-size: .88rem; padding: .7rem 1rem; }
}

/* ── Assembly Practice ────────────────────────────────────────────────── */
:root {
  --asm-shape-fill:   var(--accent-bg);
  --asm-shape-stroke: var(--accent);
  --asm-seam-stroke:  var(--text);
  --asm-label-bg:     var(--surface);
  --asm-label-stroke: var(--accent);
  --asm-label-text:   var(--text-strong);
}
[data-theme="dark"] {
  --asm-shape-fill:   rgba(226,180,65,.12);
  --asm-shape-stroke: var(--accent);
  --asm-seam-stroke:  var(--text);
  --asm-label-bg:     var(--surface-raised);
  --asm-label-stroke: var(--accent);
  --asm-label-text:   var(--text-strong);
}
#asm-container { max-width: 940px; margin: 0 auto; padding: 1rem; }
.asm-heading { margin: 0 0 .5rem; }
.asm-subhead { color: var(--muted); margin: .4rem 0 1rem; font-size: .92rem; }
#asm-header { margin-bottom: 1rem; }
.asm-controls {
  display: flex; align-items: center; gap: .8rem; flex-wrap: wrap;
  margin: .3rem 0 .2rem;
}
.asm-difficulty { display: inline-flex; gap: .3rem; flex-wrap: wrap; }
.asm-pill {
  padding: .35rem .7rem; border: 1px solid var(--border);
  background: var(--bg); color: var(--text); border-radius: 999px;
  cursor: pointer; font: inherit; font-size: .85rem;
}
.asm-pill:hover { border-color: var(--accent); }
.asm-pill-active {
  background: var(--accent-bg); border-color: var(--accent); color: var(--accent);
  font-weight: 600;
}
.asm-timer {
  margin-left: auto; font-variant-numeric: tabular-nums;
  padding: .25rem .65rem; border-radius: var(--radius-sm);
  background: var(--accent-bg); color: var(--accent);
  font-weight: 600; min-width: 3rem; text-align: center;
}
.asm-timer-warning {
  background: var(--red-bg); color: var(--red);
  animation: sim-pulse 1s ease-in-out infinite;
}
.asm-question-text {
  margin: .2rem 0 .6rem; font-size: 1.02rem; color: var(--text);
}
#asm-prompt {
  background: var(--card); border: 1px solid var(--border);
  border-radius: .5rem; padding: .6rem; margin-bottom: 1rem;
  display: flex; justify-content: center;
}
.asm-svg { display: block; width: 100%; height: auto; max-width: 100%; }
.asm-prompt-svg { max-width: 560px; }
.asm-answer-svg { max-width: 200px; }
#asm-options {
  display: grid; grid-template-columns: repeat(auto-fit, minmax(180px, 1fr));
  gap: .8rem; margin-bottom: 1rem;
}
.asm-option {
  position: relative; padding: .6rem;
  background: var(--card); border: 2px solid var(--border);
  border-radius: .5rem; cursor: pointer;
  display: flex; flex-direction: column; align-items: center;
  font: inherit; color: var(--text);
  transition: border-color .15s, opacity .2s;
}
.asm-option:hover:not(.asm-option-faded):not(.asm-option-correct):not(.asm-option-wrong) {
  border-color: var(--accent);
}
.asm-option-letter {
  position: absolute; top: .35rem; left: .5rem;
  font-weight: 700; color: var(--muted); font-size: .85rem;
}
.asm-option-correct {
  border-color: #2e8a3a;
  box-shadow: 0 0 0 2px rgba(46,138,58,.18);
}
.asm-option-wrong {
  border-color: var(--red);
  box-shadow: 0 0 0 2px rgba(196,48,37,.18);
}
.asm-option-faded { opacity: .45; cursor: default; }
#asm-feedback {
  background: var(--card); border: 1px solid var(--border);
  border-radius: .5rem; padding: .8rem 1rem; margin-bottom: 1rem;
}
.asm-feedback-msg { margin: 0 0 .35rem; font-weight: 600; }
.asm-good { color: #2e8a3a; }
.asm-bad  { color: var(--red); }
.asm-feedback-explain { margin: 0; color: var(--muted); font-size: .92rem; }
#asm-controls { text-align: right; }
.asm-error { color: var(--red); margin: 1rem 0; }
@media (max-width: 720px) {
  .asm-controls { gap: .5rem; }
  .asm-timer { margin-left: 0; }
  #asm-options { grid-template-columns: repeat(2, 1fr); }
}

/* ── Very narrow / phones <420px ─────────────────────────────────────────── */
@media (max-width: 420px) {
  #topbar h1 { font-size: 1rem; }
  .home-hero h2 { font-size: 1.25rem; }
  .topup-packs { grid-template-columns: 1fr; }
}