/* ============ DESIGN TOKENS ============ */
:root, [data-theme="light"] {
  --text-xs: clamp(0.75rem, 0.7rem + 0.25vw, 0.875rem);
  --text-sm: clamp(0.875rem, 0.8rem + 0.35vw, 1rem);
  --text-base: clamp(1rem, 0.95rem + 0.25vw, 1.125rem);
  --text-lg: clamp(1.125rem, 1rem + 0.75vw, 1.5rem);
  --text-xl: clamp(1.5rem, 1.2rem + 1.25vw, 2.25rem);

  --space-1: .25rem; --space-2: .5rem; --space-3: .75rem; --space-4: 1rem;
  --space-5: 1.25rem; --space-6: 1.5rem; --space-8: 2rem; --space-10: 2.5rem;
  --space-12: 3rem; --space-16: 4rem; --space-20: 5rem; --space-24: 6rem;

  /* Cool, precise surfaces (audit/governance tone) */
  --color-bg: #f4f7f7;
  --color-surface: #ffffff;
  --color-surface-2: #fbfdfd;
  --color-surface-offset: #eef3f2;
  --color-divider: #dde6e4;
  --color-border: #cfdbd9;

  --color-text: #172321;
  --color-text-muted: #5c6e6b;
  --color-text-faint: #93a4a1;
  --color-text-inverse: #f7faf9;

  --color-primary: #01696f;
  --color-primary-hover: #0c4e54;
  --color-primary-active: #0f3638;
  --color-primary-highlight: #cedcd8;
  --color-chart-track: #d7e2e0;

  --color-success: #437a22;
  --color-success-highlight: #d4dfcc;
  --color-error: #a12c7b;
  --color-error-highlight: #e0ced7;
  --color-warning: #964219;
  --color-warning-highlight: #ddcfc6;

  /* Domain accent set (data-viz only) */
  --domain-d1: #01696f;
  --domain-d2: #006494;
  --domain-d3: #d19900;
  --domain-d4: #da7101;
  --domain-d5: #7a39bb;

  --radius-sm: .375rem; --radius-md: .5rem; --radius-lg: .75rem; --radius-xl: 1rem; --radius-full: 9999px;
  --transition-interactive: 180ms cubic-bezier(.16,1,.3,1);
  --shadow-sm: 0 1px 2px oklch(0.2 0.02 190 / 0.06);
  --shadow-md: 0 4px 14px oklch(0.2 0.02 190 / 0.08);
  --shadow-lg: 0 16px 36px oklch(0.2 0.02 190 / 0.14);

  --font-display: 'Space Grotesk', 'Helvetica Neue', sans-serif;
  --font-body: 'Inter', 'Helvetica Neue', sans-serif;
}

[data-theme="dark"] {
  --color-bg: #10181a;
  --color-surface: #16201f;
  --color-surface-2: #1a2523;
  --color-surface-offset: #1b2523;
  --color-divider: #263030;
  --color-border: #33403f;

  --color-text: #d3ddda;
  --color-text-muted: #869896;
  --color-text-faint: #5a6a68;
  --color-text-inverse: #16201f;

  --color-primary: #4f98a3;
  --color-primary-hover: #6bb0ba;
  --color-primary-active: #83c1ca;
  --color-primary-highlight: #223635;
  --color-chart-track: #33413f;

  --color-success: #6daa45;
  --color-success-highlight: #263528;
  --color-error: #d163a7;
  --color-error-highlight: #3a2634;
  --color-warning: #bb653b;
  --color-warning-highlight: #3a2a20;

  --domain-d1: #4f98a3;
  --domain-d2: #5591c7;
  --domain-d3: #e8af34;
  --domain-d4: #fdab43;
  --domain-d5: #a86fdf;

  --shadow-sm: 0 1px 2px oklch(0 0 0 / .3);
  --shadow-md: 0 4px 14px oklch(0 0 0 / .35);
  --shadow-lg: 0 16px 36px oklch(0 0 0 / .5);
}

/* ============ BASE ============ */
*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }
html { -webkit-font-smoothing: antialiased; text-rendering: optimizeLegibility; scroll-behavior: smooth; }
body {
  min-height: 100dvh;
  line-height: 1.6;
  font-family: var(--font-body);
  font-size: var(--text-base);
  color: var(--color-text);
  background: var(--color-bg);
}
h1, h2, h3, h4 { text-wrap: balance; line-height: 1.2; font-family: var(--font-display); }
p, li { text-wrap: pretty; }
img, svg { display: block; max-width: 100%; }
button, input, select, textarea { font: inherit; color: inherit; }
:focus-visible { outline: 2px solid var(--color-primary); outline-offset: 2px; border-radius: var(--radius-sm); }
.skip-link {
  position: absolute; left: -9999px; top: 0; z-index: 100;
  background: var(--color-primary); color: var(--color-text-inverse);
  padding: var(--space-3) var(--space-4); border-radius: var(--radius-sm);
}
.skip-link:focus { left: var(--space-4); top: var(--space-4); }
@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after { animation-duration: .01ms !important; transition-duration: .01ms !important; }
}

/* ============ SHELL ============ */
.app-shell { display: flex; flex-direction: column; min-height: 100dvh; }

.topbar {
  display: flex; align-items: center; justify-content: space-between;
  gap: var(--space-4);
  padding: var(--space-3) var(--space-5);
  background: var(--color-surface);
  border-bottom: 1px solid var(--color-divider);
  position: sticky; top: 0; z-index: 20;
}
.brand { display: flex; align-items: center; gap: var(--space-3); min-width: 0; }
.menu-toggle {
  display: none; align-items: center; justify-content: center;
  width: 40px; height: 40px; border-radius: var(--radius-md);
  color: var(--color-text); flex-shrink: 0;
}
.menu-toggle:hover { background: var(--color-surface-offset); }
.brand-mark { width: 30px; height: 30px; color: var(--color-primary); flex-shrink: 0; }
.brand-text { display: flex; flex-direction: column; min-width: 0; }
.brand-title { font-family: var(--font-display); font-weight: 700; font-size: var(--text-base); line-height: 1.1; white-space: nowrap; overflow: hidden; text-overflow: ellipsis; }
.brand-sub { font-size: var(--text-xs); color: var(--color-text-muted); white-space: nowrap; overflow: hidden; text-overflow: ellipsis; }

.topbar-actions { display: flex; align-items: center; gap: var(--space-2); flex-shrink: 0; }
.btn {
  border-radius: var(--radius-md);
  padding: var(--space-2) var(--space-4);
  font-size: var(--text-sm); font-weight: 500;
  cursor: pointer; white-space: nowrap;
  min-height: 40px; display: inline-flex; align-items: center; gap: var(--space-2);
}
.btn-ghost { background: transparent; border: 1px solid var(--color-border); color: var(--color-text); }
.btn-ghost:hover { background: var(--color-surface-offset); border-color: var(--color-primary); }
.btn-primary { background: var(--color-primary); color: var(--color-text-inverse); border: 1px solid var(--color-primary); }
.btn-primary:hover { background: var(--color-primary-hover); }
.btn-primary:disabled { opacity: .5; cursor: not-allowed; }
.btn-file { cursor: pointer; }
.theme-toggle {
  width: 40px; height: 40px; border-radius: var(--radius-full);
  display: flex; align-items: center; justify-content: center;
  border: 1px solid var(--color-border); color: var(--color-text);
}
.theme-toggle:hover { border-color: var(--color-primary); color: var(--color-primary); }

.app-body { display: flex; flex: 1; min-height: 0; }

/* ============ SIDEBAR ============ */
.sidebar {
  width: 272px; flex-shrink: 0;
  border-right: 1px solid var(--color-divider);
  background: var(--color-surface);
  padding: var(--space-4) var(--space-3);
  overflow-y: auto;
  display: flex; flex-direction: column; gap: var(--space-1);
  position: sticky; top: 61px; height: calc(100dvh - 61px);
}
.nav-group { display: flex; flex-direction: column; gap: var(--space-1); margin-top: var(--space-4); }
.nav-group-label {
  font-size: var(--text-xs); font-weight: 700; text-transform: uppercase; letter-spacing: .04em;
  color: var(--color-text-faint); padding: var(--space-2) var(--space-3) var(--space-1);
}
.nav-item {
  display: flex; align-items: center; gap: var(--space-2);
  text-align: left; width: 100%;
  padding: var(--space-3); border-radius: var(--radius-md);
  font-size: var(--text-sm); color: var(--color-text);
  min-height: 44px;
}
.nav-item:hover { background: var(--color-surface-offset); }
.nav-item.active { background: var(--color-primary-highlight); color: var(--color-primary-active); font-weight: 600; }
[data-theme="dark"] .nav-item.active { color: var(--color-text); }
.nav-dot { width: 8px; height: 8px; border-radius: 50%; flex-shrink: 0; background: var(--color-primary); }
.blueprint-dot { background: var(--domain-d4); }

/* ============ MAIN CONTENT ============ */
.content { flex: 1; min-width: 0; padding: var(--space-8) var(--space-6); max-width: 1040px; }

.page-header { margin-bottom: var(--space-8); }
.eyebrow { font-size: var(--text-xs); font-weight: 700; text-transform: uppercase; letter-spacing: .06em; color: var(--color-primary); margin-bottom: var(--space-2); display: block; }
.page-title { font-size: var(--text-xl); font-weight: 700; margin-bottom: var(--space-2); }
.page-lede { color: var(--color-text-muted); font-size: var(--text-base); max-width: 68ch; }

.card {
  background: var(--color-surface); border: 1px solid var(--color-divider);
  border-radius: var(--radius-lg); padding: var(--space-6);
  box-shadow: var(--shadow-sm); margin-bottom: var(--space-6);
}
.card h3 { font-size: var(--text-lg); margin-bottom: var(--space-4); font-weight: 700; }

.meta-row { display: flex; flex-wrap: wrap; gap: var(--space-2); margin-bottom: var(--space-5); }
.badge {
  display: inline-flex; align-items: center; gap: var(--space-1);
  padding: var(--space-1) var(--space-3); border-radius: var(--radius-full);
  font-size: var(--text-xs); font-weight: 600;
  background: var(--color-surface-offset); color: var(--color-text-muted);
  border: 1px solid var(--color-border);
}
.badge-primary { background: var(--color-primary-highlight); color: var(--color-primary-active); border-color: transparent; }
[data-theme="dark"] .badge-primary { color: var(--color-text); }

.topic-list, .concept-list { display: flex; flex-direction: column; gap: var(--space-3); }
.topic-list li, .concept-list li {
  padding-left: var(--space-5); position: relative; font-size: var(--text-sm); color: var(--color-text);
}
.topic-list li::before, .concept-list li::before {
  content: ''; position: absolute; left: 0; top: .55em; width: 6px; height: 6px; border-radius: 50%;
  background: var(--color-primary);
}

/* Week complete / hours tracker */
.tracker-row {
  display: flex; flex-wrap: wrap; align-items: center; gap: var(--space-5);
  padding-top: var(--space-4); border-top: 1px solid var(--color-divider); margin-top: var(--space-4);
}
.check-field { display: flex; align-items: center; gap: var(--space-2); font-size: var(--text-sm); }
.check-field input[type="checkbox"] { width: 20px; height: 20px; accent-color: var(--color-primary); }
.hours-field { display: flex; align-items: center; gap: var(--space-2); font-size: var(--text-sm); }
.hours-field input {
  width: 72px; padding: var(--space-2) var(--space-3); border: 1px solid var(--color-border);
  border-radius: var(--radius-md); background: var(--color-surface-2); color: var(--color-text);
}

/* ============ QUIZ ============ */
.quiz-progress { display: flex; align-items: center; justify-content: space-between; margin-bottom: var(--space-4); }
.quiz-score { font-size: var(--text-sm); font-weight: 600; color: var(--color-primary); }
.quiz-question { margin-bottom: var(--space-3); font-weight: 600; font-size: var(--text-base); }
.quiz-options { display: flex; flex-direction: column; gap: var(--space-2); margin-bottom: var(--space-4); }
.quiz-option {
  display: flex; align-items: flex-start; gap: var(--space-3);
  text-align: left; width: 100%;
  padding: var(--space-3) var(--space-4); border-radius: var(--radius-md);
  border: 1px solid var(--color-border); background: var(--color-surface-2);
  font-size: var(--text-sm); min-height: 44px;
}
.quiz-option:hover:not(:disabled) { border-color: var(--color-primary); }
.quiz-option:disabled { cursor: default; }
.quiz-option.correct { background: var(--color-success-highlight); border-color: var(--color-success); }
.quiz-option.incorrect { background: var(--color-error-highlight); border-color: var(--color-error); }
.option-letter {
  flex-shrink: 0; width: 24px; height: 24px; border-radius: 50%;
  background: var(--color-surface-offset); display: flex; align-items: center; justify-content: center;
  font-size: var(--text-xs); font-weight: 700;
}
.quiz-explanation {
  padding: var(--space-4); border-radius: var(--radius-md); background: var(--color-surface-offset);
  font-size: var(--text-sm); color: var(--color-text); margin-bottom: var(--space-4);
  border-left: 3px solid var(--color-primary);
}
.quiz-explanation strong { color: var(--color-primary); }
.quiz-nav { display: flex; justify-content: flex-end; gap: var(--space-3); }
.quiz-result {
  text-align: center; padding: var(--space-8) var(--space-4);
}
.quiz-result .score-big { font-size: var(--text-xl); font-family: var(--font-display); font-weight: 700; color: var(--color-primary); margin-bottom: var(--space-2); }
.quiz-result p { color: var(--color-text-muted); margin-bottom: var(--space-5); }

/* ============ EXERCISE ============ */
.match-grid { display: grid; grid-template-columns: 1fr; gap: var(--space-4); }
@media (min-width: 640px) { .match-grid { grid-template-columns: 1fr 1fr; } }
.match-terms, .match-defs { display: flex; flex-direction: column; gap: var(--space-2); }
.match-term {
  padding: var(--space-3) var(--space-4); border-radius: var(--radius-md);
  border: 2px solid var(--color-border); background: var(--color-surface-2);
  font-size: var(--text-sm); cursor: pointer; min-height: 44px; display: flex; align-items: center;
}
.match-term.selected { border-color: var(--color-primary); background: var(--color-primary-highlight); }
.match-term.solved { border-color: var(--color-success); background: var(--color-success-highlight); cursor: default; }
.match-def {
  padding: var(--space-3) var(--space-4); border-radius: var(--radius-md);
  border: 2px dashed var(--color-border); background: var(--color-surface); font-size: var(--text-sm);
  cursor: pointer; min-height: 44px; display: flex; align-items: center;
}
.match-def.solved { border-style: solid; border-color: var(--color-success); background: var(--color-success-highlight); cursor: default; }
.match-def.wrong-flash { border-color: var(--color-error); background: var(--color-error-highlight); }

.rank-list { display: flex; flex-direction: column; gap: var(--space-2); list-style: none; }
.rank-item {
  display: flex; align-items: center; gap: var(--space-3);
  padding: var(--space-3) var(--space-4); border-radius: var(--radius-md);
  border: 1px solid var(--color-border); background: var(--color-surface-2);
  font-size: var(--text-sm); cursor: grab;
}
.rank-item.dragging { opacity: .5; }
.rank-item .rank-num { flex-shrink: 0; width: 26px; height: 26px; border-radius: 50%; background: var(--color-primary); color: var(--color-text-inverse); display: flex; align-items: center; justify-content: center; font-size: var(--text-xs); font-weight: 700; }
.rank-item .drag-handle { margin-left: auto; color: var(--color-text-faint); flex-shrink: 0; }
.rank-item.correct-pos { border-color: var(--color-success); }

.exercise-feedback { margin-top: var(--space-4); padding: var(--space-4); border-radius: var(--radius-md); font-size: var(--text-sm); }
.exercise-feedback.ok { background: var(--color-success-highlight); }

/* ============ DASHBOARD ============ */
.stat-grid { display: grid; grid-template-columns: repeat(auto-fit, minmax(180px, 1fr)); gap: var(--space-4); margin-bottom: var(--space-6); }
.stat-card { background: var(--color-surface); border: 1px solid var(--color-divider); border-radius: var(--radius-lg); padding: var(--space-5); box-shadow: var(--shadow-sm); }
.stat-label { font-size: var(--text-xs); text-transform: uppercase; letter-spacing: .04em; color: var(--color-text-muted); margin-bottom: var(--space-2); }
.stat-value { font-size: var(--text-xl); font-family: var(--font-display); font-weight: 700; }
.stat-sub { font-size: var(--text-xs); color: var(--color-text-faint); margin-top: var(--space-1); }

.progress-bar-track { height: 10px; border-radius: var(--radius-full); background: var(--color-surface-offset); overflow: hidden; margin-top: var(--space-3); }
.progress-bar-fill { height: 100%; background: var(--color-primary); border-radius: var(--radius-full); transition: width 300ms ease; }

.chart-wrap { position: relative; height: 280px; }

.week-grid { display: grid; grid-template-columns: repeat(auto-fill, minmax(210px, 1fr)); gap: var(--space-3); }
.week-tile {
  border: 1px solid var(--color-divider); border-radius: var(--radius-md); padding: var(--space-4);
  background: var(--color-surface-2); cursor: pointer; text-align: left; min-height: 44px;
}
.week-tile:hover { border-color: var(--color-primary); }
.week-tile.done { background: var(--color-success-highlight); border-color: var(--color-success); }
.week-tile-title { font-size: var(--text-sm); font-weight: 600; margin-bottom: var(--space-1); }
.week-tile-meta { font-size: var(--text-xs); color: var(--color-text-muted); }

.exam-date-row { display: flex; flex-wrap: wrap; align-items: center; gap: var(--space-3); }
.exam-date-row input[type="date"] {
  padding: var(--space-2) var(--space-3); border: 1px solid var(--color-border); border-radius: var(--radius-md);
  background: var(--color-surface-2); color: var(--color-text);
}

/* ============ BLUEPRINT ============ */
.blueprint-domain { margin-bottom: var(--space-6); }
.blueprint-domain-header { display: flex; align-items: center; justify-content: space-between; margin-bottom: var(--space-3); }
.blueprint-items { display: grid; grid-template-columns: 1fr; gap: var(--space-2); }
@media (min-width: 720px) { .blueprint-items { grid-template-columns: 1fr 1fr; } }
.blueprint-check { display: flex; align-items: flex-start; gap: var(--space-3); font-size: var(--text-sm); padding: var(--space-2); border-radius: var(--radius-sm); }
.blueprint-check:hover { background: var(--color-surface-offset); }
.blueprint-check input { width: 18px; height: 18px; margin-top: 2px; accent-color: var(--color-primary); flex-shrink: 0; }

footer.attribution {
  text-align: center; padding: var(--space-8) var(--space-4); color: var(--color-text-faint); font-size: var(--text-xs);
}

/* ============ RESPONSIVE ============ */
@media (max-width: 860px) {
  .menu-toggle { display: flex; }
  .sidebar {
    position: fixed; left: 0; top: 61px; bottom: 0; z-index: 30;
    transform: translateX(-100%); transition: transform var(--transition-interactive);
    box-shadow: var(--shadow-lg); width: 280px; height: calc(100dvh - 61px);
  }
  .sidebar.open { transform: translateX(0); }
  .brand-sub { display: none; }
  .content { padding: var(--space-6) var(--space-4); }
  .topbar-actions .btn { padding: var(--space-2) var(--space-3); font-size: var(--text-xs); }
}

@media (max-width: 520px) {
  .topbar { flex-wrap: wrap; row-gap: var(--space-2); padding: var(--space-3) var(--space-4); }
  .brand { flex: 1 1 100%; }
  .topbar-actions { flex: 1 1 100%; justify-content: flex-end; }
}