/* =========================================================
   IBM Quantum Practice Exam – Shared Stylesheet
   ========================================================= */

@import url('https://fonts.googleapis.com/css2?family=IBM+Plex+Sans:wght@300;400;500;600;700&family=IBM+Plex+Mono:wght@400;500&display=swap');

/* ---------- Reset & Base ---------- */
*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }

:root {
  --ibm-blue:      #0f62fe;
  --ibm-blue-dark: #0043ce;
  --ibm-purple:    #6929c4;
  --ibm-cyan:      #1192e8;
  --bg:            #f4f4f4;
  --surface:       #ffffff;
  --surface-2:     #e8e8e8;
  --text:          #161616;
  --text-muted:    #525252;
  --border:        #d1d1d1;
  --correct:       #24a148;
  --correct-bg:    #defbe6;
  --wrong:         #da1e28;
  --wrong-bg:      #fff1f1;
  --radius:        8px;
  --shadow:        0 2px 8px rgba(0,0,0,.10);
  --shadow-lg:     0 6px 20px rgba(0,0,0,.14);
}

html { scroll-behavior: smooth; }

body {
  font-family: 'IBM Plex Sans', system-ui, sans-serif;
  background: var(--bg);
  color: var(--text);
  line-height: 1.6;
  min-height: 100vh;
  display: flex;
  flex-direction: column;
}

/* ---------- Header / Nav ---------- */
.site-header {
  background: linear-gradient(135deg, #161616 0%, #1e1e1e 100%);
  color: #fff;
  padding: 0 2rem;
  box-shadow: 0 2px 8px rgba(0,0,0,.4);
  position: sticky;
  top: 0;
  z-index: 100;
}

.site-header .inner {
  max-width: 1100px;
  margin: 0 auto;
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 56px;
  gap: 1rem;
}

.site-logo {
  display: flex;
  align-items: center;
  gap: .6rem;
  text-decoration: none;
  color: inherit;
}

.site-logo .logo-icon {
  width: 32px;
  height: 32px;
  background: var(--ibm-blue);
  border-radius: 6px;
  display: flex;
  align-items: center;
  justify-content: center;
  font-weight: 700;
  font-size: .75rem;
  letter-spacing: -.5px;
  flex-shrink: 0;
}

.site-logo span {
  font-size: .85rem;
  font-weight: 500;
  color: #a8a8a8;
  line-height: 1.3;
}

.site-logo strong {
  display: block;
  font-size: .95rem;
  font-weight: 600;
  color: #fff;
}

.home-link {
  font-size: .85rem;
  color: #a8a8a8;
  text-decoration: none;
  display: flex;
  align-items: center;
  gap: .35rem;
  transition: color .2s;
  white-space: nowrap;
}
.home-link:hover { color: #fff; }

/* ---------- Hero Banner ---------- */
.hero {
  background: linear-gradient(135deg, #0043ce 0%, #6929c4 100%);
  color: #fff;
  text-align: center;
  padding: 3.5rem 2rem 3rem;
}

.hero h1 {
  font-size: clamp(1.5rem, 4vw, 2.4rem);
  font-weight: 700;
  line-height: 1.25;
  max-width: 760px;
  margin: 0 auto .75rem;
}

.hero p {
  font-size: 1.05rem;
  opacity: .88;
  max-width: 600px;
  margin: 0 auto 1.75rem;
}

.badge-row {
  display: flex;
  justify-content: center;
  gap: .75rem;
  flex-wrap: wrap;
}

.badge {
  background: rgba(255,255,255,.18);
  border: 1px solid rgba(255,255,255,.3);
  border-radius: 20px;
  padding: .3rem .9rem;
  font-size: .8rem;
  font-weight: 500;
}

/* ---------- Section Cards ---------- */
.main-content {
  flex: 1;
  max-width: 1100px;
  margin: 0 auto;
  padding: 3rem 1.5rem;
  width: 100%;
}

.section-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
  gap: 1.5rem;
  margin-top: .5rem;
}

.section-card {
  background: var(--surface);
  border-radius: var(--radius);
  box-shadow: var(--shadow);
  border: 1px solid var(--border);
  overflow: hidden;
  display: flex;
  flex-direction: column;
  transition: box-shadow .2s, transform .2s;
  text-decoration: none;
  color: inherit;
}

.section-card:hover {
  box-shadow: var(--shadow-lg);
  transform: translateY(-2px);
}

.card-accent {
  height: 5px;
}

.section-card:nth-child(1) .card-accent { background: var(--ibm-blue); }
.section-card:nth-child(2) .card-accent { background: var(--ibm-purple); }
.section-card:nth-child(3) .card-accent { background: var(--ibm-cyan); }

.card-body {
  padding: 1.5rem;
  flex: 1;
  display: flex;
  flex-direction: column;
  gap: .5rem;
}

.card-label {
  font-size: .75rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: .08em;
  color: var(--text-muted);
}

.card-title {
  font-size: 1.15rem;
  font-weight: 700;
  color: var(--text);
  line-height: 1.3;
}

.card-meta {
  font-size: .85rem;
  color: var(--text-muted);
  margin-top: .25rem;
}

.card-footer {
  padding: 1rem 1.5rem;
  border-top: 1px solid var(--border);
  background: var(--bg);
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.card-footer .btn {
  font-size: .85rem;
}

/* ---------- Buttons ---------- */
.btn {
  display: inline-flex;
  align-items: center;
  gap: .4rem;
  border: none;
  border-radius: 4px;
  padding: .55rem 1.1rem;
  font-family: inherit;
  font-size: .95rem;
  font-weight: 600;
  cursor: pointer;
  text-decoration: none;
  transition: background .18s, opacity .18s;
  line-height: 1.2;
}

.btn-primary {
  background: var(--ibm-blue);
  color: #fff;
}
.btn-primary:hover { background: var(--ibm-blue-dark); }

.btn-outline {
  background: transparent;
  color: var(--ibm-blue);
  border: 2px solid var(--ibm-blue);
}
.btn-outline:hover { background: #e8f1ff; }

.btn-sm {
  padding: .35rem .8rem;
  font-size: .82rem;
}

/* ---------- Page Banner (section pages) ---------- */
.page-banner {
  background: linear-gradient(135deg, #161616 0%, #262626 100%);
  color: #fff;
  padding: 2rem 2rem 1.75rem;
}

.page-banner .inner {
  max-width: 860px;
  margin: 0 auto;
}

.section-tag {
  font-size: .75rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: .1em;
  color: #a8a8a8;
  margin-bottom: .5rem;
}

.page-banner h1 {
  font-size: clamp(1.2rem, 3vw, 1.8rem);
  font-weight: 700;
  line-height: 1.3;
  margin-bottom: .5rem;
}

.page-banner .meta {
  font-size: .88rem;
  color: #a8a8a8;
  display: flex;
  gap: 1.5rem;
  flex-wrap: wrap;
}

/* ---------- Quiz Container ---------- */
.quiz-wrap {
  max-width: 860px;
  margin: 2rem auto;
  padding: 0 1.5rem 4rem;
}

/* ---------- Question Card ---------- */
.question-card {
  background: var(--surface);
  border-radius: var(--radius);
  box-shadow: var(--shadow);
  border: 1px solid var(--border);
  margin-bottom: 1.25rem;
  overflow: hidden;
  transition: border-color .2s;
}

.question-card.correct  { border-color: var(--correct); }
.question-card.wrong    { border-color: var(--wrong); }

.question-header {
  padding: 1.1rem 1.4rem .75rem;
  border-bottom: 1px solid var(--border);
  display: flex;
  gap: 1rem;
  align-items: flex-start;
}

.q-number {
  background: var(--ibm-blue);
  color: #fff;
  border-radius: 50%;
  width: 28px;
  height: 28px;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: .78rem;
  font-weight: 700;
  flex-shrink: 0;
  margin-top: .1rem;
}

.question-card.correct .q-number { background: var(--correct); }
.question-card.wrong   .q-number { background: var(--wrong); }

.q-text {
  font-size: 1rem;
  font-weight: 500;
  color: var(--text);
  line-height: 1.55;
}

.options-list {
  list-style: none;
  padding: .6rem 1.4rem;
}

.option-item {
  margin: .35rem 0;
}

.option-label {
  display: flex;
  align-items: flex-start;
  gap: .75rem;
  padding: .7rem .9rem;
  border-radius: 6px;
  border: 1.5px solid transparent;
  cursor: pointer;
  transition: background .15s, border-color .15s;
  font-size: .95rem;
  line-height: 1.5;
}

.option-label:hover {
  background: #f0f4ff;
  border-color: #c0d0ff;
}

.option-label input[type="radio"] {
  margin-top: 3px;
  accent-color: var(--ibm-blue);
  flex-shrink: 0;
  width: 16px;
  height: 16px;
  cursor: pointer;
}

/* Revealed states */
.option-label.opt-correct {
  background: var(--correct-bg);
  border-color: var(--correct);
  font-weight: 600;
}

.option-label.opt-wrong {
  background: var(--wrong-bg);
  border-color: var(--wrong);
}

.option-label.opt-selected {
  border-color: var(--ibm-blue);
  background: #edf3ff;
}

/* Explanation box */
.explanation {
  display: none;
  margin: .5rem 1.4rem 1rem;
  padding: .8rem 1rem;
  border-left: 4px solid var(--ibm-blue);
  background: #edf3ff;
  border-radius: 0 6px 6px 0;
  font-size: .88rem;
  color: var(--text);
  line-height: 1.55;
}

.question-card.correct .explanation { border-color: var(--correct); background: var(--correct-bg); }
.question-card.wrong   .explanation { border-color: var(--wrong);   background: var(--wrong-bg); }
.explanation.visible { display: block; }

/* ---------- Score Panel ---------- */
.score-panel {
  display: none;
  background: var(--surface);
  border-radius: var(--radius);
  box-shadow: var(--shadow-lg);
  border: 2px solid var(--ibm-blue);
  padding: 2rem;
  text-align: center;
  margin-bottom: 2rem;
}

.score-panel.visible { display: block; }

.score-big {
  font-size: 3.5rem;
  font-weight: 700;
  color: var(--ibm-blue);
  line-height: 1;
  margin-bottom: .25rem;
}

.score-label {
  font-size: 1.05rem;
  color: var(--text-muted);
  margin-bottom: 1rem;
}

.score-bar-wrap {
  max-width: 400px;
  margin: 0 auto 1.25rem;
}

.score-bar-bg {
  height: 10px;
  border-radius: 5px;
  background: var(--surface-2);
  overflow: hidden;
}

.score-bar-fill {
  height: 100%;
  border-radius: 5px;
  background: linear-gradient(90deg, var(--ibm-blue), var(--ibm-purple));
  transition: width .8s ease;
}

.score-grade {
  display: inline-block;
  padding: .3rem 1rem;
  border-radius: 20px;
  font-size: .9rem;
  font-weight: 600;
  margin-bottom: 1.25rem;
}

.score-grade.pass { background: var(--correct-bg); color: var(--correct); }
.score-grade.fail { background: var(--wrong-bg);   color: var(--wrong); }

/* ---------- Action Bar ---------- */
.action-bar {
  display: flex;
  gap: 1rem;
  justify-content: center;
  flex-wrap: wrap;
  margin: 1.5rem 0;
}

/* ---------- Code Inline ---------- */
code {
  font-family: 'IBM Plex Mono', 'Courier New', monospace;
  background: #e8e8e8;
  color: #161616;
  padding: .1em .35em;
  border-radius: 3px;
  font-size: .9em;
}

/* ---------- Progress Tracker ---------- */
.progress-bar-wrap {
  position: sticky;
  top: 56px;
  z-index: 50;
  background: #fff;
  border-bottom: 1px solid var(--border);
  padding: .5rem 1.5rem;
}

.progress-bar-inner {
  max-width: 860px;
  margin: 0 auto;
  display: flex;
  align-items: center;
  gap: 1rem;
  font-size: .82rem;
  color: var(--text-muted);
}

.progress-track {
  flex: 1;
  height: 6px;
  border-radius: 3px;
  background: var(--surface-2);
  overflow: hidden;
}

.progress-fill {
  height: 100%;
  border-radius: 3px;
  background: var(--ibm-blue);
  transition: width .3s;
}

/* ---------- Footer ---------- */
.site-footer {
  background: #161616;
  color: #a8a8a8;
  text-align: center;
  padding: 1.25rem 1.5rem;
  font-size: .8rem;
}

.site-footer a { color: #78a9ff; text-decoration: none; }
.site-footer a:hover { text-decoration: underline; }

/* ---------- Flashcard Section ---------- */
.flashcard-section {
  max-width: 860px;
  margin: 0 auto;
  padding: 0 1.5rem 4rem;
}

.flashcard-section h2 {
  font-size: 1.4rem;
  font-weight: 700;
  color: var(--text);
  margin: 2.5rem 0 .75rem;
  padding-bottom: .5rem;
  border-bottom: 2px solid var(--ibm-blue);
}

.flashcard-section h3 {
  font-size: 1.1rem;
  font-weight: 600;
  color: var(--ibm-purple);
  margin: 2rem 0 .6rem;
}

.flashcard-section p {
  font-size: .93rem;
  color: var(--text-muted);
  margin-bottom: 1rem;
  line-height: 1.65;
}

.flashcard-table-wrap {
  overflow-x: auto;
  margin-bottom: 1.75rem;
}

.flashcard-table {
  width: 100%;
  border-collapse: collapse;
  font-size: .9rem;
  background: var(--surface);
  border-radius: var(--radius);
  overflow: hidden;
  box-shadow: var(--shadow);
}

.flashcard-table thead th {
  background: var(--ibm-blue);
  color: #fff;
  padding: .75rem 1.1rem;
  text-align: left;
  font-weight: 600;
}

.flashcard-table tbody tr:nth-child(even) {
  background: #f0f4ff;
}

.flashcard-table tbody td {
  padding: .75rem 1.1rem;
  border-top: 1px solid var(--border);
  vertical-align: top;
  line-height: 1.6;
}

.flashcard-table tbody td:first-child {
  font-weight: 600;
  color: var(--text);
  min-width: 200px;
}

.flashcard-table tbody td:last-child {
  color: var(--text-muted);
}

.broadcasting-table {
  width: 100%;
  border-collapse: collapse;
  font-size: .88rem;
  background: var(--surface);
  border-radius: var(--radius);
  overflow: hidden;
  box-shadow: var(--shadow);
  margin-bottom: 1.75rem;
}

.broadcasting-table thead th {
  background: var(--ibm-purple);
  color: #fff;
  padding: .65rem 1rem;
  text-align: center;
  font-weight: 600;
}

.broadcasting-table tbody td {
  padding: .65rem 1rem;
  border-top: 1px solid var(--border);
  text-align: center;
  color: var(--text-muted);
}

.broadcasting-table tbody td:last-child {
  font-weight: 700;
  color: var(--ibm-blue);
}

.broadcasting-table tbody tr:nth-child(even) {
  background: #f5f0ff;
}

.code-flashcard {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  box-shadow: var(--shadow);
  margin-bottom: 1.25rem;
  overflow: hidden;
}

.code-flashcard-front {
  padding: .85rem 1.2rem;
  background: #f0f4ff;
  border-bottom: 1px solid var(--border);
  font-weight: 600;
  font-size: .93rem;
  color: var(--text);
}

.code-flashcard-front::before {
  content: "Q: ";
  color: var(--ibm-blue);
}

.code-flashcard-back {
  padding: 1rem 1.2rem;
}

.code-flashcard-back pre {
  background: #161616;
  color: #f4f4f4;
  padding: 1rem 1.2rem;
  border-radius: 6px;
  font-family: 'IBM Plex Mono', 'Courier New', monospace;
  font-size: .84rem;
  overflow-x: auto;
  line-height: 1.6;
  margin-top: .5rem;
}

/* ---------- Responsive ---------- */
@media (max-width: 600px) {
  .site-header .inner { height: 52px; }
  .hero { padding: 2.5rem 1.25rem 2rem; }
  .quiz-wrap { padding: 0 1rem 3rem; }
  .question-header { padding: .9rem 1rem .65rem; }
  .options-list { padding: .5rem 1rem; }
  .explanation { margin: .4rem 1rem .85rem; }
  .score-big { font-size: 2.8rem; }
}