/* ═══════════════════════════════════════════════
   BASE / RESET
═══════════════════════════════════════════════ */
*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }

:root {
  --bg0:      #060d1a;
  --bg1:      #0d1526;
  --bg2:      #111d33;
  --bg3:      #1a2740;
  --card:     #16213a;
  --card2:    #1e2d4a;
  --border:   #243354;
  --border2:  #2e4070;
  --accent:   #3b82f6;
  --accent2:  #2563eb;
  --accent-g: #22d3ee;
  --text:     #e8edf5;
  --text2:    #94a3b8;
  --text3:    #64748b;
  --success:  #22c55e;
  --warning:  #f59e0b;
  --danger:   #ef4444;
  --flagged:  #f59e0b;
  --radius:   8px;
  --radius-lg:12px;
  --shadow:   0 4px 24px rgba(0,0,0,.45);
}

html { font-size: 16px; scroll-behavior: smooth; }

body {
  font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
  background: var(--bg0);
  color: var(--text);
  min-height: 100vh;
  line-height: 1.6;
}

/* ═══════════════════════════════════════════════
   SCREEN SYSTEM
═══════════════════════════════════════════════ */
.screen { display: none; }
.screen.active { display: flex; flex-direction: column; min-height: 100vh; }

/* ═══════════════════════════════════════════════
   BUTTONS
═══════════════════════════════════════════════ */
.btn {
  display: inline-flex; align-items: center; justify-content: center; gap: .4rem;
  padding: .55rem 1.25rem;
  border-radius: var(--radius);
  border: 1px solid transparent;
  font-size: .9rem; font-weight: 600; cursor: pointer;
  transition: background .15s, border-color .15s, color .15s, opacity .15s;
  text-decoration: none; white-space: nowrap;
}
.btn:disabled { opacity: .4; cursor: not-allowed; }

.btn-primary  { background: var(--accent); color: #fff; }
.btn-primary:hover:not(:disabled) { background: var(--accent2); }

.btn-outline  { background: transparent; border-color: var(--border2); color: var(--text); }
.btn-outline:hover:not(:disabled) { background: var(--bg3); border-color: var(--accent); color: var(--accent); }

.btn-ghost    { background: transparent; border-color: transparent; color: var(--text2); }
.btn-ghost:hover:not(:disabled)  { color: var(--text); background: var(--bg3); }

.btn-danger   { background: var(--danger); color: #fff; }
.btn-danger:hover:not(:disabled) { background: #dc2626; }

.btn-sm  { padding: .35rem .85rem; font-size: .82rem; }
.btn-lg  { padding: .75rem 2rem; font-size: 1rem; }

/* ═══════════════════════════════════════════════
   START SCREEN
═══════════════════════════════════════════════ */
#screen-start {
  position: relative; align-items: center; justify-content: center;
  background: var(--bg0);
}
.start-bg {
  position: fixed; inset: 0; z-index: 0;
  background: radial-gradient(ellipse 80% 60% at 50% -10%, rgba(59,130,246,.18) 0%, transparent 70%);
  pointer-events: none;
}
.start-wrap {
  position: relative; z-index: 1;
  display: flex; flex-direction: column; align-items: center; gap: 2rem;
  padding: 3rem 1rem;
  width: 100%; max-width: 580px;
}
.start-logo {
  display: flex; align-items: center; gap: .6rem;
  font-size: 1.1rem; font-weight: 700; color: var(--text2);
  letter-spacing: .04em; text-transform: uppercase;
}
.start-shield { font-size: 1.4rem; }
.start-card {
  width: 100%;
  background: var(--card);
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  padding: 2.5rem 2rem;
  box-shadow: var(--shadow);
  display: flex; flex-direction: column; align-items: center; gap: 1.5rem;
}
.start-badge {
  background: var(--accent); color: #fff;
  font-size: .72rem; font-weight: 700; letter-spacing: .1em; text-transform: uppercase;
  padding: .2rem .75rem; border-radius: 100px;
}
.start-title { font-size: 2.2rem; font-weight: 800; color: var(--text); text-align: center; }
.start-subtitle { font-size: 1rem; color: var(--text2); text-align: center; margin-top: -.75rem; }

.start-specs {
  display: flex; align-items: center; gap: 0;
  background: var(--bg3); border: 1px solid var(--border);
  border-radius: var(--radius); overflow: hidden; width: 100%;
}
.spec-item { flex: 1; text-align: center; padding: 1rem .5rem; }
.spec-val { font-size: 1.8rem; font-weight: 800; color: var(--accent); }
.spec-lbl { font-size: .75rem; color: var(--text2); text-transform: uppercase; letter-spacing: .06em; margin-top: .1rem; }
.spec-div { width: 1px; background: var(--border); align-self: stretch; }

.start-domains {
  display: flex; flex-wrap: wrap; gap: .5rem; justify-content: center; width: 100%;
}
.domain-chip {
  background: var(--bg3); border: 1px solid var(--border);
  border-radius: 100px; font-size: .78rem; color: var(--text2);
  padding: .3rem .9rem;
}

.start-notice {
  font-size: .84rem; color: var(--text3); text-align: center;
  background: var(--bg3); border: 1px solid var(--border);
  border-radius: var(--radius); padding: .75rem 1rem; width: 100%;
}
.start-actions {
  display: flex; flex-direction: column; gap: .75rem; width: 100%;
}
.start-actions .btn { width: 100%; }

.resume-info {
  font-size: .84rem; color: var(--text2); text-align: center;
  border: 1px solid var(--border); border-radius: var(--radius);
  padding: .6rem 1rem; width: 100%; background: var(--bg3);
}

/* ═══════════════════════════════════════════════
   EXAM HEADER
═══════════════════════════════════════════════ */
.exam-header {
  display: flex; align-items: center; gap: 1rem;
  background: var(--card); border-bottom: 1px solid var(--border);
  padding: 0 1.25rem; height: 56px; flex-shrink: 0; z-index: 10;
}
.exam-header-left {
  display: flex; align-items: center; gap: .5rem;
  font-weight: 700; font-size: .9rem; color: var(--text2);
  min-width: 160px;
}
.header-shield { font-size: 1.15rem; }
.exam-header-center { flex: 1; }
.exam-header-right {
  display: flex; align-items: center; gap: .75rem; min-width: 240px; justify-content: flex-end;
}

.progress-wrap { display: flex; align-items: center; gap: .75rem; }
.progress-bar-outer {
  flex: 1; height: 6px; background: var(--bg3);
  border-radius: 99px; overflow: hidden; min-width: 140px;
}
.progress-bar-inner {
  height: 100%; width: 0%; background: var(--accent);
  border-radius: 99px; transition: width .4s;
}
.progress-label { font-size: .8rem; color: var(--text2); white-space: nowrap; }

.timer {
  display: flex; align-items: center; gap: .35rem;
  font-size: .95rem; font-weight: 700; font-variant-numeric: tabular-nums;
  color: var(--text); background: var(--bg3);
  border: 1px solid var(--border); border-radius: var(--radius);
  padding: .25rem .75rem;
}
.timer-icon { font-size: .9rem; }
.timer.warning { color: var(--warning); border-color: var(--warning); }
.timer.critical { color: var(--danger); border-color: var(--danger); animation: pulse-red 1s infinite; }
@keyframes pulse-red {
  0%, 100% { opacity: 1; }
  50% { opacity: .6; }
}

/* ═══════════════════════════════════════════════
   EXAM BODY (sidebar + main)
═══════════════════════════════════════════════ */
#screen-exam { flex: 1; }
.exam-body {
  display: flex; flex: 1; overflow: hidden; height: calc(100vh - 56px);
}

/* Sidebar */
.exam-sidebar {
  width: 220px; flex-shrink: 0;
  background: var(--bg1); border-right: 1px solid var(--border);
  display: flex; flex-direction: column; overflow: hidden;
}
.sidebar-head {
  padding: .85rem 1rem .6rem;
  border-bottom: 1px solid var(--border);
}
.sidebar-title { font-size: .8rem; font-weight: 700; text-transform: uppercase; letter-spacing: .07em; color: var(--text2); }
.sidebar-legend { display: flex; gap: .75rem; margin-top: .4rem; font-size: .72rem; color: var(--text3); align-items: center; }
.leg-dot { width: 8px; height: 8px; border-radius: 50%; display: inline-block; }
.leg-dot.answered { background: var(--accent); }
.leg-dot.flagged   { background: var(--flagged); }

.question-nav {
  flex: 1; overflow-y: auto; padding: .75rem .75rem;
  display: grid; grid-template-columns: repeat(5, 1fr); gap: 4px;
  align-content: start;
}
.question-nav::-webkit-scrollbar { width: 4px; }
.question-nav::-webkit-scrollbar-thumb { background: var(--border); border-radius: 2px; }

.nav-btn {
  aspect-ratio: 1; border: 1px solid var(--border); border-radius: 4px;
  font-size: .72rem; font-weight: 700; cursor: pointer;
  background: var(--bg2); color: var(--text3);
  transition: background .12s, border-color .12s, color .12s;
  display: flex; align-items: center; justify-content: center;
}
.nav-btn:hover { border-color: var(--accent); color: var(--text); }
.nav-btn.current { border-color: var(--accent); background: var(--accent); color: #fff; }
.nav-btn.answered { background: var(--bg3); border-color: var(--accent); color: var(--accent); }
.nav-btn.flagged  { border-color: var(--flagged); background: rgba(245,158,11,.12); color: var(--flagged); }
.nav-btn.flagged.answered { background: rgba(245,158,11,.2); }

.sidebar-stats {
  padding: .75rem 1rem; border-top: 1px solid var(--border);
  font-size: .78rem; color: var(--text2);
}
.stat-row { margin-bottom: .2rem; }
.stat-row span { font-weight: 700; color: var(--text); }

/* Main question area */
.exam-main {
  flex: 1; overflow-y: auto; display: flex; flex-direction: column;
  padding: 1.5rem; gap: 1rem; background: var(--bg0);
}
.exam-main::-webkit-scrollbar { width: 6px; }
.exam-main::-webkit-scrollbar-thumb { background: var(--border); border-radius: 3px; }

.question-card {
  background: var(--card); border: 1px solid var(--border);
  border-radius: var(--radius-lg); padding: 1.75rem 2rem;
  box-shadow: var(--shadow); flex: 1;
}
.qcard-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);
}
.qcard-meta { display: flex; flex-wrap: wrap; align-items: center; gap: .5rem; }

.q-number { font-size: .85rem; font-weight: 700; color: var(--text2); }
.q-domain-tag {
  font-size: .7rem; font-weight: 600; letter-spacing: .05em;
  background: rgba(59,130,246,.15); border: 1px solid rgba(59,130,246,.3);
  color: var(--accent); padding: .15rem .6rem; border-radius: 100px;
}
.q-diff-tag {
  font-size: .7rem; font-weight: 600; padding: .15rem .6rem; border-radius: 100px;
}
.q-diff-tag.easy   { background: rgba(34,197,94,.12); border: 1px solid rgba(34,197,94,.25); color: var(--success); }
.q-diff-tag.medium { background: rgba(245,158,11,.12); border: 1px solid rgba(245,158,11,.25); color: var(--warning); }
.q-diff-tag.hard   { background: rgba(239,68,68,.12);  border: 1px solid rgba(239,68,68,.25);  color: var(--danger); }

.btn-flag {
  display: flex; align-items: center; gap: .3rem;
  background: transparent; border: 1px solid var(--border);
  border-radius: var(--radius); padding: .3rem .75rem;
  font-size: .8rem; font-weight: 600; color: var(--text2); cursor: pointer;
  transition: background .12s, border-color .12s, color .12s;
}
.btn-flag:hover { border-color: var(--flagged); color: var(--flagged); }
.btn-flag.active { background: rgba(245,158,11,.12); border-color: var(--flagged); color: var(--flagged); }

.multi-notice {
  background: rgba(245,158,11,.1); border: 1px solid rgba(245,158,11,.3);
  border-radius: var(--radius); padding: .6rem 1rem;
  font-size: .85rem; color: var(--warning); margin-bottom: 1rem;
}

.q-text {
  font-size: 1.05rem; color: var(--text); line-height: 1.75;
  margin-bottom: 1.5rem;
}

.q-options { display: flex; flex-direction: column; gap: .6rem; }

.option-label {
  display: flex; align-items: flex-start; gap: .85rem;
  padding: .85rem 1rem; border-radius: var(--radius);
  border: 1px solid var(--border); background: var(--bg2);
  cursor: pointer; transition: background .12s, border-color .12s;
  font-size: .95rem; color: var(--text);
}
.option-label:hover { background: var(--bg3); border-color: var(--border2); }
.option-label.selected { background: rgba(59,130,246,.15); border-color: var(--accent); color: var(--text); }
.option-label input { display: none; }
.option-key {
  min-width: 24px; height: 24px; border-radius: 50%;
  background: var(--bg3); border: 1px solid var(--border);
  display: flex; align-items: center; justify-content: center;
  font-size: .72rem; font-weight: 700; color: var(--text2);
  flex-shrink: 0; margin-top: .1rem;
  transition: background .12s, border-color .12s, color .12s;
}
.option-label.selected .option-key {
  background: var(--accent); border-color: var(--accent); color: #fff;
}
.option-label.multi-option .option-key { border-radius: 4px; }

/* Exam navigation bar */
.exam-nav {
  display: flex; align-items: center; justify-content: space-between;
  gap: 1rem; padding: .5rem 0;
}
.nav-dots {
  display: flex; gap: 4px; align-items: center;
}
.nav-dot {
  width: 6px; height: 6px; border-radius: 50%;
  background: var(--border2); transition: background .15s;
}
.nav-dot.done { background: var(--accent); }
.nav-dot.current { background: var(--text); width: 8px; height: 8px; }

/* ═══════════════════════════════════════════════
   REVIEW SCREEN
═══════════════════════════════════════════════ */
#screen-review { background: var(--bg0); }
.review-header {
  display: flex; align-items: center; justify-content: space-between;
  padding: .85rem 1.5rem; background: var(--card);
  border-bottom: 1px solid var(--border); flex-shrink: 0;
}
.review-title { font-size: 1.1rem; font-weight: 700; }
.review-body {
  flex: 1; overflow-y: auto; padding: 1.5rem; display: flex; flex-direction: column; gap: 1.5rem;
  max-width: 900px; margin: 0 auto; width: 100%;
}
.review-summary {
  display: flex; gap: 1rem; flex-wrap: wrap;
}
.review-stat {
  flex: 1; min-width: 120px;
  background: var(--card); border: 1px solid var(--border);
  border-radius: var(--radius); padding: 1rem 1.25rem; text-align: center;
}
.review-stat-val { font-size: 2rem; font-weight: 800; }
.review-stat-lbl { font-size: .78rem; color: var(--text2); text-transform: uppercase; letter-spacing: .05em; }
.review-stat.answered .review-stat-val { color: var(--accent); }
.review-stat.unanswered .review-stat-val { color: var(--danger); }
.review-stat.flagged .review-stat-val { color: var(--flagged); }

.review-list { display: flex; flex-direction: column; gap: .4rem; }
.review-item {
  display: flex; align-items: center; gap: .75rem;
  background: var(--card); border: 1px solid var(--border);
  border-radius: var(--radius); padding: .7rem 1rem;
  cursor: pointer; transition: border-color .12s, background .12s;
}
.review-item:hover { border-color: var(--accent); background: var(--bg3); }
.review-item-num {
  min-width: 28px; height: 28px; border-radius: 50%;
  display: flex; align-items: center; justify-content: center;
  font-size: .75rem; font-weight: 700;
  background: var(--bg3); color: var(--text2); border: 1px solid var(--border);
}
.review-item.answered .review-item-num { background: rgba(59,130,246,.15); border-color: var(--accent); color: var(--accent); }
.review-item.flagged .review-item-num  { background: rgba(245,158,11,.15); border-color: var(--flagged); color: var(--flagged); }
.review-item-text { flex: 1; font-size: .88rem; color: var(--text2); line-height: 1.4; }
.review-item-status { font-size: .75rem; font-weight: 600; }
.review-item-status.ok   { color: var(--accent); }
.review-item-status.warn { color: var(--flagged); }
.review-item-status.bad  { color: var(--danger); }

.review-actions {
  display: flex; gap: 1rem; justify-content: center; padding: 1rem 0;
}

/* ═══════════════════════════════════════════════
   RESULTS SCREEN
═══════════════════════════════════════════════ */
#screen-results { background: var(--bg0); overflow-y: auto; }
.results-body { max-width: 900px; margin: 0 auto; padding: 2rem 1.5rem; }

.results-hero {
  text-align: center; padding: 2.5rem 1rem 2rem;
  background: var(--card); border: 1px solid var(--border);
  border-radius: var(--radius-lg); margin-bottom: 2rem; box-shadow: var(--shadow);
}
.results-badge-wrap { display: flex; flex-direction: column; align-items: center; gap: .5rem; margin-bottom: 1rem; }
.results-icon { font-size: 3rem; }
.results-verdict {
  font-size: 1.2rem; font-weight: 800; letter-spacing: .15em;
  padding: .3rem 1.5rem; border-radius: 100px;
}
.results-verdict.pass { background: rgba(34,197,94,.15); color: var(--success); border: 1px solid var(--success); }
.results-verdict.fail { background: rgba(239,68,68,.12); color: var(--danger); border: 1px solid var(--danger); }

.results-score { font-size: 3.5rem; font-weight: 900; color: var(--text); }
.results-pct   { font-size: 1.75rem; font-weight: 700; color: var(--text2); margin-top: -.5rem; }
.results-time-taken { font-size: .9rem; color: var(--text3); margin-top: .75rem; }

.results-grid { display: flex; flex-direction: column; gap: 2rem; }
.results-section { background: var(--card); border: 1px solid var(--border); border-radius: var(--radius-lg); padding: 1.5rem; }
.results-section-title { font-size: 1rem; font-weight: 700; margin-bottom: 1.25rem; color: var(--text2); text-transform: uppercase; letter-spacing: .06em; }

/* Domain breakdown bars */
.domain-row { margin-bottom: 1rem; }
.domain-row-head { display: flex; justify-content: space-between; margin-bottom: .35rem; font-size: .88rem; }
.domain-row-name { font-weight: 600; }
.domain-row-score { color: var(--text2); }
.domain-bar-outer { height: 8px; background: var(--bg3); border-radius: 99px; overflow: hidden; }
.domain-bar-inner { height: 100%; border-radius: 99px; transition: width .6s; }
.domain-bar-inner.good { background: var(--success); }
.domain-bar-inner.ok   { background: var(--warning); }
.domain-bar-inner.bad  { background: var(--danger); }

/* Wrong answer cards */
.wrong-card {
  background: var(--bg2); border: 1px solid var(--border);
  border-radius: var(--radius); padding: 1.25rem; margin-bottom: .75rem;
}
.wrong-card-head {
  display: flex; align-items: center; gap: .6rem;
  margin-bottom: .75rem;
}
.wrong-num {
  background: rgba(239,68,68,.15); border: 1px solid var(--danger);
  color: var(--danger); font-size: .72rem; font-weight: 700;
  padding: .15rem .6rem; border-radius: 100px;
}
.wrong-domain { font-size: .72rem; color: var(--text3); }
.wrong-q-text { font-size: .92rem; color: var(--text); margin-bottom: 1rem; line-height: 1.6; }
.wrong-answers-row { display: flex; gap: 1rem; flex-wrap: wrap; margin-bottom: .75rem; }
.answer-badge {
  font-size: .8rem; padding: .3rem .75rem; border-radius: var(--radius);
  font-weight: 600; display: flex; align-items: center; gap: .3rem;
}
.answer-badge.your-wrong { background: rgba(239,68,68,.12); border: 1px solid rgba(239,68,68,.3); color: var(--danger); }
.answer-badge.correct-ans { background: rgba(34,197,94,.12); border: 1px solid rgba(34,197,94,.3); color: var(--success); }
.wrong-explanation {
  font-size: .85rem; color: var(--text2); line-height: 1.65;
  background: var(--bg3); border-radius: var(--radius); padding: .75rem 1rem;
  border-left: 3px solid var(--accent);
}

.results-footer-actions {
  display: flex; gap: 1rem; justify-content: center; padding: 2rem 0;
}

/* ═══════════════════════════════════════════════
   MODAL
═══════════════════════════════════════════════ */
.modal-overlay {
  position: fixed; inset: 0; background: rgba(0,0,0,.7);
  z-index: 1000; display: flex; align-items: center; justify-content: center;
}
.modal-box {
  background: var(--card); border: 1px solid var(--border2);
  border-radius: var(--radius-lg); padding: 2rem;
  max-width: 440px; width: 90%; box-shadow: var(--shadow);
}
.modal-title { font-size: 1.15rem; font-weight: 700; margin-bottom: .75rem; }
.modal-body  { font-size: .92rem; color: var(--text2); margin-bottom: 1.5rem; line-height: 1.6; }
.modal-actions { display: flex; gap: .75rem; justify-content: flex-end; }

/* ═══════════════════════════════════════════════
   SCROLLBARS (global)
═══════════════════════════════════════════════ */
::-webkit-scrollbar { width: 6px; height: 6px; }
::-webkit-scrollbar-track { background: transparent; }
::-webkit-scrollbar-thumb { background: var(--border); border-radius: 3px; }
::-webkit-scrollbar-thumb:hover { background: var(--border2); }

/* ═══════════════════════════════════════════════
   RESPONSIVE
═══════════════════════════════════════════════ */
@media (max-width: 768px) {
  .exam-sidebar { width: 160px; }
  .question-nav { grid-template-columns: repeat(4, 1fr); }
  .exam-header-left { display: none; }
  .question-card { padding: 1.25rem; }
  .exam-header { padding: 0 .75rem; }
}
@media (max-width: 580px) {
  .exam-sidebar { display: none; }
  .results-body { padding: 1rem; }
}