*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }
.skip-link { position: absolute; left: -9999px; top: auto; width: 1px; height: 1px; overflow: hidden; z-index: 999; }
.skip-link:focus { position: fixed; top: 8px; left: 8px; width: auto; height: auto; padding: 8px 16px; background: var(--accent); color: #fff; border-radius: 8px; font-size: 14px; text-decoration: none; }
:root, [data-theme="dark"] {
  --bg: #0a0e17; --surface: #111827; --surface2: #1a2235; --border: #2a3550;
  --text: #e2e8f0; --text-dim: #8892a8;
  --accent: #3b82f6; --accent-glow: rgba(59,130,246,0.15);
  --correct: #10b981; --correct-bg: rgba(16,185,129,0.08); --correct-border: rgba(16,185,129,0.3);
  --wrong: #ef4444; --wrong-bg: rgba(239,68,68,0.08); --wrong-border: rgba(239,68,68,0.3);
  --orange: #f59e0b; --purple: #a78bfa;
  --code-bg: #0d1117; --code-text: #c9d1d9;
  --radius: 12px;
  --font: 'DM Sans', system-ui, -apple-system, sans-serif;
  --mono: 'JetBrains Mono', 'Fira Code', ui-monospace, SFMono-Regular, 'SF Mono', Menlo, Monaco, Consolas, 'Liberation Mono', 'Courier New', monospace;
  --display: 'Fraunces', Georgia, serif;
  --hero-overlay: radial-gradient(ellipse at 50% 0%, var(--accent-glow) 0%, transparent 60%), radial-gradient(ellipse at 20% 50%, rgba(255,212,59,0.04) 0%, transparent 50%);
  --heading-color: #fff;
  --toggle-bg: var(--surface2);
}
[data-theme="light"] {
  --bg: #f5f7fa; --surface: #ffffff; --surface2: #eef1f6; --border: #d1d9e6;
  --text: #1e293b; --text-dim: #64748b;
  --accent: #2563eb; --accent-glow: rgba(37,99,235,0.1);
  --correct: #059669; --correct-bg: rgba(5,150,105,0.08); --correct-border: rgba(5,150,105,0.3);
  --wrong: #dc2626; --wrong-bg: rgba(220,38,38,0.06); --wrong-border: rgba(220,38,38,0.3);
  --orange: #92400e; --purple: #6d28d9;
  --code-bg: #f0f2f5; --code-text: #24292f;
  --hero-overlay: radial-gradient(ellipse at 50% 0%, rgba(37,99,235,0.06) 0%, transparent 60%), radial-gradient(ellipse at 20% 50%, rgba(255,212,59,0.03) 0%, transparent 50%);
  --heading-color: #0f172a;
  --toggle-bg: #d1d9e6;
}
[data-theme="light"] .code-block .kw { color: #cf222e; }
[data-theme="light"] .code-block .str { color: #0a3069; }
[data-theme="light"] .code-block .cmt { color: #6e7781; font-style: italic; }
[data-theme="light"] .code-block .fn { color: #8250df; }
[data-theme="light"] .code-block .bi { color: #0550ae; }
[data-theme="light"] .code-block .num { color: #0550ae; }
[data-theme="light"] .code-block .dec { color: #953800; }
html { scroll-behavior: smooth; }
body { font-family: var(--font); background: var(--bg); color: var(--text); line-height: 1.6; min-height: 100vh; -webkit-font-smoothing: antialiased; }

/* HERO */
.hero { position: relative; padding: 70px 24px 50px; text-align: center; overflow: hidden; }
.hero::before { content: ''; position: absolute; top: -50%; left: -10%; width: 120%; height: 200%; background: var(--hero-overlay); pointer-events: none; }
.hero-label { display: inline-block; padding: 6px 16px; background: var(--accent-glow); border: 1px solid rgba(59,130,246,0.25); border-radius: 100px; font-size: 13px; font-weight: 600; color: var(--accent); letter-spacing: 0.05em; text-transform: uppercase; margin-bottom: 24px; position: relative; }
.hero h1 { font-family: var(--display); font-size: clamp(2rem, 5vw, 3.2rem); font-weight: 900; line-height: 1.1; color: var(--heading-color); margin-bottom: 16px; position: relative; }
.hero h1 .hl { color: var(--accent); }
.hero p { font-size: 16px; color: var(--text-dim); max-width: 640px; margin: 0 auto 28px; position: relative; line-height: 1.7; }
.hero-stats { display: flex; justify-content: center; gap: 28px; position: relative; flex-wrap: wrap; }
.hero-stat { text-align: center; }
.hero-stat-value { font-family: var(--display); font-size: 26px; font-weight: 900; color: var(--heading-color); }
.hero-stat-label { font-size: 11px; color: var(--text-dim); text-transform: uppercase; letter-spacing: 0.08em; }

/* STICKY NAV BAR */
.exam-nav { position: sticky; top: 0; z-index: 200; background: var(--bg); border-bottom: 2px solid var(--border); padding: 0; display: none; }
.exam-nav.visible { display: block; }
.exam-nav-inner { max-width: 900px; margin: 0 auto; padding: 8px 24px; display: flex; align-items: center; gap: 8px; }
.exam-nav-back { background: none; border: none; color: var(--text-dim); font-size: 18px; cursor: pointer; padding: 4px 8px; border-radius: 6px; transition: color 0.2s; }
.exam-nav-back:hover { color: var(--text); }
.exam-nav-title { font-family: var(--display); font-size: 15px; font-weight: 700; color: var(--heading-color); margin-right: 8px; white-space: nowrap; }
.exam-nav-modes { display: flex; gap: 4px; flex: 1; }
.exam-nav-mode { flex: 1; text-align: center; padding: 7px 8px; background: var(--surface); border: 1px solid var(--border); border-radius: 8px; font-family: var(--font); font-size: 12px; font-weight: 600; color: var(--text-dim); cursor: pointer; transition: all 0.2s; white-space: nowrap; }
.exam-nav-mode:hover { color: var(--text); border-color: var(--text-dim); }
.exam-nav-mode.active { background: var(--accent-glow); border-color: var(--accent); color: var(--accent); }

/* VENDOR SECTIONS */
.vendor-section { max-width: 900px; margin: 0 auto 40px; padding: 0 24px; }
.vendor-header { display: flex; align-items: center; gap: 12px; margin-bottom: 16px; }
.vendor-icon { width: 36px; height: 36px; border-radius: 10px; display: flex; align-items: center; justify-content: center; font-size: 18px; font-weight: 900; color: #fff; }
.vendor-name { font-family: var(--display); font-size: 20px; font-weight: 900; color: var(--heading-color); }
.vendor-grid { display: grid; grid-template-columns: repeat(auto-fit, minmax(320px, 1fr)); gap: 16px; }

/* EXAM CARDS */
.exam-card { background: var(--surface); border: 2px solid var(--border); border-radius: 16px; padding: 28px 24px; cursor: pointer; transition: all 0.3s; position: relative; overflow: hidden; }
.exam-card::before { content: ''; position: absolute; top: 0; left: 0; right: 0; height: 4px; }
.exam-card:hover { transform: translateY(-4px); box-shadow: 0 12px 40px rgba(0,0,0,0.3); }
.exam-card-badge { display: inline-block; padding: 4px 12px; border-radius: 6px; font-size: 11px; font-weight: 700; text-transform: uppercase; letter-spacing: 0.06em; margin-bottom: 10px; }
.exam-card h3 { font-family: var(--display); font-size: 20px; font-weight: 900; color: var(--heading-color); margin-bottom: 4px; }
.exam-card .subtitle { font-size: 13px; color: var(--text-dim); margin-bottom: 14px; line-height: 1.5; }
.exam-card-stats { display: flex; gap: 14px; flex-wrap: wrap; }
.exam-card-stat { font-size: 13px; color: var(--text-dim); }
.exam-card-stat strong { color: var(--text); }
.exam-card-progress { margin-top: 12px; font-size: 12px; color: var(--correct); font-weight: 600; }

/* MODE SELECTOR */
.mode-selector { max-width: 840px; margin: 0 auto 20px; padding: 0 24px; text-align: center; }
.mode-selector h2 { font-family: var(--display); font-size: 22px; color: var(--heading-color); margin-bottom: 16px; }
.mode-cards { display: grid; grid-template-columns: repeat(auto-fit, minmax(280px, 1fr)); gap: 16px; }
.mode-card { background: var(--surface); border: 2px solid var(--border); border-radius: 16px; padding: 28px 24px; cursor: pointer; transition: all 0.3s; text-align: center; position: relative; overflow: hidden; }
.mode-card::before { content: ''; position: absolute; top: 0; left: 0; right: 0; height: 4px; background: linear-gradient(90deg, var(--accent), var(--purple)); }
.mode-card:hover { transform: translateY(-4px); box-shadow: 0 12px 40px rgba(0,0,0,0.3); border-color: var(--accent); }
.mode-card-icon { font-size: 40px; margin-bottom: 10px; }
.mode-card-title { font-family: var(--display); font-size: 18px; font-weight: 900; color: var(--heading-color); margin-bottom: 6px; }
.mode-card-desc { font-size: 13px; color: var(--text-dim); line-height: 1.5; }

/* STRATEGY BOX */
.strategy-box { max-width: 840px; margin: 0 auto 20px; padding: 0 24px; }
.strategy-inner { background: linear-gradient(135deg, rgba(59,130,246,0.06), rgba(167,139,250,0.06)); border: 1px solid rgba(59,130,246,0.2); border-radius: 14px; padding: 24px 28px; }
.strategy-inner h3 { font-family: var(--display); font-size: 17px; color: var(--orange); margin-bottom: 10px; }
.strategy-inner p { font-size: 13.5px; color: var(--text-dim); line-height: 1.7; margin-bottom: 6px; }
.strategy-inner strong { color: var(--text); }
.tip { display: inline-block; background: rgba(255,212,59,0.12); border: 1px solid rgba(255,212,59,0.2); border-radius: 6px; padding: 2px 8px; font-size: 11px; font-weight: 700; color: var(--orange); text-transform: uppercase; letter-spacing: 0.06em; margin-right: 6px; }

/* TEST SELECTOR */
.test-selector { max-width: 840px; margin: 30px auto; padding: 0 24px; }
.test-group-label { font-family: var(--display); font-size: 16px; color: var(--text-dim); margin: 24px 0 12px; padding-left: 4px; }
.test-group-label:first-child { margin-top: 0; }
.test-grid { display: grid; grid-template-columns: repeat(auto-fill, minmax(150px, 1fr)); gap: 14px; }
.test-card { background: var(--surface); border: 1px solid var(--border); border-radius: var(--radius); padding: 20px; cursor: pointer; transition: all 0.3s; text-align: center; }
.test-card:hover { border-color: var(--accent); background: rgba(59,130,246,0.04); transform: translateY(-2px); }
.test-card.completed { border-color: var(--correct-border); }
.test-card.in-progress { border-color: rgba(245,158,11,0.45); }
.test-card-num { font-family: var(--display); font-size: 32px; font-weight: 900; color: var(--accent); }
.test-card.completed .test-card-num { color: var(--correct); }
.test-card.in-progress .test-card-num { color: var(--orange); }
.test-card-label { font-size: 12px; color: var(--text-dim); margin-top: 4px; }
.test-card-score { font-size: 12px; color: var(--correct); margin-top: 6px; font-weight: 600; display: none; }
.test-card-score.visible { display: block; }
.test-card-score.in-progress { color: var(--orange); }
.hard-badge { display: inline-block; background: rgba(239,68,68,0.12); border: 1px solid rgba(239,68,68,0.25); border-radius: 4px; padding: 1px 6px; font-size: 10px; font-weight: 700; color: var(--wrong); text-transform: uppercase; letter-spacing: 0.05em; margin-left: 4px; }

/* TABS */
.tab-bar { display: flex; gap: 4px; max-width: 840px; margin: 30px auto 0; padding: 0 24px; border-bottom: 2px solid var(--border); }
.tab-btn { padding: 10px 20px; background: var(--surface); border: 2px solid var(--border); border-bottom: 2px solid var(--border); border-radius: 10px 10px 0 0; font-family: var(--font); font-size: 13px; font-weight: 600; color: var(--text-dim); cursor: pointer; transition: all 0.2s; margin-bottom: -2px; }
.tab-btn:hover { color: var(--text); border-color: var(--text-dim); }
.tab-btn.active { background: var(--surface2); color: var(--accent); border-color: var(--accent); border-bottom-color: var(--surface2); }
.tab-content { max-width: 840px; margin: 0 auto; padding: 0 24px; }
.tab-panel { display: none; }
.tab-panel.active { display: block; }

/* STUDY GUIDE */
.study-content { background: var(--surface); border: 2px solid var(--border); border-radius: var(--radius); padding: 28px; margin-top: 20px; }
.study-content h3 { font-family: var(--display); font-size: 18px; color: var(--heading-color); margin: 24px 0 12px; }
.study-content h3:first-child { margin-top: 0; }
.study-content p { font-size: 14px; color: var(--text-dim); line-height: 1.7; margin-bottom: 10px; }
.study-content ul { margin: 8px 0 16px 20px; }
.study-content li { font-size: 13.5px; color: var(--text-dim); line-height: 1.6; margin-bottom: 4px; }
.study-content li strong { color: var(--text); }
.study-content code { font-family: var(--mono); font-weight: 700; letter-spacing: 0.06em; font-size: 1.05em; background: transparent; padding: 0 1px; border: 0; color: inherit; font-variant-ligatures: none; }

/* PROGRESS BAR */
/* THEME TOGGLE */
.theme-toggle { position: fixed; top: 16px; right: 16px; z-index: 300; width: 44px; height: 44px; border-radius: 50%; border: 1px solid var(--border); background: var(--surface); color: var(--text); font-size: 20px; cursor: pointer; display: flex; align-items: center; justify-content: center; transition: all 0.3s; box-shadow: 0 2px 8px rgba(0,0,0,0.15); }
.theme-toggle:hover { border-color: var(--accent); transform: scale(1.1); }

.progress-bar-container { position: sticky; top: 0; z-index: 100; background: color-mix(in srgb, var(--bg) 92%, transparent); -webkit-backdrop-filter: blur(12px); backdrop-filter: blur(12px); border-bottom: 1px solid var(--border); padding: 12px 24px; display: none; }
.progress-bar-container.visible { display: block; }
.progress-inner { max-width: 840px; margin: 0 auto; display: flex; align-items: center; gap: 16px; }
.progress-track { flex: 1; height: 6px; background: var(--surface2); border-radius: 3px; overflow: hidden; }
.progress-fill { height: 100%; background: linear-gradient(90deg, var(--accent), var(--purple)); border-radius: 3px; transition: width 0.4s ease; width: 0%; }
.progress-text { font-size: 13px; font-weight: 600; color: var(--text-dim); white-space: nowrap; min-width: 80px; text-align: right; }
.timer-display { font-family: var(--mono); font-size: 14px; font-weight: 600; color: var(--orange); min-width: 65px; text-align: center; }
.timer-display.warning { color: var(--wrong); animation: pulse 1s infinite; }
@keyframes pulse { 0%, 100% { opacity: 1; } 50% { opacity: 0.5; } }

/* EXAM CONTAINER */
.exam-container { max-width: 840px; margin: 0 auto; padding: 0 24px 120px; }

/* SECTION DIVIDERS */
.section-divider { margin: 48px 0 32px; padding: 24px 28px; background: var(--surface); border: 1px solid var(--border); border-left: 4px solid var(--accent); border-radius: var(--radius); }
.section-divider h2 { font-family: var(--display); font-size: 20px; font-weight: 700; color: var(--heading-color); margin-bottom: 4px; }
.section-divider p { font-size: 13.5px; color: var(--text-dim); }
.badge { display: inline-block; padding: 3px 10px; background: var(--accent-glow); border: 1px solid rgba(59,130,246,0.2); border-radius: 6px; font-size: 12px; font-weight: 600; color: var(--accent); margin-top: 8px; }

/* QUESTION CARDS */
.question-card { background: var(--surface); border: 1px solid var(--border); border-radius: var(--radius); margin-bottom: 24px; overflow: hidden; transition: border-color 0.3s; }
.question-card.answered-correct { border-color: var(--correct-border); }
.question-card.answered-wrong { border-color: var(--wrong-border); }
.question-header { padding: 20px 24px 0; display: flex; gap: 14px; align-items: flex-start; }
.q-number { flex-shrink: 0; width: 36px; height: 36px; display: flex; align-items: center; justify-content: center; background: var(--surface2); border: 1px solid var(--border); border-radius: 10px; font-weight: 700; font-size: 14px; color: var(--text-dim); transition: all 0.3s; }
.answered-correct .q-number { background: var(--correct-bg); border-color: var(--correct-border); color: var(--correct); }
.answered-wrong .q-number { background: var(--wrong-bg); border-color: var(--wrong-border); color: var(--wrong); }
.q-meta { display: flex; gap: 8px; margin: 8px 24px 0; flex-wrap: wrap; }
.q-domain-tag { font-size: 11px; padding: 2px 8px; background: var(--accent-glow); border: 1px solid rgba(59,130,246,0.2); border-radius: 5px; color: var(--accent); font-weight: 600; }
/* In light mode, domain tags come with inline colors that can be bright
   (e.g., #ffd43b "Strings"). Force a legible dark text color and a muted
   background so the tag stays readable against white. The domain's hue
   is still hinted via the inline border-color. */
[data-theme="light"] .q-domain-tag { color: var(--text) !important; background: var(--surface2) !important; }
.q-text { font-size: 15px; font-weight: 500; color: var(--text); padding-top: 6px; flex: 1; }

/* CODE & SCENARIO BLOCKS */
.code-block { background: var(--code-bg); border: 1px solid #21262d; border-radius: 8px; padding: 16px 20px; margin: 14px 24px 4px; overflow-x: auto; font-family: var(--mono); font-size: 15px; line-height: 1.75; color: var(--code-text); white-space: pre; font-variant-ligatures: none; }
.code-block .kw { color: #ff7b72; }
.code-block .str { color: #a5d6ff; }
.code-block .cmt { color: #8b949e; font-style: italic; }
.code-block .fn { color: #d2a8ff; }
.code-block .bi { color: #79c0ff; }
.code-block .num { color: #79c0ff; }
.code-block .dec { color: #ffa657; }
.code-block .op { color: #ff7b72; }
/* Dunders: same color as surrounding code — just bolder + wider letter-spacing so underscores are legible. */
.code-block .du, .code-block .str .du-in { font-weight: 600; letter-spacing: 0.04em; }
.scenario-block { background: var(--surface2); border: 1px solid var(--border); border-radius: 8px; padding: 16px 20px; margin: 14px 24px 4px; font-family: var(--mono); font-size: 13px; line-height: 1.7; color: var(--text-dim); white-space: pre-wrap; }

/* OPTIONS */
.options { padding: 14px 24px 18px; padding-left: 74px; display: flex; flex-direction: column; gap: 8px; }
.option { display: flex; align-items: flex-start; gap: 12px; padding: 11px 14px; background: var(--surface2); border: 1px solid transparent; border-radius: 10px; cursor: pointer; transition: all 0.2s; -webkit-tap-highlight-color: transparent; }
.option:hover { border-color: var(--border); background: rgba(59,130,246,0.04); }
.option:focus { outline: 2px solid var(--accent); outline-offset: 2px; }
.option:focus-visible { outline: 2px solid var(--accent); outline-offset: 2px; }
.option.selected { border-color: var(--accent); background: var(--accent-glow); }
.option.correct-answer { border-color: var(--correct-border); background: var(--correct-bg); }
.option.wrong-answer { border-color: var(--wrong-border); background: var(--wrong-bg); }
.option.disabled { pointer-events: none; }
.option-letter { flex-shrink: 0; width: 28px; height: 28px; display: flex; align-items: center; justify-content: center; border-radius: 8px; border: 1.5px solid var(--border); font-weight: 600; font-size: 13px; color: var(--text-dim); transition: all 0.2s; }
.option.selected .option-letter { border-color: var(--accent); color: var(--accent); background: rgba(59,130,246,0.1); }
.option.correct-answer .option-letter { border-color: var(--correct); color: var(--correct); background: var(--correct-bg); }
.option.wrong-answer .option-letter { border-color: var(--wrong); color: var(--wrong); background: var(--wrong-bg); }
/* Prose options use --font; pure code-output options (multiline) stay mono. */
.option-text { font-size: 14px; color: var(--text); padding-top: 3px; font-family: var(--font); line-height: 1.5; }
.option.code-option .option-text { font-family: var(--mono); line-height: 1.4; white-space: pre-line; }
/* Dunders (wrapped in <code>) in question text, options, and explanation:
   mono font, bold weight, wider letter-spacing, slightly larger than surrounding
   text — same color, no background. This makes double underscores unmistakably
   legible against prose. */
.question-card code,
.option-text code,
.q-text code,
.explanation code {
  font-family: var(--mono) !important;
  font-weight: 700 !important;
  letter-spacing: 0.06em !important;
  background: transparent !important;
  padding: 0 1px !important;
  border: 0 !important;
  color: inherit !important;
  font-size: 1.05em !important;
  font-variant-ligatures: none !important;
  font-feature-settings: "liga" 0, "calt" 0 !important;
}
/* Fenced/indented code blocks inside question and option prose. */
.q-code-block { font-family: var(--mono); font-size: 13.5px; line-height: 1.6; background: var(--code-bg); color: var(--code-text); border: 1px solid #21262d; border-radius: 8px; padding: 12px 16px; margin: 8px 0; white-space: pre-wrap; overflow-x: auto; font-variant-ligatures: none; }
.opt-sep { color: var(--text-dim); font-family: var(--mono); font-size: 11px; }
.multi-select-badge { display: inline-block; background: rgba(167,139,250,0.15); border: 1px solid rgba(167,139,250,0.3); border-radius: 6px; padding: 2px 10px; font-size: 11px; font-weight: 700; color: var(--purple); text-transform: uppercase; letter-spacing: 0.05em; margin-left: 8px; }
.option.multi .option-letter { border-radius: 4px; }

/* EXPLANATION */
.explanation { display: none; margin: 0 24px 20px; padding: 16px 20px; border-radius: 10px; font-size: 13.5px; line-height: 1.7; color: var(--text); }
.explanation.visible { display: block; }
.explanation.correct-exp { background: var(--correct-bg); border: 1px solid var(--correct-border); }
.explanation.wrong-exp { background: rgba(251,191,36,0.10); border: 1px solid rgba(251,191,36,0.40); }
.explanation strong { color: var(--heading-color); }

/* SUBMIT & RESULTS */
.submit-area { text-align: center; margin: 48px 0; }
.submit-btn { display: inline-flex; align-items: center; gap: 10px; padding: 16px 48px; background: linear-gradient(135deg, var(--accent), #6366f1); color: #fff; border: none; border-radius: 14px; font-family: var(--font); font-size: 17px; font-weight: 700; cursor: pointer; transition: all 0.3s; box-shadow: 0 4px 24px rgba(59,130,246,0.25); }
.submit-btn:hover { transform: translateY(-2px); box-shadow: 0 8px 32px rgba(59,130,246,0.35); }
.submit-btn:disabled { opacity: 0.4; cursor: not-allowed; transform: none; box-shadow: none; }
.multi-submit-area { margin: 16px 0 8px; }
.multi-submit-btn { display: inline-flex; align-items: center; gap: 8px; padding: 10px 28px; background: linear-gradient(135deg, var(--purple), var(--accent)); color: #fff; border: none; border-radius: 10px; font-family: var(--font); font-size: 14px; font-weight: 700; cursor: pointer; transition: all 0.2s; box-shadow: 0 2px 12px rgba(167,139,250,0.25); }
.multi-submit-btn:hover:not(:disabled) { transform: translateY(-1px); box-shadow: 0 4px 18px rgba(167,139,250,0.35); }
.multi-submit-btn:disabled { opacity: 0.35; cursor: not-allowed; transform: none; box-shadow: none; }

/* FLASHCARD */
.flashcard-wrap { max-width: 640px; margin: 0 auto; padding: 0 24px; }
.flashcard { box-sizing: border-box; min-height: 250px; max-height: min(70vh, 620px); background: var(--surface); border: 2px solid var(--border); border-radius: var(--radius); padding: 32px; cursor: pointer; transition: border-color 0.3s; overflow-y: auto; overflow-wrap: break-word; display: flex; flex-direction: column; align-items: stretch; justify-content: center; }
.flashcard.flipped { border-color: var(--accent); justify-content: flex-start; }
.flashcard-inner { width: 100%; text-align: center; }
.flashcard-back .flashcard-hint { text-align: center; }
.flashcard-hint { font-size: 11px; color: var(--text-dim); text-transform: uppercase; letter-spacing: 0.08em; margin-bottom: 12px; }
.flashcard-front { font-family: var(--display); font-size: 22px; font-weight: 700; color: var(--heading-color); }
.flashcard-meta { font-size: 13px; color: var(--text-dim); margin-top: 8px; }
.flashcard-back-body { text-align: left; font-size: 14px; line-height: 1.7; color: var(--text); }
.flashcard-back-body pre, .flashcard-back-body code { white-space: pre-wrap; word-break: break-word; }
.flashcard-back-body img { max-width: 100%; height: auto; }
@media (max-width: 640px) {
  .flashcard-wrap { padding: 0 14px; }
  .flashcard { padding: 20px; max-height: min(75vh, 520px); }
  .flashcard-front { font-size: 18px; }
  .flashcard-back-body { font-size: 13px; }
}
.back-btn { display: inline-flex; align-items: center; gap: 8px; padding: 10px 24px; background: var(--surface2); border: 1px solid var(--border); border-radius: 10px; color: var(--text); font-family: var(--font); font-size: 14px; font-weight: 600; cursor: pointer; transition: all 0.2s; margin-right: 16px; }
.back-btn:hover { border-color: var(--accent); color: var(--accent); }

.results-panel { display: none; background: var(--surface); border: 1px solid var(--border); border-radius: 16px; padding: 40px; margin: 48px 0; text-align: center; }
.results-panel.visible { display: block; }
.results-score { font-family: var(--display); font-size: 72px; font-weight: 900; line-height: 1; margin-bottom: 8px; }
.results-score.pass { color: var(--correct); }
.results-score.fail { color: var(--wrong); }
.results-label { font-size: 18px; color: var(--text-dim); margin-bottom: 24px; }
.results-breakdown { display: flex; justify-content: center; gap: 40px; margin: 24px 0; flex-wrap: wrap; }
.results-item { text-align: center; }
.results-item-value { font-size: 28px; font-weight: 700; }
.results-item-label { font-size: 13px; color: var(--text-dim); text-transform: uppercase; letter-spacing: 0.06em; }
.results-item.correct .results-item-value { color: var(--correct); }
.results-item.wrong .results-item-value { color: var(--wrong); }
.results-item.skipped .results-item-value { color: var(--text-dim); }
.results-sections { margin-top: 32px; text-align: left; }
.results-sections h3 { font-size: 16px; font-weight: 700; color: var(--heading-color); margin-bottom: 16px; }
.section-score-row { display: flex; justify-content: space-between; align-items: center; padding: 10px 0; border-bottom: 1px solid var(--border); font-size: 14px; }
.section-score-bar { width: 120px; height: 6px; background: var(--surface2); border-radius: 3px; overflow: hidden; margin-left: 12px; }
.section-score-fill { height: 100%; border-radius: 3px; transition: width 0.6s ease; }
.section-score-fill.good { background: var(--correct); }
.section-score-fill.mid { background: var(--orange); }
.section-score-fill.bad { background: var(--wrong); }
.retry-btn { margin-top: 32px; padding: 12px 36px; background: var(--surface2); border: 1px solid var(--border); border-radius: 10px; color: var(--text); font-family: var(--font); font-size: 15px; font-weight: 600; cursor: pointer; transition: all 0.2s; }
.retry-btn:hover { border-color: var(--accent); color: var(--accent); }

/* LOADING */
.loading { text-align: center; padding: 80px 24px; }
.loading-spinner { width: 48px; height: 48px; border: 3px solid var(--border); border-top-color: var(--accent); border-radius: 50%; animation: spin 0.8s linear infinite; margin: 0 auto 20px; }
@keyframes spin { to { transform: rotate(360deg); } }
.loading-text { color: var(--text-dim); font-size: 15px; }
.error-msg { color: var(--wrong); background: var(--wrong-bg); border: 1px solid var(--wrong-border); border-radius: var(--radius); padding: 20px; margin: 40px auto; max-width: 500px; text-align: center; }

/* PBQ SIMULATIONS */
.pbq-card { background: var(--surface); border: 1px solid var(--border); border-radius: var(--radius); margin-bottom: 24px; overflow: hidden; transition: border-color 0.3s; }
.pbq-card.answered-correct { border-color: var(--correct-border); }
.pbq-card.answered-wrong { border-color: var(--wrong-border); }
.pbq-header { padding: 20px 24px 12px; display: flex; gap: 14px; align-items: flex-start; }
.pbq-label { display: inline-flex; align-items: center; gap: 6px; padding: 3px 10px; background: rgba(245,158,11,0.12); border: 1px solid rgba(245,158,11,0.25); border-radius: 6px; font-size: 11px; font-weight: 700; color: var(--orange); text-transform: uppercase; letter-spacing: 0.05em; margin-bottom: 8px; }
.pbq-instructions { margin: 0 24px 16px; padding: 14px 18px; background: rgba(245,158,11,0.04); border: 1px solid rgba(245,158,11,0.15); border-radius: 10px; font-size: 13.5px; line-height: 1.7; color: var(--text-dim); }
.pbq-instructions strong { color: var(--text); }
.pbq-body { padding: 0 24px 20px; }
.pbq-explanation { display: none; margin: 0 24px 20px; padding: 16px 20px; border-radius: 10px; font-size: 13.5px; line-height: 1.7; color: var(--text); }
.pbq-explanation.visible { display: block; }
.pbq-explanation.correct-exp { background: var(--correct-bg); border: 1px solid var(--correct-border); }
.pbq-explanation.wrong-exp { background: rgba(251,191,36,0.10); border: 1px solid rgba(251,191,36,0.40); }
.pbq-explanation strong { color: var(--heading-color); }
.pbq-explanation code { font-family: var(--mono); background: rgba(255,255,255,0.08); padding: 1px 6px; border-radius: 4px; font-size: 12px; }

/* DRAG & DROP */
.drag-bank { display: flex; gap: 8px; flex-wrap: wrap; justify-content: center; padding: 16px; background: var(--code-bg); border: 1px solid #21262d; border-radius: 10px; margin-bottom: 16px; min-height: 56px; }
.drag-item { padding: 8px 16px; background: linear-gradient(135deg, var(--accent-glow), rgba(99,102,241,0.1)); border: 1px solid rgba(59,130,246,0.3); border-radius: 8px; font-size: 13px; font-weight: 600; color: var(--accent); cursor: grab; user-select: none; transition: all 0.2s; white-space: nowrap; touch-action: none; }
.drag-item:active { cursor: grabbing; }
.drag-item.dragging { opacity: 0.5; transform: scale(0.95); }
.drag-item.placed { background: rgba(59,130,246,0.08); border-color: rgba(59,130,246,0.2); cursor: grab; }
.drag-item.correct-item { background: var(--correct-bg); border-color: var(--correct-border); color: var(--correct); cursor: default; }
.drag-item.wrong-item { background: var(--wrong-bg); border-color: var(--wrong-border); color: var(--wrong); text-decoration: line-through; cursor: default; }
.drop-zone { min-height: 52px; background: var(--surface2); border: 2px dashed var(--border); border-radius: 10px; padding: 10px; display: flex; align-items: center; justify-content: center; gap: 8px; flex-wrap: wrap; transition: all 0.2s; }
.drop-zone.drag-over { border-color: var(--accent); background: var(--accent-glow); }
.drop-zone.correct-zone { border-color: var(--correct-border); background: var(--correct-bg); border-style: solid; }
.drop-zone.wrong-zone { border-color: var(--wrong-border); background: var(--wrong-bg); border-style: solid; }
.drop-zone .placeholder { font-size: 12px; color: var(--text-dim); font-style: italic; }

/* DEVICE PANEL */
.dev-panel { display: none; background: var(--code-bg); border-top: 2px solid var(--border); max-height: 260px; overflow-y: auto; }
.dev-panel.open { display: block; }
.dev-panel-tabs { display: flex; background: var(--surface2); border-bottom: 1px solid var(--border); flex-wrap: wrap; }
.dev-panel-tab { padding: 8px 16px; font-size: 11px; font-weight: 600; color: var(--text-dim); cursor: pointer; border-bottom: 2px solid transparent; text-transform: uppercase; letter-spacing: 0.04em; transition: all 0.2s; }
.dev-panel-tab:hover { color: var(--text); }
.dev-panel-tab.active { color: var(--accent); border-bottom-color: var(--accent); }
.dev-panel-close { padding: 8px 14px; font-size: 11px; color: var(--text-dim); cursor: pointer; margin-left: auto; }
.dev-panel-close:hover { color: var(--wrong); }
.dev-panel-content { padding: 12px 16px; font-family: var(--mono); font-size: 12px; line-height: 1.65; color: var(--code-text); white-space: pre-wrap; }
.dev-panel-content .prompt { color: var(--accent); font-weight: 600; }
.dev-panel-content .ok { color: var(--correct); }
.dev-panel-content .er { color: var(--wrong); }
.dev-panel-content .warn { color: var(--orange); }
.dev-panel-content .dim { color: var(--text-dim); }


/* ACL TABLE */
.acl-table { width: 100%; border-collapse: collapse; margin-top: 8px; }
.acl-table th { background: rgba(59,130,246,0.12); color: var(--accent); font-size: 11px; font-weight: 700; text-transform: uppercase; letter-spacing: 0.06em; padding: 10px 8px; text-align: left; border-bottom: 2px solid var(--border); }
.acl-table td { padding: 8px; border-bottom: 1px solid var(--border); vertical-align: middle; }
.acl-table .rule-num { font-family: var(--mono); font-weight: 700; color: var(--text-dim); font-size: 13px; text-align: center; width: 40px; }
.acl-select { background: var(--surface2); color: var(--text); border: 1px solid var(--border); border-radius: 6px; padding: 6px 8px; font-family: var(--font); font-size: 12.5px; width: 100%; cursor: pointer; }
.acl-select:focus { border-color: var(--accent); outline: none; }
.acl-select.correct-select { border-color: var(--correct); background: var(--correct-bg); }
.acl-select.wrong-select { border-color: var(--wrong); background: var(--wrong-bg); }
.pbq-select { background: var(--surface); color: var(--text); border: 1px solid var(--border); border-radius: 7px; padding: 8px 12px; font-family: var(--font); font-size: 13px; width: 100%; max-width: 500px; cursor: pointer; }
.pbq-select:focus { border-color: var(--accent); outline: none; }
.pbq-select.cs { border-color: var(--correct); background: var(--correct-bg); }
.pbq-select.ws { border-color: var(--wrong); background: var(--wrong-bg); }

/* PORT MATCH */
.match-row { display: flex; align-items: center; gap: 12px; margin-bottom: 10px; }
.match-left { padding: 10px 14px; background: var(--surface2); border: 1px solid var(--border); border-radius: 8px; font-size: 13px; text-align: center; font-family: var(--mono); font-weight: 600; color: var(--accent); width: 100px; flex-shrink: 0; }
.match-arrow { color: var(--text-dim); font-size: 18px; flex-shrink: 0; }
.match-drop { min-height: 44px; background: var(--surface2); border: 2px dashed var(--border); border-radius: 8px; display: flex; align-items: center; justify-content: center; flex: 1; transition: all 0.2s; }
.match-drop.drag-over { border-color: var(--accent); background: var(--accent-glow); }
.match-drop.correct-zone { border-color: var(--correct-border); background: var(--correct-bg); border-style: solid; }
.match-drop.wrong-zone { border-color: var(--wrong-border); background: var(--wrong-bg); border-style: solid; }
.match-drop .placeholder { font-size: 11px; color: var(--text-dim); font-style: italic; }

/* BACKUP SCHEDULE */
.schedule-row { display: flex; align-items: center; gap: 12px; margin-bottom: 8px; padding: 8px 12px; background: var(--surface2); border-radius: 8px; }
.schedule-day { font-weight: 600; color: var(--text); width: 100px; flex-shrink: 0; }

/* RESPONSIVE */
@media (max-width: 1024px) {
  .vendor-grid { grid-template-columns: repeat(auto-fit, minmax(280px, 1fr)); }
}
@media (max-width: 768px) {
  .hero h1 { font-size: clamp(1.6rem, 4vw, 2.4rem); }
  .tab-bar { flex-wrap: wrap; }
  .tab-btn { flex: 1; min-width: 90px; text-align: center; }
  .results-breakdown { gap: 20px; }
  .section-score-row { flex-wrap: wrap; gap: 6px; }
}
@media (max-width: 640px) {
  .hero { padding: 40px 16px 30px; }
  .hero-stats { gap: 16px; }
  .mode-cards, .vendor-grid { grid-template-columns: 1fr; }
  .test-grid { grid-template-columns: repeat(2, 1fr); }
  .question-header { padding: 14px 14px 0; }
  .code-block, .scenario-block { margin: 10px 14px 4px; padding: 10px 12px; font-size: 12px; }
  .options { padding: 10px 14px 14px; padding-left: 14px; }
  .explanation { margin: 0 14px 14px; }
  .results-panel { padding: 24px; }
  .pbq-body { padding: 0 14px 16px; }
  .pbq-explanation { margin: 0 14px 14px; }
  .acl-table { font-size: 11px; }
  .acl-select { font-size: 11px; padding: 4px 6px; }
  .dev-panel-content { font-size: 11px; }
  .match-row { flex-wrap: wrap; }
  .match-left, .schedule-day { width: auto; min-width: 60px; }
}
@media (max-width: 360px) {
  .test-grid { grid-template-columns: 1fr; }
  .hero-stats { flex-direction: column; gap: 8px; }
  .tab-btn { font-size: 11px; padding: 8px 10px; }
}

/* CABLE TESTER */
.ct-device-wrap { display:flex; justify-content:center; margin-bottom:12px; overflow-x:auto; }
.ct-device-body { background:var(--code-bg); border:2px solid var(--border); border-radius:14px; padding:16px 20px; box-shadow:0 4px 32px rgba(0,0,0,0.2); max-width:460px; width:100%; overflow:hidden; }
.ct-device-title { text-align:center; font-size:9px; font-weight:800; letter-spacing:4px; color:#3b82f6; text-transform:uppercase; margin-bottom:12px; padding-bottom:8px; border-bottom:1px solid #1e293b; }
.ct-wire-view { display:flex; align-items:flex-start; gap:4px; overflow:hidden; }
.ct-pin-side { flex-shrink:0; }
.ct-side-hdr { font-size:9px; font-weight:700; color:#475569; letter-spacing:2px; text-transform:uppercase; text-align:center; margin-bottom:4px; }
.ct-pin-row { display:flex; align-items:center; gap:5px; height:28px; }
.ct-pin-row-r { flex-direction:row-reverse; }
.ct-pin-num { font-family:monospace; font-size:11px; font-weight:700; color:#64748b; width:14px; text-align:center; }
.ct-led { display:inline-block; width:12px; height:12px; border-radius:50%; flex-shrink:0; }
.ct-led-on { background:#22c55e; box-shadow:0 0 8px #22c55e, 0 0 2px #22c55e; }
.ct-led-off { background:var(--surface2); border:1px solid var(--border); }
.ct-led-cross { background:var(--orange); box-shadow:0 0 8px var(--orange); }
.ct-tab-btn { padding:5px 14px; background:var(--surface2); border:1px solid var(--border); border-radius:6px; color:var(--text-dim); font-size:12px; font-weight:600; cursor:pointer; transition:all 0.2s; }
.ct-tab-btn:hover { color:var(--text); border-color:var(--accent); }
.ct-tab-btn.ct-active { background:var(--accent); color:#fff; border-color:var(--accent); }

/* NETWORK DIAGRAM TOPOLOGY */
.nd-topo-wrap { background:var(--surface2); border:1px solid var(--border); border-radius:10px; padding:12px; margin-bottom:14px; overflow-x:auto; }
.nd-topo { display:block; width:100%; max-width:500px; margin:0 auto; }
.nd-node-rect { fill:var(--surface); stroke:var(--border); stroke-width:1.5; rx:8; transition:stroke 0.2s; cursor:pointer; }
.nd-node-rect:hover { stroke:var(--accent); stroke-width:2; }
.nd-node-text { font-size:12px; font-weight:700; fill:var(--text); text-anchor:middle; pointer-events:none; }
.nd-node-sub { font-size:10px; fill:var(--text-dim); text-anchor:middle; pointer-events:none; }
.nd-node-g { cursor:pointer; }
.nd-node-g.nd-active .nd-node-rect { stroke:var(--accent); stroke-width:2.5; filter:drop-shadow(0 0 6px rgba(59,130,246,0.4)); }
.nd-node-g.nd-correct .nd-node-rect { stroke:var(--correct); stroke-width:2.5; }
.nd-node-g.nd-wrong .nd-node-rect { stroke:var(--wrong); stroke-width:2.5; }
.nd-panel { display:none; background:var(--code-bg); border-top:2px solid var(--border); max-height:240px; overflow-y:auto; }
.nd-panel.open { display:block; }
.nd-panel-tabs { display:flex; background:var(--surface2); border-bottom:1px solid var(--border); flex-wrap:wrap; }
.nd-panel-tab { padding:8px 16px; font-size:11px; font-weight:600; color:var(--text-dim); cursor:pointer; border-bottom:2px solid transparent; text-transform:uppercase; letter-spacing:0.04em; }
.nd-panel-tab:hover { color:var(--text); }
.nd-panel-tab.active { color:var(--accent); border-bottom-color:var(--accent); }
.nd-panel-close { padding:8px 14px; font-size:11px; color:var(--text-dim); cursor:pointer; margin-left:auto; }
.nd-panel-close:hover { color:var(--wrong); }
.nd-panel-content { padding:12px 16px; font-family:var(--mono); font-size:12px; line-height:1.65; color:var(--code-text); white-space:pre-wrap; }
.nd-panel-content .prompt { color:var(--accent); font-weight:600; }
.nd-panel-content .ok { color:var(--correct); }
.nd-panel-content .er { color:var(--wrong); }
.nd-panel-content .warn { color:var(--orange); }
.nd-panel-content .dim { color:var(--text-dim); }