:root {
    --night: #07101f;
    --night-2: #0b172a;
    --panel: #101e33;
    --panel-2: #13243d;
    --line: rgba(176, 205, 238, .15);
    --ink: #edf6ff;
    --muted: #9eb0c5;
    --cyan: #34d6e9;
    --cyan-2: #0ea5b7;
    --green: #59dda5;
    --red: #ff7b83;
    --amber: #f6c866;
    --purple: #a88cff;
    --shadow: 0 28px 80px rgba(0, 0, 0, .32);
}

* { box-sizing: border-box; }

html { color-scheme: dark; }

body {
    margin: 0;
    min-height: 100vh;
    color: var(--ink);
    background:
        radial-gradient(circle at 8% 0%, rgba(25, 177, 194, .13), transparent 29rem),
        radial-gradient(circle at 92% 12%, rgba(110, 78, 219, .10), transparent 32rem),
        var(--night);
    font-family: Inter, ui-sans-serif, system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
    line-height: 1.55;
}
.ceh-theme {
    --cyan: #a88cff;
    --cyan-2: #775ce1;
    --green: #68dfc1;
}

button, input { font: inherit; }
a { color: inherit; }
.shell { width: min(1160px, calc(100% - 36px)); margin-inline: auto; }
.topbar { padding: 24px 0; border-bottom: 1px solid var(--line); }
.nav { display: flex; align-items: center; justify-content: space-between; gap: 24px; }
.brand { display: inline-flex; align-items: center; gap: 11px; color: var(--ink); text-decoration: none; font-weight: 850; letter-spacing: -.025em; }
.brand-mark { width: 39px; height: 39px; display: grid; place-items: center; color: #02131b; border-radius: 11px; background: linear-gradient(135deg, var(--cyan), var(--green)); font-size: .72rem; font-weight: 950; box-shadow: 0 10px 28px rgba(52, 214, 233, .18); }
.nav-note { color: var(--muted); font-size: .84rem; font-weight: 650; }
.eyebrow { display: inline-flex; align-items: center; gap: 9px; color: var(--cyan); font-size: .76rem; font-weight: 850; letter-spacing: .1em; text-transform: uppercase; }
.status-dot { width: 7px; height: 7px; border-radius: 50%; background: var(--green); box-shadow: 0 0 14px var(--green); }

.home-hero { padding: 76px 0 42px; }
.home-hero h1 { margin: 18px 0 21px; max-width: 930px; font-size: clamp(3rem, 7vw, 6.6rem); line-height: .94; letter-spacing: -.072em; }
.home-hero h1 span { color: var(--cyan); }
.home-hero p { max-width: 710px; margin: 0; color: var(--muted); font-size: clamp(1rem, 2vw, 1.16rem); }

.subject-grid { display: grid; grid-template-columns: 1.12fr .88fr; gap: 18px; padding: 28px 0 48px; }
.subject-card { position: relative; min-height: 470px; display: flex; flex-direction: column; padding: clamp(24px, 4vw, 38px); overflow: hidden; border: 1px solid var(--line); border-radius: 28px; background: linear-gradient(145deg, rgba(19, 36, 61, .96), rgba(11, 25, 43, .96)); box-shadow: var(--shadow); text-decoration: none; transition: transform .18s ease, border-color .18s ease; }
.subject-card::before { content: ""; position: absolute; inset: auto -12% -48% 35%; height: 340px; border-radius: 50%; background: var(--glow); filter: blur(5px); opacity: .1; pointer-events: none; }
.subject-card:hover { transform: translateY(-4px); border-color: rgba(52, 214, 233, .48); }
.networking-card { --glow: var(--cyan); }
.ceh-card { --glow: var(--purple); }
.ceh-card:hover { border-color: rgba(168, 140, 255, .48); }
.subject-topline { display: flex; justify-content: space-between; align-items: center; gap: 20px; }
.subject-icon { width: 52px; height: 52px; display: grid; place-items: center; border: 1px solid rgba(52, 214, 233, .25); border-radius: 16px; color: var(--cyan); background: rgba(52, 214, 233, .08); font-size: 1.8rem; }
.ceh-card .subject-icon { color: var(--purple); border-color: rgba(168, 140, 255, .25); background: rgba(168, 140, 255, .08); }
.subject-state { padding: 6px 10px; color: #052217; border-radius: 999px; background: var(--green); font-size: .7rem; font-weight: 900; letter-spacing: .05em; text-transform: uppercase; }
.subject-state.muted { color: #e4dbff; background: rgba(168, 140, 255, .18); }
.subject-copy { margin-top: auto; position: relative; z-index: 1; }
.subject-kicker { color: var(--cyan); font-size: .72rem; font-weight: 850; letter-spacing: .12em; text-transform: uppercase; }
.ceh-card .subject-kicker { color: var(--purple); }
.subject-copy h2 { margin: 9px 0 13px; max-width: 540px; font-size: clamp(1.8rem, 4vw, 3.05rem); line-height: 1.05; letter-spacing: -.05em; }
.subject-copy p { max-width: 560px; margin: 0; color: var(--muted); }
.mini-progress { position: relative; z-index: 1; margin-top: 25px; }
.mini-progress-row { display: flex; justify-content: space-between; gap: 18px; margin-bottom: 9px; color: var(--muted); font-size: .8rem; }
.mini-progress-row strong { color: var(--ink); }
.progress-track { height: 7px; overflow: hidden; border-radius: 999px; background: rgba(255,255,255,.08); }
.progress-track > span { display: block; height: 100%; border-radius: inherit; background: linear-gradient(90deg, var(--cyan-2), var(--green)); transition: width .3s ease; }
.ceh-topics { position: relative; z-index: 1; display: flex; flex-wrap: wrap; gap: 7px; margin-top: 25px; }
.ceh-topics span { padding: 6px 9px; color: #cfc3f7; border: 1px solid rgba(168,140,255,.2); border-radius: 7px; background: rgba(168,140,255,.06); font-size: .72rem; font-weight: 700; }
.subject-link { position: relative; z-index: 1; display: flex; align-items: center; justify-content: space-between; margin-top: 28px; padding-top: 19px; border-top: 1px solid var(--line); color: var(--ink); font-size: .9rem; font-weight: 800; }
.subject-link b { color: var(--cyan); font-size: 1.25rem; }
.ceh-card .subject-link b { color: var(--purple); }

.workflow { display: grid; grid-template-columns: repeat(4, 1fr); gap: 1px; overflow: hidden; margin-bottom: 80px; border: 1px solid var(--line); border-radius: 18px; background: var(--line); }
.workflow div { min-height: 118px; display: flex; flex-direction: column; justify-content: space-between; padding: 20px; background: var(--night-2); }
.workflow strong { color: var(--cyan); font-size: .7rem; letter-spacing: .1em; }
.workflow span { color: var(--muted); font-size: .84rem; }
.site-footer { margin-top: auto; padding: 28px 0; color: #74879d; border-top: 1px solid var(--line); font-size: .8rem; }

/* Revision module */
.revision-page { background: var(--night); }
.revision-topbar { padding: 19px 0; border-bottom: 1px solid var(--line); background: rgba(7,16,31,.85); backdrop-filter: blur(16px); }
.back-link { color: var(--muted); text-decoration: none; font-size: .84rem; font-weight: 750; }
.back-link:hover { color: var(--cyan); }
.nav-actions { display: flex; align-items: center; gap: 18px; }
.nav-feature { color: var(--cyan); }
.revision-layout { width: min(1220px, calc(100% - 36px)); display: grid; grid-template-columns: 285px minmax(0, 760px); justify-content: center; gap: 42px; margin: 52px auto 86px; }
.progress-panel { position: sticky; top: 24px; align-self: start; padding: 24px; border: 1px solid var(--line); border-radius: 22px; background: var(--night-2); }
.progress-panel .eyebrow { font-size: .66rem; }
.progress-number { margin: 15px 0 4px; font-size: 2.45rem; line-height: 1; font-weight: 900; letter-spacing: -.055em; }
.progress-caption { margin: 0 0 17px; color: var(--muted); font-size: .8rem; }
.stats-grid { display: grid; grid-template-columns: 1fr 1fr; gap: 8px; margin: 20px 0; }
.stat-box { padding: 12px; border: 1px solid var(--line); border-radius: 11px; background: rgba(255,255,255,.025); }
.stat-box strong { display: block; font-size: 1.1rem; }
.stat-box span { color: var(--muted); font-size: .68rem; text-transform: uppercase; letter-spacing: .06em; }
.level-list { margin-top: 22px; padding-top: 18px; border-top: 1px solid var(--line); }
.level-row { display: grid; grid-template-columns: 22px 1fr auto; align-items: center; gap: 8px; padding: 6px 0; color: var(--muted); font-size: .75rem; }
.level-row .level-index { color: var(--cyan); font-family: ui-monospace, SFMono-Regular, Menlo, monospace; }
.level-row.active { color: var(--ink); }
.current-module-card { margin-top: 22px; padding-top: 18px; border-top: 1px solid var(--line); }
.current-module-card span { display: block; color: var(--muted); font-size: .66rem; font-weight: 800; letter-spacing: .07em; text-transform: uppercase; }
.current-module-card strong { display: block; margin: 7px 0 4px; font-size: .82rem; line-height: 1.35; }
.current-module-card small { display: block; color: var(--cyan); font-size: .68rem; line-height: 1.4; }
.danger-link { width: 100%; margin-top: 20px; padding: 10px; color: #bd8e94; border: 1px solid rgba(255,123,131,.16); border-radius: 10px; background: transparent; cursor: pointer; font-size: .75rem; font-weight: 750; }
.danger-link:hover { color: var(--red); border-color: rgba(255,123,131,.4); }
.question-stage { min-width: 0; }
.stage-head { margin-bottom: 23px; }
.stage-head h1 { margin: 8px 0 7px; font-size: clamp(2rem, 5vw, 3.6rem); line-height: 1; letter-spacing: -.055em; }
.stage-head p { margin: 0; color: var(--muted); }
.question-card { padding: clamp(23px, 5vw, 40px); border: 1px solid var(--line); border-radius: 25px; background: linear-gradient(145deg, var(--panel-2), #0d1b2f); box-shadow: var(--shadow); }
.question-meta { display: flex; flex-wrap: wrap; align-items: center; gap: 7px; margin-bottom: 20px; }
.pill { padding: 5px 9px; color: var(--cyan); border: 1px solid rgba(52,214,233,.18); border-radius: 999px; background: rgba(52,214,233,.07); font-size: .67rem; font-weight: 850; letter-spacing: .04em; text-transform: uppercase; }
.pill.neutral { color: var(--muted); border-color: var(--line); background: rgba(255,255,255,.025); }
.question-text { margin: 0 0 26px; font-size: clamp(1.15rem, 3vw, 1.55rem); line-height: 1.44; letter-spacing: -.02em; }
.answers { display: grid; gap: 10px; }
.answer-option { display: grid; grid-template-columns: 31px 1fr; align-items: start; gap: 12px; margin: 0; padding: 15px; color: #d9e7f5; border: 1px solid var(--line); border-radius: 13px; background: rgba(4,12,24,.32); cursor: pointer; transition: border-color .15s, background .15s, transform .15s; }
.answer-option:hover { border-color: rgba(52,214,233,.48); background: rgba(52,214,233,.045); transform: translateX(2px); }
.answer-option input { position: absolute; opacity: 0; pointer-events: none; }
.answer-letter { width: 31px; height: 31px; display: grid; place-items: center; color: var(--muted); border: 1px solid var(--line); border-radius: 9px; font-size: .72rem; font-weight: 900; }
.answer-option:has(input:checked) { border-color: var(--cyan); background: rgba(52,214,233,.08); }
.answer-option:has(input:checked) .answer-letter { color: #031a1e; border-color: var(--cyan); background: var(--cyan); }
.answer-option.locked { cursor: default; pointer-events: none; }
.answer-option.result-correct { border-color: rgba(89,221,165,.62); background: rgba(89,221,165,.08); }
.answer-option.result-correct .answer-letter { color: #052419; border-color: var(--green); background: var(--green); }
.answer-option.result-wrong { border-color: rgba(255,123,131,.6); background: rgba(255,123,131,.07); }
.answer-option.result-wrong .answer-letter { color: #2c080b; border-color: var(--red); background: var(--red); }
.question-actions { display: flex; align-items: center; justify-content: space-between; gap: 16px; margin-top: 25px; }
.keyboard-note { color: #72859b; font-size: .72rem; }
.primary-button { min-height: 48px; display: inline-flex; align-items: center; justify-content: center; gap: 9px; padding: 0 20px; color: #03171c; border: 0; border-radius: 12px; background: linear-gradient(135deg, var(--cyan), var(--green)); box-shadow: 0 10px 25px rgba(52,214,233,.15); cursor: pointer; font-weight: 900; }
.primary-button:disabled { opacity: .38; cursor: not-allowed; }
.primary-button:not(:disabled):hover { filter: brightness(1.08); }
.feedback { display: none; margin-top: 20px; padding: 18px; border: 1px solid var(--line); border-radius: 14px; background: rgba(3,10,20,.45); }
.feedback.visible { display: block; }
.feedback-title { margin: 0 0 7px; font-size: .9rem; font-weight: 900; }
.feedback.correct .feedback-title { color: var(--green); }
.feedback.incorrect .feedback-title { color: var(--red); }
.feedback p { margin: 0; color: #b6c5d6; font-size: .86rem; }
.feedback .correct-answer { margin-bottom: 9px; color: var(--ink); }
.loading-state, .complete-state, .error-state { min-height: 420px; display: grid; place-items: center; padding: 45px; text-align: center; border: 1px solid var(--line); border-radius: 25px; background: var(--night-2); }
.loader { width: 37px; height: 37px; margin: 0 auto 18px; border: 3px solid var(--line); border-top-color: var(--cyan); border-radius: 50%; animation: spin .8s linear infinite; }
.complete-state h2, .error-state h2 { margin: 0 0 8px; font-size: 2rem; }
.complete-state p, .error-state p { max-width: 480px; margin: 0 0 22px; color: var(--muted); }
.hidden { display: none !important; }
@keyframes spin { to { transform: rotate(360deg); } }

/* Complete question browser */
.question-browser { padding: 62px 0 90px; }
.browser-heading { display: flex; align-items: end; justify-content: space-between; gap: 35px; margin-bottom: 30px; }
.browser-heading h1 { margin: 13px 0 12px; font-size: clamp(2.7rem, 7vw, 5.8rem); line-height: .96; letter-spacing: -.068em; }
.browser-heading p { max-width: 720px; margin: 0; color: var(--muted); }
.browser-progress { flex: 0 0 auto; min-width: 155px; padding: 18px; border: 1px solid var(--line); border-radius: 16px; background: var(--night-2); text-align: right; }
.browser-progress strong { display: block; color: var(--green); font-size: 1.7rem; line-height: 1; }
.browser-progress span { color: var(--muted); font-size: .72rem; }
.question-filters { display: grid; grid-template-columns: minmax(240px, 1fr) minmax(210px, .45fr) auto auto; align-items: end; gap: 12px; margin-bottom: 24px; padding: 18px; border: 1px solid var(--line); border-radius: 17px; background: var(--night-2); }
.question-filters.ceh-filters { grid-template-columns: minmax(220px, 1fr) minmax(205px, .65fr) minmax(190px, .5fr) auto auto; }
.question-filters label { display: grid; gap: 7px; color: var(--muted); font-size: .73rem; font-weight: 800; }
.question-filters input, .question-filters select { width: 100%; height: 47px; padding: 0 13px; color: var(--ink); border: 1px solid var(--line); border-radius: 11px; background: #091629; outline: none; }
.question-filters input:focus, .question-filters select:focus { border-color: var(--cyan); box-shadow: 0 0 0 3px rgba(52,214,233,.1); }
.clear-filter { min-height: 47px; display: grid; place-items: center; padding: 0 10px; color: var(--muted); text-decoration: none; font-size: .78rem; font-weight: 800; }
.clear-filter:hover { color: var(--ink); }
.list-summary { display: flex; align-items: center; justify-content: space-between; gap: 20px; margin: 0 2px 13px; color: var(--muted); font-size: .8rem; }
.list-summary p { margin: 0; }
.list-summary strong { color: var(--ink); }
.question-list { display: grid; gap: 10px; }
.list-question { display: grid; grid-template-columns: 52px minmax(0, 1fr) auto; align-items: start; gap: 18px; padding: 21px; border: 1px solid var(--line); border-radius: 16px; background: linear-gradient(145deg, rgba(16,30,51,.92), rgba(10,23,40,.92)); transition: border-color .15s, transform .15s; }
.list-question:hover { border-color: rgba(52,214,233,.35); transform: translateY(-1px); }
.list-question.was-correct { border-left: 3px solid var(--green); }
.list-question.was-incorrect { border-left: 3px solid var(--red); }
.list-question-number { width: 52px; height: 42px; display: grid; place-items: center; color: var(--cyan); border: 1px solid rgba(52,214,233,.16); border-radius: 10px; background: rgba(52,214,233,.05); font-family: ui-monospace, SFMono-Regular, Menlo, monospace; font-size: .75rem; font-weight: 800; }
.list-question-body { min-width: 0; }
.list-question .question-meta { margin-bottom: 10px; }
.list-question h2 { margin: 0; font-size: clamp(.96rem, 2vw, 1.08rem); line-height: 1.45; letter-spacing: -.01em; }
.question-status { padding: 4px 8px; color: #8194aa; border-radius: 999px; background: rgba(255,255,255,.04); font-size: .64rem; font-weight: 850; text-transform: uppercase; }
.question-status.status-correct { color: var(--green); background: rgba(89,221,165,.08); }
.question-status.status-incorrect { color: var(--red); background: rgba(255,123,131,.08); }
.choice-preview { margin-top: 12px; color: var(--muted); font-size: .78rem; }
.choice-preview summary { width: fit-content; color: #8fa4ba; cursor: pointer; font-weight: 750; }
.choice-preview ol { display: grid; gap: 6px; margin: 10px 0 0; padding-left: 28px; }
.choice-preview li { padding-left: 5px; color: #b4c3d4; }
.practice-link { align-self: center; display: inline-flex; align-items: center; gap: 8px; padding: 9px 11px; color: var(--cyan); border: 1px solid rgba(52,214,233,.17); border-radius: 9px; background: rgba(52,214,233,.05); text-decoration: none; white-space: nowrap; font-size: .75rem; font-weight: 850; }
.practice-link:hover { border-color: rgba(52,214,233,.45); background: rgba(52,214,233,.1); }
.pagination { display: flex; flex-wrap: wrap; align-items: center; justify-content: center; gap: 7px; margin-top: 28px; }
.pagination a, .pagination span { min-width: 38px; height: 38px; display: grid; place-items: center; padding: 0 10px; color: var(--muted); border: 1px solid var(--line); border-radius: 9px; background: var(--night-2); text-decoration: none; font-size: .76rem; font-weight: 800; }
.pagination a:hover { color: var(--cyan); border-color: rgba(52,214,233,.4); }
.pagination a.current { color: #04191d; border-color: var(--cyan); background: var(--cyan); }
.pagination span { border-color: transparent; background: transparent; }
.empty-list { min-height: 330px; display: grid; place-content: center; justify-items: center; padding: 35px; border: 1px solid var(--line); border-radius: 18px; background: var(--night-2); text-align: center; }
.empty-list h2 { margin: 0 0 5px; }
.empty-list p { margin: 0 0 20px; color: var(--muted); }

/* CEH module placeholder */
.module-placeholder { width: min(760px, calc(100% - 36px)); margin: 75px auto; padding: clamp(28px, 6vw, 58px); border: 1px solid var(--line); border-radius: 27px; background: var(--night-2); box-shadow: var(--shadow); }
.module-placeholder h1 { margin: 15px 0 15px; font-size: clamp(2.4rem, 7vw, 5rem); line-height: .98; letter-spacing: -.065em; }
.module-placeholder h1 span { color: var(--purple); }
.module-placeholder p { color: var(--muted); }
.placeholder-list { display: grid; grid-template-columns: 1fr 1fr; gap: 9px; margin: 27px 0; }
.placeholder-list div { padding: 12px; border: 1px solid var(--line); border-radius: 10px; color: #c7bce9; background: rgba(168,140,255,.04); font-size: .82rem; }

@media (max-width: 900px) {
    .subject-grid { grid-template-columns: 1fr; }
    .subject-card { min-height: 420px; }
    .workflow { grid-template-columns: 1fr 1fr; }
    .revision-layout { grid-template-columns: 1fr; gap: 24px; margin-top: 32px; }
    .progress-panel { position: static; display: grid; grid-template-columns: 1fr 1fr; gap: 12px 24px; }
    .progress-panel > .progress-track, .progress-panel > .danger-link { grid-column: 1 / -1; }
    .level-list { display: none; }
    .stats-grid { margin: 0; }
    .question-filters { grid-template-columns: 1fr 1fr; }
    .question-filters.ceh-filters { grid-template-columns: 1fr 1fr; }
    .question-filters .primary-button, .question-filters .clear-filter { width: 100%; }
}

@media (max-width: 560px) {
    .nav-note, .keyboard-note { display: none; }
    .home-hero { padding-top: 52px; }
    .subject-card { min-height: 440px; border-radius: 22px; }
    .workflow { grid-template-columns: 1fr; }
    .workflow div { min-height: 92px; }
    .progress-panel { grid-template-columns: 1fr; }
    .progress-panel > * { grid-column: 1 !important; }
    .question-actions { align-items: stretch; flex-direction: column; }
    .primary-button { width: 100%; }
    .placeholder-list { grid-template-columns: 1fr; }
    .nav-actions { gap: 11px; }
    .nav-actions .back-link { font-size: .72rem; }
    .browser-heading { align-items: stretch; flex-direction: column; }
    .browser-progress { text-align: left; }
    .question-filters { grid-template-columns: 1fr; }
    .question-filters.ceh-filters { grid-template-columns: 1fr; }
    .list-summary { align-items: flex-start; flex-direction: column; gap: 3px; }
    .list-question { grid-template-columns: 42px minmax(0, 1fr); gap: 11px; padding: 16px; }
    .list-question-number { width: 42px; }
    .practice-link { grid-column: 2; justify-self: start; }
}