:root {
  --bg: #0f1115;
  --panel: #171a21;
  --panel-2: #1e222b;
  --line: #2a2f3a;
  --text: #e8eaef;
  --muted: #9aa1ae;
  --accent: #4f8cff;
  --ok: #2ea36b;
  --bad: #d9534f;
  --radius: 12px;
}

* { box-sizing: border-box; }

/* .auth-wrap and .boot set `display`, which would otherwise beat the browser's
   [hidden] rule and leave them on screen behind the app. */
[hidden] { display: none !important; }

body {
  margin: 0;
  background: var(--bg);
  color: var(--text);
  font-family: "Segoe UI", "Rubik", Arial, sans-serif;
  line-height: 1.6;
}

button { font-family: inherit; }

.boot {
  min-height: 100vh;
  display: grid;
  place-items: center;
  color: var(--muted);
}

/* ===== auth ===== */
.auth-wrap {
  min-height: 100vh;
  display: grid;
  place-items: center;
  padding: 24px;
}
.auth-card {
  width: 100%;
  max-width: 420px;
  background: var(--panel);
  border: 1px solid var(--line);
  border-radius: 16px;
  padding: 32px;
}
.auth-card h1 { margin: 0 0 6px; font-size: 26px; }
.auth-sub { margin: 0 0 22px; color: var(--muted); font-size: 14px; }

.auth-tabs {
  display: flex;
  gap: 6px;
  background: var(--panel-2);
  padding: 4px;
  border-radius: 10px;
  margin-bottom: 20px;
}
.auth-tab {
  flex: 1;
  padding: 9px;
  border: 0;
  border-radius: 8px;
  background: transparent;
  color: var(--muted);
  cursor: pointer;
  font-size: 14px;
}
.auth-tab.is-active { background: var(--accent); color: #fff; }

.field { display: block; margin-bottom: 14px; }
.field span { display: block; font-size: 13px; color: var(--muted); margin-bottom: 6px; }
.field input {
  width: 100%;
  padding: 11px 12px;
  background: var(--panel-2);
  border: 1px solid var(--line);
  border-radius: 9px;
  color: var(--text);
  font-size: 15px;
}
.field input:focus { outline: 2px solid var(--accent); outline-offset: 1px; }

.btn-primary {
  width: 100%;
  padding: 12px;
  border: 0;
  border-radius: 9px;
  background: var(--accent);
  color: #fff;
  font-size: 15px;
  cursor: pointer;
}
.btn-primary:disabled { opacity: .6; cursor: default; }

.auth-msg {
  margin: 0 0 12px;
  padding: 10px 12px;
  border-radius: 8px;
  font-size: 14px;
}
.auth-msg.is-error { background: rgba(217, 83, 79, .12); color: #ff9d9a; }

/* ===== chrome ===== */
.topbar {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 14px 22px;
  border-bottom: 1px solid var(--line);
  background: var(--panel);
}
.brand { font-weight: 600; }
.brand span { color: var(--muted); font-weight: 400; font-size: 13px; margin-inline-start: 8px; }
.topbar-right { display: flex; align-items: center; gap: 12px; }
.user-label { color: var(--muted); font-size: 13px; }

.btn-ghost {
  padding: 8px 14px;
  background: transparent;
  border: 1px solid var(--line);
  border-radius: 8px;
  color: var(--text);
  cursor: pointer;
  font-size: 14px;
}
.btn-ghost:hover:not(:disabled) { border-color: var(--accent); }
.btn-ghost:disabled { opacity: .4; cursor: default; }

main { max-width: 900px; margin: 0 auto; padding: 26px 20px 60px; }

/* ===== home ===== */
.hero { margin-bottom: 26px; }
.hero h1 { margin: 0 0 4px; font-size: 24px; }
.hero p { margin: 0 0 18px; color: var(--muted); font-size: 14px; }

.stats { display: flex; gap: 12px; flex-wrap: wrap; }
.stat {
  background: var(--panel);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  padding: 14px 20px;
  min-width: 96px;
}
.stat b { display: block; font-size: 22px; }
.stat span { color: var(--muted); font-size: 13px; }
.btn-reset { margin-top: 16px; }

.exam-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(240px, 1fr));
  gap: 12px;
}
.exam-card {
  text-align: start;
  background: var(--panel);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  padding: 16px;
  cursor: pointer;
  color: var(--text);
  display: block;
  width: 100%;
}
.exam-card:hover { border-color: var(--accent); }
.exam-name { display: block; font-size: 15px; margin-bottom: 4px; }
.exam-meta { display: block; color: var(--muted); font-size: 13px; margin-bottom: 10px; }
.bar { display: block; height: 5px; background: var(--panel-2); border-radius: 3px; overflow: hidden; }
.bar i { display: block; height: 100%; background: var(--accent); }

/* ===== question ===== */
.q-head {
  display: flex;
  align-items: center;
  gap: 14px;
  flex-wrap: wrap;
  margin-bottom: 14px;
}
.q-title { font-size: 15px; }
.q-count { color: var(--muted); font-size: 13px; margin-inline-start: auto; }

.topic {
  display: inline-block;
  background: var(--panel-2);
  border: 1px solid var(--line);
  border-radius: 999px;
  padding: 4px 12px;
  font-size: 12px;
  color: var(--muted);
  margin-bottom: 14px;
}

.q-image {
  background: #fff;
  border-radius: var(--radius);
  padding: 10px;
  margin-bottom: 18px;
  overflow-x: auto;
}
.q-image img { display: block; max-width: 100%; height: auto; margin: 0 auto; }

.opts { display: grid; gap: 8px; margin-bottom: 18px; }
.opt {
  display: flex;
  align-items: center;
  gap: 12px;
  width: 100%;
  text-align: start;
  padding: 12px 14px;
  background: var(--panel);
  border: 1px solid var(--line);
  border-radius: 10px;
  color: var(--text);
  cursor: pointer;
  font-size: 15px;
}
.opt:hover:not(:disabled) { border-color: var(--accent); }
.opt:disabled { cursor: default; }
.opt-n {
  flex: 0 0 28px;
  height: 28px;
  display: grid;
  place-items: center;
  background: var(--panel-2);
  border-radius: 7px;
  font-size: 13px;
}
.opt.is-correct { border-color: var(--ok); background: rgba(46, 163, 107, .12); }
.opt.is-correct .opt-n { background: var(--ok); color: #fff; }
.opt.is-wrong { border-color: var(--bad); background: rgba(217, 83, 79, .12); }
.opt.is-wrong .opt-n { background: var(--bad); color: #fff; }

.verdict {
  padding: 12px 16px;
  border-radius: 10px;
  margin-bottom: 14px;
  font-size: 15px;
}
.verdict.ok { background: rgba(46, 163, 107, .14); color: #7fe0ae; }
.verdict.bad { background: rgba(217, 83, 79, .14); color: #ff9d9a; }

.exp {
  background: var(--panel);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  padding: 16px;
  margin-bottom: 12px;
}
.exp h3 { margin: 0 0 8px; font-size: 14px; color: var(--muted); font-weight: 600; }
.exp p { margin: 0; font-size: 15px; }
.exp code {
  background: var(--panel-2);
  padding: 2px 6px;
  border-radius: 5px;
  font-size: 13px;
  direction: ltr;
  display: inline-block;
}
.exp-none { color: var(--muted); font-size: 14px; }

.q-nav { display: flex; gap: 10px; justify-content: space-between; }

@media (max-width: 560px) {
  .topbar { padding: 12px 14px; }
  main { padding: 18px 14px 48px; }
  .q-count { margin-inline-start: 0; width: 100%; }
}