/* ============================================================
   English Proficiency Test
   Theme: carbon blue on a white background.
   Mobile-first, responsive, accessible.
============================================================ */

:root{
  --carbon-950:#050b14;
  --carbon-900:#0a1626;
  --carbon-800:#0d1e35;
  --carbon-700:#123052;
  --carbon-600:#17416f;
  --blue-600:#1b5fd9;
  --blue-500:#2f7cf6;
  --blue-300:#8db8ff;
  --blue-100:#e7f0ff;
  --blue-050:#f2f7ff;
  --ink:#0f1b2d;
  --muted:#5c6c80;
  --line:#d9e2ec;
  --bg:#ffffff;
  --card-shadow:0 10px 30px rgba(10,22,38,.08);
  --radius:16px;
}

*{ box-sizing:border-box; }
html{ scroll-behavior:smooth; }

body{
  margin:0;
  font-family:"Segoe UI",Roboto,"Helvetica Neue",Arial,sans-serif;
  background:var(--bg);
  color:var(--ink);
  line-height:1.6;
  min-height:100vh;
  display:flex;
  flex-direction:column;
}

/* ---------------- Top bar (carbon blue) ---------------- */
.topbar{
  position:sticky; top:0; z-index:20;
  background-color:var(--carbon-900);
  background-image:
    repeating-linear-gradient(45deg, rgba(255,255,255,.035) 0 2px, transparent 2px 5px),
    linear-gradient(115deg, var(--carbon-950) 0%, var(--carbon-800) 55%, var(--carbon-600) 100%);
  color:#fff;
  box-shadow:0 2px 14px rgba(5,11,20,.35);
}
.topbar-inner{
  max-width:760px; margin:0 auto; padding:0 16px;
  height:60px; display:flex; align-items:center; justify-content:space-between; gap:12px;
}
.brand{
  display:flex; align-items:center; gap:10px;
  color:#fff; text-decoration:none; font-weight:700; font-size:1.05rem;
}
.brand-mark{
  width:32px; height:32px; border-radius:9px;
  display:grid; place-items:center;
  background:linear-gradient(135deg, var(--blue-500), var(--carbon-600));
  font-weight:800; font-size:1rem;
}
.brand-text b{ color:var(--blue-300); font-weight:700; }
.top-link{
  color:#cfe0ff; text-decoration:none; font-size:.88rem;
  padding:8px 14px; border:1px solid rgba(255,255,255,.25); border-radius:10px;
  transition:background .2s ease, border-color .2s ease;
  white-space:nowrap;
}
.top-link:hover{ background:rgba(255,255,255,.1); border-color:rgba(255,255,255,.45); }

/* ---------------- Layout ---------------- */
.container{
  flex:1; width:100%; max-width:760px;
  margin:0 auto; padding:28px 16px 48px;
}
.screen{ animation:rise .45s ease both; }
@keyframes rise{ from{ opacity:0; transform:translateY(14px); } to{ opacity:1; transform:none; } }

.card{
  background:#fff;
  border:1px solid var(--line);
  border-radius:var(--radius);
  box-shadow:var(--card-shadow);
  padding:28px 22px;
}
.intro-card, .result-card{ border-top:4px solid var(--blue-500); }

h1{ font-size:clamp(1.5rem, 4vw, 2rem); margin:.2rem 0 .4rem; color:var(--carbon-900); }
.result-title{ font-size:clamp(1.3rem, 3.5vw, 1.7rem); margin:.2rem 0 .2rem; color:var(--carbon-900); }
.lead{ color:var(--muted); margin:0 0 1.1rem; }
.feature-list{ margin:0 0 1.4rem; padding-left:1.2rem; }
.feature-list li{ margin:.35rem 0; }
.hint{ color:var(--muted); font-size:.85rem; text-align:center; margin:.9rem 0 0; }

/* ---------------- Buttons ---------------- */
.btn{
  display:inline-flex; align-items:center; justify-content:center; gap:8px;
  min-height:48px; padding:12px 24px;
  border:none; border-radius:12px;
  font:inherit; font-weight:600; font-size:1rem;
  text-decoration:none; cursor:pointer;
  transition:transform .15s ease, box-shadow .2s ease, background .2s ease;
}
.btn-primary{
  color:#fff;
  background:linear-gradient(135deg, var(--carbon-700), var(--blue-600) 55%, var(--blue-500));
  box-shadow:0 6px 18px rgba(31,111,235,.28);
}
@media (hover:hover){
  .btn-primary:hover{ transform:translateY(-1px); box-shadow:0 10px 24px rgba(31,111,235,.36); }
}
.btn:active{ transform:scale(.99); }
.btn:disabled{ opacity:.6; cursor:not-allowed; transform:none; }
.btn-ghost{ background:#fff; color:var(--carbon-700); border:1.5px solid var(--line); }
@media (hover:hover){ .btn-ghost:hover{ border-color:var(--blue-500); background:var(--blue-050); } }
.btn-block{ width:100%; }

/* ---------------- Quiz ---------------- */
.quiz-meta{
  display:flex; justify-content:space-between; align-items:center;
  gap:10px; flex-wrap:wrap; margin-bottom:10px;
}
.q-number{ font-weight:700; color:var(--carbon-700); }
.q-progress-label{ font-size:.85rem; color:var(--muted); }

.progress{ height:8px; border-radius:999px; background:#e9eff7; overflow:hidden; }
.progress-bar{
  height:100%; width:0; border-radius:999px;
  background:linear-gradient(90deg, var(--carbon-700), var(--blue-500));
  transition:width .35s ease;
}

.q-text{
  font-size:1.18rem; font-weight:600; color:var(--carbon-900);
  margin:22px 2px 18px; min-height:3.2em;
}

.options{ display:grid; gap:12px; }
.options.locked .option{ pointer-events:none; opacity:.72; }
.option{
  display:flex; align-items:center; gap:12px;
  width:100%; text-align:left;
  padding:13px 15px;
  border:1.5px solid var(--line); border-radius:12px;
  background:#fff; font:inherit; font-size:1rem; color:var(--ink);
  cursor:pointer;
  transition:border-color .15s ease, background .15s ease, transform .1s ease;
}
@media (hover:hover){
  .option:hover{ border-color:var(--blue-500); background:var(--blue-050); }
}
.option:active{ transform:scale(.995); }
.option-key{
  flex:0 0 auto; width:30px; height:30px; border-radius:9px;
  display:grid; place-items:center;
  background:var(--carbon-800); color:#fff; font-weight:700; font-size:.9rem;
}
.option.selected{ border-color:var(--blue-500); background:var(--blue-100); }
.option.selected .option-key{ background:var(--blue-500); }

/* ---------------- Result ---------------- */
.score-wrap{ position:relative; width:200px; height:200px; margin:12px auto 6px; }
.score-ring{ width:100%; height:100%; transform:rotate(-90deg); }
.ring-bg{ fill:none; stroke:#e7eef8; stroke-width:13; }
.ring-fg{
  fill:none; stroke:url(#ringGrad); stroke-width:13; stroke-linecap:round;
  stroke-dasharray:527.79; stroke-dashoffset:527.79;
  transition:stroke-dashoffset 1.3s cubic-bezier(.25,.8,.3,1);
}
.score-value{
  position:absolute; inset:0;
  display:flex; flex-direction:column; align-items:center; justify-content:center;
}
#score-number{ font-size:2.6rem; font-weight:800; color:var(--carbon-800); line-height:1; }
.score-unit{ font-size:.9rem; color:var(--muted); margin-top:4px; }

.result-band{ font-size:1.25rem; font-weight:700; color:var(--blue-600); margin:.7rem 0 .1rem; }
.result-cefr{ color:var(--carbon-700); font-weight:600; margin:0 0 .3rem; }
.result-desc{ color:var(--muted); max-width:46ch; margin:0 auto 1.3rem; }
.result-actions{ display:flex; gap:12px; justify-content:center; flex-wrap:wrap; }

/* ---------------- Errors & footer ---------------- */
.global-error{
  margin:14px auto 0; max-width:640px;
  padding:12px 16px; border-radius:12px;
  background:#fdecec; border:1px solid #f3c1c1; color:#7d1a1a; text-align:center;
}
.footer{
  background-color:var(--carbon-900);
  background-image:repeating-linear-gradient(45deg, rgba(255,255,255,.03) 0 2px, transparent 2px 5px);
  color:#b9c9e2; text-align:center;
  padding:18px 16px; font-size:.9rem;
}
.footer a{ color:var(--blue-300); text-decoration:none; font-weight:600; }
.footer a:hover{ text-decoration:underline; }

/* Focus visibility (accessibility) */
.btn:focus-visible,
.option:focus-visible,
.top-link:focus-visible,
.footer a:focus-visible{
  outline:3px solid var(--blue-300);
  outline-offset:2px;
}

/* ---------------- Responsive ---------------- */
@media (min-width:720px){
  .container{ padding:44px 24px 60px; }
  .card{ padding:36px 34px; }
  .q-text{ font-size:1.3rem; }
  .option{ padding:15px 18px; font-size:1.04rem; }
}
@media (max-width:420px){
  .top-link{ display:none; }
  .brand-text{ font-size:.95rem; }
  .score-wrap{ width:170px; height:170px; }
  #score-number{ font-size:2.2rem; }
}

@media (prefers-reduced-motion:reduce){
  *{ animation:none !important; transition:none !important; }
}