:root {
  --bg: #f8fafc;
  --card: #ffffff;

  /* LIGHT BORDER */
 --border: rgba(0, 0, 0, 0.25);

  --text-primary: #0f172a;
  --text-secondary: #64748b;

  --accent: #111827;
  --accent-soft: #f1f5f9;

  --correct: #22c55e;
  --wrong: #ef4444;
}

/* 🔥 DARK MODE (WHITE BORDERS FIXED) */
body.dark {
  --bg: #0b1220;
  --card: #111827;

  /* ✅ WHITE BORDER */
  --border: rgba(255,255,255,0.18);

  --text-primary: #e2e8f0;
  --text-secondary: #94a3b8;

  --accent: #ffffff;
  --accent-soft: #1e293b;
}

* {
  box-sizing: border-box;
}

body {
  margin: 0;
  font-family: "Inter", sans-serif;
  background: var(--bg);
  color: var(--text-primary);
  transition: 0.3s ease;
}

/* HEADER */
.header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 20px 40px;
  border-bottom: 1px solid var(--border);
}

.header h1 {
  font-size: 30px;
  font-weight: 700;
}

.logo {
  height: 50px;
  width: auto;
}

.logo-area {
  display: flex;
  align-items: center;
  gap: 10px;
}

.theme-btn {
  background: transparent;
  border: 1px solid var(--border);
  color: var(--text-primary);
  padding: 10px 14px;
  border-radius: 10px;
  cursor: pointer;
  transition: 0.3s;
}

.theme-btn:hover {
  background: var(--accent-soft);
}

/* MAIN */
.main {
  display: flex;
  justify-content: center;
  padding: 40px 20px;
}

.card {
  width: 100%;
  max-width: 900px;
  background: var(--card);
  border: 1px solid var(--border);
  border-radius: 18px;
  padding: 30px;

  /* PREMIUM EFFECT */
  box-shadow: 0 10px 30px rgba(0,0,0,0.05);
}

body.dark .card {
  box-shadow: 0 10px 30px rgba(0,0,0,0.6);
}

/* STATS */
.top-stats {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 15px;
  margin-bottom: 25px;
}

.stat-box {
  background: var(--accent-soft);
  padding: 15px;
  border-radius: 12px;
  text-align: center;
  border: 1px solid var(--border);
}

.stat-box span {
  font-size: 12px;
  color: var(--text-secondary);
}

.stat-box strong {
  display: block;
  margin-top: 5px;
  font-size: 20px;
}

/* CONTROLS */
.controls {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
  margin-bottom: 25px;
}

select {
  padding: 10px 12px;
  border-radius: 10px;
  border: 1px solid var(--border);
  background: var(--bg);
  color: var(--text-primary);
  cursor: pointer;
}

/* BUTTONS */
.btn {
  padding: 10px 18px;
  border-radius: 10px;
  cursor: pointer;
  font-weight: 500;
  transition: 0.25s;
}

.btn.primary {
  background: var(--accent);
  color: var(--bg);
}

.btn.primary:hover {
  transform: translateY(-1px);
  opacity: 0.9;
}

.btn.ghost {
  background: transparent;
  border: 1px solid var(--border);
  color: var(--text-primary);
}

.btn.ghost:hover {
  background: var(--accent-soft);
}

/* TEXT */
.text-display {
  padding: 20px;
  border-radius: 12px;
  border: 1px solid var(--border);
  min-height: 120px;
  line-height: 1.7;
}

/* INPUT */
textarea {
  width: 100%;
  height: 140px;
  margin-top: 15px;
  padding: 15px;
  border-radius: 12px;
  border: 1px solid var(--border);
  background: var(--bg);
  color: var(--text-primary);
  font-size: 16px;
  outline: none;
}

/* FOOTER */
.footer {
  text-align: center;
  padding: 20px 10px;
  font-size: 14px;
  color: var(--text-secondary);
  border-top: 1px solid var(--border);
  margin-top: 40px;
}

.footer .credit {
  margin-top: 5px;
  font-size: 15px;
}

.footer a {
  color: var(--accent);
  text-decoration: none;
  font-weight: 500;
  transition: 0.3s ease;
}

.footer a:hover {
  text-decoration: underline;
  opacity: 0.8;
}

/* STATES */
.correct { color: var(--correct); }
.wrong { color: var(--wrong); }

/* RESPONSIVE */
@media (max-width: 600px) {
  .top-stats {
    grid-template-columns: 1fr;
  }
}