/* ============================================================
   Vocabulary Trainer — Illia Hudz
   Shares the portfolio's design language (tokens, fonts, theme)
   ============================================================ */

/* ---------- Tokens ---------- */
:root {
  color-scheme: light;
  --bg:        #ffffff;
  --bg-soft:   #f5f7fa;
  --ink:       #16181a;
  --ink-soft:  #4d5358;
  --ink-faint: #868d92;
  --accent:    #4A6FA5;
  --accent-soft:#e7edf5;
  --on-accent: #ffffff;
  --line:      #e6e8ec;
  --danger:    #c0463b;
  --ok:        #2e8b6f;

  --display: "Playfair Display", Georgia, serif;
  --sans:    "DM Sans", system-ui, sans-serif;

  --maxw: 660px;
  --pad: clamp(1.25rem, 5vw, 3rem);
}

[data-theme="dark"] {
  color-scheme: dark;
  --bg:        #14161a;
  --bg-soft:   #1d2026;
  --ink:       #f1f2f4;
  --ink-soft:  #b4b9c0;
  --ink-faint: #7e848c;
  --accent:    #8aa9de;
  --accent-soft:#232b3a;
  --on-accent: #11141a;
  --line:      #2a2e37;
  --danger:    #e08178;
  --ok:        #6fcab0;
}

/* ---------- Reset ---------- */
*, *::before, *::after { box-sizing: border-box; }
html { -webkit-text-size-adjust: 100%; }
body {
  margin: 0; min-height: 100vh;
  background: var(--bg); color: var(--ink);
  font-family: var(--sans); font-weight: 400;
  font-size: clamp(1rem, 0.96rem + 0.2vw, 1.0625rem);
  line-height: 1.7; letter-spacing: 0.005em;
  -webkit-font-smoothing: antialiased;
  display: flex; flex-direction: column;
  transition: background-color .3s ease, color .3s ease;
}
a { color: inherit; text-decoration: none; }
button { font-family: inherit; }
::selection { background: var(--accent); color: var(--on-accent); }
[hidden] { display: none !important; }

/* ---------- Layout ---------- */
.wrap { width: 100%; max-width: var(--maxw); margin: 0 auto; padding-inline: var(--pad); }
.app { flex: 1; padding-bottom: 4rem; }

/* ---------- Nav ---------- */
header.nav {
  position: sticky; top: 0; z-index: 50;
  background: color-mix(in srgb, var(--bg) 82%, transparent);
  backdrop-filter: saturate(180%) blur(10px);
  -webkit-backdrop-filter: saturate(180%) blur(10px);
  border-bottom: 1px solid transparent;
  transition: border-color .3s ease, background .3s ease;
}
header.nav.scrolled { border-bottom-color: var(--line); }
.nav-inner {
  max-width: var(--maxw); margin: 0 auto; padding: 1rem var(--pad);
  display: flex; align-items: center; justify-content: space-between; gap: 1rem;
}
.brand { font-family: var(--display); font-size: 1.2rem; font-weight: 700; letter-spacing: -0.01em; }
.brand span { color: var(--accent); }
.nav-right { display: flex; align-items: center; gap: 1.25rem; }
.back-link {
  display: inline-flex; align-items: center; gap: 0.35rem;
  font-size: 0.9rem; font-weight: 500; color: var(--ink-soft);
  transition: color .2s ease, transform .2s ease;
}
.back-link svg { width: 17px; height: 17px; }
.back-link:hover { color: var(--accent); transform: translateX(-2px); }

.theme-toggle {
  display: inline-grid; place-items: center;
  width: 38px; height: 38px; flex: none;
  border: 1px solid var(--line); border-radius: 999px;
  background: transparent; color: var(--ink-soft); cursor: pointer;
  transition: color .2s ease, border-color .2s ease, transform .2s ease;
}
.theme-toggle:hover { color: var(--accent); border-color: var(--accent); transform: translateY(-1px); }
.theme-toggle svg { width: 18px; height: 18px; }
.theme-toggle .icon-sun { display: none; }
[data-theme="dark"] .theme-toggle .icon-sun { display: block; }
[data-theme="dark"] .theme-toggle .icon-moon { display: none; }

/* Language toggle */
.lang-toggle {
  height: 38px; padding: 0 0.85rem; flex: none;
  border: 1px solid var(--line); border-radius: 999px;
  background: transparent; color: var(--ink-soft); cursor: pointer;
  font-family: var(--sans); font-size: 0.78rem; font-weight: 600; letter-spacing: 0.06em;
  transition: color .2s ease, border-color .2s ease, transform .2s ease;
}
.lang-toggle:hover { color: var(--accent); border-color: var(--accent); transform: translateY(-1px); }

/* ---------- App header ---------- */
.app-head { padding-block: clamp(2.5rem, 8vw, 4rem) clamp(1.5rem, 4vw, 2.25rem); }
.eyebrow {
  font-size: 0.75rem; font-weight: 700; letter-spacing: 0.2em;
  text-transform: uppercase; color: var(--accent); margin: 0 0 1rem;
}
.app-head h1 {
  font-family: var(--display); font-weight: 600; line-height: 1.12; letter-spacing: -0.01em;
  font-size: clamp(2.25rem, 1.5rem + 3vw, 3.25rem); margin: 0;
}
.lead { color: var(--ink-soft); max-width: 54ch; margin: 1rem 0 0; }
.lead strong { color: var(--ink); font-weight: 600; }

/* ---------- Buttons ---------- */
.btn {
  display: inline-flex; align-items: center; gap: 0.5rem;
  font-size: 0.9rem; font-weight: 500; letter-spacing: 0.01em;
  padding: 0.65rem 1.1rem; border: 1px solid var(--line); border-radius: 3px;
  color: var(--ink); background: transparent; cursor: pointer; white-space: nowrap;
  transition: border-color .2s ease, color .2s ease, background .2s ease, transform .2s ease;
}
.btn:hover { border-color: var(--accent); color: var(--accent); transform: translateY(-1px); }
.btn--solid { background: var(--ink); color: var(--bg); border-color: var(--ink); }
.btn--solid:hover { background: var(--accent); border-color: var(--accent); color: var(--on-accent); }
.btn svg { width: 16px; height: 16px; }

/* ---------- Controls ---------- */
.controls { display: flex; flex-wrap: wrap; gap: 1rem; align-items: flex-end; justify-content: space-between; margin-bottom: 1.25rem; }
.control { display: grid; gap: 0.35rem; }
.control-label { font-size: 0.72rem; font-weight: 700; letter-spacing: 0.1em; text-transform: uppercase; color: var(--ink-faint); }
#deck-select {
  font-family: var(--sans); font-size: 0.95rem; color: var(--ink);
  background: var(--bg); border: 1px solid var(--line); border-radius: 4px;
  padding: 0.6rem 0.75rem; min-width: 200px; cursor: pointer;
}
#deck-select:focus { outline: none; border-color: var(--accent); box-shadow: 0 0 0 3px var(--accent-soft); }
.control-btns { display: flex; gap: 0.5rem; flex-wrap: wrap; }
.control-btns .btn { padding: 0.55rem 0.85rem; font-size: 0.84rem; }

/* ---------- Add-word form ---------- */
.add-card { display: flex; gap: 0.6rem; margin-bottom: 1.5rem; flex-wrap: wrap; }
.add-card input {
  flex: 1; min-width: 140px; font-family: var(--sans); font-size: 1rem; color: var(--ink);
  padding: 0.7rem 0.85rem; border: 1px solid var(--line); border-radius: 4px; background: var(--bg);
  transition: border-color .2s ease, box-shadow .2s ease;
}
.add-card input::placeholder { color: var(--ink-faint); }
.add-card input:focus { outline: none; border-color: var(--accent); box-shadow: 0 0 0 3px var(--accent-soft); }

/* ---------- Stats / Leitner boxes ---------- */
.stats { margin-bottom: 1.75rem; }
.boxes { display: flex; gap: 0.5rem; }
.box { flex: 1; text-align: center; border: 1px solid var(--line); border-radius: 6px; padding: 0.5rem 0.25rem; background: var(--bg); transition: border-color .2s ease, background .2s ease; }
.box .box-n { display: block; font-size: 0.62rem; letter-spacing: 0.08em; text-transform: uppercase; color: var(--ink-faint); }
.box .box-c { display: block; font-family: var(--display); font-size: 1.2rem; font-weight: 600; margin-top: 0.1rem; }
.box.has .box-c { color: var(--accent); }
.box.mastered { border-color: var(--accent); background: var(--accent-soft); }
.stat-line { margin: 0.8rem 0 0; font-size: 0.85rem; color: var(--ink-faint); }
.stat-line strong { color: var(--ink); font-weight: 600; }

/* ---------- Flashcard ---------- */
.card-area { margin-top: 0.5rem; }
.flashcard {
  display: block; width: 100%; height: 240px; padding: 0; border: none; background: none;
  cursor: pointer; perspective: 1200px;
}
.fc-inner {
  position: relative; width: 100%; height: 100%;
  transition: transform .5s cubic-bezier(.2,.7,.2,1); transform-style: preserve-3d;
}
.flashcard.flipped .fc-inner { transform: rotateY(180deg); }
.face {
  position: absolute; inset: 0; backface-visibility: hidden; -webkit-backface-visibility: hidden;
  display: grid; place-content: center; gap: 0.75rem; text-align: center;
  border: 1px solid var(--line); border-radius: 12px; background: var(--bg-soft); padding: 1.5rem;
}
.face.back { transform: rotateY(180deg); background: var(--accent-soft); border-color: var(--accent); }
.fc-lang { font-size: 0.72rem; font-weight: 700; letter-spacing: 0.14em; text-transform: uppercase; color: var(--accent); }
.fc-term { font-family: var(--display); font-weight: 600; font-size: clamp(1.6rem, 1rem + 3vw, 2.4rem); line-height: 1.2; color: var(--ink); }
.flashcard:focus-visible { outline: none; }
.flashcard:focus-visible .face.front { border-color: var(--accent); box-shadow: 0 0 0 3px var(--accent-soft); }

.fc-hint { text-align: center; color: var(--ink-faint); font-size: 0.85rem; margin: 0.9rem 0 0; }
.fc-hint kbd {
  font-family: var(--sans); font-size: 0.85em; border: 1px solid var(--line); border-bottom-width: 2px;
  border-radius: 4px; padding: 0.05em 0.4em; background: var(--bg-soft); color: var(--ink-soft);
}

/* ---------- Grade buttons ---------- */
.grade { display: flex; gap: 0.75rem; margin-top: 1.25rem; justify-content: center; }
.grade .btn { flex: 1; max-width: 200px; justify-content: center; padding: 0.7rem 1rem; }
.grade-miss svg { color: var(--danger); }
.grade-got svg { color: var(--ok); }
.grade-miss:hover { border-color: var(--danger); color: var(--danger); }
.grade-got:hover { border-color: var(--ok); color: var(--ok); }

/* ---------- Done / empty ---------- */
.done { text-align: center; color: var(--ink-faint); padding: 3rem 1rem; border: 1px dashed var(--line); border-radius: 10px; }
.done svg { width: 42px; height: 42px; color: var(--accent); opacity: 0.6; margin: 0 auto 0.85rem; }
.done p { margin: 0 0 1.25rem; font-size: 1.05rem; color: var(--ink-soft); }

/* ---------- Footer ---------- */
footer.foot {
  border-top: 1px solid var(--line); padding-block: 2rem;
  font-size: 0.8rem; color: var(--ink-faint); letter-spacing: 0.02em;
  display: flex; flex-wrap: wrap; gap: 0.5rem 1.5rem; justify-content: space-between;
}

@media (prefers-reduced-motion: reduce) {
  .fc-inner { transition: none; }
  .btn:hover, .theme-toggle:hover, .lang-toggle:hover, .back-link:hover { transform: none; }
  body { transition: none; }
}