:root{
  --bg1:#f3faf6;
  --bg2:#e8f1ec;
  --grid:rgba(34, 197, 94, 0.085);
  --ink:#0e1624;
  --muted:#4b5563;
  --shadow: 0 18px 50px rgba(2, 8, 23, 0.22);
  --round: 22px;
  --mono: ui-monospace, SFMono-Regular, Menlo, Monaco, Consolas, "Liberation Mono", "Courier New", monospace;
  --ui: system-ui, -apple-system, Segoe UI, Roboto, Arial, sans-serif;
}

*{ box-sizing:border-box; }
html,body{ height:100%; }

body{
  margin:0;
  font-family:var(--ui);
  color:var(--ink);
  background:
    radial-gradient(900px 320px at 50% 0%, rgba(34,197,94,0.18), transparent 60%),
    linear-gradient(135deg, var(--bg1), var(--bg2)),
    linear-gradient(0deg, transparent 24%, var(--grid) 25%, var(--grid) 26%, transparent 27%, transparent 74%, var(--grid) 75%, var(--grid) 76%, transparent 77%, transparent),
    linear-gradient(90deg, transparent 24%, var(--grid) 25%, var(--grid) 26%, transparent 27%, transparent 74%, var(--grid) 75%, var(--grid) 76%, transparent 77%, transparent);
  background-size: auto, auto, 44px 44px, 44px 44px;
}

.topbar{
  display:flex;
  justify-content:space-between;
  align-items:center;
  padding:18px 22px;
  border-bottom:1px solid rgba(15,23,42,0.12);
  background:rgba(255,255,255,0.70);
  backdrop-filter: blur(10px);
  position:sticky;
  top:0;
  z-index:10;
}

.brand{ display:flex; align-items:center; gap:14px; }
.logo-block{
  width:44px; height:44px;
  border-radius:12px;
  background:
    linear-gradient(180deg, #dcfce7, #86efac),
    linear-gradient(90deg, transparent 24%, rgba(0,0,0,0.10) 25%, rgba(0,0,0,0.10) 26%, transparent 27%, transparent 74%, rgba(0,0,0,0.10) 75%, rgba(0,0,0,0.10) 76%, transparent 77%, transparent);
  background-size:auto, 10px 10px;
  border:3px solid rgba(2,6,23,0.25);
  box-shadow: 0 10px 18px rgba(2,6,23,0.18);
}

.brand-title{ font-weight:900; letter-spacing:0.2px; font-size:18px; }
.brand-subtitle{ color:var(--muted); font-size:12.8px; margin-top:2px; }

.navlink{
  text-decoration:none;
  color:#14532d;
  font-weight:800;
  padding:10px 12px;
  border-radius:12px;
  border:1px solid rgba(15,23,42,0.12);
  background:rgba(255,255,255,0.7);
}
.navlink:hover{ background:#fff; }

.wrap{
  max-width: 1100px;
  margin: 0 auto;
  padding: 26px 18px 50px;
  display:flex;
  flex-direction:column;
  align-items:center;
  gap:14px;
}

.hint{
  color:var(--muted);
  font-size:14px;
}

.card-shell{
  width: min(980px, 96vw);
  height: min(560px, 70vh);
  position:relative;
  perspective: 1400px;
  cursor:pointer;
  outline:none;
}
.card-shell:focus-visible{
  outline: 4px solid rgba(34,197,94,0.35);
  border-radius: var(--round);
}

.card-face{
  position:absolute;
  inset:0;
  border-radius: var(--round);
  box-shadow: var(--shadow), inset 0 0 0 2px rgba(34,197,94,0.12);
  backface-visibility:hidden;
  overflow:hidden;
  border: 6px solid rgba(2,6,23,0.28);
}

/* Subtle Minecraft-style "stone" texture */
.card-face::after{
  content:"";
  position:absolute;
  inset:0;
  pointer-events:none;
  background:
    repeating-linear-gradient(
      45deg,
      rgba(0,0,0,0.030) 0,
      rgba(0,0,0,0.030) 2px,
      transparent 2px,
      transparent 4px
    );
  mix-blend-mode: overlay;
}

.card-front{
  background:
    linear-gradient(180deg, #f6f8fb, #dde6f2),
    linear-gradient(0deg, transparent 24%, rgba(0,0,0,0.06) 25%, rgba(0,0,0,0.06) 26%, transparent 27%, transparent 74%, rgba(0,0,0,0.06) 75%, rgba(0,0,0,0.06) 76%, transparent 77%, transparent),
    linear-gradient(90deg, transparent 24%, rgba(0,0,0,0.06) 25%, rgba(0,0,0,0.06) 26%, transparent 27%, transparent 74%, rgba(0,0,0,0.06) 75%, rgba(0,0,0,0.06) 76%, transparent 77%, transparent);
  background-size:auto, 46px 46px, 46px 46px;
}

.card-back{
  transform: rotateY(180deg);
  background: linear-gradient(180deg, #0f172a, #0b1222);
  color: #eaf0ff;
}

.card-shell.is-flipped .card-front{ transform: rotateY(180deg); }
.card-shell.is-flipped .card-back{ transform: rotateY(360deg); }

.card-front, .card-back{
  transition: transform 480ms cubic-bezier(.2,.8,.2,1);
}

.front-top{ padding:22px 24px 0; position:relative; z-index:1; }
.pill{
  display:inline-block;
  padding:10px 12px;
  border-radius:14px;
  font-weight:900;
  letter-spacing:1px;
  font-size:12px;
  background: rgba(15,23,42,0.08);
  border: 2px solid rgba(2,6,23,0.18);
}

.front-center{
  height: calc(100% - 120px);
  display:flex;
  flex-direction:column;
  justify-content:center;
  align-items:center;
  text-align:center;
  padding: 0 26px;
  gap: 12px;
  position:relative;
  z-index:1;
}
.category-title{
  font-size: clamp(34px, 4vw, 56px);
  line-height: 1.05;
  margin:0;
  font-weight: 950;
}
.front-note{
  font-size: 18px;
  color: rgba(15,23,42,0.75);
  font-weight: 650;
}
.front-bottom{
  padding: 0 24px 22px;
  display:flex;
  justify-content:space-between;
  align-items:flex-end;
  position:relative;
  z-index:1;
}
.micro{
  font-family:var(--mono);
  font-size: 12px;
  color: rgba(15,23,42,0.62);
}

.back-top{
  padding: 18px 20px 10px;
  border-bottom: 1px solid rgba(255,255,255,0.14);
  display:flex;
  justify-content:space-between;
  align-items:baseline;
  gap:14px;
  position:relative;
  z-index:1;
}
.back-title{
  font-size: 20px;
  font-weight: 950;
}
.back-step{
  font-family:var(--mono);
  font-size: 12px;
  opacity: 0.85;
}

/* Scrollable content area */
.back-body{
  padding: 16px 18px 18px;
  height: calc(100% - 56px);
  overflow-y:auto;
  -webkit-overflow-scrolling: touch;
  position:relative;
  z-index:1;
}

.section{
  background: rgba(255,255,255,0.06);
  border: 1px solid rgba(255,255,255,0.14);
  border-radius: 16px;
  padding: 14px 14px;
  margin-bottom: 12px;
}

.word-grid{
  display:flex;
  flex-wrap:wrap;
  gap:10px;
}
.word-chip{
  padding: 10px 12px;
  border-radius: 14px;
  font-size: 20px;
  font-weight: 900;
  background: rgba(255,255,255,0.10);
  border: 1px solid rgba(255,255,255,0.16);
  color:#f4f7ff;
}

.table{
  width:100%;
  border-collapse: separate;
  border-spacing: 0;
  overflow:hidden;
  border-radius: 14px;
  border: 1px solid rgba(255,255,255,0.14);
  background: rgba(255,255,255,0.05);
}
.table th, .table td{
  padding: 12px 12px;
  vertical-align: top;
  text-align:left;
  color:#f3f6ff;
}
.table th{
  font-size: 13px;
  letter-spacing: 0.6px;
  text-transform: uppercase;
  opacity: 0.9;
  border-bottom: 1px solid rgba(255,255,255,0.12);
}
.table td{
  font-size: 16px;
  line-height: 1.45;
  border-bottom: 1px solid rgba(255,255,255,0.08);
}
.table tr:last-child td{ border-bottom:none; }

.actions{
  display:flex;
  gap: 10px;
  margin-top: 6px;
}
.btn{
  border:none;
  border-radius: 14px;
  padding: 12px 14px;
  font-weight: 950;
  cursor:pointer;
  background: #14532d;
  color:#fff;
  box-shadow: 0 10px 18px rgba(2,6,23,0.16);
}
.btn:hover{ filter:brightness(1.05); }
.btn:active{ transform: translateY(1px); }

.btn-ghost{
  background: rgba(255,255,255,0.8);
  color:#14532d;
  border: 1px solid rgba(15,23,42,0.14);
  box-shadow: none;
}
.btn-ghost:hover{ background:#fff; }

.foot{
  margin-top: 8px;
  color: var(--muted);
  font-size: 13px;
}
code{
  font-family: var(--mono);
  background: rgba(15,23,42,0.08);
  border: 1px solid rgba(15,23,42,0.14);
  padding: 2px 6px;
  border-radius: 10px;
}

@media (max-width: 640px){
  .brand-subtitle{ display:none; }
  .card-shell{ height: 68vh; }
  .word-chip{ font-size: 18px; }
  .table td{ font-size: 15px; }
}