:root{
  --bg:#f7f8ff;
  --bg-soft:#eef4ff;
  --card:rgba(255,255,255,.72);
  --card-strong:#ffffff;
  --text:#1f2937;
  --muted:#667085;

  --primary:#5b6cff;
  --primary-2:#8b5cf6;
  --accent:#b7ff3c;
  --accent-2:#ff8bd1;
  --success:#22c55e;
  --danger:#ff5d73;

  --border:rgba(91,108,255,.16);
  --border-strong:rgba(91,108,255,.28);

  --shadow:
    0 10px 30px rgba(80, 92, 200, .12),
    0 4px 12px rgba(0, 0, 0, .05);

  --glow:0 0 0 6px rgba(183,255,60,.18);

  --panel-gradient:
    linear-gradient(180deg, rgba(255,255,255,.88) 0%, rgba(245,249,255,.82) 100%);

  --item-gradient:
    linear-gradient(135deg, rgba(255,255,255,.92) 0%, rgba(240,247,255,.88) 100%);

  --badge-bg:linear-gradient(135deg, #eef2ff 0%, #fdf2ff 100%);
  --table-head:linear-gradient(135deg, #f4f7ff 0%, #eefcff 100%);
  --highlight:rgba(183,255,60,.16);
}

*{box-sizing:border-box}

html{
  scroll-behavior:smooth;
}

body{
  margin:0;
  font-family:Arial, Helvetica, sans-serif;
  color:var(--text);
  background:
    radial-gradient(circle at top left, rgba(183,255,60,.18), transparent 28%),
    radial-gradient(circle at top right, rgba(255,139,209,.16), transparent 24%),
    radial-gradient(circle at bottom left, rgba(91,108,255,.16), transparent 24%),
    linear-gradient(180deg, var(--bg) 0%, var(--bg-soft) 100%);
  transition:
    background .45s ease,
    color .25s ease;
}

.app{
  max-width:900px;
  margin:0 auto;
  min-height:100vh;
  padding:18px;
  display:flex;
  flex-direction:column;
  gap:16px;
}

.panel{
  position:relative;
  overflow:hidden;
  background:var(--panel-gradient);
  border:1px solid var(--border);
  border-radius:24px;
  padding:16px;
  box-shadow:var(--shadow);
  backdrop-filter:blur(10px);
  transition:
    transform .28s ease,
    box-shadow .28s ease,
    border-color .28s ease,
    background .35s ease;
}

.panel::before{
  content:"";
  position:absolute;
  inset:0;
  pointer-events:none;
  background:
    linear-gradient(120deg, transparent 0%, rgba(255,255,255,.35) 45%, transparent 60%);
  transform:translateX(-120%);
  transition:transform .8s ease;
}

.panel:hover{
  transform:translateY(-2px);
  box-shadow:
    0 16px 36px rgba(80, 92, 200, .18),
    0 8px 18px rgba(0, 0, 0, .06);
  border-color:var(--border-strong);
}

.panel:hover::before{
  transform:translateX(120%);
}

.hidden{display:none !important}
.muted{color:var(--muted)}

.topbar{
  display:flex;
  justify-content:space-between;
  align-items:center;
  gap:10px;
  flex-wrap:wrap;
  margin-bottom:12px;
}

.badge{
  background:var(--badge-bg);
  color:var(--primary);
  padding:8px 14px;
  border-radius:999px;
  font-weight:800;
  font-size:14px;
  border:1px solid var(--border);
  box-shadow:0 4px 14px rgba(91,108,255,.10);
  transition:
    transform .22s ease,
    box-shadow .22s ease,
    background .35s ease,
    color .25s ease;
}

.badge:hover{
  transform:translateY(-1px) scale(1.02);
  box-shadow:0 8px 18px rgba(91,108,255,.16);
}

.form-grid{
  display:grid;
  gap:12px;
}

input, select, textarea, button{
  width:100%;
  border-radius:16px;
  padding:14px;
  font-size:16px;
  transition:
    transform .18s ease,
    box-shadow .22s ease,
    border-color .22s ease,
    background .28s ease,
    color .22s ease;
}

input, select, textarea{
  border:1px solid var(--border);
  background:rgba(255,255,255,.88);
  color:var(--text);
  box-shadow:inset 0 1px 0 rgba(255,255,255,.5);
}

input:focus, select:focus, textarea:focus{
  outline:none;
  border-color:var(--primary);
  box-shadow:
    0 0 0 4px rgba(91,108,255,.14),
    var(--glow);
  transform:translateY(-1px);
}

button{
  border:none;
  cursor:pointer;
  font-weight:800;
  letter-spacing:.2px;
}

button:hover{
  transform:translateY(-2px);
}

button:active{
  transform:translateY(0);
}

.btn-primary{
  background:linear-gradient(135deg, var(--primary) 0%, var(--primary-2) 100%);
  color:#fff;
  box-shadow:0 10px 24px rgba(91,108,255,.24);
}

.btn-success{
  background:linear-gradient(135deg, #34d399 0%, var(--success) 100%);
  color:#fff;
  box-shadow:0 10px 24px rgba(34,197,94,.22);
}

.btn-danger{
  background:linear-gradient(135deg, #ff7b8f 0%, var(--danger) 100%);
  color:#fff;
  box-shadow:0 10px 24px rgba(255,93,115,.22);
}

.btn-secondary{
  background:linear-gradient(135deg, #ffffff 0%, #eef2ff 100%);
  color:#111827;
  border:1px solid var(--border);
}

.actions{
  display:flex;
  gap:12px;
  flex-wrap:wrap;
  margin-top:16px;
}

.actions > *{flex:1}

.list{
  display:grid;
  gap:12px;
}

.item{
  position:relative;
  overflow:hidden;
  background:var(--item-gradient);
  border:1px solid var(--border);
  border-radius:18px;
  padding:14px 14px 14px 18px;
  box-shadow:0 6px 18px rgba(0,0,0,.04);
  transition:
    transform .24s ease,
    box-shadow .24s ease,
    border-color .24s ease,
    background .35s ease;
}

.item::before{
  content:"";
  position:absolute;
  top:10px;
  bottom:10px;
  left:8px;
  width:6px;
  border-radius:999px;
  background:linear-gradient(180deg, var(--accent) 0%, var(--primary) 100%);
  box-shadow:0 0 12px rgba(183,255,60,.35);
}

.item:hover{
  transform:translateY(-3px) scale(1.01);
  border-color:var(--border-strong);
  box-shadow:
    0 14px 28px rgba(80,92,200,.12),
    0 6px 14px rgba(0,0,0,.05);
}

.item h3{
  margin:0 0 6px;
  transition:color .22s ease;
}

.item:hover h3{
  color:var(--primary);
}

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

.error{
  color:#8a1c1c;
  background:linear-gradient(135deg, #ffe4e7 0%, #fff1f2 100%);
  border:1px solid #fecdd3;
  padding:12px;
  border-radius:14px;
  animation:popIn .28s ease;
}

.success{
  color:#166534;
  background:linear-gradient(135deg, #dcfce7 0%, #f0fdf4 100%);
  border:1px solid #86efac;
  padding:12px;
  border-radius:14px;
  animation:popIn .28s ease;
}

.stats{
  display:grid;
  grid-template-columns:repeat(2,1fr);
  gap:12px;
}

.stat{
  background:linear-gradient(180deg, rgba(255,255,255,.95) 0%, rgba(243,248,255,.85) 100%);
  border:1px solid var(--border);
  border-radius:18px;
  padding:14px;
  text-align:center;
  transition:
    transform .22s ease,
    box-shadow .22s ease,
    border-color .22s ease;
}

.stat:hover{
  transform:translateY(-3px);
  border-color:var(--border-strong);
  box-shadow:0 14px 28px rgba(91,108,255,.12);
}

.stat-number{
  font-size:32px;
  font-weight:900;
  background:linear-gradient(135deg, var(--primary) 0%, var(--accent-2) 100%);
  -webkit-background-clip:text;
  background-clip:text;
  color:transparent;
}

.card-wrap{perspective:1400px}

.flashcard{
  width:100%;
  min-height:360px;
  position:relative;
  transform-style:preserve-3d;
  transition:transform .7s cubic-bezier(.2,.8,.2,1);
  cursor:pointer;
}

.flashcard:hover{
  transform:rotateY(0deg) translateY(-4px);
}

.flashcard.flipped{
  transform:rotateY(180deg);
}

.face{
  position:absolute;
  inset:0;
  backface-visibility:hidden;
  -webkit-backface-visibility:hidden;
  border-radius:28px;
  background:
    linear-gradient(180deg, rgba(255,255,255,.95) 0%, rgba(246,250,255,.88) 100%);
  border:1px solid var(--border);
  box-shadow:
    0 18px 38px rgba(80,92,200,.14),
    inset 0 1px 0 rgba(255,255,255,.55);
  display:flex;
  flex-direction:column;
  justify-content:center;
  align-items:center;
  padding:24px;
  text-align:center;
  transition:
    border-color .28s ease,
    box-shadow .28s ease,
    background .35s ease;
}

.face::after{
  content:"";
  position:absolute;
  inset:0;
  border-radius:inherit;
  pointer-events:none;
  background:
    radial-gradient(circle at top right, rgba(183,255,60,.18), transparent 22%),
    radial-gradient(circle at bottom left, rgba(255,139,209,.14), transparent 22%);
}

.face.back{
  transform:rotateY(180deg);
  justify-content:flex-start;
  align-items:stretch;
  text-align:left;
  overflow:auto;
}

.letter{
  font-size:18px;
  color:var(--muted);
  font-weight:800;
  margin-bottom:12px;
  align-self:flex-start;
}

.acronym{
  font-size:42px;
  font-weight:900;
  line-height:1.1;
  background:linear-gradient(135deg, var(--primary) 0%, var(--accent-2) 55%, var(--accent) 100%);
  -webkit-background-clip:text;
  background-clip:text;
  color:transparent;
  text-shadow:0 10px 24px rgba(91,108,255,.14);
}

.full{
  font-size:28px;
  font-weight:900;
  margin-bottom:16px;
  color:var(--primary);
  line-height:1.2;
}

.desc{
  font-size:17px;
  line-height:1.6;
  white-space:pre-line;
}

.table{
  width:100%;
  border-collapse:separate;
  border-spacing:0;
  overflow:hidden;
  background:rgba(255,255,255,.92);
  border-radius:18px;
  box-shadow:0 8px 24px rgba(0,0,0,.05);
}

.table th,.table td{
  border:1px solid var(--border);
  padding:10px;
  text-align:left;
  font-size:14px;
  transition:background .22s ease, color .22s ease;
}

.table th{
  background:var(--table-head);
  font-weight:800;
  color:var(--primary);
}

.table tbody tr{
  transition:transform .18s ease, background .22s ease;
}

.table tbody tr:hover td{
  background:var(--highlight);
}

@keyframes popIn{
  from{
    opacity:0;
    transform:translateY(6px) scale(.98);
  }
  to{
    opacity:1;
    transform:translateY(0) scale(1);
  }
}

@media (min-width:700px){
  .flashcard{min-height:420px}
  .acronym{font-size:56px}
  .full{font-size:32px}
}