:root {
  --brand: #f59e0b;
  --brand-700: #d97706;
  --bg: #ffffff;
}

/* پایه */
body {
  margin: 0; height: 100vh; overflow: hidden;
  font-family: Inter, sans-serif;
  display: flex; justify-content: center; align-items: center;
  background: linear-gradient(-45deg,#ffb703,#f59e0b,#92400e,#ffb703);
  background-size: 600% 600%;
  animation: gradientBG 18s ease infinite;
}

@keyframes gradientBG {
  0% { background-position:0% 50%; }
  50% { background-position:100% 50%; }
  100% { background-position:0% 50%; }
}

/* ذرات */
#particles { position: fixed; inset:0; z-index:0; }

/* کارت فرم */
.card {
  position: relative; z-index:1;
  background: rgba(255,255,255,0.15);
  backdrop-filter: blur(24px);
  border-radius:32px;
  padding:50px 60px;
  width:680px;
  max-width:90vw;
  box-shadow:0 24px 50px rgba(0,0,0,.35);
  animation: slideIn 0.8s ease forwards;
  opacity:0;
}

@keyframes slideIn {
  from { opacity:0; transform:translateY(80px); }
  to { opacity:1; transform:translateY(0); }
}
.card form {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 24px;
}

.card form input,
.card form .drop-down-menu {
    width: 100%;
    margin-bottom: 0;
    box-sizing: border-box;
}

.card form .btn {
    grid-column: 1 / -1;
    margin-top: 16px;
}

/* تیتر فرم */
.card h2 {
  text-align: center;
  margin-bottom: 32px;
  color: #fff;
  font-size: 2rem;
  text-shadow: 0 2px 6px rgba(0,0,0,.4);
}

input {
  padding: 18px; 
  margin-bottom: 24px;
  border-radius: 18px;
  border: none;
  background: rgba(255,255,255,0.2);
  color: #fff;
  font-size: 1rem;
  outline: none;
  transition: 0.4s;
  box-shadow: 0 4px 20px rgba(0,0,0,.25);
  box-sizing: border-box;
}

input:focus {
  border: 2px solid #ffde7d;
  box-shadow: 0 6px 25px rgba(255,222,125,.35);
}

/* دکمه */
.btn {
  width: 100%;
  padding: 18px;
  border: none;
  border-radius: 18px;
  background: linear-gradient(135deg,#ffb703,#f59e0b);
  color: #fff;
  font-weight: 700;
  cursor: pointer;
  font-size: 1rem;
  transition: 0.3s;
  perspective: 1000px;
  box-shadow: 0 8px 28px rgba(0,0,0,.4);
}

.btn:hover {
  transform: rotateX(8deg) rotateY(4deg) scale(1.08);
  box-shadow: 0 12px 36px rgba(0,0,0,.55),0 0 20px #ffde7d;
}

/* پیام خطا */
.msg {
  text-align:center; margin-bottom:16px;
  animation: fadeShake 0.6s;
}

@keyframes fadeShake {
  0% { opacity:1; transform:translateX(-10px); }
  50% { opacity:1; transform:translateX(10px); }
  100% { opacity:1; transform:translateX(0); }
}

/* لینک ثبت نام */
.link {
  text-align: center;
  display: block;
  margin-top: 16px;
  color: #fff;
  font-weight: 600;
  text-shadow: 0 0 6px rgba(0,0,0,.4);
}

/* watermark Erdos */
.erdos-watermark {
  position: absolute;
  top: 30%;
  margin-left: 6%;
  font-size: clamp(80px, 25vw, 140px);
  font-weight: 900;
  color: #f59e0b;
  text-transform: uppercase;
  letter-spacing: 8px;
  pointer-events: none;
  user-select: none;
  mix-blend-mode: lighten;
  animation: neonPulse 2.5s ease-in-out infinite, floatWave 6s ease-in-out infinite alternate;
  text-shadow: 
     0 0 5px #f59e0b,
     0 0 15px #fbbf24,
     0 0 30px #fcd34d,
     0 0 60px #f59e0b,
     0 0 90px #fbbf24;
}

@keyframes neonPulse {
  0%, 100% {
    text-shadow: 
       0 0 5px #f59e0b,
       0 0 15px #fbbf24,
       0 0 30px #fcd34d,
       0 0 60px #f59e0b,
       0 0 90px #fbbf24;
    opacity: 0.9;
  }
  50% {
    text-shadow: 
       0 0 10px #f59e0b,
       0 0 25px #fbbf24,
       0 0 45px #fcd34d,
       0 0 90px #f59e0b,
       0 0 140px #fbbf24;
    opacity: 1;
  }
}

@keyframes floatWave {
  0% { transform: translateY(0); }
  50% { transform: translateY(-18px); }
  100% { transform: translateY(0); }
}

/* ریسپانسیو */
@media (max-width: 768px) {
  .card { padding: 30px 20px; width: 95vw; }
  input { padding: 14px; margin-bottom: 20px; }
  .btn { padding: 14px; font-size: 0.95rem; }
  .erdos-watermark { font-size: clamp(60px, 40vw, 100px); }
}

@media (max-width: 480px) {
  .card { padding: 25px 15px; }
  input { padding: 12px; margin-bottom: 16px; }
  .btn { padding: 12px; font-size: 0.9rem; }

}
.drop-down-menu {
  padding: 18px;
  margin-bottom: 24px;
  border-radius: 18px;
  border: none;
  background: rgba(255,255,255,0.2);
  color: #fff;
  font-size: 1rem;
  outline: none;
  transition: 0.4s;
  box-shadow: 0 4px 20px rgba(0,0,0,.25);
  appearance: none;
  -webkit-appearance: none;
  -moz-appearance: none;
  background-image: url("data:image/svg+xml;charset=US-ASCII,<svg xmlns='http://www.w3.org/2000/svg' width='16' height='16' fill='white'><polygon points='0,0 16,0 8,8'/></svg>");
  background-repeat: no-repeat;
  background-position: right 12px center;
  background-size: 12px;
  box-sizing: border-box;
}
.drop-down-menu:focus {
  border: 2px solid #ffde7d;
  box-shadow: 0 6px 25px rgba(255,222,125,.35);
}
.drop-down-menu option {
  background: rgb(0, 0, 0); /* Match input background */
  color: #fff;                       /* Match input text color */
  padding: 18px;                     /* Match input padding */
  font-size: 1rem;
  border-radius: 18px;
  box-shadow: 0 4px 20px rgba(0,0,0,.25); /* Match input shadow */
  transition: 0.4s;
}

/* Hover and checked states to match input focus */
.drop-down-menu option:hover,
.drop-down-menu option:checked {
  background: rgba(255, 255, 255, 0.35);
  color: #000000;
  box-shadow: 0 6px 25px rgba(255,222,125,.35);
  border: 2px solid #000000;
}