/* ===== Variables ===== */
:root {
  --glass-bg: rgba(255, 255, 255, 0.85);
  --glass-border: rgba(255, 255, 255, 0.35);
  --shadow-lg: 0 25px 50px -12px rgba(0, 0, 0, 0.35);
  --shadow-glow-valid: 0 0 40px rgba(34, 197, 94, 0.25);
  --shadow-glow-invalid: 0 0 40px rgba(239, 68, 68, 0.2);
  --transition-smooth: 0.35s cubic-bezier(0.4, 0, 0.2, 1);
  --transition-spring: 0.5s cubic-bezier(0.34, 1.56, 0.64, 1);
}

/* ===== Base & Animated Background ===== */
* {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

body {
  font-family: Tahoma, sans-serif;
  min-height: 100vh;
  color: #333;
  padding: 2rem 1rem;
  overflow-x: hidden;
  position: relative;
}

/* Animated gradient mesh background */
body::before {
  content: '';
  position: fixed;
  inset: 0;
  z-index: -2;
  background: linear-gradient(135deg, #0f0c29 0%, #302b63 35%, #24243e 60%, #1a1a2e 100%);
  background-size: 400% 400%;
  animation: gradientShift 12s ease infinite;
}

body::after {
  content: '';
  position: fixed;
  inset: 0;
  z-index: -1;
  background-image:
    linear-gradient(rgba(255,255,255,0.03) 1px, transparent 1px),
    linear-gradient(90deg, rgba(255,255,255,0.03) 1px, transparent 1px),
    radial-gradient(ellipse 80% 50% at 20% 20%, rgba(99, 102, 241, 0.15) 0%, transparent 50%),
    radial-gradient(ellipse 60% 40% at 80% 80%, rgba(34, 197, 94, 0.08) 0%, transparent 50%),
    radial-gradient(ellipse 50% 30% at 50% 50%, rgba(168, 85, 247, 0.06) 0%, transparent 50%);
  background-size: 48px 48px, 48px 48px, 100% 100%, 100% 100%, 100% 100%;
  background-position: 0 0, 0 0, 0 0, 0 0, 0 0;
  pointer-events: none;
  animation: meshPulse 8s ease-in-out infinite;
}

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

@keyframes meshPulse {
  0%, 100% { opacity: 1; }
  50% { opacity: 0.7; }
}

body {
  background: transparent;
}

.container {
  max-width: 560px;
  margin: 0 auto;
}

/* ===== Header with entrance animation ===== */
header {
  text-align: center;
  margin-bottom: 2.5rem;
  color: #e8e8e8;
  animation: fadeSlideDown 0.8s var(--transition-smooth) both;
}

@keyframes fadeSlideDown {
  from {
    opacity: 0;
    transform: translateY(-24px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

header h1 {
  font-size: 1.85rem;
  font-weight: 600;
  margin-bottom: 0.5rem;
  text-shadow: 0 2px 20px rgba(0, 0, 0, 0.3);
  letter-spacing: 0.02em;
}

header p {
  font-size: 0.95rem;
  opacity: 0.9;
  animation: fadeSlideDown 0.8s 0.15s var(--transition-smooth) both;
}

/* ===== Glassmorphism form card ===== */
.form-card {
  background: var(--glass-bg);
  backdrop-filter: blur(20px);
  -webkit-backdrop-filter: blur(20px);
  border: 1px solid var(--glass-border);
  border-radius: 20px;
  padding: 2rem;
  margin-bottom: 1.5rem;
  box-shadow: var(--shadow-lg);
  animation: fadeSlideUp 0.7s 0.2s var(--transition-smooth) both;
  transition: transform var(--transition-smooth), box-shadow var(--transition-smooth);
}

.form-card:hover {
  box-shadow: 0 30px 60px -15px rgba(0, 0, 0, 0.4);
}

@keyframes fadeSlideUp {
  from {
    opacity: 0;
    transform: translateY(20px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

.form-group {
  margin-bottom: 1.35rem;
}

.form-group:last-of-type {
  margin-bottom: 1.75rem;
}

.form-group label {
  display: block;
  font-weight: 500;
  margin-bottom: 0.5rem;
  color: #333;
  transition: color var(--transition-smooth);
}

.form-group input {
  width: 100%;
  padding: 0.85rem 1.1rem;
  border: 2px solid rgba(0, 0, 0, 0.08);
  border-radius: 12px;
  font-size: 1rem;
  font-family: Tahoma, sans-serif;
  background: rgba(255, 255, 255, 0.7);
  transition: border-color var(--transition-smooth), box-shadow var(--transition-smooth),
              transform var(--transition-smooth), background var(--transition-smooth);
}

.form-group input:hover {
  border-color: rgba(99, 102, 241, 0.3);
  background: rgba(255, 255, 255, 0.9);
}

.form-group input:focus {
  outline: none;
  border-color: #6366f1;
  box-shadow: 0 0 0 4px rgba(99, 102, 241, 0.2);
  transform: translateY(-1px);
  background: #fff;
}

.form-group input::placeholder {
  color: #888;
}

/* ===== Modern gradient button with effects ===== */
button[type="submit"] {
  width: 100%;
  padding: 1rem 1.5rem;
  background: linear-gradient(135deg, #6366f1 0%, #4f46e5 50%, #4338ca 100%);
  background-size: 200% 200%;
  color: #fff;
  border: none;
  border-radius: 12px;
  font-size: 1rem;
  font-weight: 600;
  cursor: pointer;
  font-family: Tahoma, sans-serif;
  position: relative;
  overflow: hidden;
  transition: transform var(--transition-spring), box-shadow var(--transition-smooth),
              background-position 0.6s ease;
  box-shadow: 0 4px 20px rgba(99, 102, 241, 0.4);
}

button[type="submit"]::before {
  content: '';
  position: absolute;
  inset: 0;
  background: linear-gradient(120deg, transparent, rgba(255,255,255,0.2), transparent);
  transform: translateX(-100%);
  transition: transform 0.6s ease;
}

button[type="submit"]:hover:not(:disabled) {
  transform: translateY(-2px) scale(1.01);
  box-shadow: 0 8px 30px rgba(99, 102, 241, 0.5);
  background-position: 100% 0;
}

button[type="submit"]:hover:not(:disabled)::before {
  transform: translateX(100%);
}

button[type="submit"]:active:not(:disabled) {
  transform: translateY(0) scale(0.99);
  transition-duration: 0.1s;
}

button[type="submit"]:disabled {
  background: linear-gradient(135deg, #94a3b8 0%, #64748b 100%);
  cursor: not-allowed;
  box-shadow: none;
}

/* ===== Result container entrance ===== */
.result-container {
  margin-top: 1.25rem;
  animation: resultReveal 0.6s var(--transition-spring) both;
}

.result-container.hidden {
  display: none;
}

@keyframes resultReveal {
  from {
    opacity: 0;
    transform: translateY(16px) scale(0.98);
  }
  to {
    opacity: 1;
    transform: translateY(0) scale(1);
  }
}

.result-card {
  border-radius: 20px;
  overflow: hidden;
  box-shadow: var(--shadow-lg);
  transition: box-shadow var(--transition-smooth), transform var(--transition-smooth);
}

.result-card:hover {
  transform: translateY(-2px);
}

/* Valid: light green with glow */
.result-card.valid {
  background: linear-gradient(145deg, #f0fdf4 0%, #dcfce7 100%);
  border: 1px solid rgba(34, 197, 94, 0.4);
  box-shadow: var(--shadow-lg), var(--shadow-glow-valid);
}

.result-card.valid .result-header {
  background: linear-gradient(90deg, rgba(34, 197, 94, 0.15) 0%, rgba(34, 197, 94, 0.08) 100%);
  color: #166534;
  border-bottom: 1px solid rgba(34, 197, 94, 0.3);
}

.result-card.valid .result-badge {
  background: linear-gradient(135deg, #22c55e 0%, #16a34a 100%);
  color: #fff;
  box-shadow: 0 4px 14px rgba(34, 197, 94, 0.4);
  animation: badgePop 0.5s var(--transition-spring) 0.2s both;
}

/* Invalid: light red with glow */
.result-card.invalid {
  background: linear-gradient(145deg, #fef2f2 0%, #fee2e2 100%);
  border: 1px solid rgba(239, 68, 68, 0.4);
  box-shadow: var(--shadow-lg), var(--shadow-glow-invalid);
}

.result-card.invalid .result-header {
  background: linear-gradient(90deg, rgba(239, 68, 68, 0.12) 0%, rgba(239, 68, 68, 0.06) 100%);
  color: #991b1b;
  border-bottom: 1px solid rgba(239, 68, 68, 0.3);
}

.result-card.invalid .result-badge {
  background: linear-gradient(135deg, #ef4444 0%, #dc2626 100%);
  color: #fff;
  box-shadow: 0 4px 14px rgba(239, 68, 68, 0.4);
  animation: badgePop 0.5s var(--transition-spring) 0.2s both;
}

@keyframes badgePop {
  from {
    transform: scale(0);
    opacity: 0;
  }
  to {
    transform: scale(1);
    opacity: 1;
  }
}

.result-header {
  padding: 1.1rem 1.35rem;
  display: flex;
  align-items: center;
  gap: 0.85rem;
}

.result-badge {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 40px;
  height: 40px;
  border-radius: 50%;
  font-size: 1.15rem;
  font-weight: bold;
  flex-shrink: 0;
}

.result-header h2 {
  font-size: 1.1rem;
  font-weight: 600;
}

.result-body {
  padding: 1.35rem;
}

/* Staggered result rows */
.result-row {
  display: flex;
  justify-content: space-between;
  align-items: flex-start;
  padding: 0.6rem 0;
  border-bottom: 1px solid rgba(0, 0, 0, 0.06);
  gap: 1rem;
  opacity: 0;
  animation: rowFadeIn 0.4s var(--transition-smooth) forwards;
}

.result-row:last-child {
  border-bottom: none;
}

.result-row .label {
  font-weight: 500;
  color: #555;
  min-width: 140px;
}

.result-row .value {
  text-align: left;
  color: #222;
  word-break: break-word;
}

.result-card.valid .result-row .value {
  color: #166534;
}

.result-card.invalid .result-row .value {
  color: #991b1b;
}

@keyframes rowFadeIn {
  from {
    opacity: 0;
    transform: translateX(8px);
  }
  to {
    opacity: 1;
    transform: translateX(0);
  }
}

/* ===== Error message with shake ===== */
.error-message {
  background: linear-gradient(145deg, #fef2f2 0%, #fee2e2 100%);
  border: 1px solid rgba(239, 68, 68, 0.4);
  color: #991b1b;
  padding: 1.1rem 1.35rem;
  border-radius: 12px;
  margin-top: 1rem;
  animation: errorShake 0.5s var(--transition-smooth);
  box-shadow: 0 4px 20px rgba(239, 68, 68, 0.15);
}

.error-message.hidden {
  display: none;
}

@keyframes errorShake {
  0%, 100% { transform: translateX(0); }
  20% { transform: translateX(-6px); }
  40% { transform: translateX(6px); }
  60% { transform: translateX(-4px); }
  80% { transform: translateX(4px); }
}

/* ===== Loading with modern spinner ===== */
.loading {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 0.85rem;
  padding: 1.75rem;
  color: #e8e8e8;
  animation: fadeIn 0.3s ease;
}

.loading.hidden {
  display: none;
}

@keyframes fadeIn {
  from { opacity: 0; }
  to { opacity: 1; }
}

.loading span {
  text-shadow: 0 2px 10px rgba(0, 0, 0, 0.3);
}

.spinner {
  width: 28px;
  height: 28px;
  border: 3px solid rgba(255, 255, 255, 0.2);
  border-top-color: #a5b4fc;
  border-radius: 50%;
  animation: spin 0.8s linear infinite;
}

@keyframes spin {
  to {
    transform: rotate(360deg);
  }
}