:root {
  --bg: radial-gradient(circle at 15% 20%, rgba(45, 211, 231, 0.14), transparent 32%),
        radial-gradient(circle at 85% 0%, rgba(99, 102, 241, 0.18), transparent 30%),
        linear-gradient(135deg, #0b1220, #0c1828 55%, #0f1f33);
  --panel: rgba(255, 255, 255, 0.08);
  --panel-strong: rgba(255, 255, 255, 0.12);
  --accent: #22d3ee;
  --accent-strong: #6366f1;
  --text: #e7ecf5;
  --muted: #94a3b8;
  --border: rgba(255, 255, 255, 0.15);
  --error: #f97316;
  --success: #10b981;
  --radius: 18px;
  --shadow: 0 20px 70px rgba(0, 0, 0, 0.45);
  --glass: blur(24px) saturate(140%);
}

* { box-sizing: border-box; }

body {
  margin: 0;
  min-height: 100vh;
  display: grid;
  place-items: center;
  padding: clamp(12px, 4vw, 22px);
  font-family: 'Space Grotesk', system-ui, -apple-system, sans-serif;
  color: var(--text);
  background: var(--bg);
}

.card {
  width: min(100%, 558px);
  background: linear-gradient(160deg, var(--panel), rgba(255, 255, 255, 0.04));
  border: 1px solid var(--border);
  border-radius: clamp(14px, 3vw, 20px);
  box-shadow: var(--shadow);
  padding: clamp(16px, 4vw, 23px);
  position: relative;
  overflow: hidden;
  isolation: isolate;
  backdrop-filter: var(--glass);
  -webkit-backdrop-filter: var(--glass);
}

.card::after {
  content: '';
  position: absolute;
  inset: -40% 25% auto;
  height: 340px;
  background: radial-gradient(circle, rgba(99, 102, 241, 0.25), transparent 60%);
  z-index: 0;
  filter: blur(18px);
}

header {
  position: relative;
  z-index: 1;
  display: grid;
  grid-template-columns: auto 1fr;
  align-items: center;
  justify-content: center;
  gap: 0px;
  margin-bottom: 22px;
  text-align: center;
}

.hero-icon {
  width: clamp(48px, 12vw, 61px);
  height: clamp(48px, 12vw, 61px);
  border-radius: clamp(14px, 3vw, 18px);
  background: linear-gradient(140deg, rgba(34, 211, 238, 0.22), rgba(99, 102, 241, 0.6));
  display: grid;
  place-items: center;
  color: #f8fafc;
  font-weight: 700;
  font-size: clamp(20px, 5vw, 26px);
  border: 1px solid rgba(255, 255, 255, 0.18);
  box-shadow: 0 12px 30px rgba(99, 102, 241, 0.35);
}

.hero-text {
  display: grid;
  gap: 2px;
  text-align: center;
}

.eyebrow {
  margin: 0;
  font-size: 12px;
  letter-spacing: 0.16em;
  text-transform: uppercase;
  color: rgba(231, 236, 245, 0.7);
}

h1 {
  margin: 0;
  font-weight: 700;
  letter-spacing: -0.01em;
  font-size: clamp(26px, 3vw, 32px);
}

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

.grid {
  position: relative;
  z-index: 1;
  display: grid;
  grid-template-columns: 1fr;
  gap: 16px;
}

.panel {
  background: linear-gradient(180deg, var(--panel), rgba(255, 255, 255, 0.04));
  border: 1px solid rgba(255, 255, 255, 0.12);
  border-radius: 16px;
  padding: 18px;
  display: grid;
  gap: 12px;
  transition: border-color 0.2s ease, transform 0.2s ease, box-shadow 0.2s ease;
  backdrop-filter: blur(16px);
  -webkit-backdrop-filter: blur(16px);
}

.panel:hover {
  border-color: rgba(34, 211, 238, 0.45);
  transform: translateY(-1px);
  box-shadow: 0 14px 36px rgba(0, 0, 0, 0.35);
}

.panel h2 {
  margin: 0;
  font-size: 16px;
  font-weight: 700;
  color: #f8fafc;
  letter-spacing: 0.01em;
}

label {
  display: grid;
  gap: 6px;
  font-size: 13px;
  color: var(--muted);
}

.two-col {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(140px, 1fr));
  gap: clamp(8px, 2vw, 12px);
  align-items: start;
}

.result-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(140px, 1fr));
  gap: clamp(8px, 2vw, 12px);
}

.input-row {
  display: grid;
  grid-template-columns: 1fr 104px;
  gap: 10px;
  align-items: center;
  background: rgba(255, 255, 255, 0.04);
  border: 1px solid rgba(255, 255, 255, 0.12);
  border-radius: 12px;
  padding: 4px;
}

input[type="number"] {
  width: 100%;
  padding: 12px 12px;
  border-radius: 10px;
  border: 1px solid transparent;
  background: rgba(255, 255, 255, 0.08);
  color: #f8fafc;
  font-size: 16px;
  transition: border-color 0.2s ease, box-shadow 0.2s ease, background 0.2s ease;
  appearance: textfield;
}

input[type="number"]:focus {
  outline: none;
  border-color: rgba(34, 211, 238, 0.7);
  box-shadow: 0 0 0 3px rgba(34, 211, 238, 0.2);
  background: rgba(255, 255, 255, 0.12);
}

input[type="number"]::-webkit-outer-spin-button,
input[type="number"]::-webkit-inner-spin-button {
  appearance: none;
  margin: 0;
}

.unit {
  text-align: center;
  padding: 10px 12px;
  border-radius: 10px;
  background: linear-gradient(135deg, rgba(34, 211, 238, 0.9), rgba(99, 102, 241, 0.9));
  border: 1px solid rgba(255, 255, 255, 0.18);
  color: #0b1220;
  font-weight: 800;
  letter-spacing: 0.06em;
  box-shadow: 0 8px 20px rgba(34, 211, 238, 0.35);
}

.actions {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
  margin: 20px 0 6px;
  position: relative;
  z-index: 1;
  justify-content: center;
}

.mini-footer {
  margin-top: 10px;
  text-align: center;
  background: linear-gradient(135deg, rgba(34, 211, 238, 0.9), rgba(99, 102, 241, 0.9));
  -webkit-background-clip: text;
  background-clip: text;
  color: transparent;
  font-size: 12px;
  letter-spacing: 0.06em;
  text-transform: uppercase;
}

button {
  border: none;
  border-radius: 12px;
  padding: 12px 16px;
  font-weight: 700;
  letter-spacing: 0.01em;
  cursor: pointer;
  transition: transform 0.15s ease, box-shadow 0.2s ease, background 0.2s ease, opacity 0.2s ease;
  color: #0b1220;
}

.primary {
  background: linear-gradient(120deg, var(--accent), var(--accent-strong));
  box-shadow: 0 16px 32px rgba(34, 211, 238, 0.35);
}

.primary:hover { transform: translateY(-1px) scale(1.01); }

.ghost {
  background: rgba(255, 255, 255, 0.08);
  color: #f8fafc;
  border: 1px solid rgba(255, 255, 255, 0.18);
}

.ghost:hover { border-color: rgba(255, 255, 255, 0.28); }

.info {
  position: relative;
  z-index: 1;
  margin-top: 8px;
  color: var(--muted);
  font-size: 13px;
  display: flex;
  align-items: center;
  gap: 10px;
  background: rgba(255, 255, 255, 0.04);
  border: 1px solid rgba(255, 255, 255, 0.1);
  border-radius: 12px;
  padding: 10px 12px;
}

.error { color: var(--error); }
.success { color: var(--success); }

.result-box {
  background: rgba(16, 185, 129, 0.08);
  border: 1px solid rgba(16, 185, 129, 0.35);
  border-radius: var(--radius);
  padding: 14px;
  display: grid;
  gap: 8px;
}

.result-title { font-weight: 600; color: #a7f3d0; }
.result-value { font-size: 22px; letter-spacing: 0.01em; color: #ecfdf3; }

/* Малки телефони (до 480px) */
@media (max-width: 480px) {
  header {
    grid-template-columns: 1fr;
    justify-items: center;
    gap: 8px;
  }
  
  .hero-text {
    gap: 4px;
  }
  
  h1 {
    font-size: 22px;
  }
  
  .rate {
    font-size: 12px;
  }
  
  .eyebrow {
    font-size: 10px;
  }
  
  .grid {
    gap: 12px;
  }
  
  .panel {
    padding: 14px;
    gap: 10px;
  }
  
  .panel h2 {
    font-size: 14px;
  }
  
  .two-col,
  .result-grid {
    grid-template-columns: 1fr;
    gap: 10px;
  }
  
  .input-row {
    grid-template-columns: 1fr 80px;
    gap: 8px;
  }
  
  input[type="number"] {
    font-size: 15px;
    padding: 10px;
  }
  
  .unit {
    padding: 8px 10px;
    font-size: 12px;
  }
  
  .actions {
    flex-direction: column;
    gap: 10px;
  }
  
  button {
    width: 100%;
    padding: 12px;
    font-size: 14px;
  }
  
  .mini-footer {
    font-size: 10px;
    margin-top: 8px;
  }
  
  .result-value {
    font-size: 18px;
  }
}

/* Средни телефони и малки таблети (481px - 768px) */
@media (min-width: 481px) and (max-width: 768px) {
  .card {
    width: min(100%, 520px);
  }
  
  .two-col,
  .result-grid {
    grid-template-columns: 1fr;
  }
  
  .input-row {
    grid-template-columns: 1fr 90px;
  }
  
  .actions {
    flex-direction: row;
    flex-wrap: wrap;
  }
  
  button {
    flex: 1;
    min-width: 140px;
  }
}

/* Таблети (769px - 1024px) */
@media (min-width: 769px) and (max-width: 1024px) {
  .card {
    width: min(100%, 600px);
  }
}

/* Десктоп (над 1024px) */
@media (min-width: 1025px) {
  .card {
    width: min(100%, 680px);
  }
  
  .panel:hover {
    transform: translateY(-2px);
  }
}