:root{
  --bg: #0b1220;
  --panel: rgba(255,255,255,0.06);
  --panel-strong: rgba(255,255,255,0.10);
  --text: rgba(255,255,255,0.92);
  --muted: rgba(255,255,255,0.72);
  --border: rgba(255,255,255,0.14);
  --primary: #4ade80;
  --primary-pressed: #22c55e;
  --danger: #fb7185;
  --shadow: 0 18px 55px rgba(0,0,0,0.45);
}

*{ box-sizing: border-box; }

body{
  margin: 0;
  font-family: ui-sans-serif, system-ui, -apple-system, "Segoe UI", Roboto, Arial, "Noto Sans", "Liberation Sans", sans-serif;
  color: var(--text);
  min-height: 100vh;
  background:
    radial-gradient(1100px 500px at 20% -10%, rgba(74,222,128,0.25), transparent 60%),
    radial-gradient(900px 450px at 90% 0%, rgba(96,165,250,0.18), transparent 55%),
    radial-gradient(900px 450px at 50% 110%, rgba(251,113,133,0.12), transparent 55%),
    var(--bg);
}

.container{
  max-width: 980px;
  margin: 0 auto;
  padding: 40px 18px 60px;
}

.header{
  text-align: center;
  margin-bottom: 18px;
}

h1{
  margin: 0 0 8px;
  font-size: clamp(1.75rem, 3vw, 2.4rem);
  letter-spacing: -0.02em;
}

.subtitle{
  margin: 0;
  color: var(--muted);
}

form{
  max-width: 560px;
  margin: 18px auto 0;
  padding: 22px;
  border-radius: 18px;
  background: linear-gradient(180deg, rgba(255,255,255,0.08), rgba(255,255,255,0.05));
  border: 1px solid var(--border);
  box-shadow: var(--shadow);
  backdrop-filter: blur(10px);
}

.field{
  margin: 14px 0 16px;
}

label{
  display: block;
  font-weight: 700;
  margin-bottom: 8px;
}

.hint{
  margin: 8px 0 0;
  color: var(--muted);
  font-size: 0.95rem;
}

.input-row{
  display: grid;
  grid-template-columns: auto 1fr auto;
  align-items: center;
  gap: 10px;
  padding: 10px 12px;
  border-radius: 12px;
  border: 1px solid var(--border);
  background: var(--panel);
}

.prefix, .suffix{
  color: var(--muted);
  font-weight: 700;
  user-select: none;
}

input, select{
  width: 100%;
  font: inherit;
  color: var(--text);
  background: transparent;
  border: 0;
  outline: none;
  min-width: 0;
}

select{
  width: 100%;
  padding: 12px;
  border-radius: 12px;
  border: 1px solid var(--border);
  background: var(--panel);
}

input::placeholder{ color: rgba(255,255,255,0.45); }

.input-row:focus-within,
select:focus{
  border-color: rgb(49, 146, 84);
  box-shadow: 0 0 0 4px rgba(74,222,128,0.16);
}

.actions{
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 12px;
  margin-top: 6px;
}

button{
  border: 1px solid rgba(255,255,255,0.12);
  border-radius: 12px;
  padding: 12px 14px;
  font: inherit;
  font-weight: 800;
  cursor: pointer;
  transition: transform 120ms ease, background-color 120ms ease, border-color 120ms ease;
}

button:active{
  transform: translateY(1px);
}

button#calculate-btn{
  background: rgba(74,222,128,0.20);
  border-color: rgba(74,222,128,0.35);
}
button#calculate-btn:hover{
  background: rgba(74,222,128,0.26);
}

button.secondary{
  background: rgba(255,255,255,0.07);
}
button.secondary:hover{
  background: rgba(255,255,255,0.10);
}

.result{
  margin-top: 18px;
  padding: 14px 14px 10px;
  border-radius: 14px;
  border: 1px solid var(--border);
  background: var(--panel-strong);
}

.total{
  margin: 0;
  display: flex;
  align-items: baseline;
  justify-content: space-between;
  gap: 10px;
  font-weight: 800;
}

#total-amount{
  color: var(--primary);
  font-size: 1.25rem;
}

.breakdown{
  margin-top: 10px;
  display: grid;
  gap: 6px;
  color: var(--muted);
}

.breakdown p{
  margin: 0;
  display: flex;
  justify-content: space-between;
  gap: 10px;
}

.error{
  margin: 12px 0 0;
  color: var(--danger);
  font-weight: 700;
}

@media (max-width: 520px){
  .actions{ grid-template-columns: 1fr; }
  .total{ flex-direction: column; align-items: flex-start; }
}