:root {
    --bg: #f6f8fb;
    --card: #ffffff;
    --accent: #0F6CFF;
    --muted: #6b7280;
    --success: #10B981;
    --radius: 12px;
    --shadow: 0 6px 18px rgba(17, 24, 39, 0.08);
    font-family: Inter, ui-sans-serif, system-ui, -apple-system, "Segoe UI", Roboto, "Helvetica Neue", Arial;
}

html, body {
  margin: 0;
  background: var(--bg);
  display: flex;
  flex-direction: column;
  min-height: 100vh;
}

.container {
    max-width: 75%;
    flex: 1;
    margin: 32px auto;
    padding: 24px;
}

/* Header / Nav */
header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 4px 4px;
}

header .brand {
    display: flex;
    align-items: center;
    gap: 12px;
}

header .logo {
    width: 48px;
    height: 48px;
    border-radius: 10px;
    background: linear-gradient(45deg, var(--accent), #06b6d4);
    display: flex;
    justify-content: center;
    align-items: center;
    color: #fff;
    font-weight: 700;
    font-size: 1.1rem;
}

nav a {
    margin-left: 12px;
    margin-right: 12px;
    text-decoration: none;
    color: var(--muted);
    font-weight: 500;
}

/* Card */
.card {
    background: var(--card);
    border-radius: var(--radius);
    box-shadow: var(--shadow);
    padding: 20px;
    display: grid;
    grid-template-columns: 3fr 2fr;
    gap: 20px;
    align-items: start;
}

label {
    display: block;
    margin-bottom: 4px;
    color: #111827;
    font-size: 0.9rem;
}

input[type="number"], select {
    width: 90%;
    padding: 10px;
    border-radius: 10px;
    border: 1px solid #e6eef8;
    font-size: 1rem;
}

.btn {
    display: inline-block;
    padding: 10px 14px;
    background: var(--accent);
    color: #fff;
    border-radius: 8px;
    border: none;
    font-weight: 600;
    cursor: pointer;
}

.muted {
    color: var(--muted);
    font-size: 0.9rem;
}

#result {
    background: linear-gradient(45deg, rgba(28, 70, 136, 0.1), rgba(22, 106, 241, 0.15));
    padding: 12px;
    border-radius: 8px;
}

.stat {
    display: flex;
    justify-content: space-between;
    padding: 10px 0;
    border-bottom: 1px solid rgba(80, 80, 80, 0.5);
}

.stat:last-child {
    border-bottom: none;
}

.ads {
    background: #fff;
    border-radius: 8px;
    padding: 12px;
    border: 1px dashed #e6eef8;
    text-align: center;
    color: var(--muted);
    font-size: 0.9rem;
}

footer {
    margin-top: auto;
    text-align: center;
    color: var(--muted);
    font-size: 0.85rem;
    padding: 8px;
}

@media (max-width: 900px) {
    .card {
    grid-template-columns: 1fr;
    }
}