:root {
  --primary: #2563eb;
  --primary-hover: #1d4ed8;
  --success: #16a34a;
  --success-hover: #15803d;
  --danger: #ef4444;
  --bg-main: #f8fafc;
  --card-bg: #ffffff;
  --text-dark: #0f172a;
  --text-muted: #64748b;
  --border-color: #e2e8f0;
  --radius-sm: 8px;
  --radius-md: 14px;
  --radius-lg: 20px;
  --shadow-sm: 0 1px 3px rgba(0, 0, 0, 0.05);
  --shadow-md: 0 4px 14px rgba(0, 0, 0, 0.08);
}

* {
  box-sizing: border-box;
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Oxygen, Ubuntu, Cantarell, sans-serif;
  margin: 0;
  padding: 0;
  -webkit-tap-highlight-color: transparent;
}

body {
  background-color: var(--bg-main);
  color: var(--text-dark);
  padding: 12px;
  min-height: 100vh;
  display: flex;
  flex-direction: column;
}

.container {
  width: 100%;
  max-width: 480px;
  margin: 0 auto;
}

.card {
  background: var(--card-bg);
  padding: 20px;
  border-radius: var(--radius-md);
  box-shadow: var(--shadow-md);
  border: 1px solid var(--border-color);
  margin-bottom: 16px;
}

/* Modern Header */
.app-header {
  background: #0f172a;
  color: #ffffff;
  padding: 14px 18px;
  border-radius: var(--radius-md);
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: 16px;
}
.app-header h2 { font-size: 1.15rem; font-weight: 700; letter-spacing: -0.3px; }
.app-header a { font-size: 0.85rem; color: #94a3b8; text-decoration: none; font-weight: 600; }

/* Inputs & Form Elements */
.form-group { margin-bottom: 14px; text-align: left; }
.form-group label {
  display: block;
  font-weight: 600;
  margin-bottom: 6px;
  font-size: 0.85rem;
  color: var(--text-muted);
}
input[type="text"], input[type="tel"], input[type="number"] {
  width: 100%;
  padding: 14px;
  border: 1.5px solid var(--border-color);
  border-radius: var(--radius-sm);
  font-size: 1rem;
  outline: none;
  background: #fdfdfd;
  transition: border-color 0.2s;
}
input:focus {
  border-color: var(--primary);
  background: #ffffff;
}

/* Buttons */
.btn {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  width: 100%;
  padding: 14px;
  border: none;
  border-radius: var(--radius-sm);
  font-size: 1rem;
  font-weight: 600;
  cursor: pointer;
  transition: background-color 0.2s, transform 0.1s;
}
.btn:active { transform: scale(0.98); }
.btn-primary { background: var(--primary); color: #ffffff; }
.btn-primary:hover { background: var(--primary-hover); }
.btn-secondary { background: #f1f5f9; color: var(--text-dark); border: 1px solid var(--border-color); width: auto; }
.btn-success { background: var(--success); color: #ffffff; }
.btn-success:hover { background: var(--success-hover); }

/* Cart Item Cards */
.cart-items {
  margin: 14px 0;
  display: flex;
  flex-direction: column;
  gap: 10px;
  max-height: 280px;
  overflow-y: auto;
  padding-right: 4px;
}
.cart-item {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 12px;
  background: #f8fafc;
  border: 1px solid var(--border-color);
  border-radius: var(--radius-sm);
}
.btn-del {
  background: #fee2e2;
  color: var(--danger);
  border: none;
  border-radius: 6px;
  width: 32px;
  height: 32px;
  cursor: pointer;
  font-size: 16px;
  font-weight: bold;
}

/* Total Bar */
.total-bar {
  display: flex;
  justify-content: space-between;
  align-items: center;
  font-size: 1.25rem;
  font-weight: 800;
  padding: 16px 0 12px;
  border-top: 2px solid var(--border-color);
}

/* Paid Badge & Animation */
.paid-stamp {
  display: inline-block;
  padding: 8px 22px;
  border: 3px solid var(--success);
  color: var(--success);
  font-size: 1.8rem;
  font-weight: 900;
  transform: rotate(-6deg);
  margin: 15px 0;
  border-radius: var(--radius-sm);
  letter-spacing: 2px;
}