:root {
  --bg: #f4f7fb;
  --card: #ffffff;
  --primary: #4f46e5;
  --primary-dark: #3730a3;
  --text: #172033;
  --muted: #6b7280;
  --border: #e5e7eb;
  --success: #16a34a;
  --danger: #dc2626;
  --warning: #d97706;
  --shadow: 0 12px 35px rgba(15, 23, 42, 0.08);
  --radius: 18px;
}

* {
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
}

body {
  margin: 0;
  font-family:
    Inter,
    ui-sans-serif,
    system-ui,
    -apple-system,
    BlinkMacSystemFont,
    "Segoe UI",
    sans-serif;
  background:
    radial-gradient(circle at top left, #e0e7ff 0, transparent 32%),
    radial-gradient(circle at top right, #dbeafe 0, transparent 28%),
    var(--bg);
  color: var(--text);
  min-height: 100vh;
}

.hidden {
  display: none !important;
}

/* =========================
   LOGIN
========================= */

#loginScreen {
  min-height: 100vh;
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 24px;
}

.login-card {
  width: 100%;
  max-width: 430px;
  padding: 42px 34px;
  text-align: center;
  border-radius: 28px;
  background: rgba(255, 255, 255, 0.92);
  backdrop-filter: blur(18px);
  box-shadow: 0 25px 70px rgba(30, 41, 59, 0.14);
}

.login-card h1 {
  font-size: 36px;
  margin-bottom: 8px;
  letter-spacing: -1px;
}

.login-card > p {
  color: var(--muted);
  margin-bottom: 28px;
}

/* =========================
   CARDS
========================= */

.card {
  background: var(--card);
  border: 1px solid rgba(229, 231, 235, 0.9);
  border-radius: var(--radius);
  padding: 24px;
  margin: 20px auto;
  max-width: 1000px;
  box-shadow: var(--shadow);
}

.card h2 {
  font-size: 23px;
  margin-bottom: 18px;
}

.card h3 {
  margin-top: 24px;
}

/* =========================
   INPUTS
========================= */

input {
  width: 100%;
  padding: 14px 15px;
  margin-top: 10px;
  border: 1px solid var(--border);
  border-radius: 12px;
  background: #fff;
  color: var(--text);
  font-size: 16px;
  outline: none;
  transition: 0.2s;
}

input:focus {
  border-color: var(--primary);
  box-shadow: 0 0 0 4px rgba(79, 70, 229, 0.12);
}

/* =========================
   BUTTONS
========================= */

button {
  width: 100%;
  padding: 13px 16px;
  margin-top: 10px;
  border: 0;
  border-radius: 12px;
  background: linear-gradient(
    135deg,
    var(--primary),
    #6366f1
  );
  color: white;
  font-size: 15px;
  font-weight: 700;
  cursor: pointer;
  transition:
    transform 0.15s,
    box-shadow 0.15s,
    opacity 0.15s;
  box-shadow: 0 7px 18px rgba(79, 70, 229, 0.22);
}

button:hover {
  transform: translateY(-1px);
  box-shadow: 0 10px 22px rgba(79, 70, 229, 0.28);
}

button:active {
  transform: translateY(0);
}

button.secondary {
  width: auto;
  background: rgba(255, 255, 255, 0.16);
  box-shadow: none;
  border: 1px solid rgba(255, 255, 255, 0.28);
}

/* =========================
   TOPBAR
========================= */

.topbar {
  position: sticky;
  top: 0;
  z-index: 100;
  padding: 18px 28px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 20px;
  color: white;
  background:
    linear-gradient(
      135deg,
      #3730a3,
      #4f46e5 55%,
      #6366f1
    );
  box-shadow: 0 8px 25px rgba(30, 41, 59, 0.18);
}

.topbar h1 {
  margin: 0;
  font-size: 25px;
  letter-spacing: -0.5px;
}

#userName {
  display: inline-block;
  margin-top: 4px;
  opacity: 0.82;
  font-size: 14px;
}

/* =========================
   NAVIGATION
========================= */

.tabs {
  position: sticky;
  top: 82px;
  z-index: 90;
  display: flex;
  gap: 8px;
  padding: 12px;
  max-width: 1000px;
  margin: 18px auto 0;
  background: rgba(255, 255, 255, 0.86);
  backdrop-filter: blur(15px);
  border: 1px solid var(--border);
  border-radius: 16px;
  box-shadow: 0 8px 25px rgba(15, 23, 42, 0.06);
}

.tabs button {
  margin: 0;
  background: transparent;
  color: var(--muted);
  box-shadow: none;
}

.tabs button:hover {
  background: #eef2ff;
  color: var(--primary);
  box-shadow: none;
}

/* =========================
   PRODUCTS
========================= */

.product-row {
  display: grid;
  grid-template-columns: 1fr 110px 110px;
  gap: 14px;
  align-items: center;
  padding: 16px 4px;
  border-bottom: 1px solid var(--border);
}

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

.product-name {
  font-size: 17px;
  font-weight: 750;
}

.product-price {
  text-align: right;
  color: var(--primary);
  font-weight: 750;
}

.product-quantity {
  margin: 0;
  text-align: center;
}

/* =========================
   SALE SUMMARY
========================= */

.sale-summary {
  margin-top: 24px;
  padding: 20px;
  background: linear-gradient(
    135deg,
    #f8fafc,
    #eef2ff
  );
  border-radius: 16px;
}

.sale-summary h3 {
  margin-top: 0;
  font-size: 22px;
}

.sale-summary label,
.card label {
  display: block;
  margin-top: 14px;
  font-weight: 700;
}

/* =========================
   CREDIT
========================= */

.credit-box {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 14px;
  font-size: 17px;
}

.credit-box p {
  margin: 0;
  padding: 20px;
  background: linear-gradient(
    135deg,
    #f8fafc,
    #eef2ff
  );
  border: 1px solid var(--border);
  border-radius: 16px;
}

.credit-box strong {
  display: block;
  margin-top: 8px;
  font-size: 26px;
  color: var(--primary);
}

/* =========================
   HISTORY
========================= */

.history-row {
  padding: 15px 0;
  border-bottom: 1px solid var(--border);
}

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

/* =========================
   MESSAGES
========================= */

.message {
  margin-top: 14px;
  font-weight: 700;
}

.success {
  background: #ecfdf3;
  color: #166534;
  border: 1px solid #bbf7d0;
  padding: 14px;
  border-radius: 12px;
  margin-top: 10px;
}

.warning {
  background: #fffbeb;
  color: #92400e;
  border: 1px solid #fde68a;
  padding: 14px;
  border-radius: 12px;
  margin-top: 10px;
}

.danger {
  background: #fef2f2;
  color: #991b1b;
  border: 1px solid #fecaca;
  padding: 14px;
  border-radius: 12px;
  margin-top: 10px;
}

/* =========================
   ADMIN
========================= */

.admin-product,
.admin-user,
.admin-day {
  padding: 16px 0;
  border-bottom: 1px solid var(--border);
}

.admin-product:last-child,
.admin-user:last-child,
.admin-day:last-child {
  border-bottom: none;
}

.admin-product strong,
.admin-user strong {
  font-size: 17px;
}

.admin-product button {
  margin-top: 12px;
}

/* =========================
   SECTIONS
========================= */

main {
  padding: 0 18px 40px;
}

hr {
  border: 0;
  border-top: 1px solid var(--border);
  margin: 28px 0;
}

/* =========================
   MOBILE
========================= */

@media (max-width: 700px) {

  body {
    background: #f4f7fb;
  }

  #loginScreen {
    padding: 16px;
  }

  .login-card {
    padding: 32px 22px;
    border-radius: 22px;
  }

  .login-card h1 {
    font-size: 30px;
  }

  .topbar {
    padding: 16px;
    align-items: stretch;
    flex-direction: column;
  }

  .topbar button.secondary {
    width: 100%;
  }

  .tabs {
    top: 128px;
    margin: 10px 0;
    flex-direction: column;
    border-radius: 14px;
  }

  main {
    padding: 0 10px 30px;
  }

  .card {
    padding: 18px;
    border-radius: 16px;
  }

  .product-row {
    grid-template-columns: 1fr 90px;
    gap: 10px;
  }

  .product-price {
    text-align: left;
    grid-column: 1;
    color: var(--primary);
  }

  .product-quantity {
    grid-column: 2;
    grid-row: 1 / span 2;
    align-self: center;
  }

  .credit-box {
    grid-template-columns: 1fr;
  }

  .credit-box p {
    padding: 16px;
  }

  .credit-box strong {
    font-size: 24px;
  }

  button {
    min-height: 48px;
  }

  input {
    min-height: 48px;
  }
}