/* ===================================================================
   RESET & BASE
=================================================================== */

*,
*::before,
*::after {
  box-sizing: border-box;
}

:root {
  --bg-body: #020617;
  --bg-surface: #0f172a;
  --bg-surface-soft: #020617;
  --bg-elevated: #020617;
  --bg-input: #020617;
  --bg-input-alt: #020617;

  --border-subtle: rgba(148, 163, 184, 0.25);
  --border-strong: #334155;

  --text-main: #e5e7eb;
  --text-soft: #9ca3af;
  --text-softer: #6b7280;
  --text-strong: #f9fafb;

  --accent: #38bdf8;
  --accent-soft: rgba(56, 189, 248, 0.15);
  --accent-strong: #0ea5e9;

  --danger: #f97373;
  --danger-soft: rgba(248, 113, 113, 0.15);

  --radius-lg: 18px;
  --radius-md: 12px;
  --radius-pill: 999px;

  --shadow-soft: 0 18px 45px rgba(15, 23, 42, 0.75);
  --shadow-subtle: 0 8px 20px rgba(15, 23, 42, 0.65);

  --transition-fast: 150ms ease-out;
  --transition-med: 200ms ease-out;
}

html,
body {
  height: 100%;
}

body {
  margin: 0;
  padding: 0;
  font-family: system-ui, -apple-system, BlinkMacSystemFont, "SF Pro Text",
    "Segoe UI", sans-serif;
  background: radial-gradient(circle at top, #0b1120 0, #020617 40%, #020617 100%);
  color: var(--text-main);
  -webkit-font-smoothing: antialiased;
}

/* ===================================================================
   APP SHELL
=================================================================== */

.app-root {
  min-height: 100vh;
  max-width: 1120px;
  margin: 0 auto;
  padding: 16px 12px 24px;
  display: flex;
  flex-direction: column;
  gap: 12px;
}

.app-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 12px;
  padding: 10px 14px;
  border-radius: var(--radius-lg);
  background: linear-gradient(135deg, rgba(15, 23, 42, 0.85), rgba(15, 23, 42, 0.98));
  border: 1px solid rgba(148, 163, 184, 0.2);
  box-shadow: var(--shadow-soft);
  position: sticky;
  top: 8px;
  z-index: 20;
  backdrop-filter: blur(18px);
}

.app-header-main {
  display: flex;
  flex-direction: column;
  gap: 2px;
}

.app-title {
  margin: 0;
  font-size: 1.15rem;
  letter-spacing: 0.04em;
  text-transform: uppercase;
  color: var(--text-strong);
}

.app-subtitle {
  margin: 0;
  font-size: 0.82rem;
  color: var(--text-soft);
}

.app-header-meta {
  display: flex;
  align-items: center;
}

.badge {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  padding: 4px 10px;
  border-radius: var(--radius-pill);
  font-size: 0.72rem;
  letter-spacing: 0.03em;
  text-transform: uppercase;
  border: 1px solid rgba(56, 189, 248, 0.4);
  background: linear-gradient(135deg, rgba(8, 47, 73, 0.5), rgba(8, 47, 73, 0.9));
  color: #e0f2fe;
}

.app-main {
  flex: 1;
  display: flex;
  flex-direction: column;
  gap: 12px;
}

/* ===================================================================
   TABS
=================================================================== */

.tab-bar {
  display: flex;
  gap: 6px;
  padding: 4px;
  border-radius: 999px;
  background: rgba(15, 23, 42, 0.9);
  border: 1px solid rgba(148, 163, 184, 0.28);
  box-shadow: var(--shadow-subtle);
  overflow: hidden;
}

.tab-button {
  flex: 1;
  border: 0;
  padding: 7px 10px;
  border-radius: 999px;
  font-size: 0.8rem;
  font-weight: 500;
  text-align: center;
  color: var(--text-soft);
  background: transparent;
  cursor: pointer;
  position: relative;
  transition: background var(--transition-fast), color var(--transition-fast),
    transform 120ms ease-out, box-shadow 120ms ease-out;
}

.tab-button .tab-label {
  position: relative;
  z-index: 1;
}

.tab-button::before {
  content: "";
  position: absolute;
  inset: 1px;
  border-radius: 999px;
  opacity: 0;
  background: radial-gradient(circle at top left, rgba(56, 189, 248, 0.18), transparent 55%);
  transition: opacity var(--transition-fast);
}

.tab-button.active {
  color: var(--text-strong);
  background: linear-gradient(
    135deg,
    rgba(15, 118, 178, 0.95),
    rgba(56, 189, 248, 0.9)
  );
  box-shadow: 0 0 0 1px rgba(34, 211, 238, 0.6), 0 12px 28px rgba(8, 47, 73, 0.8);
  transform: translateY(-1px);
}

.tab-button.active::before {
  opacity: 0.18;
}

.tab-button:active {
  transform: translateY(0px) scale(0.99);
  box-shadow: 0 6px 16px rgba(15, 23, 42, 0.9);
}

.tab-content {
  display: none;
}

.tab-content.active {
  display: block;
  animation: fadeSlideIn 220ms ease-out;
}

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

.card {
  background: radial-gradient(circle at top left, #020617 0, #020617 52%, #020617 100%);
  border-radius: 22px;
  border: 1px solid rgba(148, 163, 184, 0.25);
  box-shadow: var(--shadow-soft);
  overflow: hidden;
}

.card-header {
  padding: 14px 18px 8px;
  border-bottom: 1px solid rgba(148, 163, 184, 0.18);
}

.card-header h2 {
  margin: 0;
  font-size: 1rem;
  color: var(--text-strong);
}

.card-header p {
  margin: 4px 0 0;
  font-size: 0.78rem;
  color: var(--text-soft);
}

.card-body {
  padding: 14px 18px 16px;
}

.card-footer {
  padding: 10px 18px 14px;
  border-top: 1px solid rgba(148, 163, 184, 0.18);
}

.card-footer.no-border {
  border-top: none;
  padding-top: 4px;
}

.card-footer-actions {
  display: flex;
  align-items: center;
  gap: 10px;
  flex-wrap: wrap;
}

/* Advanced panel below main card grid */
.advanced-panel {
  border-top: 1px dashed rgba(148, 163, 184, 0.3);
  background: radial-gradient(circle at top, rgba(15, 23, 42, 0.9), #020617 70%);
}

/* ===================================================================
   LAYOUT HELPERS
=================================================================== */

.grid-2 {
  display: grid;
  grid-template-columns: minmax(0, 1.1fr) minmax(0, 1.1fr);
  gap: 16px;
}

.results-grid {
  align-items: flex-start;
}

.form-section {
  display: flex;
  flex-direction: column;
  gap: 9px;
  padding: 6px 0;
}

.section-title {
  margin: 0 0 2px;
  font-size: 0.9rem;
  color: var(--text-strong);
}

/* ===================================================================
   FORMS & INPUTS
=================================================================== */

.form-row,
.form-row-inline {
  margin-top: 6px;
  display: flex;
  flex-direction: column;
  gap: 4px;
}

.form-row-inline {
  flex-direction: row;
  gap: 8px;
}

.form-field {
  flex: 1;
  display: flex;
  flex-direction: column;
  gap: 3px;
}

label {
  font-size: 0.8rem;
  color: var(--text-soft);
}

input,
select,
textarea {
  font-family: inherit;
  font-size: 0.86rem;
  padding: 7px 10px;
  border-radius: 10px;
  border: 1px solid rgba(148, 163, 184, 0.2);
  background-color: rgba(15, 23, 42, 0.95);
  color: var(--text-main);
  outline: none;
  transition: border-color var(--transition-fast), box-shadow var(--transition-fast),
    background-color var(--transition-fast), transform 80ms ease-out;
  -webkit-appearance: none;
}

input::placeholder,
textarea::placeholder {
  color: rgba(148, 163, 184, 0.7);
}

input:focus,
select:focus,
textarea:focus {
  border-color: rgba(56, 189, 248, 0.9);
  box-shadow: 0 0 0 1px rgba(56, 189, 248, 0.75);
  background-color: #020617;
  transform: translateY(-0.5px);
}

input[type="number"] {
  -moz-appearance: textfield;
}

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

textarea {
  resize: vertical;
  min-height: 70px;
}

.input-row {
  display: flex;
  gap: 6px;
  align-items: center;
}

.unit {
  font-size: 0.76rem;
  color: var(--text-soft);
  margin-left: 2px;
}

.unit-inline {
  font-size: 0.75rem;
  font-weight: 500;
  color: var(--text-soft);
  margin-left: 4px;
}

.hint {
  margin: 0;
  font-size: 0.74rem;
  color: var(--text-softer);
}

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

.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 6px;
  padding: 7px 12px;
  border-radius: 999px;
  border: 1px solid transparent;
  font-size: 0.8rem;
  font-weight: 500;
  cursor: pointer;
  user-select: none;
  transition: background var(--transition-fast), border-color var(--transition-fast),
    box-shadow var(--transition-fast), transform 90ms ease-out;
  background-color: #020617;
  color: var(--text-main);
}

.btn-primary {
  background: linear-gradient(135deg, #0ea5e9, #38bdf8);
  border-color: rgba(56, 189, 248, 0.9);
  color: #0b1120;
  box-shadow: 0 12px 28px rgba(8, 47, 73, 0.9);
}

.btn-primary:hover {
  background: linear-gradient(135deg, #06b6d4, #38bdf8);
  box-shadow: 0 16px 34px rgba(8, 47, 73, 1);
  transform: translateY(-1px);
}

.btn-primary:active {
  transform: translateY(0) scale(0.985);
  box-shadow: 0 8px 18px rgba(8, 47, 73, 0.9);
}

.btn-secondary {
  background: rgba(15, 23, 42, 0.9);
  border-color: rgba(148, 163, 184, 0.6);
  color: var(--text-main);
  box-shadow: 0 8px 20px rgba(15, 23, 42, 0.85);
}

.btn-secondary:hover {
  background: rgba(30, 64, 175, 0.6);
  border-color: rgba(129, 140, 248, 0.9);
  box-shadow: 0 12px 26px rgba(15, 23, 42, 0.95);
  transform: translateY(-1px);
}

.btn-ghost {
  background: rgba(15, 23, 42, 0.6);
  border-color: rgba(148, 163, 184, 0.35);
  color: var(--text-soft);
}

.btn-ghost:hover {
  background: rgba(30, 64, 175, 0.45);
  border-color: rgba(148, 163, 184, 0.7);
  color: var(--text-main);
  box-shadow: 0 10px 24px rgba(15, 23, 42, 0.9);
  transform: translateY(-1px);
}

/* B3: Red ghost delete buttons */
.btn-ghost.danger {
  border-color: transparent;
  background: transparent;
  color: #fecaca;
  box-shadow: none;
  padding: 3px 6px;
  font-size: 0.74rem;
  letter-spacing: 0.01em;
}

.btn-ghost.danger:hover {
  background: transparent;
  border-color: transparent;
  color: #fee2e2;
  box-shadow: none;
  transform: none;
  text-decoration: underline;
}

.btn-ghost.danger:active {
  transform: none;
  text-decoration: underline;
  opacity: 0.85;
}

.btn:disabled,
.btn[disabled] {
  opacity: 0.45;
  cursor: default;
  box-shadow: none;
  transform: none;
}

/* ===================================================================
   RESULTS
=================================================================== */

.results-block {
  padding: 6px 0 0;
  display: flex;
  flex-direction: column;
  gap: 8px;
}

.result-row {
  display: grid;
  grid-template-columns: minmax(0, 1.2fr) minmax(0, auto) minmax(0, auto);
  align-items: baseline;
  gap: 6px;
  padding: 7px 10px;
  border-radius: 12px;
  background: rgba(15, 23, 42, 0.95);
  border: 1px solid rgba(148, 163, 184, 0.35);
}

.result-row.subtle {
  background: rgba(15, 23, 42, 0.8);
  border-style: dashed;
  border-color: rgba(148, 163, 184, 0.4);
}

.result-label {
  font-size: 0.82rem;
  color: var(--text-soft);
}

.result-value {
  justify-self: end;
  font-size: 1rem;
  font-feature-settings: "tnum" 1, "lnum" 1;
  color: var(--text-strong);
}

.result-unit {
  font-size: 0.78rem;
  color: var(--text-softer);
}

.calc-message {
  font-size: 0.8rem;
  color: var(--text-softer);
}

/* ===================================================================
   HUB PREVIEW
=================================================================== */

.hub-preview {
  margin-top: 10px;
  padding: 8px 10px 10px;
  border-radius: 14px;
  border: 1px dashed rgba(148, 163, 184, 0.4);
  background: radial-gradient(circle at top, rgba(15, 23, 42, 0.9), #020617 75%);
}

.hub-preview-header {
  font-size: 0.8rem;
  color: var(--text-soft);
  margin-bottom: 6px;
}

.hub-preview-body {
  position: relative;
  height: 60px;
  border-radius: 999px;
  background: radial-gradient(circle at center, #020617 0, #020617 65%, #020617 100%);
  border: 1px solid rgba(31, 41, 55, 0.9);
  overflow: hidden;
}

.hub-preview-center-line {
  position: absolute;
  left: 50%;
  top: 0;
  bottom: 0;
  width: 1px;
  background: rgba(148, 163, 184, 0.7);
}

.hub-preview-axle {
  position: absolute;
  left: 12%;
  right: 12%;
  top: 50%;
  transform: translateY(-50%);
  height: 8px;
  border-radius: 999px;
  background: linear-gradient(90deg, #0f172a, #1f2937);
  box-shadow: 0 0 0 1px rgba(15, 23, 42, 0.9);
}

.hub-preview-flange {
  position: absolute;
  top: 50%;
  width: 16px;
  height: 28px;
  transform: translateY(-50%);
  border-radius: 999px;
  border: 1px solid rgba(148, 163, 184, 0.7);
  background: radial-gradient(circle at center, #020617 0, #020617 55%, #020617 100%);
}

.hub-preview-flange-left {
  right: 50%;
  transform-origin: right center;
}

.hub-preview-flange-right {
  left: 50%;
  transform-origin: left center;
}

/* ===================================================================
   LISTS (HUBS, RIMS, BUILDS)
=================================================================== */

.item-list {
  list-style: none;
  margin: 8px 0 0;
  padding: 0;
  display: flex;
  flex-direction: column;
  gap: 6px;
}

.item-list li {
  border-radius: 14px;
  padding: 8px 10px;
  background: rgba(15, 23, 42, 0.94);
  border: 1px solid rgba(148, 163, 184, 0.34);
  cursor: pointer;
  transition: background var(--transition-fast), transform 90ms ease-out,
    box-shadow var(--transition-fast), border-color var(--transition-fast);
  display: flex;
  flex-direction: column;
}

.item-list li:hover {
  background: radial-gradient(circle at top left, rgba(56, 189, 248, 0.18), #020617 70%);
  box-shadow: 0 10px 24px rgba(15, 23, 42, 0.95);
  border-color: rgba(56, 189, 248, 0.8);
  transform: translateY(-1px);
}

.item-list li:active {
  transform: translateY(0) scale(0.986);
  box-shadow: 0 6px 16px rgba(15, 23, 42, 0.95);
}

.item-title {
  font-size: 0.88rem;
  color: var(--text-strong);
  margin-bottom: 2px;
}

.item-meta {
  font-size: 0.74rem;
  color: var(--text-softer);
}

/* Delete button inside list items */
.item-list li .btn-ghost.danger {
  align-self: flex-start;
  margin-top: 4px;
}

/* small separators between inline meta spans if you ever split them */
.item-meta span + span::before {
  content: "·";
  margin: 0 4px;
}

.list-empty {
  margin-top: 6px;
  padding: 10px 12px;
  border-radius: 12px;
  border: 1px dashed rgba(148, 163, 184, 0.5);
  font-size: 0.78rem;
  color: var(--text-soft);
  background: rgba(15, 23, 42, 0.7);
}

/* ===================================================================
   TOOLBAR & FILE INPUT
=================================================================== */

.toolbar {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  margin-bottom: 8px;
}

.file-input-label {
  display: inline-flex;
}

/* ===================================================================
   FOOTER
=================================================================== */

.app-footer {
  margin-top: 6px;
  padding: 8px 4px 0;
  font-size: 0.7rem;
  color: var(--text-softer);
  display: flex;
  justify-content: space-between;
  flex-wrap: wrap;
  gap: 4px;
  border-top: 1px solid rgba(31, 41, 55, 0.8);
}

/* ===================================================================
   ANIMATIONS
=================================================================== */

@keyframes fadeSlideIn {
  from {
    opacity: 0;
    transform: translateY(4px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

/* ===================================================================
   RESPONSIVE
=================================================================== */

@media (max-width: 800px) {
  .app-root {
    padding: 10px 10px 18px;
  }

  .app-header {
    flex-direction: column;
    align-items: flex-start;
    padding: 10px 12px;
  }

  .grid-2 {
    grid-template-columns: minmax(0, 1fr);
  }

  .card-body {
    padding: 12px 12px 14px;
  }

  .card-header {
    padding: 12px 12px 6px;
  }

  .card-footer {
    padding: 8px 12px 12px;
  }

  .tab-bar {
    border-radius: 16px;
  }

  .tab-button {
    padding: 7px 6px;
    font-size: 0.78rem;
  }

  .result-row {
    grid-template-columns: minmax(0, 1.3fr) auto auto;
  }

  .hub-preview-body {
    height: 54px;
  }

  .item-list li {
    padding: 7px 9px;
  }

  .item-list li .btn-ghost.danger {
    margin-top: 2px;
  }
}

@media (max-width: 480px) {
  .app-title {
    font-size: 1.02rem;
  }

  .app-subtitle {
    font-size: 0.78rem;
  }

  .app-footer {
    flex-direction: column;
    align-items: flex-start;
  }
}