/* ========== Reset & Base ========== */
*,
*::before,
*::after {
  box-sizing: border-box;
}

:root {
  --radius: 14px;
  --radius-sm: 10px;
  --gap: 16px;
  --gap-lg: 22px;
  --pad: 18px;
  --pad-lg: 24px;
  --mono: ui-monospace, SFMono-Regular, Menlo, Monaco, Consolas,
    "Liberation Mono", monospace;
  --sans: system-ui, -apple-system, "Segoe UI", Roboto, Inter,
    "Helvetica Neue", Arial, "Noto Sans", "Apple Color Emoji",
    "Segoe UI Emoji", "Segoe UI Symbol", sans-serif;
  --scrim: rgba(0, 0, 0, 0.64);
  --help-text-color: #f0f0f0;
}

/* ========== Theme: Distribution (Blue) ========== */
body.theme-distribution {
  --bg: #0b1020;
  --bg-gradient:
    radial-gradient(1200px 800px at 10% -10%, #33415533, transparent),
    radial-gradient(1000px 700px at 110% 10%, #1d4ed822, transparent),
    linear-gradient(180deg, #0b1224, #0b1320);
  --surface: #121931;
  --surface-2: #0e142a;
  --text: #e9edff;
  --text-subtle: #a8b0d3;
  --primary: #3b82f6;
  --primary-600: #2563eb;
  --primary-700: #1d4ed8;
  --border: #2a3b60;
  --ring: #93c5fd;
  --shadow: 0 10px 30px rgba(15, 23, 42, 0.35);
}

@media (prefers-color-scheme: light) {
  body.theme-distribution {
    --bg: #f6f7fb;
    --bg-gradient:
      radial-gradient(1200px 800px at 10% -10%, #2563eb0f, transparent),
      radial-gradient(1000px 700px at 110% 10%, #3b82f61c, transparent),
      linear-gradient(180deg, #fbfcff, #f6f9ff);
    --surface: #ffffff;
    --surface-2: #f7f8fc;
    --text: #0f172a;
    --text-subtle: #6b7280;
    --primary: #3b82f6;
    --primary-600: #2563eb;
    --primary-700: #1d4ed8;
    --border: #dbe7ff;
    --ring: #93c5fd;
    --shadow: 0 10px 30px rgba(2, 8, 23, 0.08);
  }
}

/* ========== Theme: Miter (Green/Teal) ========== */
body.theme-miter {
  --bg: #0a1a14;
  --bg-gradient:
    radial-gradient(1200px 800px at 10% -10%, #134e4a33, transparent),
    radial-gradient(1000px 700px at 110% 10%, #10b98122, transparent),
    linear-gradient(180deg, #0a1f1a, #0b2018);
  --surface: #0f2419;
  --surface-2: #0c1e15;
  --text: #d4f4e4;
  --text-subtle: #7fa899;
  --primary: #10b981;
  --primary-600: #059669;
  --primary-700: #047857;
  --border: #1a3b2e;
  --ring: #6ee7b7;
  --shadow: 0 10px 30px rgba(10, 30, 20, 0.35);
}

@media (prefers-color-scheme: light) {
  body.theme-miter {
    --bg: #f0f7f4;
    --bg-gradient:
      radial-gradient(1200px 800px at 10% -10%, #05966910, transparent),
      radial-gradient(1000px 700px at 110% 10%, #10b9811c, transparent),
      linear-gradient(180deg, #f0fdf9, #f0f7f4);
    --surface: #ffffff;
    --surface-2: #f0f7f4;
    --text: #0f1f17;
    --text-subtle: #5a7a6e;
    --primary: #059669;
    --primary-600: #047857;
    --primary-700: #065f46;
    --border: #c4e8d4;
    --ring: #6ee7b7;
    --shadow: 0 10px 30px rgba(10, 30, 20, 0.08);
  }
}

/* ========== Theme: Spacing (Amber/Orange) ========== */
body.theme-spacing {
  --bg: #1a1208;
  --bg-gradient:
    radial-gradient(1200px 800px at 10% -10%, #5b451533, transparent),
    radial-gradient(1000px 700px at 110% 10%, #f59e0b22, transparent),
    linear-gradient(180deg, #1a1208, #1a160a);
  --surface: #2a1f10;
  --surface-2: #221a0e;
  --text: #f5e8d0;
  --text-subtle: #b8a888;
  --primary: #f59e0b;
  --primary-600: #d97706;
  --primary-700: #b45309;
  --border: #4a3a1a;
  --ring: #fcd34d;
  --shadow: 0 10px 30px rgba(20, 15, 5, 0.35);
}

@media (prefers-color-scheme: light) {
  body.theme-spacing {
    --bg: #faf6f0;
    --bg-gradient:
      radial-gradient(1200px 800px at 10% -10%, #d9770610, transparent),
      radial-gradient(1000px 700px at 110% 10%, #f59e0b1c, transparent),
      linear-gradient(180deg, #fffdf8, #faf6f0);
    --surface: #ffffff;
    --surface-2: #f7f3ed;
    --text: #1f1810;
    --text-subtle: #8a7a64;
    --primary: #d97706;
    --primary-600: #b45309;
    --primary-700: #92400e;
    --border: #e8dcc8;
    --ring: #fcd34d;
    --shadow: 0 10px 30px rgba(20, 15, 5, 0.08);
  }
}

/* ========== Base Layout ========== */
html,
body {
  height: 100%;
}

body {
  margin: 0;
  font-family: var(--sans);
  color: var(--text);
  background: var(--bg-gradient), var(--bg);
  display: grid;
  place-items: center;
  padding: 24px;
}

/* ========== App Layout ========== */
.app {
  width: 100%;
  max-width: 860px;
  display: grid;
  gap: var(--gap-lg);
}

.app-header {
  text-align: center;
}

.app-title {
  margin: 0;
  font-size: clamp(1.35rem, 1.2rem + 1vw, 1.8rem);
  letter-spacing: 0.2px;
}

.app-subtitle {
  margin: 6px 0 0;
  color: var(--text-subtle);
  font-size: 0.98rem;
}

/* ========== Tabs ========== */
.tabs {
  display: flex;
  gap: 4px;
  padding: 4px;
  background: color-mix(in srgb, var(--surface) 80%, transparent);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  overflow-x: auto;
}

.tab {
  flex: 1;
  white-space: nowrap;
  padding: 10px 16px;
  border: none;
  background: transparent;
  color: var(--text-subtle);
  border-radius: var(--radius-sm);
  font-weight: 600;
  font-size: 0.95rem;
  cursor: pointer;
  transition: background 200ms ease, color 200ms ease;
}

.tab.active {
  background: linear-gradient(180deg, var(--primary), var(--primary-600));
  color: #fff;
  box-shadow: 0 2px 8px color-mix(in srgb, var(--primary) 40%, transparent);
}

.tab:not(.active):hover {
  background: color-mix(in srgb, var(--surface-2) 50%, transparent);
  color: var(--text);
}

/* ========== Calculator Panels ========== */
.calc-panel {
  display: none;
  gap: var(--gap);
}

.calc-panel.active {
  display: grid;
  animation: fadeIn 250ms ease;
}

@keyframes fadeIn {
  from {
    opacity: 0;
    transform: translateY(6px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

.panel-header {
  text-align: center;
}

.panel-title {
  margin: 0;
  font-size: 1.1rem;
  font-weight: 700;
}

.panel-subtitle {
  margin: 4px 0 0;
  color: var(--text-subtle);
  font-size: 0.9rem;
}

/* ========== Card ========== */
.card {
  background: linear-gradient(180deg, var(--surface), var(--surface-2));
  border: 1px solid var(--border);
  border-radius: var(--radius);
  box-shadow: var(--shadow);
  padding: var(--pad-lg);
}

/* ========== Form Fields ========== */
.inputs-grid {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: var(--gap);
}

@media (max-width: 720px) {
  .inputs-grid {
    grid-template-columns: 1fr;
  }
}

.field {
  display: grid;
  gap: 8px;
}

label {
  font-weight: 600;
  color: var(--text);
}

input[type="number"] {
  height: 46px;
  padding: 10px 12px;
  font-size: 16px;
  color: var(--text);
  background: color-mix(in srgb, var(--surface) 70%, transparent);
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  outline: none;
  transition:
    border-color 180ms ease,
    box-shadow 180ms ease,
    background 180ms ease;
}

input[type="number"]::placeholder {
  color: var(--text-subtle);
}

input[type="number"]:focus {
  border-color: var(--ring);
  box-shadow: 0 0 0 4px color-mix(in srgb, var(--ring) 30%, transparent);
  background: color-mix(in srgb, var(--surface) 90%, transparent);
}

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

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

/* ========== Actions ========== */
.actions {
  display: flex;
  gap: var(--gap);
  margin-top: var(--gap-lg);
  flex-wrap: wrap;
}

.btn {
  --btn-bg: var(--surface-2);
  --btn-color: var(--text);
  --btn-border: var(--border);
  --btn-hover: color-mix(in srgb, var(--btn-bg), #000 6%);

  border: 1px solid var(--btn-border);
  background: var(--btn-bg);
  color: var(--btn-color);
  padding: 12px 16px;
  border-radius: 12px;
  font-weight: 600;
  letter-spacing: 0.2px;
  cursor: pointer;
  transition:
    background 160ms ease,
    transform 80ms ease,
    border-color 160ms ease;
}

.btn:hover {
  background: var(--btn-hover);
}

.btn:active {
  transform: translateY(1px);
}

.btn.primary {
  --btn-bg: linear-gradient(180deg, var(--primary), var(--primary-600));
  --btn-color: #fff;
  --btn-border: color-mix(in srgb, var(--primary-700), #000 20%);
}

.btn.ghost {
  --btn-bg: color-mix(in srgb, var(--surface-2), transparent 50%);
}

/* ========== Results ========== */
.results {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  margin-top: var(--gap-lg);
  gap: var(--gap);
}

@media (max-width: 720px) {
  .results {
    grid-template-columns: 1fr;
  }
}

.result {
  background: color-mix(in srgb, var(--surface-2) 92%, transparent);
  border: 1px dashed var(--border);
  border-radius: var(--radius);
  padding: var(--pad);
}

.result-label {
  color: var(--text-subtle);
  font-size: 0.95rem;
  margin-bottom: 6px;
}

.result-value {
  font: 700 1.8rem var(--mono);
  letter-spacing: 0.2px;
}

/* ========== Footer ========== */
.app-footer {
  text-align: center;
  color: var(--text-subtle);
}

kbd {
  background: color-mix(in srgb, var(--surface-2), #fff 4%);
  border: 1px solid var(--border);
  border-bottom-width: 2px;
  border-radius: 6px;
  padding: 0 6px;
  font: 600 0.82rem var(--mono);
  color: var(--text-subtle);
}

/* ========== Bottom Drawer (History) ========== */
.scrim {
  position: fixed;
  inset: 0;
  background: rgba(2, 8, 23, 0.45);
  opacity: 0;
  pointer-events: none;
  transition: opacity 200ms ease;
  z-index: 40;
}

.scrim.visible {
  opacity: 1;
  pointer-events: auto;
}

.drawer {
  --peek-height: 68px;
  --drawer-max-h: 70vh;
  position: fixed;
  left: 0;
  right: 0;
  bottom: 0;
  height: min(var(--drawer-max-h), 560px);
  background: linear-gradient(180deg, var(--surface), var(--surface-2));
  border-top: 1px solid var(--border);
  border-top-left-radius: var(--radius);
  border-top-right-radius: var(--radius);
  box-shadow: var(--shadow);
  z-index: 50;
  transform: translateY(calc(100% - var(--peek-height)));
  transition: transform 280ms cubic-bezier(0.2, 0.8, 0.2, 1);
  will-change: transform;
  touch-action: none;
}

.drawer.dragging {
  transition: none;
}

.drawer-header {
  position: sticky;
  top: 0;
  display: grid;
  grid-template-columns: 1fr auto 1fr;
  align-items: center;
  gap: 8px;
  padding: 10px var(--pad);
  background: color-mix(in srgb, var(--surface-2) 92%, transparent);
  border-bottom: 1px solid color-mix(in srgb, var(--border), #000 6%);
  border-top-left-radius: var(--radius);
  border-top-right-radius: var(--radius);
  cursor: ns-resize;
}

.drawer-grip {
  justify-self: center;
  width: 44px;
  height: 5px;
  border-radius: 999px;
  background: color-mix(in srgb, var(--text-subtle), transparent 40%);
}

.drawer-title {
  grid-column: 2 / 3;
  margin: 0;
  text-align: center;
  font-weight: 700;
  font-size: 0.98rem;
}

.drawer-actions {
  grid-column: 3 / 4;
  display: flex;
  justify-content: end;
}

.btn.small {
  padding: 8px 10px;
  border-radius: 10px;
  font-size: 0.85rem;
}

.drawer-content {
  padding: 8px var(--pad);
  max-height: calc(100% - 54px);
  overflow: auto;
}

/* ========== History List ========== */
.history-list {
  list-style: none;
  margin: 0;
  padding: 0;
  display: grid;
  gap: 10px;
}

.history-item {
  background: color-mix(in srgb, var(--surface-2) 94%, transparent);
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  padding: 10px 12px;
}

.history-item .row1 {
  display: flex;
  align-items: center;
  gap: 10px;
  font-size: 0.9rem;
  color: var(--text-subtle);
  margin-bottom: 4px;
}

.history-item .row1 .tag {
  padding: 2px 8px;
  border: 1px solid var(--border);
  border-radius: 999px;
  font-weight: 600;
  color: var(--text);
  background: color-mix(in srgb, var(--surface), transparent 35%);
}

.history-item .row2 {
  font-family: var(--mono);
  font-size: 0.95rem;
}

.history-item .row2 strong {
  font-weight: 800;
}

.history-list .empty {
  text-align: center;
  color: var(--text-subtle);
  padding: 14px 0;
  border: 1px dashed var(--border);
  border-radius: var(--radius-sm);
}

/* ========== Utilities ========== */
.sr-only {
  position: absolute;
  width: 1px;
  height: 1px;
  padding: 0;
  margin: -1px;
  overflow: hidden;
  clip: rect(0, 0, 0, 0);
  border: 0;
}

/* ========== Help Button ========== */
.help-button {
  position: fixed;
  top: 16px;
  right: 16px;
  z-index: 1000;
  display: grid;
  place-items: center;
  min-width: 44px;
  min-height: 44px;
  padding: 6px;
  border: 0;
  background: transparent;
  color: #fff;
  cursor: pointer;
}

.help-icon {
  display: block;
  font-family: system-ui, -apple-system, "Segoe UI", Roboto,
    "Helvetica Neue", Arial, sans-serif;
  font-weight: 500;
  font-size: 28px;
  line-height: 1;
  color: currentColor;
  text-shadow: 0 2px 6px rgba(0, 0, 0, 0.55);
  transition: transform 0.18s ease, text-shadow 0.18s ease;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

.help-button:hover .help-icon {
  transform: translateY(-1px);
  text-shadow: 0 4px 12px rgba(0, 0, 0, 0.6);
}

.help-button:active .help-icon {
  transform: translateY(0);
  text-shadow: 0 2px 6px rgba(0, 0, 0, 0.55);
}

.help-button:focus-visible {
  outline: 2px solid rgba(255, 255, 255, 0.95);
  outline-offset: 2px;
  border-radius: 6px;
  background: rgba(255, 255, 255, 0.06);
}

/* ========== Help Overlay ========== */
.help-overlay {
  position: fixed;
  inset: 0;
  z-index: 9999;
  display: grid;
  place-items: center;
  background: var(--scrim, rgba(0, 0, 0, 0.64));
  color: var(--help-text-color, #f0f0f0);
  opacity: 0;
  pointer-events: none;
  transition: opacity 0.18s ease-out;
  -webkit-backdrop-filter: blur(2px);
  backdrop-filter: blur(2px);
}

.help-overlay[aria-hidden="false"] {
  opacity: 1;
  pointer-events: auto;
}

.help-overlay__close {
  position: absolute;
  top: 16px;
  right: 16px;
  border: 0;
  background: none;
  color: #fff;
  font-size: 28px;
  line-height: 1;
  padding: 4px 8px;
  cursor: pointer;
}

.help-overlay__panel {
  background: transparent;
  max-width: min(760px, 90vw);
  padding: 24px;
  text-align: left;
}

.help-overlay__panel :is(h1, h2, h3) {
  margin: 0 0 0.5rem;
  color: #fff;
}

.help-overlay__panel :is(p, li) {
  color: var(--help-text-color, #f0f0f0);
  line-height: 1.6;
}

.help-overlay__panel ul {
  padding-left: 1.2rem;
}

@media (prefers-reduced-motion: reduce) {
  .help-overlay {
    transition: none;
  }
  .calc-panel.active {
    animation: none;
  }
}