* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

:root {
  --blue-50: #1e293b;
  --blue-100: #1e3a5f;
  --blue-500: #3b82f6;
  --blue-600: #60a5fa;
  --blue-700: #93bbfd;
  --green-600: #4ade80;
  --red-600: #f87171;
  --gray-50: #0f172a;
  --gray-100: #1e293b;
  --gray-200: #334155;
  --gray-300: #475569;
  --gray-500: #94a3b8;
  --gray-700: #cbd5e1;
  --gray-900: #f1f5f9;
  --surface: #1e293b;
  --radius: 12px;
}

body {
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
  background: var(--gray-50);
  color: var(--gray-900);
  line-height: 1.6;
  min-height: 100vh;
}

/* ========================
   Navigation
   ======================== */
.site-nav {
  display: flex;
  justify-content: center;
  gap: 0.25rem;
  padding: 0.75rem 1rem;
  background: var(--surface);
  border-bottom: 1px solid var(--gray-200);
  position: sticky;
  top: 0;
  z-index: 100;
}

.site-nav a {
  padding: 0.4rem 0.85rem;
  border-radius: 8px;
  text-decoration: none;
  font-size: 0.85rem;
  font-weight: 500;
  color: var(--gray-500);
  transition: all 0.15s ease;
}

.site-nav a:hover {
  color: var(--blue-600);
  background: var(--blue-50);
}

.site-nav a.active {
  color: var(--blue-700);
  background: var(--blue-50);
  font-weight: 600;
}

/* ========================
   Header
   ======================== */
header {
  text-align: center;
  padding: 1.5rem 1rem 1rem;
}

header h1 {
  font-size: 1.75rem;
  font-weight: 700;
  color: var(--gray-900);
}

.subtitle {
  color: var(--gray-500);
  font-size: 0.95rem;
  margin-top: 0.25rem;
}

/* ========================
   Layout
   ======================== */
main {
  max-width: 640px;
  margin: 0 auto;
  padding: 0 1rem 2rem;
}

/* ========================
   Cards
   ======================== */
.card {
  background: var(--surface);
  border-radius: var(--radius);
  padding: 1.5rem;
  margin-bottom: 1rem;
  border: 1px solid var(--gray-200);
}

.card h2 {
  font-size: 1.1rem;
  font-weight: 600;
  margin-bottom: 0.75rem;
}

.hint {
  font-size: 0.85rem;
  color: var(--gray-500);
  margin-bottom: 0.75rem;
}

.hint a {
  color: var(--blue-600);
}

.hint.error {
  color: var(--red-600);
}

/* ========================
   Inputs
   ======================== */
.input-group {
  display: flex;
  flex-direction: column;
  gap: 0.25rem;
}

.input-group label {
  font-size: 0.85rem;
  font-weight: 500;
  color: var(--gray-700);
}

.input-row {
  display: grid;
  grid-template-columns: 1fr 1fr 1fr;
  gap: 0.75rem;
}

.source-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 0.75rem;
}

input[type="number"],
select {
  padding: 0.5rem 0.75rem;
  border: 1px solid var(--gray-300);
  border-radius: 8px;
  font-size: 1rem;
  background: var(--gray-50);
  color: var(--gray-900);
  width: 100%;
}

input[type="number"]:focus,
select:focus {
  outline: none;
  border-color: var(--blue-500);
  box-shadow: 0 0 0 3px rgba(59, 130, 246, 0.3);
}

.input-with-unit {
  display: flex;
  gap: 0.5rem;
}

.input-with-unit input {
  flex: 1;
}

.input-with-unit select {
  width: 120px;
  flex-shrink: 0;
}

/* ========================
   Buttons (profiles, buffers, presets)
   ======================== */
.source-water-tags {
  display: flex;
  flex-wrap: wrap;
  gap: 0.5rem;
  margin-top: 0.5rem;
}

.profile-buttons,
.source-presets {
  display: flex;
  flex-wrap: wrap;
  gap: 0.5rem;
  margin-bottom: 1rem;
}

.profile-btn,
.preset-btn,
.taste-preset-btn {
  padding: 0.5rem 1rem;
  border: 1px solid var(--gray-300);
  border-radius: 8px;
  background: var(--gray-50);
  font-size: 0.9rem;
  cursor: pointer;
  transition: all 0.15s ease;
  color: var(--gray-700);
}

.profile-btn:hover,
.preset-btn:hover,
.taste-preset-btn:hover {
  border-color: var(--blue-500);
  color: var(--blue-600);
}

.profile-btn.active,
.preset-btn.active,
.taste-preset-btn.active {
  background: var(--blue-50);
  border-color: var(--blue-500);
  color: var(--blue-700);
  font-weight: 500;
}

.profile-description {
  font-size: 0.85rem;
  color: var(--gray-500);
  font-style: italic;
}

.target-inputs {
  margin-bottom: 0.75rem;
}

/* ========================
   Results (index page)
   ======================== */
.results-card {
  border-color: var(--blue-500);
  border-width: 2px;
}

.results-card .save-bar {
  margin-top: 1.5rem;
}

.results {
  display: flex;
  flex-direction: column;
  gap: 0.75rem;
}

.result-item {
  display: flex;
  align-items: center;
  gap: 1rem;
  padding: 0.75rem;
  background: var(--gray-50);
  border-radius: 8px;
}

.result-info {
  flex: 1;
  display: flex;
  flex-direction: column;
}

.result-name {
  font-weight: 600;
  font-size: 0.95rem;
}

.result-detail {
  font-size: 0.8rem;
  color: var(--gray-500);
}

.result-value {
  font-size: 1.25rem;
  font-weight: 700;
  color: var(--blue-600);
  white-space: nowrap;
}

.result-summary {
  margin-top: 1rem;
  padding: 0.75rem;
  background: var(--blue-50);
  border-radius: 8px;
  font-size: 0.85rem;
  color: var(--gray-700);
  line-height: 1.5;
}

.result-summary:empty {
  display: none;
}

/* ========================
   Minerals page
   ======================== */
.mineral-list {
  display: flex;
  flex-direction: column;
  gap: 0.5rem;
}

.mineral-item {
  border: 1px solid var(--gray-200);
  border-radius: 8px;
  padding: 0.75rem;
  transition: all 0.15s ease;
}

.mineral-item.selected {
  border-color: var(--blue-500);
  background: var(--blue-50);
}

.mineral-label {
  display: flex;
  align-items: flex-start;
  gap: 0.75rem;
  cursor: pointer;
}

.mineral-label input[type="checkbox"] {
  margin-top: 0.25rem;
  width: 18px;
  height: 18px;
  accent-color: var(--blue-600);
  flex-shrink: 0;
}

.mineral-info {
  display: flex;
  flex-direction: column;
}

.mineral-name {
  font-weight: 600;
  font-size: 0.95rem;
}

.mineral-formula {
  font-size: 0.8rem;
  color: var(--gray-500);
  font-family: "Georgia", serif;
}

.mineral-desc {
  font-size: 0.8rem;
  color: var(--gray-500);
  margin-top: 0.15rem;
}

.alkalinity-source-options {
  display: flex;
  flex-direction: column;
  gap: 0.5rem;
}

.alkalinity-option {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  cursor: pointer;
  font-size: 0.95rem;
}

.alkalinity-option input[type="radio"] {
  accent-color: var(--blue-600);
}

/* Save bar (custom profile naming) */
.save-bar {
  display: flex;
  gap: 0.5rem;
  margin-bottom: 1rem;
}

.save-bar input[type="text"] {
  flex: 1;
  padding: 0.5rem 0.75rem;
  border: 1px solid var(--gray-300);
  border-radius: 8px;
  font-size: 0.9rem;
  background: var(--gray-50);
  color: var(--gray-900);
}

.save-bar input[type="text"]:focus {
  outline: none;
  border-color: var(--blue-500);
  box-shadow: 0 0 0 3px rgba(59, 130, 246, 0.3);
}

/* Delete button on custom preset buttons */
.preset-delete {
  margin-left: 0.35rem;
  font-size: 1rem;
  line-height: 1;
  color: var(--gray-500);
  cursor: pointer;
}

.preset-delete:hover {
  color: var(--red-600);
}

/* Edit bar (save changes to existing profile) */
.edit-bar {
  display: flex;
  gap: 0.5rem;
  margin-bottom: 1rem;
}

/* Confirmation modal */
.confirm-overlay {
  position: fixed;
  inset: 0;
  background: rgba(0, 0, 0, 0.6);
  display: flex;
  align-items: center;
  justify-content: center;
  z-index: 200;
}

.confirm-dialog {
  background: var(--surface);
  border: 1px solid var(--gray-200);
  border-radius: var(--radius);
  padding: 1.5rem;
  max-width: 360px;
  width: 90%;
}

.confirm-dialog p {
  margin-bottom: 1.25rem;
  font-size: 0.95rem;
  text-align: center;
}

.confirm-actions {
  display: flex;
  gap: 0.75rem;
  justify-content: center;
}

/* Save status toast */
.save-status {
  text-align: center;
  font-size: 0.85rem;
  font-weight: 500;
  color: var(--green-600);
  margin-top: 0.75rem;
  opacity: 0;
  transition: opacity 0.3s ease;
}

.save-status.visible {
  opacity: 1;
}

.save-status.error {
  color: var(--red-600);
}

/* ========================
   Taste Tuner page — Sliders
   ======================== */
.slider-group {
  display: flex;
  flex-direction: column;
  gap: 1.5rem;
}

.slider-item {
  padding-bottom: 1.25rem;
  border-bottom: 1px solid var(--gray-100);
}

.slider-item:last-child {
  border-bottom: none;
  padding-bottom: 0;
}

.slider-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: 0.25rem;
}

.slider-header label {
  font-weight: 600;
  font-size: 0.95rem;
}

.slider-value {
  font-weight: 700;
  font-size: 0.9rem;
  color: var(--blue-600);
  min-width: 2rem;
  text-align: right;
}

.slider-labels {
  display: flex;
  justify-content: space-between;
  font-size: 0.75rem;
  color: var(--gray-500);
  margin-bottom: 0.35rem;
}

input[type="range"] {
  width: 100%;
  height: 6px;
  -webkit-appearance: none;
  appearance: none;
  background: var(--gray-200);
  border-radius: 3px;
  outline: none;
}

input[type="range"]::-webkit-slider-thumb {
  -webkit-appearance: none;
  appearance: none;
  width: 22px;
  height: 22px;
  border-radius: 50%;
  background: var(--blue-600);
  cursor: pointer;
  border: 3px solid var(--surface);
  box-shadow: 0 1px 3px rgba(0, 0, 0, 0.4);
}

input[type="range"]::-moz-range-thumb {
  width: 22px;
  height: 22px;
  border-radius: 50%;
  background: var(--blue-600);
  cursor: pointer;
  border: 3px solid var(--surface);
  box-shadow: 0 1px 3px rgba(0, 0, 0, 0.4);
}

.slider-hint {
  font-size: 0.75rem;
  color: var(--gray-500);
  font-style: italic;
  margin-top: 0.35rem;
}

/* Taste result grid */
.result-grid {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 0.5rem;
  margin-bottom: 1rem;
}

.result-cell {
  text-align: center;
  padding: 0.75rem 0.5rem;
  background: var(--gray-50);
  border-radius: 8px;
}

.result-label {
  display: block;
  font-size: 0.75rem;
  color: var(--gray-500);
  font-weight: 500;
}

.result-ppm {
  display: block;
  font-size: 1.25rem;
  font-weight: 700;
  color: var(--gray-900);
}

.result-unit {
  display: block;
  font-size: 0.7rem;
  color: var(--gray-500);
}

.result-delta {
  display: block;
  font-size: 0.75rem;
  font-weight: 600;
  min-height: 1.1em;
}

.result-delta.positive {
  color: var(--green-600);
}

.result-delta.negative {
  color: var(--red-600);
}

/* ========================
   Metrics row (GH, KH, TDS)
   ======================== */
.metrics-row {
  display: flex;
  gap: 0.75rem;
  margin-top: 1rem;
  margin-bottom: 1rem;
}

.metric {
  flex: 1;
  text-align: center;
  padding: 0.75rem;
  background: var(--gray-50);
  border-radius: 8px;
}

.metric.highlight {
  background: var(--blue-50);
}

.metric-box {
  border: 1px solid var(--gray-300);
  border-radius: 0.5rem;
}

.metric-label {
  display: block;
  font-size: 0.75rem;
  font-weight: 600;
  color: var(--gray-500);
  text-transform: uppercase;
  letter-spacing: 0.05em;
}

.metric-value {
  display: block;
  font-size: 1.1rem;
  font-weight: 700;
  color: var(--blue-700);
}

.metric-unit {
  display: block;
  font-size: 0.65rem;
  color: var(--gray-500);
}

/* ========================
   Recipe Builder page
   ======================== */
.base-water-summary {
  display: flex;
  flex-wrap: wrap;
  gap: 0.5rem;
}

.base-tag {
  display: inline-block;
  padding: 0.25rem 0.75rem;
  background: var(--gray-100);
  border-radius: 6px;
  font-size: 0.8rem;
  color: var(--gray-700);
}

.mineral-inputs {
  display: flex;
  flex-direction: column;
  gap: 0.75rem;
}

.mineral-input-row {
  display: flex;
  align-items: center;
  gap: 1rem;
  padding: 0.75rem;
  background: var(--gray-50);
  border-radius: 8px;
}

.mineral-input-info {
  flex: 1;
  display: flex;
  flex-direction: column;
}

.mineral-input-name {
  font-weight: 600;
  font-size: 0.9rem;
}

.mineral-input-formula {
  font-size: 0.8rem;
  color: var(--gray-500);
}

.mineral-input-field {
  display: flex;
  align-items: center;
  gap: 0.35rem;
}

.mineral-input-field input {
  width: 90px;
  text-align: right;
}

.mineral-input-unit {
  font-size: 0.8rem;
  color: var(--gray-500);
  white-space: nowrap;
}

/* PPM grid */
.ppm-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 0.5rem;
  margin-bottom: 0.5rem;
}

.ppm-cell {
  text-align: center;
  padding: 0.75rem 0.5rem;
  background: var(--gray-50);
  border-radius: 8px;
}

.ppm-label {
  display: block;
  font-size: 0.75rem;
  color: var(--gray-500);
  font-weight: 500;
}

.ppm-value {
  display: block;
  font-size: 1.25rem;
  font-weight: 700;
  color: var(--gray-900);
}

.ppm-unit {
  display: block;
  font-size: 0.7rem;
  color: var(--gray-500);
}

/* ========================
   Footer
   ======================== */
footer {
  text-align: center;
  padding: 1rem;
  font-size: 0.8rem;
  color: var(--gray-500);
}

/* ========================
   Responsive
   ======================== */
@media (max-width: 500px) {
  .input-row {
    grid-template-columns: 1fr;
  }

  .source-grid {
    grid-template-columns: 1fr;
  }

  .profile-buttons,
  .source-presets {
    flex-direction: column;
  }

  .profile-btn,
  .preset-btn,
  .taste-preset-btn {
    width: 100%;
    text-align: center;
  }

  .result-value {
    font-size: 1.1rem;
  }

  .result-grid {
    grid-template-columns: repeat(2, 1fr);
  }

  .ppm-grid {
    grid-template-columns: repeat(2, 1fr);
  }

  .site-nav {
    flex-wrap: wrap;
  }

  .metrics-row {
    flex-direction: column;
  }
}