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

html {
  font-size: 16px;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

body {
  margin: 0;
  padding: 24px;
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Oxygen, Ubuntu, sans-serif;
  font-size: 0.875rem;
  line-height: 1.5;
  color: #1a1a1a;
  background: #fafafa;
}

h1, h2, h3 {
  margin: 0;
  font-weight: 600;
}

ul {
  list-style: none;
  margin: 0;
  padding: 0;
}

button {
  font-family: inherit;
  cursor: pointer;
}

input, select {
  font-family: inherit;
}

.app {
  display: grid;
  grid-template-columns: 1fr 280px;
  grid-template-rows: auto 1fr;
  gap: 24px;
  max-width: 1200px;
  margin: 0 auto;
}

.header {
  grid-column: 1/-1;
  padding-bottom: 16px;
  border-bottom: 1px solid #f0f0f0;
}
.header__top {
  display: flex;
  align-items: baseline;
  justify-content: space-between;
  gap: 24px;
}
.header h1 {
  font-size: 1.5rem;
  font-weight: 700;
  letter-spacing: -0.02em;
}
.header .tagline {
  margin: 4px 0 0;
  color: #666666;
  font-size: 0.875rem;
}

.nav {
  display: flex;
  gap: 16px;
}
.nav__link {
  font-size: 0.875rem;
  color: #666666;
  text-decoration: none;
  padding: 2px 0;
  border-bottom: 1px solid transparent;
  transition: color 0.15s ease, border-color 0.15s ease;
}
.nav__link:hover {
  color: #1a1a1a;
}
.nav__link--active {
  color: #1a1a1a;
  border-bottom-color: #1a1a1a;
}

.main {
  display: flex;
  flex-direction: column;
  gap: 24px;
}

.sidebar {
  display: flex;
  flex-direction: column;
  gap: 24px;
}

.panel {
  background: #ffffff;
  border: 1px solid #e0e0e0;
  border-radius: 8px;
  padding: 24px;
}
.panel__title {
  font-size: 0.75rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  color: #666666;
  margin-bottom: 16px;
}

.panel--input {
  display: flex;
  flex-direction: column;
  gap: 16px;
}

.panel--preview {
  flex: 1;
  min-height: 200px;
}

.panel--export[hidden] {
  display: none;
}

.panel--history .panel__title,
.panel--starred .panel__title {
  margin-bottom: 8px;
}

.input-group {
  display: flex;
  flex-direction: column;
  gap: 4px;
}
.input-group > label {
  font-size: 0.75rem;
  font-weight: 500;
  color: #666666;
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.label-hint {
  font-weight: 400;
  color: #999999;
}

.input-row {
  display: flex;
  gap: 8px;
  align-items: center;
}

input[type=text],
input[type=number] {
  width: 100%;
  padding: 8px 16px;
  font-size: 0.875rem;
  border: 1px solid #e0e0e0;
  border-radius: 6px;
  background: #ffffff;
  transition: border-color 0.15s ease;
}
input[type=text]:focus,
input[type=number]:focus {
  outline: none;
  border-color: #2F6FED;
}
input[type=text]::placeholder,
input[type=number]::placeholder {
  color: #999999;
}
input[type=text].is-invalid,
input[type=number].is-invalid {
  border-color: #d32f2f;
}

.color-picker {
  width: 40px;
  height: 36px;
  padding: 2px;
  border: 1px solid #e0e0e0;
  border-radius: 6px;
  background: #ffffff;
  cursor: pointer;
  flex-shrink: 0;
}
.color-picker::-webkit-color-swatch-wrapper {
  padding: 0;
}
.color-picker::-webkit-color-swatch {
  border: none;
  border-radius: 4px;
}

.slider-container {
  display: flex;
  align-items: center;
  gap: 8px;
}

.slider-label {
  font-size: 0.6875rem;
  color: #999999;
  flex-shrink: 0;
  width: 40px;
}
.slider-label--left {
  text-align: right;
}
.slider-label--right {
  text-align: left;
}

.temperature-value {
  font-family: "SF Mono", SFMono-Regular, Consolas, "Liberation Mono", Menlo, monospace;
  font-size: 0.6875rem;
  color: #666666;
  background: #fafafa;
  padding: 2px 6px;
  border-radius: 4px;
}

input[type=range] {
  -webkit-appearance: none;
  appearance: none;
  flex: 1;
  height: 4px;
  background: #e0e0e0;
  border-radius: 2px;
  outline: none;
}
input[type=range]::-webkit-slider-thumb {
  -webkit-appearance: none;
  appearance: none;
  width: 16px;
  height: 16px;
  background: #2F6FED;
  border-radius: 50%;
  cursor: pointer;
  transition: transform 0.1s ease;
}
input[type=range]::-webkit-slider-thumb:hover {
  transform: scale(1.1);
}
input[type=range]::-moz-range-thumb {
  width: 16px;
  height: 16px;
  background: #2F6FED;
  border: none;
  border-radius: 50%;
  cursor: pointer;
}

.button-group {
  display: flex;
  gap: 1px;
  background: #e0e0e0;
  border-radius: 6px;
  overflow: hidden;
}

.btn-toggle {
  flex: 1;
  padding: 8px 16px;
  font-size: 0.8125rem;
  font-weight: 500;
  background: #fafafa;
  border: none;
  color: #666666;
  transition: background-color 0.15s ease, color 0.15s ease;
}
.btn-toggle:hover {
  background: #ffffff;
}
.btn-toggle[aria-pressed=true] {
  background: #2F6FED;
  color: white;
}

.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 4px;
  padding: 8px 24px;
  font-size: 0.875rem;
  font-weight: 500;
  border: none;
  border-radius: 6px;
  transition: background-color 0.15s ease, opacity 0.15s ease;
}
.btn:disabled {
  opacity: 0.5;
  cursor: not-allowed;
}

.btn--primary {
  background: #2F6FED;
  color: white;
}
.btn--primary:hover:not(:disabled) {
  background: #1a5ad9;
}

.btn--secondary {
  background: #fafafa;
  color: #1a1a1a;
  border: 1px solid #e0e0e0;
}
.btn--secondary:hover:not(:disabled) {
  background: #f0f0f0;
}

.btn--ghost {
  background: transparent;
  color: #2F6FED;
  padding: 4px 8px;
}
.btn--ghost:hover:not(:disabled) {
  background: rgba(47, 111, 237, 0.08);
}

.btn--danger {
  background: transparent;
  color: #d32f2f;
  border: 1px solid #e0e0e0;
}
.btn--danger:hover:not(:disabled) {
  background: rgba(211, 47, 47, 0.08);
  border-color: #d32f2f;
}

.btn--small {
  padding: 4px 8px;
  font-size: 0.75rem;
}

.ramp {
  display: flex;
  gap: 2px;
  height: 120px;
}

.swatch {
  flex: 1;
  display: flex;
  flex-direction: column;
  justify-content: flex-end;
  border-radius: 4px;
  overflow: hidden;
  position: relative;
}
.swatch__hex {
  font-family: "SF Mono", SFMono-Regular, Consolas, "Liberation Mono", Menlo, monospace;
  font-size: 0.625rem;
  text-align: center;
  padding: 4px;
  background: rgba(255, 255, 255, 0.9);
  color: #1a1a1a;
  backdrop-filter: blur(4px);
}

.swatch-strip {
  display: flex;
  height: 16px;
  border-radius: 2px;
  overflow: hidden;
}
.swatch-strip .swatch-mini {
  flex: 1;
}

.history-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-bottom: 8px;
}
.history-header .panel__title {
  margin-bottom: 0;
}
.history-header .btn[hidden] {
  display: none;
}

.history-list {
  display: flex;
  flex-direction: column;
  gap: 4px;
}

.history-entry {
  display: flex;
  flex-direction: column;
  gap: 4px;
  padding: 8px;
  background: #fafafa;
  border-radius: 6px;
  cursor: pointer;
  transition: background-color 0.15s ease;
}
.history-entry:hover {
  background: #f0f0f0;
}
.history-entry.is-active {
  outline: 2px solid #2F6FED;
  outline-offset: -2px;
}

.history-entry__header {
  display: flex;
  align-items: center;
  gap: 8px;
}

.history-entry__info {
  flex: 1;
  min-width: 0;
}

.history-entry__label {
  font-size: 0.8125rem;
  font-weight: 500;
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
}

.history-entry__hex {
  font-family: "SF Mono", SFMono-Regular, Consolas, "Liberation Mono", Menlo, monospace;
  font-size: 0.6875rem;
  color: #666666;
}

.history-entry__custom {
  font-size: 0.75rem;
  color: #888888;
  font-style: italic;
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
}

.history-entry__actions {
  display: flex;
  gap: 2px;
  flex-shrink: 0;
}

.btn-icon {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 24px;
  height: 24px;
  padding: 0;
  background: transparent;
  border: none;
  border-radius: 4px;
  color: #999999;
  font-size: 0.875rem;
  transition: background-color 0.15s ease, color 0.15s ease;
}
.btn-icon:hover {
  background: rgba(0, 0, 0, 0.08);
  color: #1a1a1a;
}
.btn-icon--star:hover, .btn-icon--star.is-starred {
  color: #f59e0b;
}
.btn-icon--remove:hover {
  color: #d32f2f;
}

.history-empty {
  font-size: 0.8125rem;
  color: #999999;
  text-align: center;
  padding: 16px;
}
.history-empty[hidden] {
  display: none;
}

.history-actions {
  padding-top: 8px;
  border-top: 1px solid #f0f0f0;
}

.export-hint {
  font-size: 0.75rem;
  color: #888888;
  margin: 0 0 12px 0;
  font-style: italic;
}

.export-format {
  display: flex;
  flex-direction: column;
  gap: 16px;
}

.export-header {
  display: flex;
  align-items: center;
  gap: 16px;
}
.export-header label {
  font-size: 0.75rem;
  font-weight: 500;
  color: #666666;
}
.export-header select {
  flex: 1;
  padding: 4px 8px;
  font-size: 0.8125rem;
  border: 1px solid #e0e0e0;
  border-radius: 4px;
  background: #ffffff;
}
.export-header select:focus {
  outline: none;
  border-color: #2F6FED;
}

.export-code {
  margin: 0;
  padding: 16px;
  font-family: "SF Mono", SFMono-Regular, Consolas, "Liberation Mono", Menlo, monospace;
  font-size: 0.75rem;
  line-height: 1.6;
  background: #fafafa;
  border: 1px solid #f0f0f0;
  border-radius: 6px;
  overflow-x: auto;
  white-space: pre;
  max-height: 200px;
  overflow-y: auto;
}

.export-actions {
  display: flex;
  align-items: center;
  gap: 16px;
}

.copy-feedback,
.add-feedback {
  font-size: 0.75rem;
  color: #2e7d32;
  font-weight: 500;
}
.copy-feedback[hidden],
.add-feedback[hidden] {
  display: none;
}

.preview-status {
  font-weight: 400;
  color: #999999;
  font-size: 0.6875rem;
  text-transform: none;
  letter-spacing: 0;
}

.action-row {
  display: flex;
  align-items: center;
  gap: 12px;
}

/* About page */
.app--about {
  display: block;
  max-width: 640px;
}

.about {
  padding-top: 32px;
}

.about__content {
  line-height: 1.7;
}

.about__section {
  margin-bottom: 32px;
}
.about__section:last-child {
  margin-bottom: 0;
}

.about__section h2 {
  font-size: 1.125rem;
  font-weight: 600;
  margin: 0 0 12px 0;
  color: #1a1a1a;
}

.about__section p {
  margin: 0 0 12px 0;
  color: #333333;
}
.about__section p:last-child {
  margin-bottom: 0;
}

.about__section ul {
  margin: 0 0 12px 0;
  padding-left: 20px;
  color: #333333;
}
.about__section ul:last-child {
  margin-bottom: 0;
}

.about__section li {
  margin-bottom: 6px;
}
.about__section li:last-child {
  margin-bottom: 0;
}

.about__section ul ul {
  margin-top: 6px;
  margin-bottom: 0;
}

@media (max-width: 768px) {
  body {
    padding: 12px;
  }
  .app {
    grid-template-columns: 1fr;
    gap: 16px;
  }
  .sidebar {
    order: 2;
  }
  .main {
    order: 1;
  }

  /* Panel padding */
  .panel {
    padding: 16px;
  }

  /* Vertical ramp */
  .ramp {
    flex-direction: column;
    height: auto;
    gap: 2px;
  }
  .swatch {
    flex: none;
    height: 28px;
    flex-direction: row;
    align-items: center;
    justify-content: flex-start;
  }
  .swatch__hex {
    background: rgba(255, 255, 255, 0.9);
    padding: 2px 8px;
    font-size: 0.6875rem;
    text-align: left;
  }

  /* Slider touch targets */
  input[type=range] {
    height: 6px;
  }
  input[type=range]::-webkit-slider-thumb {
    width: 24px;
    height: 24px;
  }
  input[type=range]::-moz-range-thumb {
    width: 24px;
    height: 24px;
  }

  /* Button toggle padding */
  .btn-toggle {
    padding: 8px 12px;
  }

  /* Touch-target minimum for buttons */
  .btn {
    min-height: 44px;
  }

  /* Export code wrapping */
  .export-code {
    white-space: pre-wrap;
    word-break: break-all;
  }
}