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

:root {
  --bg: #f4f6f8;
  --card: #ffffff;
  --text: #1a1f2e;
  --text-muted: #5c6578;
  --border: #e2e6ed;
  --accent: #2563eb;
  --accent-light: #dbeafe;
  --actual: #dc2626;
  --summary-bg: #f8fafc;
  --radius: 12px;
  --shadow: 0 4px 24px rgba(15, 23, 42, 0.08);
}

body {
  margin: 0;
  min-height: 100vh;
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
  font-size: 16px;
  line-height: 1.5;
  color: var(--text);
  background: var(--bg);
}

.container {
  max-width: 1080px;
  margin: 0 auto;
  padding: 2rem 1.25rem 3rem;
}

.currency-control {
  width: 7.5rem;
  flex-shrink: 0;
  margin-left: auto;
}

.layout {
  display: grid;
  grid-template-columns: 1fr;
  gap: 1.25rem;
  align-items: start;
}

.header {
  display: flex;
  align-items: flex-start;
  justify-content: space-between;
  gap: 1.5rem;
  margin-bottom: 1.5rem;
}

.header__text {
  flex: 1;
  min-width: 0;
}

.header h1 {
  margin: 0 0 0.25rem;
  font-size: 1.75rem;
  font-weight: 700;
  letter-spacing: -0.02em;
}

.visually-hidden {
  position: absolute;
  width: 1px;
  height: 1px;
  padding: 0;
  margin: -1px;
  overflow: hidden;
  clip: rect(0, 0, 0, 0);
  white-space: nowrap;
  border: 0;
}

.subtitle {
  margin: 0;
  color: var(--text-muted);
  font-size: 0.95rem;
}

.card {
  background: var(--card);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  box-shadow: var(--shadow);
  padding: 1.5rem;
}

.layout > .card + .card {
  margin-top: 0;
}

.controls {
  display: flex;
  flex-direction: column;
  gap: 1.25rem;
}

.control-group {
  display: flex;
  flex-direction: column;
  gap: 0.5rem;
}

.control-label {
  display: flex;
  justify-content: space-between;
  align-items: baseline;
  gap: 1rem;
}

label {
  font-weight: 600;
  font-size: 0.9rem;
}

.value-readout {
  font-variant-numeric: tabular-nums;
  font-weight: 600;
  color: var(--accent);
  white-space: nowrap;
}

input[type="month"] {
  width: 100%;
  padding: 0.625rem 0.75rem;
  border: 1px solid var(--border);
  border-radius: 8px;
  font-size: 1rem;
  color: var(--text);
  background: var(--card);
}

input[type="month"]:focus {
  outline: 2px solid var(--accent);
  outline-offset: 2px;
}

input[type="range"] {
  width: 100%;
  height: 6px;
  accent-color: var(--accent);
  cursor: pointer;
}

input[type="range"]:focus {
  outline: 2px solid var(--accent);
  outline-offset: 4px;
}

.currency-dropdown {
  position: relative;
}

.currency-dropdown__trigger {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 0.5rem;
  width: 100%;
  padding: 0.625rem 0.75rem;
  border: 1px solid var(--border);
  border-radius: 8px;
  font-size: 1rem;
  font-weight: 400;
  font-variant-numeric: tabular-nums;
  color: var(--text);
  background: var(--card);
  cursor: pointer;
  transition: outline-color 0.15s;
}

.currency-dropdown__trigger:hover {
  border-color: #c5ccd6;
}

.currency-dropdown__trigger:focus-visible {
  outline: 2px solid var(--accent);
  outline-offset: 2px;
}

.currency-dropdown__trigger[aria-expanded="true"] {
  outline: 2px solid var(--accent);
  outline-offset: 2px;
}

.currency-dropdown__chevron {
  flex-shrink: 0;
  color: var(--text-muted);
  transition: transform 0.15s;
}

.currency-dropdown__trigger[aria-expanded="true"] .currency-dropdown__chevron {
  transform: rotate(180deg);
}

.currency-dropdown__menu {
  position: absolute;
  top: calc(100% + 0.25rem);
  right: 0;
  left: 0;
  z-index: 10;
  margin: 0;
  padding: 0.25rem;
  list-style: none;
  background: var(--card);
  border: 1px solid var(--border);
  border-radius: 8px;
  box-shadow: var(--shadow);
}

.currency-dropdown__option {
  padding: 0.625rem 0.75rem;
  border-radius: 6px;
  font-size: 1rem;
  font-weight: 400;
  font-variant-numeric: tabular-nums;
  color: var(--text);
  cursor: pointer;
  transition: background 0.15s, color 0.15s;
}

.currency-dropdown__option:hover {
  background: var(--summary-bg);
}

.currency-dropdown__option[aria-selected="true"] {
  color: var(--accent);
  background: var(--accent-light);
  font-weight: 600;
}

.chart-wrapper {
  position: relative;
  height: 320px;
  width: 100%;
}

.chart-wrapper ul {
  display: none !important;
}

.chart-placeholder {
  display: flex;
  align-items: center;
  justify-content: center;
  height: 320px;
  border: 1px dashed var(--border);
  border-radius: 8px;
  color: var(--text-muted);
  font-size: 0.95rem;
}

.chart-placeholder.hidden {
  display: none;
}

.chart-wrapper.hidden {
  display: none;
}

.summary {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(140px, 1fr));
  gap: 1rem;
  margin: 0 0 1.25rem;
  padding: 1rem;
  background: var(--summary-bg);
  border-radius: 8px;
}

.summary--equation {
  display: flex;
  flex-wrap: wrap;
  align-items: flex-end;
  justify-content: center;
  gap: 0.5rem 0.75rem;
  grid-template-columns: unset;
  margin: 1.25rem 0 0;
}

.summary--controls {
  margin: 0;
}

.summary-item {
  display: flex;
  flex-direction: column;
  gap: 0.25rem;
  min-width: 0;
}

.summary-label,
.summary dt {
  font-size: 0.65rem;
  font-weight: 500;
  color: var(--text-muted);
  text-transform: uppercase;
  letter-spacing: 0.04em;
}

.summary-value,
.summary dd {
  margin: 0;
  font-size: 1.125rem;
  font-weight: 700;
  font-variant-numeric: tabular-nums;
}

.summary-operator {
  flex-shrink: 0;
  font-size: 1.25rem;
  font-weight: 600;
  line-height: 1;
  color: var(--text-muted);
  padding-bottom: 0.2rem;
}

.summary-operator--equals {
  color: var(--text);
}

.summary-item--final .summary-value,
.summary-item--final dd {
  color: var(--accent);
}

.summary-item--tax .summary-value,
.summary-item--tax dd {
  color: var(--actual);
}

.summary-item--gain .summary-value,
.summary-item--gain dd {
  color: #16a34a;
}

@media (min-width: 640px) {
  .layout {
    grid-template-columns: minmax(200px, 260px) minmax(0, 1fr);
    align-items: stretch;
  }

  .layout > .controls {
    grid-column: 1;
  }

  .layout > .output {
    grid-column: 2;
    display: flex;
    flex-direction: column;
  }

  .output .chart-wrapper,
  .output .chart-placeholder {
    flex: 1;
    min-height: 320px;
    height: auto;
  }
}

@media (max-width: 480px) {
  .container {
    padding: 1.25rem 1rem 2rem;
  }

  .header h1 {
    font-size: 1.5rem;
  }

  .currency-control {
    width: 6.5rem;
  }

  .summary:not(.summary--equation) {
    grid-template-columns: 1fr;
  }

  .summary--equation {
    gap: 0.75rem 0.5rem;
  }

  .summary-operator {
    font-size: 1.1rem;
  }
}