@import url('https://fonts.googleapis.com/css2?family=IBM+Plex+Mono:wght@400;500;700&family=IBM+Plex+Sans:wght@400;500&display=swap');

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

:root {
  --color-bg:            #0B0F1A;
  --color-surface:       #111827;
  --color-surface-alt:   #1C2333;
  --color-primary:       #1D4ED8;
  --color-primary-hover: #2563EB;
  --color-primary-muted: #1E3A8A;
  --color-text:          #E8ECF0;
  --color-text-secondary:#8A95A3;
  --color-text-disabled: #3D4A5C;
  --color-destructive:   #DC2626;
  --color-success:       #16A34A;
  --color-border:        #1F2D3D;
  --color-border-focus:  #1D4ED8;

  --space-1:  4px;
  --space-2:  8px;
  --space-3:  12px;
  --space-4:  16px;
  --space-6:  24px;
  --space-8:  32px;
  --space-12: 48px;
  --space-16: 64px;

  --text-xs:   11px;
  --text-sm:   13px;
  --text-base: 15px;
  --text-lg:   18px;
  --text-xl:   24px;
  --text-2xl:  32px;
}

html, body {
  height: 100%;
}

body {
  background: var(--color-bg);
  color: var(--color-text);
  font-family: 'IBM Plex Sans', sans-serif;
  font-size: var(--text-base);
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
}

/* ── HEADER ── */
header {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  height: 48px;
  background: var(--color-bg);
  border-bottom: 1px solid var(--color-border);
  display: flex;
  align-items: center;
  padding: 0 40px;
  z-index: 100;
}

.header-title {
  font-family: 'IBM Plex Mono', monospace;
  font-weight: 700;
  font-size: var(--text-lg);
  line-height: 1.4;
  letter-spacing: -0.01em;
  color: var(--color-text);
}

.header-subtitle {
  font-family: 'IBM Plex Mono', monospace;
  font-size: var(--text-xs);
  color: var(--color-text-secondary);
  letter-spacing: 0.04em;
  margin-left: var(--space-4);
  padding-left: var(--space-4);
  border-left: 1px solid var(--color-border);
  line-height: 1.4;
}

/* ── MAIN LAYOUT ── */
main {
  margin-top: 48px;
  padding: 32px 40px;
  max-width: 680px;
  margin-left: auto;
  margin-right: auto;
  margin-top: 48px;
}

/* ── SECTION LABEL ── */
.section-label {
  font-family: 'IBM Plex Mono', monospace;
  font-weight: 500;
  font-size: var(--text-xs);
  line-height: 1.4;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--color-text-secondary);
  margin-bottom: var(--space-3);
}

section {
  margin-bottom: var(--space-8);
}

/* ── CARD ── */
.card {
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: 4px;
  padding: var(--space-4);
}

/* ── ADD PARTICIPANT FORM ── */
.add-form {
  display: grid;
  grid-template-columns: 1fr 1fr auto;
  gap: var(--space-4);
  align-items: end;
}

.field {
  display: flex;
  flex-direction: column;
}

label {
  font-family: 'IBM Plex Mono', monospace;
  font-weight: 500;
  font-size: var(--text-xs);
  line-height: 1.4;
  letter-spacing: 0.04em;
  text-transform: uppercase;
  color: var(--color-text-secondary);
  margin-bottom: 6px;
}

.label-hint {
  font-weight: 400;
  text-transform: none;
  letter-spacing: 0;
  opacity: 0.6;
}

input[type="text"],
input[type="number"] {
  height: 36px;
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: 3px;
  padding: 0 var(--space-3);
  font-family: 'IBM Plex Mono', monospace;
  font-weight: 400;
  font-size: 14px;
  color: var(--color-text);
  outline: none;
  transition: border-color 120ms ease-out;
  -moz-appearance: textfield;
}

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

input::placeholder {
  color: var(--color-text-disabled);
}

input:focus {
  border-color: var(--color-border-focus);
}

/* ── BUTTONS ── */
button {
  cursor: pointer;
  border: none;
  border-radius: 3px;
  font-family: 'IBM Plex Mono', monospace;
  font-weight: 500;
  font-size: var(--text-sm);
  letter-spacing: 0.06em;
  text-transform: uppercase;
  transition: background 120ms ease-out, border-color 120ms ease-out, color 120ms ease-out;
}

button:active {
  transform: scale(0.98);
  transition: transform 80ms ease-out;
}

.btn-primary {
  height: 36px;
  padding: 0 var(--space-4);
  background: var(--color-primary);
  color: #ffffff;
}

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

.btn-secondary {
  height: 36px;
  padding: 0 var(--space-4);
  background: transparent;
  border: 1px solid var(--color-border);
  color: var(--color-text);
}

.btn-secondary:hover {
  border-color: var(--color-primary);
  color: var(--color-primary);
}

.btn-destructive {
  height: 28px;
  padding: 0 var(--space-3);
  background: transparent;
  border: 1px solid var(--color-border);
  color: var(--color-text-secondary);
  font-size: var(--text-xs);
}

.btn-destructive:hover {
  background: var(--color-destructive);
  border-color: var(--color-destructive);
  color: #ffffff;
}

/* ── PARTICIPANT LIST ── */
.participant-list {
  display: flex;
  flex-direction: column;
  gap: 1px;
  background: var(--color-border);
  border: 1px solid var(--color-border);
  border-radius: 4px;
  overflow: hidden;
}

.participant-list:empty {
  display: none;
}

.participant-row {
  display: grid;
  grid-template-columns: 1fr auto auto;
  align-items: center;
  gap: var(--space-4);
  padding: var(--space-3) var(--space-4);
  background: var(--color-surface);
}

.participant-row:first-child {
  border-radius: 3px 3px 0 0;
}

.participant-row:last-child {
  border-radius: 0 0 3px 3px;
}

.participant-row:only-child {
  border-radius: 3px;
}

.participant-name {
  font-family: 'IBM Plex Mono', monospace;
  font-weight: 400;
  font-size: var(--text-sm);
  color: var(--color-text);
}

.participant-amount {
  font-family: 'IBM Plex Mono', monospace;
  font-weight: 400;
  font-size: var(--text-sm);
  color: var(--color-text-secondary);
  text-align: right;
  min-width: 80px;
}

.empty-state {
  padding: var(--space-6) var(--space-4);
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: 4px;
  font-family: 'IBM Plex Mono', monospace;
  font-size: var(--text-sm);
  color: var(--color-text-disabled);
  text-align: center;
  letter-spacing: 0.02em;
}

/* ── ACTIONS ROW ── */
.actions-row {
  display: flex;
  gap: var(--space-3);
  align-items: center;
}

.participant-count {
  font-family: 'IBM Plex Mono', monospace;
  font-size: var(--text-xs);
  color: var(--color-text-disabled);
  margin-left: auto;
  letter-spacing: 0.04em;
}

/* ── DIVIDER ── */
.divider {
  width: 100%;
  height: 1px;
  background: var(--color-border);
  margin: var(--space-8) 0;
}

/* ── RESULTS ── */
#results-section {
  display: none;
}

#results-section.visible {
  display: block;
}

.results-list {
  display: flex;
  flex-direction: column;
  gap: 1px;
  background: var(--color-border);
  border: 1px solid var(--color-border);
  border-radius: 4px;
  overflow: hidden;
}

.result-row {
  display: grid;
  grid-template-columns: 1fr auto 1fr auto;
  align-items: center;
  gap: var(--space-3);
  padding: var(--space-3) var(--space-4);
  background: var(--color-surface);
  opacity: 0;
  transform: translateY(4px);
  animation: fadeIn 150ms ease-out forwards;
}

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

.result-source {
  font-family: 'IBM Plex Mono', monospace;
  font-weight: 500;
  font-size: var(--text-sm);
  color: var(--color-text);
}

.result-arrow {
  font-family: 'IBM Plex Mono', monospace;
  font-size: var(--text-xs);
  color: var(--color-text-disabled);
  letter-spacing: 0.04em;
}

.result-target {
  font-family: 'IBM Plex Mono', monospace;
  font-weight: 500;
  font-size: var(--text-sm);
  color: var(--color-text);
}

.result-amount {
  font-family: 'IBM Plex Mono', monospace;
  font-weight: 700;
  font-size: var(--text-sm);
  color: var(--color-text);
  text-align: right;
}

.no-transfers {
  padding: var(--space-6) var(--space-4);
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: 4px;
  font-family: 'IBM Plex Mono', monospace;
  font-size: var(--text-sm);
  text-align: center;
  opacity: 0;
  animation: fadeIn 150ms ease-out forwards;
}

/* ── STATUS BADGES ── */
.badge {
  display: inline-block;
  font-family: 'IBM Plex Mono', monospace;
  font-size: var(--text-xs);
  font-weight: 500;
  letter-spacing: 0.04em;
  text-transform: uppercase;
  padding: 2px 6px;
  border-radius: 2px;
}

.badge-success {
  background: #14532D;
  color: #4ADE80;
}

.badge-error {
  background: #450A0A;
  color: #F87171;
}

.badge-info {
  background: var(--color-primary-muted);
  color: #93C5FD;
}

/* ── ERROR MESSAGE ── */
.error-msg {
  font-family: 'IBM Plex Sans', sans-serif;
  font-style: italic;
  font-size: var(--text-sm);
  color: #F87171;
  margin-top: var(--space-2);
  display: none;
}

.error-msg.visible {
  display: block;
}

@keyframes shake {
  0%, 100% { transform: translateX(0); }
  20%       { transform: translateX(-20px); }
  40%       { transform: translateX(20px); }
  60%       { transform: translateX(-20px); }
  80%       { transform: translateX(20px); }
}

.shake {
  animation: shake 300ms ease-out;
}

/* ── SUMMARY ROW ── */
.summary-row {
  display: grid;
  grid-template-columns: 1fr 1fr 1fr;
  gap: var(--space-4);
  margin-bottom: var(--space-4);
}

.summary-stat {
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: 4px;
  padding: var(--space-3) var(--space-4);
}

.summary-stat-label {
  font-family: 'IBM Plex Mono', monospace;
  font-size: var(--text-xs);
  color: var(--color-text-secondary);
  letter-spacing: 0.04em;
  text-transform: uppercase;
  margin-bottom: var(--space-1);
}

.summary-stat-value {
  font-family: 'IBM Plex Mono', monospace;
  font-weight: 700;
  font-size: var(--text-lg);
  color: var(--color-text);
}

/* ── RESPONSIVE ── */
@media (max-width: 600px) {
  header {
    padding: 0 16px;
  }

  main {
    padding: 20px 16px;
  }

  /* Prevent iOS auto-zoom on input focus */
  input[type="text"],
  input[type="number"] {
    font-size: 16px;
    height: 44px;
  }

  .btn-primary,
  .btn-secondary {
    height: 44px;
  }

  /* Larger tap target for remove button */
  .btn-destructive {
    height: 36px;
    padding: 0 var(--space-4);
  }

  .add-form {
    grid-template-columns: 1fr;
  }

  .add-form .btn-primary {
    grid-column: 1 / -1;
    width: 100%;
  }

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

  .actions-row button {
    width: 100%;
  }

  .participant-row {
    grid-template-columns: 1fr auto;
    grid-template-rows: auto auto;
    gap: var(--space-2) var(--space-3);
  }

  .participant-amount {
    grid-column: 1;
    grid-row: 2;
    font-size: var(--text-xs);
    color: var(--color-text-disabled);
    text-align: left;
    min-width: unset;
  }

  .btn-destructive {
    grid-column: 2;
    grid-row: 1 / 3;
    align-self: center;
  }

  .summary-row {
    grid-template-columns: 1fr 1fr;
  }

  .summary-row .summary-stat:last-child {
    grid-column: 1 / -1;
  }

  .result-row {
    grid-template-columns: 1fr auto;
    grid-template-rows: auto auto;
    gap: var(--space-1) var(--space-3);
  }

  .result-arrow {
    display: none;
  }

  .result-target {
    color: var(--color-text-secondary);
    font-size: var(--text-xs);
  }

  .result-amount {
    grid-row: 1 / 3;
    grid-column: 2;
    align-self: center;
  }

  .header-subtitle {
    display: none;
  }
}

footer {
  text-align: center;
  padding: 24px 0 16px;
  font-size: 0.75rem;
  color: var(--color-muted, #6b7280);
  display: flex;
  justify-content: center;
  align-items: center;
  gap: 6px;
}

footer a {
  color: var(--color-muted, #6b7280);
  text-decoration: underline;
}

footer a:hover {
  color: var(--color-text, #e5e7eb);
}