/* ============ RESET & BASE ============ */
*, *::before, *::after { box-sizing: border-box; }
html, body { margin: 0; padding: 0; }
body {
  font-family: -apple-system, BlinkMacSystemFont, "Inter", "Segoe UI", Roboto, Oxygen, Ubuntu, sans-serif;
  font-size: 15px;
  line-height: 1.55;
  background: var(--bg);
  color: var(--text);
  transition: background 0.3s ease, color 0.3s ease;
  min-height: 100vh;
  -webkit-font-smoothing: antialiased;
}

/* ============ THEME VARIABLES ============ */
:root[data-theme="light"] {
  --bg: #f6f8fc;
  --surface: #ffffff;
  --surface-alt: #f9fafc;
  --surface-hover: #f1f4fa;
  --text: #0f172a;
  --text-muted: #64748b;
  --border: #e2e8f0;
  --border-strong: #cbd5e1;
  --primary: #2563eb;
  --primary-hover: #1d4ed8;
  --primary-soft: #dbeafe;
  --accent-green: #10b981;
  --accent-red: #ef4444;
  --accent-orange: #f59e0b;
  --accent-purple: #8b5cf6;
  --shadow-sm: 0 1px 2px rgba(15, 23, 42, 0.04);
  --shadow: 0 1px 3px rgba(15, 23, 42, 0.06), 0 4px 12px rgba(15, 23, 42, 0.04);
  --shadow-lg: 0 8px 24px rgba(15, 23, 42, 0.08);
  --focus-ring: 0 0 0 3px rgba(37, 99, 235, 0.22);
  --chart-principal: #2563eb;
  --chart-interest: #f59e0b;
  --chart-line: #2563eb;
  --chart-grid: #e5e7eb;
  --gradient: linear-gradient(135deg, #2563eb 0%, #7c3aed 100%);
}
:root[data-theme="dark"] {
  --bg: #0b1020;
  --surface: #141a2e;
  --surface-alt: #1a2238;
  --surface-hover: #222b45;
  --text: #e6e9f2;
  --text-muted: #94a3b8;
  --border: #273049;
  --border-strong: #33415c;
  --primary: #3b82f6;
  --primary-hover: #60a5fa;
  --primary-soft: #1e3a5f;
  --accent-green: #22c55e;
  --accent-red: #f87171;
  --accent-orange: #fbbf24;
  --accent-purple: #a78bfa;
  --shadow-sm: 0 1px 2px rgba(0, 0, 0, 0.3);
  --shadow: 0 1px 3px rgba(0, 0, 0, 0.4), 0 4px 12px rgba(0, 0, 0, 0.3);
  --shadow-lg: 0 8px 24px rgba(0, 0, 0, 0.5);
  --focus-ring: 0 0 0 3px rgba(59, 130, 246, 0.35);
  --chart-principal: #60a5fa;
  --chart-interest: #fbbf24;
  --chart-line: #60a5fa;
  --chart-grid: #273049;
  --gradient: linear-gradient(135deg, #3b82f6 0%, #a78bfa 100%);
}

/* ============ LAYOUT ============ */
.app-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  gap: 1rem;
  padding: 1.25rem 1.75rem;
  background: var(--surface);
  border-bottom: 1px solid var(--border);
  position: sticky;
  top: 0;
  z-index: 100;
  box-shadow: var(--shadow-sm);
  backdrop-filter: blur(8px);
}
.header-left .app-title {
  margin: 0;
  font-size: 1.35rem;
  font-weight: 700;
  letter-spacing: -0.01em;
  background: var(--gradient);
  -webkit-background-clip: text;
  background-clip: text;
  -webkit-text-fill-color: transparent;
}
.header-left .app-subtitle {
  margin: 0.15rem 0 0;
  color: var(--text-muted);
  font-size: 0.85rem;
}
.header-right { display: flex; gap: 0.5rem; }

.toggle-btn {
  display: inline-flex;
  align-items: center;
  gap: 0.45rem;
  padding: 0.55rem 0.95rem;
  background: var(--surface-alt);
  color: var(--text);
  border: 1px solid var(--border);
  border-radius: 999px;
  cursor: pointer;
  font-size: 0.85rem;
  font-weight: 500;
  transition: all 0.2s ease;
}
.toggle-btn:hover {
  background: var(--primary-soft);
  border-color: var(--primary);
  transform: translateY(-1px);
}
.toggle-btn:focus-visible { outline: none; box-shadow: var(--focus-ring); }

.app-main {
  display: grid;
  grid-template-columns: 1fr;
  gap: 1.5rem;
  padding: 1.5rem;
  max-width: 1440px;
  margin: 0 auto;
}

.inputs-column, .results-column {
  display: flex;
  flex-direction: column;
  gap: 1.25rem;
}

.app-footer {
  padding: 1.75rem;
  text-align: center;
  color: var(--text-muted);
  font-size: 0.8rem;
  border-top: 1px solid var(--border);
  margin-top: 2rem;
}

/* ============ CARDS ============ */
.card {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 16px;
  padding: 1.35rem;
  box-shadow: var(--shadow);
  transition: box-shadow 0.25s ease, transform 0.25s ease;
}
.card:hover { box-shadow: var(--shadow-lg); }
.card-title {
  margin: 0 0 1.1rem;
  font-size: 1.05rem;
  font-weight: 600;
  color: var(--text);
  letter-spacing: -0.01em;
}

/* ============ FORMS ============ */
.input-group { margin-bottom: 0.95rem; }
.input-group label {
  display: block;
  margin-bottom: 0.4rem;
  font-size: 0.82rem;
  font-weight: 500;
  color: var(--text-muted);
  letter-spacing: 0.01em;
}
.input-group input, .input-group select {
  width: 100%;
  padding: 0.7rem 0.9rem;
  background: var(--surface-alt);
  color: var(--text);
  border: 1px solid var(--border);
  border-radius: 10px;
  font-size: 0.95rem;
  font-family: inherit;
  font-variant-numeric: tabular-nums;
  transition: border-color 0.15s, box-shadow 0.15s, background 0.15s;
}
.input-group input:hover, .input-group select:hover {
  border-color: var(--border-strong);
}
.input-group input:focus, .input-group select:focus {
  outline: none;
  border-color: var(--primary);
  background: var(--surface);
  box-shadow: var(--focus-ring);
}

.input-with-prefix, .input-with-suffix {
  display: flex;
  align-items: stretch;
  background: var(--surface-alt);
  border: 1px solid var(--border);
  border-radius: 10px;
  overflow: hidden;
  transition: border-color 0.15s, box-shadow 0.15s, background 0.15s;
}
.input-with-prefix:hover, .input-with-suffix:hover {
  border-color: var(--border-strong);
}
.input-with-prefix:focus-within, .input-with-suffix:focus-within {
  border-color: var(--primary);
  background: var(--surface);
  box-shadow: var(--focus-ring);
}
.input-with-prefix input, .input-with-suffix input {
  border: none;
  background: transparent;
  border-radius: 0;
}
.input-with-prefix input:focus, .input-with-suffix input:focus { box-shadow: none; }
.prefix, .suffix {
  display: flex;
  align-items: center;
  padding: 0 0.85rem;
  color: var(--text-muted);
  font-weight: 600;
  background: var(--surface);
  border-right: 1px solid var(--border);
  font-size: 0.9rem;
}
.input-with-suffix .suffix { border-right: none; border-left: 1px solid var(--border); }

.row-2 { display: grid; grid-template-columns: 1fr 1fr; gap: 0.85rem; }

.button-row { margin-top: 0.75rem; }
.btn-primary {
  width: 100%;
  padding: 0.85rem 1rem;
  background: var(--gradient);
  color: #fff;
  border: none;
  border-radius: 12px;
  font-size: 1rem;
  font-weight: 600;
  cursor: pointer;
  transition: transform 0.15s, box-shadow 0.2s, opacity 0.2s;
  box-shadow: 0 4px 14px rgba(37, 99, 235, 0.25);
  letter-spacing: 0.01em;
}
.btn-primary:hover {
  transform: translateY(-1px);
  box-shadow: 0 6px 20px rgba(37, 99, 235, 0.35);
}
.btn-primary:active { transform: translateY(0); }
.btn-primary:focus-visible { outline: none; box-shadow: var(--focus-ring); }
.btn-primary:disabled { opacity: 0.6; cursor: not-allowed; }

/* ============ TOGGLE SWITCH ============ */
.toggle-row {
  display: flex;
  align-items: flex-start;
  gap: 0.85rem;
  margin-bottom: 0.95rem;
}
.toggle-row .flex-1 { flex: 1; margin-bottom: 0; }
.toggle-switch {
  position: relative;
  display: inline-block;
  width: 42px;
  height: 24px;
  margin-top: 1.6rem;
  flex-shrink: 0;
}
.toggle-switch input { opacity: 0; width: 0; height: 0; }
.toggle-switch .slider {
  position: absolute;
  cursor: pointer;
  inset: 0;
  background: var(--border-strong);
  border-radius: 999px;
  transition: background 0.2s;
}
.toggle-switch .slider::before {
  content: "";
  position: absolute;
  height: 18px;
  width: 18px;
  left: 3px;
  top: 3px;
  background: #fff;
  border-radius: 50%;
  transition: transform 0.2s;
  box-shadow: 0 1px 3px rgba(0,0,0,0.2);
}
.toggle-switch input:checked + .slider { background: var(--primary); }
.toggle-switch input:checked + .slider::before { transform: translateX(18px); }
.toggle-switch input:focus-visible + .slider { box-shadow: var(--focus-ring); }

/* ============ COLLAPSIBLE ============ */
.collapsible { padding: 0; overflow: hidden; }
.collapsible-title {
  padding: 1.35rem;
  margin: 0;
  cursor: pointer;
  list-style: none;
  display: flex;
  justify-content: space-between;
  align-items: center;
  user-select: none;
  font-weight: 600;
}
.collapsible-title::-webkit-details-marker { display: none; }
.collapsible-title::after {
  content: "▾";
  font-size: 1rem;
  color: var(--text-muted);
  transition: transform 0.25s ease;
}
.collapsible[open] .collapsible-title::after { transform: rotate(180deg); }
.advanced-form, .compare-grid { padding: 0 1.35rem 1.35rem; }

/* ============ COMPARE SCENARIOS ============ */
.compare-grid { display: grid; grid-template-columns: 1fr 1fr; gap: 1rem; }
.scenario-form {
  padding: 1.1rem;
  background: var(--surface-alt);
  border: 1px solid var(--border);
  border-radius: 12px;
  transition: border-color 0.2s, transform 0.2s;
}
.scenario-form:hover { border-color: var(--primary); }
.scenario-title {
  margin: 0 0 0.85rem;
  font-size: 0.95rem;
  color: var(--primary);
  font-weight: 600;
}

/* ============ RESULTS ============ */
.total-payment {
  display: flex;
  justify-content: space-between;
  align-items: baseline;
  padding: 1rem 1.15rem;
  background: var(--primary-soft);
  border: 1px solid var(--primary);
  border-radius: 12px;
  margin-bottom: 1.1rem;
}
.total-label { font-weight: 500; color: var(--text); }
.total-value {
  font-size: 1.75rem;
  font-weight: 700;
  color: var(--primary);
  font-variant-numeric: tabular-nums;
  letter-spacing: -0.02em;
}

.breakdown-list { display: flex; flex-direction: column; gap: 0.35rem; }
.breakdown-item {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 0.6rem 0.25rem;
  border-bottom: 1px dashed var(--border);
  font-size: 0.9rem;
  transition: background 0.15s;
}
.breakdown-item:hover { background: var(--surface-alt); border-radius: 6px; }
.breakdown-item:last-child { border-bottom: none; }
.breakdown-item .label { color: var(--text-muted); display: flex; align-items: center; gap: 0.55rem; }
.breakdown-item .dot { width: 9px; height: 9px; border-radius: 50%; display: inline-block; }
.breakdown-item .value { font-weight: 600; color: var(--text); font-variant-numeric: tabular-nums; }

.stats-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(180px, 1fr));
  gap: 0.85rem;
}
.stat {
  padding: 0.95rem;
  background: var(--surface-alt);
  border: 1px solid var(--border);
  border-radius: 12px;
  transition: border-color 0.2s, transform 0.2s;
}
.stat:hover { border-color: var(--primary); transform: translateY(-1px); }
.stat-label {
  display: block;
  font-size: 0.76rem;
  color: var(--text-muted);
  margin-bottom: 0.3rem;
  text-transform: uppercase;
  letter-spacing: 0.04em;
  font-weight: 500;
}
.stat-value {
  display: block;
  font-size: 1.08rem;
  font-weight: 600;
  color: var(--text);
  word-break: break-word;
  font-variant-numeric: tabular-nums;
}
.stat-value.positive { color: var(--accent-green); }

/* ============ CHARTS ============ */
.charts-card .chart-wrap { margin-bottom: 1.75rem; }
.charts-card .chart-wrap:last-child { margin-bottom: 0; }
.chart-title {
  margin: 0 0 0.85rem;
  font-size: 0.88rem;
  color: var(--text-muted);
  font-weight: 500;
}
.chart { width: 100%; overflow-x: auto; }
.chart svg { width: 100%; height: auto; display: block; min-height: 240px; }
.chart-legend {
  display: flex;
  gap: 1.25rem;
  margin-top: 0.65rem;
  font-size: 0.82rem;
  color: var(--text-muted);
}
.chart-legend .swatch {
  display: inline-block;
  width: 12px;
  height: 12px;
  border-radius: 3px;
  margin-right: 0.4rem;
  vertical-align: middle;
}

/* ============ AMORTIZATION ============ */
.amort-container {
  max-height: 640px;
  overflow-y: auto;
  border: 1px solid var(--border);
  border-radius: 10px;
}
.amort-year { border-bottom: 1px solid var(--border); }
.amort-year:last-child { border-bottom: none; }
.amort-year-header {
  display: grid;
  grid-template-columns: 1fr 1fr 1fr 1fr 1fr auto;
  gap: 0.5rem;
  padding: 0.85rem 1.1rem;
  background: var(--surface-alt);
  cursor: pointer;
  font-size: 0.85rem;
  font-weight: 600;
  align-items: center;
  user-select: none;
  transition: background 0.15s;
}
.amort-year-header:hover { background: var(--primary-soft); }
.amort-year-header .toggle-arrow {
  transition: transform 0.25s;
  color: var(--text-muted);
}
.amort-year.open .toggle-arrow { transform: rotate(90deg); }
.amort-months { display: none; }
.amort-year.open .amort-months { display: block; animation: fadeIn 0.2s ease; }

@keyframes fadeIn {
  from { opacity: 0; transform: translateY(-4px); }
  to { opacity: 1; transform: translateY(0); }
}

.amort-month-row, .amort-header-row {
  display: grid;
  grid-template-columns: 1fr 1fr 1fr 1fr 1fr;
  gap: 0.5rem;
  padding: 0.55rem 1.1rem 0.55rem 2rem;
  font-size: 0.82rem;
  border-top: 1px solid var(--border);
  font-variant-numeric: tabular-nums;
}
.amort-header-row {
  background: var(--surface);
  font-weight: 600;
  color: var(--text-muted);
  font-size: 0.72rem;
  text-transform: uppercase;
  letter-spacing: 0.04em;
  cursor: default;
}
.amort-header-row:hover { background: var(--surface); }
.amort-month-row:nth-child(even) { background: var(--surface-alt); }
.amort-month-row:hover { background: var(--primary-soft); }

/* ============ COMPARE RESULTS ============ */
.compare-results-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 1rem;
}
.compare-scenario {
  padding: 1.1rem;
  background: var(--surface-alt);
  border: 1px solid var(--border);
  border-radius: 12px;
}
.compare-scenario h3 {
  margin: 0 0 0.85rem;
  color: var(--primary);
  font-size: 1rem;
  font-weight: 600;
}
.compare-row {
  display: flex;
  justify-content: space-between;
  padding: 0.5rem 0;
  border-bottom: 1px dashed var(--border);
  font-size: 0.87rem;
}
.compare-row:last-child { border-bottom: none; }
.compare-row .label { color: var(--text-muted); }
.compare-row .value { font-weight: 600; font-variant-numeric: tabular-nums; }
.compare-row.highlight .value { color: var(--accent-green); }

/* ============ LOADING STATE ============ */
.loading {
  position: relative;
  pointer-events: none;
  opacity: 0.7;
}
.loading::after {
  content: "";
  position: absolute;
  top: 50%;
  left: 50%;
  width: 24px;
  height: 24px;
  margin: -12px 0 0 -12px;
  border: 2px solid var(--border);
  border-top-color: var(--primary);
  border-radius: 50%;
  animation: spin 0.7s linear infinite;
}
@keyframes spin { to { transform: rotate(360deg); } }

/* ============ RESPONSIVE ============ */
@media (min-width: 1024px) {
  .app-main {
    grid-template-columns: minmax(380px, 480px) 1fr;
    align-items: start;
  }
  .results-column {
    position: sticky;
    top: 90px;
    max-height: calc(100vh - 110px);
    overflow-y: auto;
    padding-right: 0.25rem;
  }
  .results-column::-webkit-scrollbar { width: 8px; }
  .results-column::-webkit-scrollbar-track { background: transparent; }
  .results-column::-webkit-scrollbar-thumb {
    background: var(--border);
    border-radius: 4px;
  }
  .results-column::-webkit-scrollbar-thumb:hover { background: var(--border-strong); }
}

@media (min-width: 768px) and (max-width: 1023px) {
  .app-main { grid-template-columns: 1fr; }
  .row-2 { grid-template-columns: 1fr 1fr; }
  .stats-grid { grid-template-columns: repeat(2, 1fr); }
}

@media (max-width: 767px) {
  .app-header {
    flex-direction: column;
    align-items: flex-start;
    padding: 1rem 1.15rem;
  }
  .header-right { width: 100%; justify-content: flex-start; }
  .app-main { padding: 1rem; gap: 1rem; }
  .row-2 { grid-template-columns: 1fr; }
  .compare-grid { grid-template-columns: 1fr; }
  .compare-results-grid { grid-template-columns: 1fr; }
  .stats-grid { grid-template-columns: 1fr 1fr; }
  .amort-year-header, .amort-month-row, .amort-header-row {
    grid-template-columns: 1fr 1fr 1fr;
    font-size: 0.78rem;
  }
  .amort-year-header .col-hide-sm,
  .amort-month-row .col-hide-sm,
  .amort-header-row .col-hide-sm { display: none; }
  .total-value { font-size: 1.35rem; }
  .card { padding: 1.05rem; border-radius: 14px; }
  .toggle-btn { padding: 0.45rem 0.75rem; font-size: 0.8rem; }
}

@media (max-width: 420px) {
  .stats-grid { grid-template-columns: 1fr; }
}