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

/* ── TEMAS ─────────────────────────────────────────────────── */
:root,
[data-theme="dark"] {
  --bg:        #0d0d0f;
  --surface:   #16161a;
  --panel:     #1e1e24;
  --btn:       #252530;
  --btn-hover: #2e2e3c;
  --btn-active:#373747;
  --border:    rgba(255,255,255,0.06);
  --text:      #e8e8f0;
  --text-dim:  #6b6b88;
  --accent:    #e63956;
  --accent-h:  #f04d69;
  --op-color:  #7c6af7;
  --glow:      rgba(230, 57, 86, 0.25);
  --shadow:    rgba(0,0,0,0.6);
  --bg-grad-1: rgba(124,106,247,0.08);
  --bg-grad-2: rgba(230,57,86,0.06);
  --toggle-bg: #252530;
  --toggle-border: rgba(255,255,255,0.1);
}

[data-theme="light"] {
  --bg:        #f0f0f5;
  --surface:   #ffffff;
  --panel:     #f7f7fb;
  --btn:       #ebebf2;
  --btn-hover: #dddde8;
  --btn-active:#d0d0de;
  --border:    rgba(0,0,0,0.07);
  --text:      #1a1a2e;
  --text-dim:  #8888aa;
  --accent:    #e63956;
  --accent-h:  #f04d69;
  --op-color:  #6a58e8;
  --glow:      rgba(230, 57, 86, 0.2);
  --shadow:    rgba(0,0,0,0.12);
  --bg-grad-1: rgba(106,88,232,0.06);
  --bg-grad-2: rgba(230,57,86,0.04);
  --toggle-bg: #e0e0ec;
  --toggle-border: rgba(0,0,0,0.08);
}

/* ── BASE ───────────────────────────────────────────────────── */
body {
  min-height: 100vh;
  display: flex;
  align-items: center;
  justify-content: center;
  background: var(--bg);
  font-family: 'Outfit', sans-serif;
  background-image:
    radial-gradient(ellipse 60% 50% at 50% 0%, var(--bg-grad-1) 0%, transparent 70%),
    radial-gradient(ellipse 40% 30% at 80% 80%, var(--bg-grad-2) 0%, transparent 60%);
  transition: background 0.35s ease, background-image 0.35s ease;
}

/* ── TOGGLE TEMA ────────────────────────────────────────────── */
.calc-wrapper {
  perspective: 1000px;
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 12px;
}

.theme-toggle-row {
  display: flex;
  justify-content: flex-end;
  width: 320px;
}

.theme-toggle {
  background: var(--toggle-bg);
  border: 1px solid var(--toggle-border);
  border-radius: 50px;
  padding: 6px 14px;
  cursor: pointer;
  display: flex;
  align-items: center;
  gap: 6px;
  font-size: 1rem;
  transition: background 0.25s, transform 0.1s;
}

.theme-toggle:hover  { background: var(--btn-hover); }
.theme-toggle:active { transform: scale(0.94); }

/* Mostrar/ocultar íconos según tema */
[data-theme="dark"]  .icon-sun  { display: inline; }
[data-theme="dark"]  .icon-moon { display: none; }
[data-theme="light"] .icon-sun  { display: none; }
[data-theme="light"] .icon-moon { display: inline; }

/* ── CALCULADORA ────────────────────────────────────────────── */
.calculadora {
  width: 320px;
  background: var(--surface);
  border-radius: 24px;
  padding: 20px;
  border: 1px solid var(--border);
  box-shadow:
    0 40px 80px var(--shadow),
    0 0 0 1px rgba(255,255,255,0.04) inset,
    0 1px 0 rgba(255,255,255,0.08) inset;
  animation: slideIn 0.5s cubic-bezier(0.34, 1.56, 0.64, 1);
  transition: background 0.35s ease, box-shadow 0.35s ease, border-color 0.35s ease;
}

@keyframes slideIn {
  from { opacity: 0; transform: translateY(30px) scale(0.95); }
  to   { opacity: 1; transform: translateY(0) scale(1); }
}

/* ── PANTALLA ───────────────────────────────────────────────── */
.pantalla {
  background: var(--panel);
  border-radius: 14px;
  padding: 16px 18px 14px;
  margin-bottom: 18px;
  border: 1px solid var(--border);
  min-height: 100px;
  display: flex;
  flex-direction: column;
  justify-content: flex-end;
  align-items: flex-end;
  gap: 4px;
  overflow: hidden;
  transition: background 0.35s ease, border-color 0.35s ease;
}

.formula {
  font-family: 'Share Tech Mono', monospace;
  font-size: 0.8rem;
  color: var(--text-dim);
  min-height: 1.1em;
  word-break: break-all;
  text-align: right;
  transition: color 0.35s ease;
}

.resultado {
  font-family: 'Share Tech Mono', monospace;
  font-size: 2.4rem;
  color: var(--text);
  letter-spacing: -1px;
  word-break: break-all;
  text-align: right;
  transition: font-size 0.15s ease, color 0.35s ease;
  line-height: 1;
}

.resultado.animar {
  animation: popIn 0.15s ease;
}

@keyframes popIn {
  0%   { transform: scale(0.96); opacity: 0.6; }
  100% { transform: scale(1);    opacity: 1; }
}

/* ── GRID DE BOTONES ────────────────────────────────────────── */
.btn-grid {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 8px;
}

.btn {
  background: var(--btn);
  color: var(--text);
  border: 1px solid var(--border);
  border-radius: 12px;
  font-family: 'Outfit', sans-serif;
  font-size: 1rem;
  font-weight: 400;
  padding: 0;
  height: 64px;
  cursor: pointer;
  transition: background 0.12s, transform 0.08s, box-shadow 0.12s, color 0.35s, border-color 0.35s;
  position: relative;
  overflow: hidden;
  user-select: none;
  -webkit-tap-highlight-color: transparent;
}

.btn::after {
  content: '';
  position: absolute;
  inset: 0;
  background: white;
  opacity: 0;
  border-radius: inherit;
  transition: opacity 0.15s;
}

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

.btn:active {
  background: var(--btn-active);
  transform: scale(0.94);
}

.btn:active::after { opacity: 0.04; }

/* ── Variantes de botón ─────────────────────────────────────── */
.btn-op {
  color: var(--op-color);
  font-weight: 500;
  font-size: 1.2rem;
}

.btn-op:hover { background: rgba(124,106,247,0.1); }

.btn-fn {
  color: var(--text-dim);
  font-size: 0.9rem;
  font-weight: 500;
  letter-spacing: 0.03em;
  text-transform: uppercase;
}

.btn-fn:hover { background: rgba(128,128,128,0.1); }

#btn-borrar { font-size: 1.2rem; }

#btn-igual {
  background: var(--accent);
  color: white;
  font-size: 1.4rem;
  font-weight: 500;
  grid-row: span 2;
  box-shadow: 0 4px 20px var(--glow);
  border-color: rgba(230,57,86,0.4);
}

#btn-igual:hover {
  background: var(--accent-h);
  box-shadow: 0 6px 28px var(--glow);
}

#btn-igual:active {
  background: var(--accent);
  transform: scale(0.94);
}

#btn-cero { grid-column: span 2; }

/* ── Hint teclado ───────────────────────────────────────────── */
.kb-hint {
  text-align: center;
  margin-top: 14px;
  font-size: 0.7rem;
  color: var(--text-dim);
  letter-spacing: 0.05em;
  transition: color 0.35s ease;
}