/*
  base.css
  Qui metto TUTTA la struttura grafica (layout, spacing, bottoni),
  ma i colori reali arrivano dalle variabili definite nei file tema.
*/

/*
  STEP 1: VARIABILI "STRUTTURALI"
  Queste non cambiano tra temi: raggi, font base, misure.
*/
:root {
  --r-xl: 24px;
  --r-lg: 18px;
  --r-md: 16px;

  --shadow-soft: 0 1px 0 rgba(0, 0, 0, 0.04);
}

/* STEP 2: RESET MINIMO */
* {
  box-sizing: border-box;
}

/*
  STEP 3: BODY
  Lo sfondo usa 2 spot (variabili) + bg base.
  Le variabili vengono dal tema.
*/
body {
  margin: 0;
  min-height: 100vh;
  display: grid;
  place-items: center;

  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
  color: var(--text);

  background:
    radial-gradient(900px 500px at 15% 10%, var(--bgSpot1), transparent 55%),
    radial-gradient(900px 500px at 85% 15%, var(--bgSpot2), transparent 60%),
    var(--bg);
}

/* STEP 4: WRAPPER RESPONSIVE */
.wrap {
  width: min(420px, calc(100vw - 28px));
}

/*
  STEP 5: CARD CALCOLATRICE
  background, border e shadow arrivano dal tema.
*/
.calc {
  background: var(--card);
  border: 1px solid var(--border);
  border-radius: var(--r-xl);
  box-shadow: var(--shadow);
  padding: 18px;
}

/*
  STEP 6: TOPBAR (titolo + bottone tema)
*/
.topbar {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 12px;
  margin-bottom: 12px;
}

.title {
  font-size: 14px;
  font-weight: 650;
  color: var(--muted);
  letter-spacing: 0.2px;
}

/*
  STEP 6.1: bottone tema
  Lo tratto come un bottone minimal, coerente con i tasti.
*/
.themeBtn {
  border: 1px solid var(--border);
  background: var(--btnBg);
  color: var(--text);
  border-radius: 999px;
  padding: 10px 12px;
  font-size: 13px;
  font-weight: 650;
  cursor: pointer;
  user-select: none;
  transition: transform 0.08s ease, background 0.15s ease, border-color 0.15s ease;
}

.themeBtn:hover {
  background: var(--btnHover);
  border-color: var(--borderStrong);
}

.themeBtn:active {
  transform: scale(0.99);
}

.themeBtn:focus-visible {
  outline: 3px solid var(--focusRing);
  outline-offset: 2px;
}

/*
  STEP 7: DISPLAY
  surface = un bianco/grigio leggermente diverso dal card.
*/
.display {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--r-lg);
  padding: 16px 14px;
  text-align: right;
  margin-bottom: 14px;
  min-height: 78px;

  display: grid;
  align-content: center;
  gap: 6px;
}

.display__prev {
  font-size: 13px;
  color: var(--muted);
  min-height: 18px;
  overflow-wrap: anywhere;
}

.display__curr {
  font-size: 34px;
  font-weight: 700;
  letter-spacing: 0.2px;
  overflow-wrap: anywhere;
}

/* STEP 8: GRIGLIA TASTI */
.keys {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 10px;
}

/*
  STEP 9: TASTO BASE
  Tutti i colori arrivano dal tema.
*/
.key {
  border: 1px solid var(--border);
  background: var(--btnBg);
  color: var(--text);
  border-radius: var(--r-md);
  padding: 14px 12px;

  font-size: 18px;
  font-weight: 650;

  cursor: pointer;
  user-select: none;

  transition:
    transform 0.08s ease,
    box-shadow 0.15s ease,
    background 0.15s ease,
    border-color 0.15s ease;

  box-shadow: var(--btnShadow, var(--shadow-soft));
}

.key:hover {
  background: var(--btnHover);
  border-color: var(--borderStrong);
}

.key:active {
  transform: scale(0.985);
  box-shadow: 0 0 0 rgba(0, 0, 0, 0);
}

/* STEP 9.1: FOCUS ACCESSIBILE */
.key:focus-visible {
  outline: 3px solid var(--focusRing);
  outline-offset: 2px;
}

/* STEP 10: OPERATORI */
.key--op {
  background: var(--opBg);
  border-color: var(--opBorder);
  color: var(--opText);
}

/* STEP 11: UGUALE */
.key--equals {
  background: var(--eqBg);
  border-color: var(--eqBorder);
  color: var(--eqText);
  font-size: 20px;
}

/* STEP 12: TASTI LARGHI */
.key--wide {
  grid-column: span 2;
}

/* STEP 13: HINT */
.hint {
  margin: 12px 2px 2px;
  font-size: 12.5px;
  color: var(--muted);
  line-height: 1.35;
}