/* ============================================================
   CALCULATOR.CSS — Component layout & styles
   ============================================================ */

/* ── App wrapper ── */
.app-wrapper {
  position: relative;
  z-index: 1;
  display: flex;
  align-items: flex-start;       /* don't force vertical centering — let it grow */
  justify-content: center;
  gap: 16px;
  padding: 24px 16px;
  width: 100%;
  min-height: 100dvh;
}

/* ── Backdrop overlay ── */
.app-backdrop {
  display: none;
  position: fixed;
  inset: 0;
  background: var(--bg-overlay);
  z-index: 10;
  backdrop-filter: blur(2px);
  animation: fadeIn var(--t-base) ease;
}
.app-backdrop.visible { display: block; }

/* ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
   HISTORY PANEL
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ */
.history-panel {
  position: fixed;
  top: 0;
  right: 0;
  height: 100dvh;
  width: 320px;
  background: var(--bg-history);
  border-left: 1px solid var(--border-card);
  z-index: 20;
  display: flex;
  flex-direction: column;
  transform: translateX(100%);
  transition: transform var(--t-slow);
  box-shadow: -8px 0 40px rgba(0,0,0,0.3);
}
.history-panel.open { transform: translateX(0); }

.history-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 20px 18px 16px;
  border-bottom: 1px solid var(--border-card);
  flex-shrink: 0;
}
.history-title {
  font-size: 1rem;
  font-weight: 600;
  color: var(--text-primary);
  letter-spacing: 0.02em;
}
.history-actions { display: flex; gap: 8px; }

.history-list {
  flex: 1;
  overflow-y: auto;
  padding: 12px 10px;
  display: flex;
  flex-direction: column;
  gap: 6px;
}
.history-list::-webkit-scrollbar { width: 4px; }
.history-list::-webkit-scrollbar-thumb { background: var(--border-card); border-radius: 4px; }

.history-empty {
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  flex: 1;
  gap: 10px;
  color: var(--text-muted);
  font-size: 0.85rem;
  padding: 40px 20px;
  text-align: center;
}
.history-empty svg { opacity: 0.3; }

.history-item {
  background: var(--bg-btn);
  border: 1px solid var(--border-btn);
  border-radius: 12px;
  padding: 12px 14px;
  cursor: pointer;
  transition: background var(--t-fast), border-color var(--t-fast), transform var(--t-fast);
  animation: slideInRight 0.25s cubic-bezier(0.4, 0, 0.2, 1);
}
.history-item:hover {
  background: var(--bg-btn-hover);
  border-color: var(--border-operator);
  transform: translateX(-2px);
}
.history-expr {
  font-size: 0.78rem;
  color: var(--text-secondary);
  margin-bottom: 4px;
  font-weight: 400;
  overflow: hidden;
  text-overflow: ellipsis;
  white-space: nowrap;
}
.history-result {
  font-size: 1.15rem;
  font-weight: 600;
  color: var(--text-primary);
}

/* ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
   CALCULATOR CARD
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ */
.calculator {
  width: var(--card-width);
  background: var(--bg-card);
  backdrop-filter: blur(20px) saturate(180%);
  -webkit-backdrop-filter: blur(20px) saturate(180%);
  border-radius: var(--card-radius);
  border: 1px solid var(--border-card);
  box-shadow: var(--shadow-card);
  padding: 18px;
  display: flex;
  flex-direction: column;
  gap: 14px;
  transition: box-shadow var(--t-slow), background var(--t-slow);
  position: relative;
  z-index: 1;
}
.calculator:hover { box-shadow: var(--shadow-card), var(--shadow-glow); }

/* ── Card header ── */
.calc-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
}
.calc-title {
  font-size: 0.8rem;
  font-weight: 600;
  color: var(--text-muted);
  letter-spacing: 0.12em;
  text-transform: uppercase;
}
.header-controls { display: flex; gap: 6px; }

/* ── Icon buttons (header) ── */
.icon-btn {
  width: 34px;
  height: 34px;
  border-radius: 10px;
  background: var(--bg-btn);
  border: 1px solid var(--border-btn);
  color: var(--text-secondary);
  display: flex;
  align-items: center;
  justify-content: center;
  transition: background var(--t-fast), color var(--t-fast), transform var(--t-fast);
  font-size: 0.85rem;
}
.icon-btn:hover {
  background: var(--bg-btn-hover);
  color: var(--text-primary);
  transform: scale(1.08);
}
.icon-btn.active {
  background: var(--bg-operator);
  border-color: var(--border-operator);
  color: var(--text-operator);
}

/* ── Display area ── */
.display-area {
  background: rgba(0,0,0,0.15);
  border: 1px solid var(--border-btn);
  border-radius: 18px;
  padding: 16px 18px 14px;
  min-height: 96px;
  display: flex;
  flex-direction: column;
  justify-content: space-between;
  overflow: hidden;
  position: relative;
}
[data-theme="light"] .display-area { background: rgba(0,0,0,0.04); }

.display-expression {
  font-size: 0.82rem;
  color: var(--text-secondary);
  text-align: right;
  min-height: 18px;
  font-weight: 400;
  overflow: hidden;
  text-overflow: ellipsis;
  white-space: nowrap;
  transition: opacity var(--t-fast);
  letter-spacing: 0.01em;
}

.display-result {
  font-size: 2.6rem;
  font-weight: 300;
  color: var(--text-primary);
  text-align: right;
  line-height: 1.15;
  overflow: hidden;
  text-overflow: ellipsis;
  white-space: nowrap;
  transition: font-size var(--t-fast);
  letter-spacing: -0.02em;
}
.display-result.small  { font-size: 1.9rem; }
.display-result.xsmall { font-size: 1.45rem; }

.display-footer {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-top: 6px;
}
.memory-indicator {
  font-size: 0.68rem;
  color: var(--text-memory);
  font-weight: 600;
  letter-spacing: 0.06em;
  opacity: 0;
  transition: opacity var(--t-fast);
}
.memory-indicator.visible { opacity: 1; }

.copy-btn {
  font-size: 0.68rem;
  color: var(--text-muted);
  font-weight: 500;
  padding: 3px 8px;
  border-radius: 6px;
  background: transparent;
  border: 1px solid transparent;
  transition: all var(--t-fast);
  letter-spacing: 0.04em;
}
.copy-btn:hover {
  background: var(--bg-btn);
  border-color: var(--border-btn);
  color: var(--text-secondary);
}
.copy-btn.copied { color: var(--text-memory); border-color: var(--border-memory); }

/* ── Mode tabs ── */
.mode-tabs {
  display: flex;
  background: var(--bg-btn);
  border-radius: 10px;
  padding: 3px;
  gap: 2px;
}
.mode-tab {
  flex: 1;
  height: 30px;
  border-radius: 7px;
  font-size: 0.75rem;
  font-weight: 500;
  color: var(--text-secondary);
  transition: all var(--t-fast);
  letter-spacing: 0.03em;
}
.mode-tab.active {
  background: var(--bg-card-solid);
  color: var(--text-primary);
  box-shadow: 0 2px 8px rgba(0,0,0,0.2);
}
.mode-tab:hover:not(.active) { color: var(--text-primary); }

/* ── Button grids ── */
.btn-grid {
  display: grid;
  gap: var(--gap);
}
.btn-grid-4 { grid-template-columns: repeat(4, 1fr); }
.btn-grid-5 { grid-template-columns: repeat(5, 1fr); }

/* Scientific section — must be display:grid so btn-grid-5 columns work */
.scientific-section {
  display: none;
  gap: var(--gap);
  grid-template-columns: repeat(5, 1fr); /* 5-col grid for sci buttons */
}
.scientific-section.visible { display: grid; }

/* ── Buttons ── */
.btn {
  height: var(--btn-height);
  border-radius: var(--btn-radius);
  font-size: 1rem;
  font-weight: 500;
  color: var(--text-primary);
  background: var(--bg-btn);
  border: 1px solid var(--border-btn);
  transition: background var(--t-fast), transform var(--t-fast), box-shadow var(--t-fast), border-color var(--t-fast);
  position: relative;
  overflow: hidden;
  display: flex;
  align-items: center;
  justify-content: center;
  box-shadow: var(--shadow-btn);
  user-select: none;
  -webkit-user-select: none;
  letter-spacing: 0.01em;
}
.btn:hover {
  background: var(--bg-btn-hover);
  transform: translateY(-1px);
  box-shadow: 0 4px 14px rgba(0,0,0,0.3);
}
.btn:active {
  transform: scale(0.94);
  background: var(--bg-btn-active);
  box-shadow: none;
}

/* Button variants */
.btn-operator {
  background: var(--bg-operator);
  border-color: var(--border-operator);
  color: var(--text-operator);
  font-weight: 600;
}
.btn-operator:hover { background: var(--bg-operator-hover); }

.btn-clear {
  background: var(--bg-clear);
  border-color: var(--border-clear);
  color: var(--text-clear);
  font-weight: 600;
}
.btn-clear:hover { background: var(--bg-clear-hover); }

.btn-equal {
  background: var(--bg-equal);
  border: none;
  color: var(--text-equal);
  font-size: 1.3rem;
  font-weight: 600;
  box-shadow: 0 4px 18px rgba(124, 58, 237, 0.4);
}
.btn-equal:hover {
  background: var(--bg-equal-hover);
  box-shadow: 0 6px 24px rgba(124, 58, 237, 0.55);
  transform: translateY(-2px);
}
.btn-equal:active { transform: scale(0.94); }

.btn-memory {
  background: var(--bg-memory);
  border-color: var(--border-memory);
  color: var(--text-memory);
  font-size: 0.78rem;
  font-weight: 600;
  height: 44px;
  letter-spacing: 0.04em;
}
.btn-memory:hover { background: var(--bg-memory-hover); }

.btn-sci {
  background: var(--bg-sci);
  border-color: var(--border-sci);
  color: var(--text-sci);
  font-size: 0.82rem;
  font-weight: 500;
  height: 50px;
}
.btn-sci:hover { background: var(--bg-sci-hover); }

.btn-delete {
  font-size: 1.1rem;
  color: var(--text-secondary);
}

/* Span utilities */
.col-span-2 { grid-column: span 2; }

/* ── Keyboard hint badge ── */
.kbd-hint {
  display: none;
  position: absolute;
  bottom: 3px;
  right: 4px;
  font-size: 0.5rem;
  color: var(--text-muted);
  font-weight: 500;
  letter-spacing: 0.03em;
  pointer-events: none;
}
.btn:hover .kbd-hint { display: block; }

/* ── Ripple ── */
.ripple {
  position: absolute;
  border-radius: 50%;
  background: rgba(255,255,255,0.22);
  transform: scale(0);
  animation: ripple 0.5s linear;
  pointer-events: none;
}

/* ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
   KEYBOARD SHORTCUTS PANEL
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ */
.shortcuts-panel {
  position: absolute;
  bottom: calc(100% + 10px);
  left: 50%;
  transform: translateX(-50%) translateY(6px);
  background: var(--bg-card-solid);
  border: 1px solid var(--border-card);
  border-radius: 14px;
  padding: 14px 16px;
  width: 300px;
  box-shadow: 0 12px 40px rgba(0,0,0,0.4);
  opacity: 0;
  pointer-events: none;
  transition: opacity var(--t-base), transform var(--t-base);
  z-index: 30;
}
.shortcuts-panel.visible {
  opacity: 1;
  pointer-events: all;
  transform: translateX(-50%) translateY(0);
}
.shortcuts-title {
  font-size: 0.75rem;
  font-weight: 600;
  color: var(--text-muted);
  text-transform: uppercase;
  letter-spacing: 0.1em;
  margin-bottom: 10px;
}
.shortcuts-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 6px 16px;
}
.shortcut-item {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 8px;
}
.shortcut-label { font-size: 0.75rem; color: var(--text-secondary); }
.shortcut-key {
  font-size: 0.68rem;
  background: var(--bg-btn);
  border: 1px solid var(--border-btn);
  border-radius: 5px;
  padding: 2px 6px;
  color: var(--text-primary);
  font-family: monospace;
  white-space: nowrap;
}

/* ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
   RESPONSIVE
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ */
@media (max-width: 400px) {
  :root {
    --card-width: calc(100vw - 24px);
    --btn-height: 56px;
    --gap: 8px;
    --card-radius: 22px;
    --btn-radius: 12px;
  }
  .display-result { font-size: 2.2rem; }
  .history-panel { width: 85vw; }
}
@media (max-width: 360px) {
  :root { --btn-height: 50px; }
  .btn { font-size: 0.9rem; }
}