:root {
  --bg: #0f172a;
  --panel: #111827;
  --txt-main: #e2e8f0;
  --txt-weak: #94a3b8;
  --accent: #7c3aed;
  --accent-2: #5eead4;
  --glass: rgba(255,255,255,0.05);
  --btn-bg: rgba(255,255,255,0.04);
}


:root[data-theme="light"] {
  --bg: #f5f7fa;
  --panel: #ffffff;
  --txt-main: #1e293b;
  --txt-weak: #64748b;
  --accent: #6366f1;
  --accent-2: #10b981;
  --glass: rgba(0,0,0,0.06);
  --btn-bg: rgba(0,0,0,0.04);
}

html, body {
  margin: 0;
  padding: 0;
  height: 100%;
  background: var(--bg);
  color: var(--txt-main);
  font-family: Inter, "Segoe UI", system-ui;
}

.page-wrapper {
  min-height: 100vh;
  display: flex;
  flex-direction: column;
}

.app {
  flex: 1;
  display: flex;
  flex-direction: column;
  padding: 16px;
}


.topbar {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 14px;
}

.brand {
  display: flex;
  align-items: center;
  gap: 10px;
}

.logo {
  width: 42px;
  height: 42px;
  background: var(--accent);
  color: white;
  display: flex;
  justify-content: center;
  align-items: center;
  border-radius: 10px;
  font-weight: bold;
}

.controls button {
  width: 40px;
  height: 40px;
  border: none;
  background: var(--panel);
  border-radius: 10px;
  color: var(--txt-main);
  cursor: pointer;
  font-size: 18px;
}

.screen-area {
  background: var(--glass);
  padding: 16px;
  border-radius: 12px;
  margin-bottom: 14px;
}

.expression {
  font-size: 16px;
  color: var(--txt-weak);
}

.result {
  font-size: 36px;
  font-weight: bold;
}


.kbd-area {
  display: flex;
  flex-direction: column;
  gap: 10px;
}

.row {
  display: flex;
  gap: 10px;
}

.btn {
  flex: 1;
  padding: 16px;
  border: none;
  border-radius: 12px;
  background: var(--btn-bg);
  color: var(--txt-main);
  font-size: 20px;
  cursor: pointer;
}

.btn.op {
  color: var(--accent-2);
}

.btn.eq {
  background: var(--accent);
  color: white;
}


.history {
  position: fixed;
  right: 16px;
  bottom: 90px;
  width: 260px;
  background: var(--panel);
  padding: 16px;
  border-radius: 12px;
}

.hidden {
  display: none;
}

.history-list li {
  padding: 8px;
  background: var(--glass);
  border-radius: 8px;
  margin-bottom: 6px;
  color: var(--txt-main);
  cursor: pointer;
}


.app-footer {
  text-align: center;
  padding: 18px 0;
  background: var(--panel);
  border-top: 1px solid var(--glass);
}

.footer-social {
  display: flex;
  justify-content: center;
  gap: 20px;
}

.footer-social i {
  font-size: 22px;
  color: var(--txt-main);
  transition: 0.3s;
}

.footer-social i:hover {
  color: var(--accent-2);
  transform: scale(1.2);
}

.footer-credit {
  margin-top: 6px;
  font-size: 14px;
  color: var(--txt-weak);
}