:root {
  --bg1: #fff2fb;
  --bg2: #f2fbff;
  --bg3: #f6fff2;

  --txt: #151a33;
  --muted: rgba(21, 26, 51, 0.65);
  --stroke: rgba(30, 40, 90, 0.12);

  --p1: #7c5cff;
  --p2: #12d6df;
  --p3: #ff4fd8;
  --p4: #ffb703;
  --good: #20d6a0;
  --bad: #ff4d6d;

  --r: 22px;
  --shadow: 0 22px 60px rgba(20, 30, 80, 0.14);
  --shadow2: 0 12px 28px rgba(20, 30, 80, 0.1);
  --ease: cubic-bezier(0.2, 0.9, 0.2, 1);
}

* {
  box-sizing: border-box;
}

body {
  margin: 0;
  font-family:
    Inter,
    system-ui,
    -apple-system,
    Segoe UI,
    Roboto,
    Arial,
    sans-serif;
  color: var(--txt);
  background:
    radial-gradient(
      900px 700px at 10% 15%,
      rgba(255, 79, 216, 0.28),
      transparent 55%
    ),
    radial-gradient(
      900px 700px at 85% 10%,
      rgba(18, 214, 223, 0.26),
      transparent 55%
    ),
    radial-gradient(
      900px 700px at 75% 90%,
      rgba(255, 183, 3, 0.22),
      transparent 55%
    ),
    linear-gradient(180deg, var(--bg1), var(--bg2) 45%, var(--bg3));
  overflow-x: hidden;
  min-height: 100vh;
  display: flex;
  align-items: center;
}

.bg {
  position: fixed;
  inset: 0;
  pointer-events: none;
  filter: blur(16px);
  opacity: 0.95;
}
.orb {
  position: absolute;
  width: 520px;
  height: 520px;
  border-radius: 50%;
  animation: float 10s var(--ease) infinite;
  mix-blend-mode: multiply;
}
.o1 {
  left: -180px;
  top: -120px;
  background: radial-gradient(
    circle at 30% 30%,
    rgba(255, 79, 216, 0.9),
    transparent 62%
  );
}
.o2 {
  right: -180px;
  top: -80px;
  background: radial-gradient(
    circle at 30% 30%,
    rgba(18, 214, 223, 0.9),
    transparent 62%
  );
  animation-delay: -2.5s;
}
.o3 {
  left: 35%;
  bottom: -280px;
  background: radial-gradient(
    circle at 30% 30%,
    rgba(124, 92, 255, 0.7),
    transparent 62%
  );
  animation-delay: -5s;
}

@keyframes float {
  0%,
  100% {
    transform: translate(0, 0) scale(1);
  }
  50% {
    transform: translate(30px, -22px) scale(1.05);
  }
}

.wrap {
  width: 980px;
  max-width: 100%;
  margin: 0 auto;
  padding: 34px 18px 44px;
  position: relative;
}

.hdr {
  display: flex;
  align-items: flex-end;
  justify-content: space-between;
  gap: 14px;
  flex-wrap: wrap;
  margin-bottom: 18px;
}
.brand {
  display: flex;
  gap: 14px;
  align-items: center;
}
.logo {
  width: 52px;
  height: 52px;
  border-radius: 18px;
  display: grid;
  place-items: center;
  color: white;
  font-weight: 950;
  font-size: 22px;
  background: linear-gradient(135deg, var(--p3), var(--p2));
  box-shadow:
    0 20px 40px rgba(255, 79, 216, 0.2),
    0 20px 40px rgba(18, 214, 223, 0.16);
}
h1 {
  margin: 0;
  letter-spacing: -0.6px;
  line-height: 1.1;
}
.hdr p {
  margin: 6px 0 0;
  color: var(--muted);
  font-size: 13px;
}

.help {
  color: var(--muted);
  font-size: 12px;
  display: flex;
  align-items: center;
  gap: 8px;
  flex-wrap: wrap;
}

@media (max-width: 575px) {
  .help {
    gap: 5px;
    font-size: 10px;
  }
}

.kbd {
  display: inline-block;
  padding: 6px 10px;
  border-radius: 999px;
  border: 1px solid var(--stroke);
  background: rgba(255, 255, 255, 0.78);
  box-shadow: var(--shadow2);
  font-weight: 900;
  color: var(--txt);
}
.dot {
  opacity: 0.6;
}

.grid {
  display: grid;
  grid-template-columns: 1.2fr 0.8fr;
  gap: 14px;
}
@media (max-width: 900px) {
  .grid {
    grid-template-columns: 1fr;
  }
}

.card {
  background: rgba(255, 255, 255, 0.72);
  border: 1px solid var(--stroke);
  border-radius: var(--r);
  box-shadow: var(--shadow);
  overflow: hidden;
}

.screen {
  padding: 18px;
  background: linear-gradient(
    180deg,
    rgba(255, 255, 255, 0.9),
    rgba(255, 255, 255, 0.58)
  );
  border-bottom: 1px solid var(--stroke);
}
.expr {
  font-size: 34px;
  font-weight: 950;
  letter-spacing: -0.6px;
  word-break: break-all;
}
.mini {
  margin-top: 6px;
  font-size: 12px;
  color: var(--muted);
}

.keys {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 10px;
  padding: 14px;
}
.k {
  border: 1px solid var(--stroke);
  background: rgba(255, 255, 255, 0.86);
  border-radius: 18px;
  padding: 14px 10px;
  font-size: 16px;
  font-weight: 950;
  cursor: pointer;
  box-shadow: 0 12px 26px rgba(20, 30, 80, 0.08);
  transition:
    transform 0.14s var(--ease),
    box-shadow 0.18s var(--ease);
}
.k:hover {
  transform: translateY(-2px);
  box-shadow: 0 16px 34px rgba(20, 30, 80, 0.11);
}
.k:active {
  transform: translateY(0) scale(0.99);
}

.k.op {
  color: white;
  border: none;
  background: linear-gradient(135deg, var(--p1), var(--p3));
}
.k.equal {
  grid-column: span 2;
  border: none;
  color: white;
  background: linear-gradient(135deg, var(--good), var(--p2));
}

.history {
  padding: 14px;
}
.histTop {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding-bottom: 10px;
  border-bottom: 1px solid var(--stroke);
}
.history h2 {
  margin: 0;
  font-size: 16px;
  letter-spacing: -0.2px;
}
.miniBtn {
  border: 1px solid var(--stroke);
  background: rgba(255, 255, 255, 0.86);
  border-radius: 999px;
  padding: 8px 10px;
  cursor: pointer;
  font-weight: 950;
  box-shadow: var(--shadow2);
}

.histList {
  margin-top: 10px;
  display: flex;
  flex-direction: column;
  gap: 10px;
  max-height: 420px;
  overflow: auto;
  padding-right: 4px;
}
.histItem {
  border: 1px solid var(--stroke);
  background: rgba(255, 255, 255, 0.86);
  border-radius: 18px;
  padding: 10px 12px;
  cursor: pointer;
  box-shadow: 0 12px 26px rgba(20, 30, 80, 0.08);
  transition: transform 0.14s var(--ease);
}
.histItem:hover {
  transform: translateY(-2px);
}
.histExpr {
  font-weight: 950;
}
.histRes {
  color: var(--muted);
  font-size: 12px;
  margin-top: 4px;
}

.ft {
  margin-top: 12px;
  color: var(--muted);
  font-size: 12px;
}
.ft strong {
  color: var(--txt);
}

/* ===== Info Button ===== */
.info-btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 38px;
  height: 38px;
  border-radius: 50%;
  border: 1.5px solid var(--stroke);
  background: rgba(255, 255, 255, 0.72);
  box-shadow: var(--shadow2);
  cursor: pointer;
  font-size: 15px;
  font-weight: 900;
  color: var(--p1);
  transition:
    transform 0.18s var(--ease),
    box-shadow 0.18s var(--ease),
    background 0.18s;
  flex-shrink: 0;
}
.info-btn:hover {
  transform: translateY(-2px) scale(1.08);
  box-shadow: 0 16px 34px rgba(124, 92, 255, 0.18);
  background: rgba(255, 255, 255, 0.95);
}
.info-btn:active {
  transform: scale(0.96);
}

@media (max-width: 575px) {
  .info-btn {
    height: 25px;
    width: 25px;
  }
}

/* ===== Popup Overlay ===== */
.popup-overlay {
  position: fixed;
  inset: 0;
  background: rgba(21, 26, 51, 0.52);
  backdrop-filter: blur(6px);
  -webkit-backdrop-filter: blur(6px);
  display: flex;
  align-items: center;
  justify-content: center;
  z-index: 9999;
  padding: 20px;
  opacity: 0;
  pointer-events: none;
  transition: opacity 0.28s var(--ease);
}
.popup-overlay.active {
  opacity: 1;
  pointer-events: all;
}

.popup-card {
  background: rgba(255, 255, 255, 0.92);
  border: 1px solid var(--stroke);
  border-radius: 28px;
  box-shadow: 0 40px 100px rgba(20, 30, 80, 0.22);
  width: 100%;
  max-width: 560px;
  max-height: 88vh;
  overflow-y: auto;
  transform: translateY(32px) scale(0.97);
  transition:
    transform 0.32s var(--ease),
    opacity 0.28s var(--ease);
  opacity: 0;
}
.popup-overlay.active .popup-card {
  transform: translateY(0) scale(1);
  opacity: 1;
}

/* Popup Header */
.popup-header {
  padding: 32px 32px 24px;
  background: linear-gradient(135deg, var(--p1), var(--p3));
  border-radius: 28px 28px 0 0;
  text-align: center;
  position: relative;
  overflow: hidden;
}
.popup-header::before {
  content: "";
  position: absolute;
  inset: 0;
  background:
    radial-gradient(
      ellipse at 30% 0%,
      rgba(255, 255, 255, 0.18),
      transparent 60%
    ),
    radial-gradient(
      ellipse at 80% 100%,
      rgba(18, 214, 223, 0.22),
      transparent 55%
    );
  pointer-events: none;
}
.popup-logo {
  width: 64px;
  height: 64px;
  border-radius: 22px;
  background: rgba(255, 255, 255, 0.22);
  border: 1.5px solid rgba(255, 255, 255, 0.35);
  display: grid;
  place-items: center;
  font-size: 28px;
  font-weight: 950;
  color: white;
  margin: 0 auto 16px;
  box-shadow: 0 8px 24px rgba(0, 0, 0, 0.12);
  position: relative;
}
.popup-header h2 {
  margin: 0 0 6px;
  font-size: 26px;
  font-weight: 950;
  letter-spacing: -0.5px;
  color: white;
  position: relative;
}
.popup-tagline {
  font-size: 13px;
  color: rgba(255, 255, 255, 0.82);
  position: relative;
}

/* Popup Close */
.popup-close {
  position: absolute;
  top: 16px;
  right: 16px;
  width: 34px;
  height: 34px;
  border-radius: 50%;
  background: rgba(255, 255, 255, 0.18);
  border: 1px solid rgba(255, 255, 255, 0.28);
  color: white;
  font-size: 16px;
  cursor: pointer;
  display: grid;
  place-items: center;
  transition:
    background 0.16s,
    transform 0.16s;
  z-index: 1;
}
.popup-close:hover {
  background: rgba(255, 255, 255, 0.32);
  transform: scale(1.1);
}

/* Popup Body */
.popup-body {
  padding: 0 32px 28px;
}

.popup-section {
  padding: 20px 0;
  border-bottom: 1px solid var(--stroke);
}
.popup-section:last-of-type {
  border-bottom: none;
}
.popup-section h3 {
  font-size: 14px;
  font-weight: 900;
  letter-spacing: 0.2px;
  margin-bottom: 10px;
  color: var(--txt);
  display: flex;
  align-items: center;
  gap: 8px;
}
.popup-section h3 .sec-icon {
  font-size: 16px;
}
.popup-section p,
.popup-section li {
  font-size: 13.5px;
  color: var(--muted);
  line-height: 1.7;
}
.popup-section ul {
  padding-left: 18px;
  margin: 6px 0 0;
  display: flex;
  flex-direction: column;
  gap: 5px;
}
.popup-section li strong {
  color: var(--txt);
  font-weight: 800;
}

/* Highlight box */
.highlight-box {
  background: rgba(124, 92, 255, 0.06);
  border-left: 3.5px solid var(--p1);
  border-radius: 0 14px 14px 0;
  padding: 14px 16px;
  margin-top: 8px;
}

/* Op tags */
.op-tags {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  margin-top: 10px;
}
.op-tag {
  padding: 6px 14px;
  border-radius: 999px;
  font-size: 13px;
  font-weight: 900;
  border: 1.5px solid var(--stroke);
  background: rgba(255, 255, 255, 0.86);
  color: var(--p1);
  box-shadow: var(--shadow2);
  letter-spacing: 0.3px;
}
.op-tag.accent {
  background: linear-gradient(135deg, var(--p1), var(--p3));
  color: white;
  border: none;
}

/* CTA button */
.popup-cta {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 10px;
  width: 100%;
  margin-top: 24px;
  padding: 15px 24px;
  border: none;
  border-radius: 999px;
  background: linear-gradient(135deg, var(--good), var(--p2));
  color: white;
  font-size: 15px;
  font-weight: 900;
  letter-spacing: 0.2px;
  cursor: pointer;
  box-shadow:
    0 10px 30px rgba(18, 214, 223, 0.3),
    0 6px 16px rgba(32, 214, 160, 0.2);
  transition:
    transform 0.18s var(--ease),
    box-shadow 0.18s var(--ease);
}
.popup-cta:hover {
  transform: translateY(-3px);
  box-shadow:
    0 16px 40px rgba(18, 214, 223, 0.38),
    0 8px 20px rgba(32, 214, 160, 0.26);
}
.popup-cta:active {
  transform: scale(0.98);
}

/* Scrollbar for popup */
.popup-card::-webkit-scrollbar {
  width: 6px;
}
.popup-card::-webkit-scrollbar-track {
  background: transparent;
}
.popup-card::-webkit-scrollbar-thumb {
  background: rgba(124, 92, 255, 0.25);
  border-radius: 99px;
}