:root {
  --void: #000000;
  --black: #050505;
  --charcoal: #0a0a0a;
  --charcoal-2: #101010;

  --lime: #c4ff00;
  --lime-bright: #7cff00;
  --lime-gradient: linear-gradient(110deg, #c4ff00 0%, #7cff00 100%);

  --cyan: #00e5ff;
  --magenta: #ff00c8;

  --white: #ffffff;
  --soft-white: #e8e8e8;
  --gray: #929292;
  --muted: #5f5f5f;

  --border: rgba(255, 255, 255, 0.09);
  --border-strong: rgba(196, 255, 0, 0.22);

  --radius-lg: 28px;
  --radius-md: 18px;
  --radius-sm: 12px;

  --shadow: 0 30px 80px rgba(0, 0, 0, 0.55);
}

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

html {
  scroll-behavior: smooth;
}

body {
  min-height: 100vh;
  overflow-x: hidden;

  font-family: "Space Grotesk", sans-serif;
  background:
    radial-gradient(
      circle at 50% -10%,
      rgba(196, 255, 0, 0.07),
      transparent 30%
    ),
    var(--void);

  color: var(--white);
  font-weight: 500;
}

button,
input {
  font: inherit;
}

button {
  -webkit-tap-highlight-color: transparent;
}

.ambient {
  position: fixed;
  width: 420px;
  height: 420px;
  border-radius: 50%;
  filter: blur(120px);
  opacity: 0.06;
  pointer-events: none;
  z-index: -1;
}

.ambient-one {
  top: 15%;
  left: -220px;
  background: var(--cyan);
}

.ambient-two {
  right: -220px;
  bottom: 5%;
  background: var(--magenta);
}

/* HEADER */

.site-header {
  position: relative;
  border-bottom: 1px solid var(--border);
  background: rgba(0, 0, 0, 0.78);
  backdrop-filter: blur(20px);
  -webkit-backdrop-filter: blur(20px);
}

.nav-container {
  width: min(1180px, calc(100% - 40px));
  min-height: 82px;
  margin: auto;

  display: grid;
  grid-template-columns: 1fr auto 1fr;
  align-items: center;
  gap: 20px;
}

.back-link {
  width: fit-content;

  display: inline-flex;
  align-items: center;
  gap: 10px;

  color: var(--gray);
  text-decoration: none;

  font-size: 13px;
  font-weight: 600;
  letter-spacing: 0.04em;

  transition: 0.3s ease;
}

.back-link:hover {
  color: var(--lime);
  transform: translateX(-3px);
}

.back-icon {
  font-size: 18px;
  transition: 0.3s ease;
}

.brand-lockup {
  text-align: center;
}

.brand-name {
  display: flex;
  justify-content: center;
  align-items: baseline;
  gap: 5px;

  font-size: 18px;
  font-weight: 700;
  letter-spacing: 0.12em;
}

.brand-name span {
  color: var(--white);
}

.brand-name strong {
  background: linear-gradient(
    90deg,
    var(--cyan),
    var(--magenta)
  );

  -webkit-background-clip: text;
  background-clip: text;
  -webkit-text-fill-color: transparent;
}

.brand-tagline {
  display: block;
  margin-top: 3px;

  color: var(--muted);

  font-size: 8px;
  font-weight: 600;
  letter-spacing: 0.22em;
  text-transform: uppercase;
}

.status-pill {
  justify-self: end;

  display: inline-flex;
  align-items: center;
  gap: 7px;

  color: var(--gray);
  font-size: 9px;
  font-weight: 700;
  letter-spacing: 0.14em;
}

.status-dot {
  width: 6px;
  height: 6px;
  border-radius: 50%;
  background: var(--lime);
  box-shadow: 0 0 12px rgba(196, 255, 0, 0.8);
}

/* MAIN */

.main-container {
  width: min(980px, calc(100% - 40px));
  margin: auto;
  padding: 75px 0 45px;
}

/* HERO */

.hero {
  text-align: center;
  margin-bottom: 45px;
}

.eyebrow {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 12px;

  color: var(--lime);

  font-size: 9px;
  font-weight: 700;
  letter-spacing: 0.24em;
}

.eyebrow-line {
  width: 35px;
  height: 1px;
  background: linear-gradient(
    90deg,
    transparent,
    var(--lime)
  );
}

.eyebrow-line:last-child {
  transform: rotate(180deg);
}

.hero h1 {
  margin-top: 18px;

  font-size: clamp(46px, 8vw, 82px);
  line-height: 0.94;
  letter-spacing: -0.055em;
  font-weight: 700;
}

.hero h1 span {
  display: block;

  background: var(--lime-gradient);
  -webkit-background-clip: text;
  background-clip: text;
  -webkit-text-fill-color: transparent;
}

.hero p {
  max-width: 510px;
  margin: 22px auto 0;

  color: var(--gray);

  font-size: 15px;
  line-height: 1.7;
}

/* TOOL */

.tool-shell {
  position: relative;
  overflow: hidden;

  background:
    linear-gradient(
      145deg,
      rgba(255, 255, 255, 0.035),
      rgba(255, 255, 255, 0.012)
    ),
    var(--charcoal);

  border: 1px solid var(--border);
  border-radius: var(--radius-lg);

  box-shadow: var(--shadow);
}

.tool-shell::before {
  content: "";
  position: absolute;
  inset: 0;

  border-radius: inherit;
  pointer-events: none;

  background:
    linear-gradient(
      120deg,
      rgba(196, 255, 0, 0.12),
      transparent 20%,
      transparent 80%,
      rgba(0, 229, 255, 0.06)
    );

  opacity: 0.6;
}

.tool-topbar {
  position: relative;

  display: flex;
  align-items: center;
  justify-content: space-between;

  padding: 28px 30px;

  border-bottom: 1px solid var(--border);
}

.tool-code {
  display: block;
  margin-bottom: 7px;

  color: var(--muted);

  font-size: 9px;
  font-weight: 700;
  letter-spacing: 0.18em;
}

.tool-topbar h2 {
  font-size: 25px;
  letter-spacing: -0.03em;
}

.pro-badge {
  display: flex;
  align-items: center;
  gap: 9px;

  padding: 8px 11px;

  border: 1px solid rgba(196, 255, 0, 0.2);
  border-radius: 999px;

  background: rgba(196, 255, 0, 0.04);
}

.pro-badge span {
  color: var(--lime);
  font-size: 9px;
  font-weight: 700;
  letter-spacing: 0.15em;
}

.pro-badge small {
  color: var(--gray);
  font-size: 9px;
}

/* MODE SELECTOR */

.mode-selector {
  position: relative;

  display: grid;
  grid-template-columns: repeat(3, 1fr);

  border-bottom: 1px solid var(--border);
}

.mode-btn {
  position: relative;

  min-height: 91px;
  padding: 18px;

  display: flex;
  align-items: center;
  gap: 13px;

  border: 0;
  border-right: 1px solid var(--border);

  background: transparent;
  color: var(--gray);

  text-align: left;
  cursor: pointer;

  transition:
    background 0.3s ease,
    color 0.3s ease;
}

.mode-btn:last-child {
  border-right: 0;
}

.mode-btn:hover {
  color: var(--white);
  background: rgba(255, 255, 255, 0.025);
}

.mode-btn.active {
  color: var(--white);
  background: rgba(196, 255, 0, 0.055);
}

.mode-btn.active::after {
  content: "";

  position: absolute;
  bottom: 0;
  left: 18px;
  right: 18px;

  height: 2px;

  background: var(--lime-gradient);
  box-shadow: 0 0 18px rgba(196, 255, 0, 0.35);
}

.mode-number {
  width: 30px;
  height: 30px;
  flex-shrink: 0;

  display: grid;
  place-items: center;

  border: 1px solid var(--border);
  border-radius: 9px;

  color: var(--muted);
  font-size: 9px;
  font-weight: 700;
}

.mode-btn.active .mode-number {
  border-color: rgba(196, 255, 0, 0.3);
  color: var(--lime);
  background: rgba(196, 255, 0, 0.05);
}

.mode-btn strong {
  display: block;

  font-size: 12px;
  line-height: 1.3;
}

.mode-btn small {
  display: block;
  margin-top: 4px;

  color: var(--muted);
  font-size: 9px;
  line-height: 1.35;
}

/* CALCULATOR */

.calculator-area {
  position: relative;
  padding: 35px 30px 30px;
}

.calculation-panel {
  display: none;

  min-height: 225px;
  animation: panelIn 0.35s ease both;
}

.calculation-panel.active-panel {
  display: block;
}

@keyframes panelIn {
  from {
    opacity: 0;
    transform: translateY(8px);
  }

  to {
    opacity: 1;
    transform: translateY(0);
  }
}

.question-label {
  display: flex;
  align-items: center;
  gap: 10px;

  color: var(--gray);

  font-size: 11px;
  font-weight: 600;
  letter-spacing: 0.08em;
  text-transform: uppercase;
}

.question-index {
  color: var(--lime);
  font-size: 9px;
}

.equation {
  min-height: 130px;
  margin-top: 20px;

  display: flex;
  justify-content: center;
  align-items: center;
  flex-wrap: wrap;
  gap: 12px;

  color: var(--soft-white);

  font-size: clamp(20px, 3vw, 28px);
  font-weight: 600;
}

.input-wrap {
  position: relative;

  display: flex;
  align-items: center;

  width: 160px;
}

.input-wrap.compact-input {
  width: 120px;
}

.input-wrap input {
  width: 100%;
  height: 62px;

  padding: 0 18px;

  border: 1px solid rgba(255, 255, 255, 0.11);
  border-radius: 14px;

  outline: none;

  background: #000;
  color: var(--white);

  font-size: 20px;
  font-weight: 600;

  transition:
    border-color 0.25s ease,
    box-shadow 0.25s ease,
    background 0.25s ease;
}

.input-wrap input:hover {
  border-color: rgba(196, 255, 0, 0.25);
}

.input-wrap input:focus {
  border-color: var(--lime);

  background: #030303;

  box-shadow:
    0 0 0 3px rgba(196, 255, 0, 0.07),
    0 0 30px rgba(196, 255, 0, 0.05);
}

.input-wrap span {
  position: absolute;
  right: 17px;

  color: var(--lime);
  font-size: 15px;
  font-weight: 700;
}

.formula-hint {
  text-align: center;

  color: var(--muted);
  font-size: 10px;
}

.formula-hint code {
  color: #767676;
  font-family: "Space Grotesk", sans-serif;
}

/* INCREASE / DECREASE */

.equation-stack {
  flex-wrap: nowrap;
  margin-top: 30px;
}

.value-field {
  flex: 1;
  max-width: 250px;
}

.value-field label {
  display: block;
  margin-bottom: 8px;

  color: var(--muted);

  font-size: 9px;
  font-weight: 700;
  letter-spacing: 0.12em;
  text-transform: uppercase;
}

.value-field .input-wrap {
  width: 100%;
}

.direction-arrow {
  color: var(--lime);
  font-size: 24px;
  margin-top: 22px;
}

/* CALCULATE */

.calculate-row {
  margin-top: 5px;
}

.calculate-btn {
  width: 100%;
  min-height: 60px;

  display: flex;
  align-items: center;
  justify-content: space-between;

  padding: 0 21px;

  border: 0;
  border-radius: 14px;

  background: var(--lime-gradient);
  color: #000;

  font-size: 14px;
  font-weight: 700;

  cursor: pointer;

  box-shadow:
    0 8px 30px rgba(124, 255, 0, 0.08);

  transition:
    transform 0.25s ease,
    box-shadow 0.25s ease;
}

.calculate-btn:hover {
  transform: translateY(-2px);

  box-shadow:
    0 14px 40px rgba(124, 255, 0, 0.16);
}

.calculate-btn:active {
  transform: translateY(0);
}

.button-arrow {
  font-size: 22px;
}

/* PAYWALL */

.paywall {
  display: none;

  margin-top: 20px;
  padding: 25px;

  border: 1px solid rgba(196, 255, 0, 0.18);
  border-radius: 18px;

  background:
    radial-gradient(
      circle at 10% 20%,
      rgba(196, 255, 0, 0.07),
      transparent 35%
    ),
    #050505;

  animation: panelIn 0.4s ease both;
}

.paywall.visible {
  display: grid;

  grid-template-columns: auto 1fr;
  gap: 18px;
}

.paywall-icon {
  width: 52px;
  height: 52px;

  display: grid;
  place-items: center;

  border-radius: 15px;

  background: var(--lime-gradient);
  color: #000;

  font-size: 22px;
  font-weight: 700;
}

.unlock-label {
  color: var(--lime);

  font-size: 8px;
  font-weight: 700;
  letter-spacing: 0.2em;
}

.paywall-copy h3 {
  margin: 5px 0;

  font-size: 18px;
}

.paywall-copy p {
  max-width: 480px;

  color: var(--gray);

  font-size: 11px;
  line-height: 1.6;
}

.paywall-features {
  grid-column: 1 / -1;

  display: flex;
  flex-wrap: wrap;
  gap: 8px;
}

.paywall-features span {
  padding: 8px 10px;

  border: 1px solid var(--border);
  border-radius: 8px;

  color: var(--gray);
  font-size: 9px;
}

.pay-btn {
  grid-column: 1 / -1;

  min-height: 51px;

  display: flex;
  justify-content: space-between;
  align-items: center;

  padding: 0 17px;

  border: 0;
  border-radius: 11px;

  background: var(--lime-gradient);
  color: #000;

  font-size: 12px;
  font-weight: 700;

  cursor: pointer;

  transition: 0.25s ease;
}

.pay-btn:hover {
  transform: translateY(-2px);
}

.secure-note {
  grid-column: 1 / -1;

  text-align: center;

  color: var(--muted);
  font-size: 8px;
}

/* RESULT */

.result-card {
  display: none;

  margin-top: 20px;
  padding: 25px;

  border: 1px solid rgba(196, 255, 0, 0.18);
  border-radius: 18px;

  background:
    linear-gradient(
      135deg,
      rgba(196, 255, 0, 0.045),
      transparent 40%
    ),
    #050505;

  animation: resultIn 0.5s ease both;
}

.result-card.visible {
  display: block;
}

@keyframes resultIn {
  from {
    opacity: 0;
    transform: translateY(15px) scale(0.99);
  }

  to {
    opacity: 1;
    transform: translateY(0) scale(1);
  }
}

.result-header {
  display: flex;
  align-items: center;
  justify-content: space-between;

  padding-bottom: 18px;

  border-bottom: 1px solid var(--border);
}

.result-label {
  color: var(--lime);

  font-size: 8px;
  font-weight: 700;
  letter-spacing: 0.2em;
}

.result-header h3 {
  margin-top: 4px;
  font-size: 15px;
}

.result-status {
  display: flex;
  align-items: center;
  gap: 6px;

  color: var(--gray);

  font-size: 8px;
  font-weight: 700;
  letter-spacing: 0.1em;
}

.result-status span {
  width: 5px;
  height: 5px;
  border-radius: 50%;

  background: var(--lime);
}

.result-main {
  padding: 35px 0 20px;
  text-align: center;
}

.result-prefix {
  display: block;

  color: var(--muted);

  font-size: 8px;
  font-weight: 700;
  letter-spacing: 0.2em;
}

.result-main strong {
  display: block;
  margin-top: 8px;

  background: var(--lime-gradient);

  -webkit-background-clip: text;
  background-clip: text;
  -webkit-text-fill-color: transparent;

  font-size: clamp(48px, 8vw, 75px);
  line-height: 1;
  letter-spacing: -0.06em;
}

.result-description {
  padding: 14px;

  border-radius: 10px;

  background: rgba(255, 255, 255, 0.025);

  color: var(--gray);

  text-align: center;
  font-size: 11px;
}

.result-actions {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 10px;

  margin-top: 12px;
}

.secondary-btn {
  min-height: 45px;

  display: flex;
  justify-content: space-between;
  align-items: center;

  padding: 0 13px;

  border: 1px solid var(--border);
  border-radius: 10px;

  background: transparent;
  color: var(--gray);

  font-size: 10px;
  font-weight: 700;

  cursor: pointer;

  transition: 0.25s ease;
}

.secondary-btn:hover {
  border-color: rgba(196, 255, 0, 0.25);
  color: var(--lime);
  background: rgba(196, 255, 0, 0.03);
}

/* TOOL FOOTER */

.tool-footer {
  display: flex;
  justify-content: space-between;
  align-items: center;

  padding: 15px 30px;

  border-top: 1px solid var(--border);

  color: var(--muted);

  font-size: 8px;
  font-weight: 700;
  letter-spacing: 0.14em;
}

/* BRAND FOOTER */

.brand-footer {
  display: flex;
  justify-content: space-between;
  align-items: center;

  padding-top: 40px;

  color: var(--muted);

  font-size: 9px;
  letter-spacing: 0.08em;
}

.brand-footer-mark {
  display: flex;
  align-items: baseline;
  gap: 4px;

  color: var(--white);

  font-weight: 700;
  letter-spacing: 0.12em;
}

.brand-footer-mark strong {
  background: linear-gradient(
    90deg,
    var(--cyan),
    var(--magenta)
  );

  -webkit-background-clip: text;
  background-clip: text;
  -webkit-text-fill-color: transparent;
}

/* TOAST */

.toast {
  position: fixed;
  left: 50%;
  bottom: 25px;

  transform: translate(-50%, 20px);

  padding: 12px 16px;

  border: 1px solid rgba(196, 255, 0, 0.2);
  border-radius: 10px;

  background: #0a0a0a;
  color: var(--white);

  box-shadow: 0 15px 40px rgba(0, 0, 0, 0.5);

  font-size: 11px;
  font-weight: 600;

  opacity: 0;
  pointer-events: none;

  transition: 0.3s ease;

  z-index: 100;
}

.toast.show {
  opacity: 1;
  transform: translate(-50%, 0);
}

.toast.success {
  border-color: rgba(196, 255, 0, 0.35);
}

.toast.error {
  border-color: rgba(255, 0, 200, 0.35);
}

/* RESPONSIVE */

@media (max-width: 800px) {
  .nav-container {
    grid-template-columns: 1fr auto;
  }

  .brand-lockup {
    display: none;
  }

  .main-container {
    padding-top: 55px;
  }

  .mode-selector {
    grid-template-columns: 1fr;
  }

  .mode-btn {
    min-height: 70px;
    border-right: 0;
    border-bottom: 1px solid var(--border);
  }

  .mode-btn:last-child {
    border-bottom: 0;
  }

  .mode-btn.active::after {
    left: 0;
    right: auto;
    top: 0;
    bottom: 0;

    width: 2px;
    height: auto;
  }

  .equation-stack {
    flex-direction: column;
  }

  .value-field {
    width: 100%;
    max-width: none;
  }

  .direction-arrow {
    margin: 0;
    transform: rotate(90deg);
  }
}

@media (max-width: 560px) {
  .main-container {
    width: min(100% - 24px, 980px);
    padding-top: 45px;
  }

  .hero {
    margin-bottom: 30px;
  }

  .hero p {
    font-size: 13px;
  }

  .tool-topbar {
    padding: 22px 18px;
  }

  .calculator-area {
    padding: 25px 18px 20px;
  }

  .tool-footer {
    padding: 13px 18px;
  }

  .tool-footer span:nth-child(2) {
    display: none;
  }

  .equation {
    gap: 8px;
    font-size: 18px;
  }

  .input-wrap,
  .input-wrap.compact-input {
    width: 125px;
  }

  .input-wrap input {
    height: 54px;
    font-size: 17px;
    padding: 0 13px;
  }

  .paywall.visible {
    grid-template-columns: 1fr;
  }

  .paywall-icon {
    width: 45px;
    height: 45px;
  }

  .paywall-copy {
    grid-column: 1;
  }

  .paywall-features {
    grid-column: 1;
  }

  .pay-btn {
    grid-column: 1;
  }

  .secure-note {
    grid-column: 1;
  }

  .brand-footer {
    flex-direction: column;
    gap: 10px;
    text-align: center;
  }
}