:root {
  --royal-blue: #0b2947;
  --royal-blue-deep: #051627;
  --royal-blue-night: #08101d;
  --royal-blue-soft: #163b61;
  --gold-accent: #c4a05e;
  --gold-bright: #e4c67f;
  --paper-white: #fcfbf8;
  --paper-soft: #f5efe5;
  --ink-dark: #1d1d1b;
  --ink-soft: #5f625f;
  --canvas-glow: rgba(214, 181, 113, 0.22);
  --canvas-mist: rgba(120, 160, 192, 0.08);
  --font-heading: "Merriweather", "Times New Roman", serif;
  --font-body: "Manrope", -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
}

*,
*::before,
*::after {
  box-sizing: border-box;
}

html,
body {
  margin: 0;
  width: 100%;
  height: 100%;
}

body {
  font-family: var(--font-body);
  color: var(--ink-dark);
  background:
    radial-gradient(circle at top left, rgba(196, 160, 94, 0.1), transparent 28%),
    linear-gradient(128deg, #f7f1e8, #fdfaf6 42%, #f1eadf);
  overflow: hidden;
}

.hidden {
  display: none !important;
}

.layout {
  display: flex;
  width: 100%;
  height: 100%;
}

.canvas-container,
.form-container {
  width: 50%;
  flex: 0 0 50%;
  height: 100%;
  position: relative;
}

.canvas-container {
  overflow: hidden;
  background:
    radial-gradient(circle at 22% 18%, rgba(228, 198, 127, 0.08), transparent 24%),
    radial-gradient(circle at 52% 46%, rgba(10, 33, 60, 0.18), transparent 46%),
    linear-gradient(150deg, var(--royal-blue-night), #071d35 44%, #103558 78%, #13395c);
  border-right: 1px solid rgba(255, 255, 255, 0.08);
}

.canvas-container::before,
.canvas-container::after {
  content: "";
  position: absolute;
  inset: 0;
  pointer-events: none;
}

.canvas-container::before {
  background:
    radial-gradient(circle at 30% 38%, var(--canvas-glow), transparent 30%),
    radial-gradient(circle at 72% 72%, rgba(196, 160, 94, 0.08), transparent 24%);
  mix-blend-mode: screen;
  opacity: 0.72;
}

.canvas-container::after {
  background:
    linear-gradient(120deg, rgba(255, 255, 255, 0.025), transparent 34%, rgba(255, 255, 255, 0.015) 58%, transparent 82%),
    radial-gradient(circle at center, transparent 48%, rgba(1, 6, 14, 0.16));
  opacity: 0.9;
}

#math-canvas {
  width: 100%;
  height: 100%;
  display: block;
}

.canvas-vignette {
  position: absolute;
  inset: 0;
  pointer-events: none;
  background:
    radial-gradient(circle at 50% 48%, transparent 0 32%, rgba(9, 16, 28, 0.08) 48%, rgba(2, 7, 15, 0.72) 100%),
    linear-gradient(96deg, rgba(2, 8, 18, 0.34), transparent 24%, transparent 72%, rgba(0, 0, 0, 0.3));
}

.canvas-vignette::after {
  content: "";
  position: absolute;
  inset: 0;
  background-image:
    linear-gradient(rgba(255, 255, 255, 0.016) 1px, transparent 1px),
    linear-gradient(90deg, rgba(255, 255, 255, 0.012) 1px, transparent 1px);
  background-size: 80px 80px;
  opacity: 0.12;
  mask-image: radial-gradient(circle at center, rgba(0, 0, 0, 0.18), transparent 72%);
}

.form-container {
  display: grid;
  place-items: center;
  padding: 2.2rem;
  background:
    radial-gradient(circle at 82% 14%, rgba(196, 160, 94, 0.16), transparent 30%),
    radial-gradient(circle at 8% 86%, rgba(11, 41, 71, 0.08), transparent 24%),
    linear-gradient(180deg, #fdfbf8, var(--paper-soft));
}

.form-backdrop {
  position: absolute;
  inset: 0;
  pointer-events: none;
  background-image:
    linear-gradient(to right, rgba(11, 41, 71, 0.035) 1px, transparent 1px),
    linear-gradient(to bottom, rgba(11, 41, 71, 0.035) 1px, transparent 1px);
  background-size: 30px 30px;
  opacity: 0.44;
}

.form-card {
  width: min(480px, 90%);
  position: relative;
  padding: 2.2rem 2rem 1.85rem;
  border-radius: 28px;
  background:
    linear-gradient(180deg, rgba(255, 255, 255, 0.84), rgba(255, 255, 255, 0.74)),
    rgba(255, 255, 255, 0.74);
  border: 1px solid rgba(11, 41, 71, 0.1);
  backdrop-filter: blur(12px);
  box-shadow:
    0 18px 38px rgba(8, 29, 52, 0.08),
    0 34px 60px rgba(8, 29, 52, 0.05);
  transition:
    box-shadow 0.36s ease,
    border-color 0.36s ease,
    transform 0.36s ease,
    background 0.36s ease;
  animation: cardBreath 7.2s ease-in-out infinite;
}

.form-card[data-form-tone="account"] {
  border-color: rgba(196, 160, 94, 0.28);
  box-shadow:
    0 18px 38px rgba(8, 29, 52, 0.08),
    0 28px 56px rgba(196, 160, 94, 0.09);
}

.form-card[data-form-tone="password"] {
  border-color: rgba(11, 41, 71, 0.18);
  box-shadow:
    0 18px 38px rgba(8, 29, 52, 0.12),
    0 30px 58px rgba(11, 41, 71, 0.1);
}

.form-card[data-form-tone="register"] {
  border-color: rgba(196, 160, 94, 0.24);
  background:
    linear-gradient(180deg, rgba(255, 255, 255, 0.88), rgba(255, 249, 239, 0.74)),
    rgba(255, 255, 255, 0.74);
}

.brand-logo-wrap {
  position: absolute;
  top: 0.95rem;
  right: 1rem;
  width: 120px;
  pointer-events: none;
}

.brand-logo {
  display: block;
  width: 100%;
  height: auto;
  filter: drop-shadow(0 10px 22px rgba(8, 29, 52, 0.12));
}

.brand-kicker {
  margin: 0 8.6rem 0.55rem 0;
  text-transform: uppercase;
  letter-spacing: 0.2em;
  font-size: 0.66rem;
  color: var(--ink-soft);
}

h1 {
  margin: 0 0 1.35rem;
  font-family: var(--font-heading);
  font-size: clamp(1.7rem, 2.3vw, 2.15rem);
  line-height: 1.2;
  color: var(--royal-blue);
  letter-spacing: -0.02em;
}

h1::after {
  content: "";
  display: block;
  margin-top: 0.75rem;
  width: 62px;
  height: 2px;
  background: linear-gradient(90deg, var(--gold-accent), transparent);
}

.tabs {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 0.6rem;
  margin-bottom: 1.15rem;
}

.tab-panels {
  position: relative;
  overflow: hidden;
}

.notice {
  margin-bottom: 1rem;
  border-radius: 10px;
  padding: 10px 12px;
  font-size: 0.9rem;
  border: 1px solid rgba(11, 41, 71, 0.08);
  background: rgba(255, 255, 255, 0.84);
  backdrop-filter: blur(8px);
}

.notice.success {
  border-color: rgba(15, 139, 109, 0.12);
  background: rgba(15, 139, 109, 0.1);
  color: #0f8b6d;
}

.notice.error {
  border-color: rgba(198, 40, 40, 0.12);
  background: rgba(198, 40, 40, 0.1);
  color: #c62828;
}

.tab {
  border: 1px solid rgba(11, 41, 71, 0.12);
  border-radius: 999px;
  background: rgba(255, 255, 255, 0.9);
  color: var(--royal-blue);
  font-family: var(--font-body);
  font-size: 0.84rem;
  font-weight: 700;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  padding: 0.68rem 0.6rem;
  cursor: pointer;
  transition:
    all 0.28s cubic-bezier(0.4, 0, 0.2, 1),
    box-shadow 0.32s ease;
}

.tab:hover {
  border-color: rgba(196, 160, 94, 0.55);
  transform: translateY(-1px);
}

.tab.is-active {
  background: linear-gradient(108deg, var(--royal-blue), var(--royal-blue-soft));
  color: #fbfaf7;
  border-color: transparent;
  box-shadow: 0 10px 20px rgba(8, 29, 52, 0.18);
}

.tab-panel {
  opacity: 0;
  transform: translateY(10px) scale(0.99);
  transform-origin: top center;
  transition: opacity 0.32s ease, transform 0.32s ease;
}

.tab-panel.is-active {
  opacity: 1;
  transform: translateY(0);
}

.tab-panel-body {
  width: 100%;
}

.auth-form {
  display: grid;
  gap: 0.92rem;
}

.auth-form label {
  display: grid;
  gap: 0.38rem;
  font-size: 0.82rem;
  color: var(--royal-blue);
  font-weight: 700;
}

.field-note {
  font-size: 0.72rem;
  font-weight: 500;
  color: rgba(95, 98, 95, 0.92);
}

.auth-form input[type="text"],
.auth-form input[type="email"],
.auth-form input[type="password"] {
  border: 1px solid rgba(11, 41, 71, 0.16);
  border-radius: 12px;
  padding: 0.78rem 0.9rem;
  background: rgba(255, 255, 255, 0.88);
  color: var(--ink-dark);
  font-family: var(--font-body);
  font-size: 0.92rem;
  outline: none;
  transition:
    border-color 0.22s ease,
    box-shadow 0.22s ease,
    transform 0.22s ease,
    background-color 0.22s ease;
}

.auth-form input::placeholder {
  color: #9b9a95;
}

.auth-form input:focus {
  border-color: var(--gold-accent);
  box-shadow: 0 0 0 4px rgba(196, 160, 94, 0.15);
  transform: translateY(-1px);
  background: rgba(255, 255, 255, 0.97);
}

.form-row {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-top: -0.1rem;
}

.auth-form label.remember {
  display: inline-flex;
  align-items: center;
  grid-auto-flow: column;
  justify-self: start;
  gap: 0.44rem;
  margin: 0;
  color: var(--ink-soft);
  font-size: 0.8rem;
  font-weight: 500;
}

.remember input[type="checkbox"] {
  accent-color: var(--royal-blue);
}

.helper-link {
  text-decoration: none;
  color: #735933;
  font-size: 0.8rem;
  font-weight: 700;
}

.helper-link:hover {
  color: var(--royal-blue);
  text-decoration: underline;
}

.primary-btn {
  margin-top: 0.25rem;
  border: 1px solid rgba(11, 41, 71, 0.08);
  border-radius: 999px;
  padding: 0.84rem 0.95rem;
  background: linear-gradient(108deg, var(--royal-blue), var(--royal-blue-soft));
  color: #f8f6f1;
  font-family: var(--font-body);
  font-weight: 700;
  font-size: 0.83rem;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  cursor: pointer;
  box-shadow: 0 1px 2px rgba(0, 0, 0, 0.12);
  transition:
    transform 0.28s ease,
    box-shadow 0.28s ease,
    background 0.28s ease,
    color 0.28s ease;
  animation: buttonBreath 5.2s ease-in-out infinite;
}

.primary-btn:hover {
  transform: translateY(-2px);
  background: linear-gradient(108deg, var(--gold-accent), var(--gold-bright));
  color: var(--royal-blue);
  box-shadow: 0 12px 22px rgba(8, 29, 52, 0.2);
}

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

.primary-btn:disabled {
  cursor: wait;
  opacity: 0.72;
  transform: none;
  box-shadow: none;
}

@keyframes cardBreath {
  0%,
  100% {
    transform: translateY(0) scale(1);
  }
  50% {
    transform: translateY(-2px) scale(1.004);
  }
}

@keyframes buttonBreath {
  0%,
  100% {
    box-shadow: 0 1px 2px rgba(0, 0, 0, 0.12);
  }
  50% {
    box-shadow: 0 9px 16px rgba(8, 29, 52, 0.18);
  }
}

@media (prefers-reduced-motion: reduce) {
  .form-card,
  .primary-btn,
  .tab-panel,
  .tab {
    animation: none;
    transition-duration: 0.01ms;
  }
}

@media (max-width: 1100px) {
  .form-container {
    padding: 1.4rem;
  }

  .form-card {
    width: min(460px, 94%);
  }
}

@media (max-width: 767px) {
  .canvas-container {
    display: none;
  }

  .form-container {
    width: 100%;
    background: var(--royal-blue);
  }

  .form-backdrop {
    opacity: 0.2;
    background-image: none;
  }

  .form-card {
    width: min(530px, 94%);
    background: rgba(255, 255, 255, 0.94);
  }

  .brand-logo-wrap {
    width: 98px;
    right: 0.9rem;
  }

  .brand-kicker {
    margin-right: 7rem;
  }
}