body {
  margin: 0;
  padding: 0;
  min-height: 100vh;
  background: var(--bg, #fff);
  color: var(--text, #181818);
  font-family: 'Inter', Arial, sans-serif;
  transition: background 0.3s, color 0.3s;
}
:root {
  --blue: #76cfff;
  --violet: #a97ff7;
  --orange: #FF9900;
  --orange-light: #FFB347;
  --bg: #fff;
  --text: #181818;
  --input-border: #d0d0d0;
  --input-focus: var(--orange);
  --btn-bg: linear-gradient(90deg, var(--orange-light), var(--orange));
  --btn-text: #fff;
  --label-focus: var(--orange);
}
body.dark {
  --bg: #181818;
  --text: #fff;
  --input-border: #444;
  --input-focus: var(--orange-light);
  --btn-bg: linear-gradient(90deg, var(--orange), var(--orange-light));
  --btn-text: #fff;
  --label-focus: var(--orange-light);
}
.background-lines {
  position: fixed;
  inset: 0;
  width: 100vw;
  height: 100vh;
  z-index: 0;
  pointer-events: none;
  overflow: hidden;
}
.background-lines svg {
  width: 100vw;
  height: 100vh;
  display: block;
}
.theme-toggle {
  position: absolute;
  top: 1.5rem;
  right: 2rem;
  background: transparent;
  border: 2px solid var(--input-focus);
  border-radius: 0.8rem;
  cursor: pointer;
  z-index: 10;
  padding: 0;
  width: 2.5rem;
  height: 2.5rem;
  display: flex;
  align-items: center;
  justify-content: center;
  transition: border-color 0.18s, box-shadow 0.18s;
}
.theme-toggle:hover {
  border-color: var(--label-focus);
  box-shadow: 0 0 0 2px var(--label-focus)33;
}
.centered-form {
  min-height: 100vh;
  width: 100vw;
  display: flex;
  align-items: center;
  justify-content: center;
  flex-direction: column;
  animation: fadeInUp 0.7s cubic-bezier(.4,0,.2,1);
}
.demo-note {
  max-width: 360px;
  text-align: center;
  font-size: 0.95rem;
  color: var(--text);
  background: rgba(255,153,0,0.12);
  border: 1px solid rgba(255,153,0,0.35);
  border-radius: 1rem;
  padding: 0.8rem 1rem;
  margin-bottom: 1.5rem;
  box-shadow: 0 4px 18px rgba(255,153,0,0.12);
}
@keyframes fadeInUp {
  from { opacity: 0; transform: translateY(40px); }
  to   { opacity: 1; transform: translateY(0); }
}
#login-form {
  display: flex;
  flex-direction: column;
  gap: 2.1rem;
  width: 100%;
  max-width: 340px;
  align-items: stretch;
  animation: fadeInUp 1s cubic-bezier(.4,0,.2,1);
  background: transparent;
  margin: 0 auto;
}
.form-group {
  position: relative;
  width: 100%;
  animation: fadeInUp 1.2s cubic-bezier(.4,0,.2,1);
  margin-bottom: 0.2rem;
}
.form-group input {
  width: 100%;
  padding: 1.1rem 0.9rem 0.5rem 0.9rem;
  background: transparent;
  border: 2px solid var(--input-border);
  border-radius: 2rem;
  color: var(--text);
  font-size: 1.05rem;
  outline: none;
  transition: border-color 0.22s cubic-bezier(.4,0,.2,1), box-shadow 0.22s;
  font-weight: 400;
  box-shadow: 0 2px 12px 0 rgba(255,153,0,0.04);
  display: block;
}
.form-group input:focus,
.form-group input:hover {
  border-color: var(--input-focus);
  box-shadow: 0 0 0 2px var(--input-focus, #FF9900)22;
}
.form-group label {
  position: absolute;
  left: 1.1rem;
  top: 1.1rem;
  color: #aaa;
  font-size: 1rem;
  pointer-events: none;
  background: transparent;
  transition: 0.2s cubic-bezier(.4,0,.2,1);
  padding: 0 0.2rem;
}
.form-group input:focus + label,
.form-group input:not(:placeholder-shown):not(:focus) + label,
.form-group input:valid + label {
  top: -0.8rem;
  left: 0.9rem;
  font-size: 0.85rem;
  color: var(--label-focus);
  background: var(--bg);
}
button[type="submit"] {
  width: 90%;
  padding: 0.9rem 0;
  border: none;
  border-radius: 2rem;
  background: var(--btn-bg);
  color: var(--btn-text);
  font-size: 1.08rem;
  font-weight: 600;
  cursor: pointer;
  transition: background 0.2s, color 0.2s, transform 0.1s, box-shadow 0.2s;
  box-shadow: 0 2px 12px 0 rgba(255,153,0,0.07);
  letter-spacing: 0.01em;
  margin-top: 0.2rem;
  margin-left: auto;
  animation: fadeInUp 1.3s cubic-bezier(.4,0,.2,1);
  align-self: flex-end;
}
button[type="submit"]:hover {
  filter: brightness(1.08);
  transform: translateY(-1px) scale(1.02);
  box-shadow: 0 4px 18px 0 rgba(255,153,0,0.13);
}
@media (max-width: 600px) {
  #login-form {
    max-width: 98vw;
    padding: 0 1vw;
  }
  button[type="submit"] {
    width: 100%;
    margin-left: 0;
    align-self: stretch;
  }
}