:root {
  --bg: #ffffff;
  --panel: #ffffff;
  --input-bg: #ffffff;
  --fg: #0f172a;
  --accent: #0ea5a4;
  --accent-dark: #0d9488;
  --error-bg: #fef2f2;
  --error-fg: #991b1b;
  --radius: 8px;
  --transition: 0.3s ease;
}

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

body {
  background: var(--bg);
  color: var(--fg);
  font-family: Arial, sans-serif;
  display: flex;
  align-items: center;
  justify-content: center;
  min-height: 100vh;
  padding: 20px;
}

.box {
  background: var(--panel);
  border: 1px solid #e2e8f0;
  border-radius: var(--radius);
  padding: 40px 30px;
  width: 100%;
  max-width: 400px;
  box-shadow: 0 1px 2px rgba(15,23,42,.05), 0 6px 20px rgba(15,23,42,.06);
}

.logo img {
  display: block;
  margin: 0 auto 20px;
  max-width: 120px;
}

h1 {
  text-align: center;
  margin-bottom: 25px;
  font-size: 2rem;
  color: var(--accent);
  display: inline-flex;
  align-items: center;
  gap: 8px;
}

.alert {
  background: var(--error-bg);
  color: var(--error-fg);
  padding: 12px 15px;
  border-radius: var(--radius);
  margin-bottom: 20px;
  text-align: center;
  font-weight: bold;
  display: inline-flex;
  align-items: center;
  gap: 8px;
  width: 100%;
  border: 1px solid #fecaca;
}

.alert i {
  font-size: 1.2rem;
}

.form-group {
  margin-bottom: 20px;
}

.form-group label {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  margin-bottom: 6px;
  font-weight: bold;
  color: var(--accent);
}

.form-group label i {
  width: 20px;
  text-align: center;
}

.form-group input {
  width: 100%;
  padding: 12px 14px;
  background: var(--input-bg);
  color: var(--fg);
  border: 1px solid #e2e8f0;
  border-radius: var(--radius);
  font-size: 1rem;
  transition: border-color var(--transition), box-shadow var(--transition);
}

.form-group input::placeholder {
  color: #94a3b8;
}

.form-group input:focus {
  border: 2px solid var(--accent);
  box-shadow: 0 0 0 3px rgba(14,165,164,.25);
  outline: none;
}

.button-container {
  text-align: center;
  margin-top: 10px;
}

.btn {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 12px 20px;
  border: none;
  border-radius: var(--radius);
  font-size: 1rem;
  font-weight: bold;
  cursor: pointer;
  transition: background var(--transition), transform var(--transition), box-shadow var(--transition);
  text-decoration: none;
}

.btn-primary {
  background: var(--accent);
  color: #ffffff;
  border: 1px solid var(--accent);
}

.btn-primary:hover {
  background: var(--accent-dark);
  border-color: var(--accent-dark);
  transform: translateY(-2px);
  box-shadow: 0 8px 20px rgba(14,165,164,.18);
}

.btn-primary i {
  font-size: 1.2rem;
}

/* ======== Responsive ======== */
@media (max-width: 768px) {
  body {
    min-height: 100vh;
    display: flex;
    align-items: center;
    justify-content: center;
    flex-direction: column;
    padding: 10px;
    font-size: 1rem;
  }

  .box {
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    padding: 25px 12px;
    max-width: 100vw;
    width: 100%;
    min-width: 0;
    border-radius: 0;
    margin: 0 auto;
    border-width: 0;
    box-shadow: none;
  }

  .logo {
    width: 100%;
    display: flex;
    justify-content: center;
  }

  .logo img {
    max-width: 80px;
    margin-bottom: 16px;
  }

  h1 {
    width: 100%;
    font-size: 1.3rem;
    margin-bottom: 18px;
    word-break: break-word;
    gap: 6px;
    text-align: center;
    display: flex;
    justify-content: center;
    align-items: center;
  }

  .alert {
    width: 100%;
    font-size: 0.97rem;
    padding: 10px 10px;
    border-radius: 6px;
    gap: 6px;
    margin-bottom: 12px;
    text-align: center;
    display: flex;
    align-items: center;
    justify-content: center;
  }

  .alert i {
    font-size: 1rem;
  }

  .form-group {
    width: 100%;
    margin-bottom: 13px;
    display: flex;
    flex-direction: column;
    align-items: center;
  }

  .form-group label {
    width: 100%;
    font-size: 0.96rem;
    gap: 5px;
    margin-bottom: 4px;
    text-align: left;
    display: flex;
    align-items: center;
  }

  .form-group input {
    width: 100%;
    padding: 10px 12px;
    font-size: 0.98rem;
    border-radius: 6px;
    box-sizing: border-box;
  }

  .button-container {
    width: 100%;
    margin-top: 6px;
    display: flex;
    justify-content: center;
  }

  .btn {
    width: 100%;
    justify-content: center;
    padding: 13px 0;
    font-size: 1rem;
    border-radius: 6px;
    gap: 7px;
    display: flex;
    align-items: center;
  }

  .btn-primary {
    font-size: 1.03rem;
  }

  .btn-primary i {
    font-size: 1.07rem;
  }
}

@media (max-width: 480px) {
  body {
    padding: 3vw;
    font-size: 0.98rem;
  }

  .box {
    padding: 10vw 2vw;
    max-width: 100vw;
    border-radius: 0;
    border-width: 0;
  }

  .logo img {
    max-width: 52px;
    margin-bottom: 12px;
  }

  h1 {
    font-size: 1.08rem;
    margin-bottom: 13px;
    gap: 5px;
  }

  .alert {
    font-size: 0.93rem;
    padding: 8px 6px;
    border-radius: 5px;
    margin-bottom: 8px;
    gap: 5px;
  }

  .form-group label {
    font-size: 0.91rem;
    margin-bottom: 2px;
  }

  .form-group input {
    font-size: 0.95rem;
    padding: 9px 9px;
    border-radius: 5px;
  }

  .btn, .btn-primary {
    font-size: 0.97rem;
    padding: 11px 0;
    border-radius: 5px;
    gap: 6px;
  }
}