:root {
  --bg-page: #f5f7fb;
  --bg-card: #ffffff;
  --color-text: #1f2937;
  --color-muted: #6b7280;
  --color-label: #374151;
  --color-input-border: #d1d5db;
  --color-input-focus: #2563eb;
  --color-primary: #2563eb;
  --color-primary-hover: #1d4ed8;
  --color-primary-disabled: #93c5fd;
  --color-error-bg: #fef2f2;
  --color-error-border: #fecaca;
  --color-error-text: #991b1b;
  --shadow-card: 0 12px 32px rgba(15, 23, 42, 0.08), 0 2px 6px rgba(15, 23, 42, 0.05);
  --radius: 12px;
  --radius-sm: 8px;
  --transition: 150ms ease;
  --font-system: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
}

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

html,
body {
  margin: 0;
  padding: 0;
  height: 100%;
  font-family: var(--font-system);
  color: var(--color-text);
  background: var(--bg-page);
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

.login-shell {
  min-height: 100vh;
  display: grid;
  place-items: center;
  padding: 24px;
  background:
    radial-gradient(ellipse at top left, #eef2ff 0%, transparent 60%),
    radial-gradient(ellipse at bottom right, #f0f9ff 0%, transparent 60%),
    var(--bg-page);
}

.login-card {
  width: 100%;
  max-width: 420px;
  background: var(--bg-card);
  border-radius: var(--radius);
  box-shadow: var(--shadow-card);
  padding: 36px 32px 28px;
  display: flex;
  flex-direction: column;
  gap: 24px;
}

.brand {
  display: flex;
  flex-direction: column;
  align-items: center;
  text-align: center;
  gap: 12px;
}

.brand-logo {
  width: 56px;
  height: 56px;
  object-fit: contain;
}

.brand-title {
  margin: 0;
  font-size: 20px;
  font-weight: 600;
  letter-spacing: -0.01em;
  color: #111827;
  line-height: 1.3;
}

.brand-subtitle {
  margin: 0;
  font-size: 14px;
  color: var(--color-muted);
  line-height: 1.5;
  max-width: 320px;
}

.login-form {
  display: flex;
  flex-direction: column;
  gap: 16px;
}

.field {
  display: flex;
  flex-direction: column;
  gap: 6px;
}

.field label {
  font-size: 13px;
  font-weight: 500;
  color: var(--color-label);
}

.field input {
  width: 100%;
  padding: 11px 12px;
  font-size: 14px;
  font-family: inherit;
  color: var(--color-text);
  background: #fff;
  border: 1px solid var(--color-input-border);
  border-radius: var(--radius-sm);
  outline: none;
  transition: border-color var(--transition), box-shadow var(--transition);
}

.field input::placeholder {
  color: #9ca3af;
}

.field input:focus {
  border-color: var(--color-input-focus);
  box-shadow: 0 0 0 3px rgba(37, 99, 235, 0.15);
}

.input-with-action {
  position: relative;
  display: flex;
  align-items: stretch;
}

.input-with-action input {
  flex: 1;
  padding-right: 78px;
}

.toggle-visibility {
  position: absolute;
  right: 6px;
  top: 50%;
  transform: translateY(-50%);
  padding: 4px 10px;
  font-size: 12px;
  font-weight: 500;
  font-family: inherit;
  color: var(--color-muted);
  background: transparent;
  border: none;
  border-radius: 6px;
  cursor: pointer;
  transition: background var(--transition), color var(--transition);
}

.toggle-visibility:hover {
  background: #f3f4f6;
  color: var(--color-text);
}

.toggle-visibility:focus-visible {
  outline: 2px solid var(--color-input-focus);
  outline-offset: 2px;
}

.toggle-visibility .t-hide { display: none; }
.toggle-visibility[data-state="visible"] .t-show { display: none; }
.toggle-visibility[data-state="visible"] .t-hide { display: inline; }

.alert {
  display: flex;
  align-items: flex-start;
  gap: 10px;
  padding: 10px 12px;
  border-radius: var(--radius-sm);
  font-size: 13px;
  line-height: 1.45;
}

/* HTML `hidden` özelliği `.alert` üzerindeki display:flex tarafından
   geçersiz kılınmasın diye explicit kural. */
.alert[hidden] {
  display: none;
}

.alert-error {
  background: var(--color-error-bg);
  border: 1px solid var(--color-error-border);
  color: var(--color-error-text);
}

.alert-icon {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 18px;
  height: 18px;
  border-radius: 50%;
  font-weight: 700;
  background: var(--color-error-text);
  color: #fff;
  flex-shrink: 0;
  font-size: 11px;
  line-height: 1;
}

.btn-primary {
  position: relative;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 10px;
  width: 100%;
  padding: 12px 16px;
  font-size: 15px;
  font-weight: 600;
  font-family: inherit;
  color: #fff;
  background: var(--color-primary);
  border: none;
  border-radius: var(--radius-sm);
  cursor: pointer;
  transition: background var(--transition), transform var(--transition);
}

.btn-primary:hover:not(:disabled) {
  background: var(--color-primary-hover);
}

.btn-primary:active:not(:disabled) {
  transform: translateY(1px);
}

.btn-primary:disabled {
  background: var(--color-primary-disabled);
  cursor: not-allowed;
}

.btn-spinner {
  display: none;
  width: 16px;
  height: 16px;
  border: 2px solid rgba(255, 255, 255, 0.45);
  border-top-color: #fff;
  border-radius: 50%;
  animation: btn-spin 700ms linear infinite;
}

.btn-primary[data-loading="true"] .btn-spinner {
  display: inline-block;
}

@keyframes btn-spin {
  to { transform: rotate(360deg); }
}

@media (max-width: 480px) {
  .login-card {
    padding: 28px 22px 22px;
  }
  .brand-title {
    font-size: 18px;
  }
}

@media (prefers-reduced-motion: reduce) {
  .btn-spinner {
    animation: none;
  }
  .btn-primary,
  .toggle-visibility,
  .field input {
    transition: none;
  }
}