feat: improve responsive admin experience

static/css/app.src.css

@@ -184,6 +184,107 @@
     border-color: rgba(0, 94, 184, .22);
     border-top-color: #005EB8;
   }
+
+  /* Authentication-specific controls, compiled with the shared Tailwind bundle. */
+  .password-toggle {
+    position: absolute;
+    top: 50%;
+    right: .75rem;
+    display: inline-flex;
+    width: 32px;
+    height: 32px;
+    align-items: center;
+    justify-content: center;
+    transform: translateY(-50%);
+    border: 0;
+    border-radius: .5rem;
+    background: transparent;
+    color: #64748b;
+    padding: 0;
+    transition: background-color .15s ease, color .15s ease;
+  }
+
+  .password-toggle:hover {
+    background: rgba(148, 163, 184, .16);
+    color: #005EB8;
+  }
+
+  .password-toggle:focus-visible {
+    outline: 2px solid #005EB8;
+    outline-offset: 2px;
+  }
+
+  .password-toggle:disabled {
+    cursor: not-allowed;
+    opacity: .45;
+  }
+
+  .password-toggle .material-symbols-outlined {
+    font-size: 20px;
+    line-height: 1;
+  }
+
+  .auth-input-error {
+    border-color: #dc2626 !important;
+    background: #fff7f7 !important;
+    box-shadow: 0 0 0 3px rgba(220, 38, 38, .12) !important;
+  }
+
+  .captcha-token {
+    -webkit-user-select: none;
+    user-select: none;
+  }
+
+  .dot-grid {
+    background-image: radial-gradient(circle at 1px 1px, rgba(148, 163, 184, .30) 1.2px, transparent 0);
+    background-size: 42px 42px;
+  }
+
+  .panel-frame {
+    border: none;
+    box-shadow: none;
+  }
+
+  .gradient-board {
+    background: linear-gradient(180deg, #2455a3 0%, #123e7d 100%);
+  }
+
+  .auth-alert {
+    pointer-events: none;
+    top: max(1rem, env(safe-area-inset-top));
+    right: auto;
+    left: 50%;
+    width: calc(100vw - 2rem);
+    max-width: 26rem;
+    max-height: calc(100dvh - 2rem);
+    overflow-y: auto;
+    opacity: 0;
+    transform: translate(-50%, .5rem);
+  }
+
+  .auth-alert::before {
+    position: absolute;
+    top: -7px;
+    left: 24px;
+    width: 14px;
+    height: 14px;
+    transform: rotate(45deg);
+    border-top: 1px solid currentColor;
+    border-left: 1px solid currentColor;
+    background: #fff;
+    color: #bfdbfe;
+    content: '';
+  }
+
+  .auth-alert.is-error::before {
+    color: #fecaca;
+  }
+
+  .auth-alert.is-visible {
+    pointer-events: auto;
+    opacity: 1;
+    transform: translate(-50%, 0);
+  }
 }
 
 @keyframes spin {
@@ -191,3 +292,23 @@
     transform: rotate(360deg);
   }
 }
+
+@media (min-width: 1280px) {
+  .auth-alert {
+    width: 320px;
+    max-width: calc(100vw - 2rem);
+    transform: translateX(.75rem);
+  }
+
+  .auth-alert::before {
+    top: var(--auth-alert-arrow-top, 44px);
+    left: -7px;
+    border: 0;
+    border-bottom: 1px solid currentColor;
+    border-left: 1px solid currentColor;
+  }
+
+  .auth-alert.is-visible {
+    transform: translateX(0);
+  }
+}