/* ============================================
   CSS Variables (Light & Dark Themes)
   ============================================ */
:root {
  /* Light Theme (default) */
  --bg-gradient-start: #f0f4f8;
  --bg-gradient-end: #d9e2ec;
  --card-bg: rgba(255, 255, 255, 0.85);
  --card-border: rgba(255, 255, 255, 0.3);
  --text-primary: #1a202c;
  --text-secondary: #2d3748;
  --text-muted: #718096;
  --input-bg: #ffffff;
  --input-border: #e2e8f0;
  --input-focus: #3182ce;
  --btn-primary-bg: #2b6cb0;
  --btn-primary-hover: #2c5282;
  --btn-primary-text: #ffffff;
  --shadow: 0 8px 32px rgba(0, 0, 0, 0.12);
  --radius: 16px;
  --transition: 0.3s ease;
}

/* Dark Theme */
[data-theme="dark"] {
  --bg-gradient-start: #0f172a;
  --bg-gradient-end: #1e293b;
  --card-bg: rgba(30, 41, 59, 0.9);
  --card-border: rgba(255, 255, 255, 0.1);
  --text-primary: #f1f5f9;
  --text-secondary: #cbd5e1;
  --text-muted: #94a3b8;
  --input-bg: #1e293b;
  --input-border: #334155;
  --input-focus: #60a5fa;
  --btn-primary-bg: #3b82f6;
  --btn-primary-hover: #2563eb;
  --btn-primary-text: #ffffff;
  --shadow: 0 8px 32px rgba(0, 0, 0, 0.5);
}

/* System default – uses prefers-color-scheme */
@media (prefers-color-scheme: dark) {
  :root:not([data-theme="light"]):not([data-theme="dark"]) {
    --bg-gradient-start: #0f172a;
    --bg-gradient-end: #1e293b;
    --card-bg: rgba(30, 41, 59, 0.9);
    --card-border: rgba(255, 255, 255, 0.1);
    --text-primary: #f1f5f9;
    --text-secondary: #cbd5e1;
    --text-muted: #94a3b8;
    --input-bg: #1e293b;
    --input-border: #334155;
    --input-focus: #60a5fa;
    --btn-primary-bg: #3b82f6;
    --btn-primary-hover: #2563eb;
    --btn-primary-text: #ffffff;
    --shadow: 0 8px 32px rgba(0, 0, 0, 0.5);
  }
}

/* ============================================
   Global Reset & Base
   ============================================ */
* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

body {
  font-family: 'Segoe UI', system-ui, -apple-system, sans-serif;
  min-height: 100vh;
  display: flex;
  align-items: center;
  justify-content: center;
  background: linear-gradient(135deg, var(--bg-gradient-start), var(--bg-gradient-end));
  transition: background 0.5s ease, color 0.3s ease;
  color: var(--text-primary);
  padding: 20px;
}

/* ============================================
   Theme Toggle (floating)
   ============================================ */
.theme-toggle {
  position: fixed;
  top: 20px;
  right: 20px;
  display: flex;
  gap: 8px;
  background: var(--card-bg);
  backdrop-filter: blur(12px);
  padding: 6px 12px;
  border-radius: 40px;
  box-shadow: var(--shadow);
  border: 1px solid var(--card-border);
  z-index: 1000;
}

.theme-toggle button {
  background: transparent;
  border: none;
  padding: 6px 12px;
  border-radius: 30px;
  cursor: pointer;
  font-size: 14px;
  font-weight: 500;
  color: var(--text-muted);
  transition: var(--transition);
}

.theme-toggle button.active {
  background: var(--btn-primary-bg);
  color: var(--btn-primary-text);
  box-shadow: 0 2px 8px rgba(43, 108, 176, 0.3);
}

.theme-toggle button:hover:not(.active) {
  color: var(--text-primary);
}

/* ============================================
   Card Container
   ============================================ */
.card {
  background: var(--card-bg);
  backdrop-filter: blur(16px);
  border: 1px solid var(--card-border);
  border-radius: var(--radius);
  padding: 40px 36px;
  max-width: 440px;
  width: 100%;
  box-shadow: var(--shadow);
  transition: all 0.4s ease;
  animation: fadeSlideUp 0.6s ease forwards;
}

@keyframes fadeSlideUp {
  0% { opacity: 0; transform: translateY(30px); }
  100% { opacity: 1; transform: translateY(0); }
}

.card h2 {
  font-size: 28px;
  font-weight: 700;
  margin-bottom: 6px;
  color: var(--text-primary);
}

.card .subtitle {
  color: var(--text-muted);
  margin-bottom: 24px;
  font-size: 14px;
}

/* ============================================
   Form Elements
   ============================================ */
.form-group {
  margin-bottom: 18px;
}

.form-group label {
  display: block;
  font-size: 14px;
  font-weight: 500;
  margin-bottom: 6px;
  color: var(--text-secondary);
}

.form-group input[type="text"],
.form-group input[type="password"],
.form-group input[type="email"] {
  width: 100%;
  padding: 12px 16px;
  background: var(--input-bg);
  border: 2px solid var(--input-border);
  border-radius: 10px;
  font-size: 15px;
  color: var(--text-primary);
  transition: border 0.3s, box-shadow 0.3s;
  outline: none;
}

.form-group input:focus {
  border-color: var(--input-focus);
  box-shadow: 0 0 0 4px rgba(49, 130, 206, 0.15);
}

/* Radio buttons (for contact selection) */
.radio-group {
  display: flex;
  flex-direction: column;
  gap: 10px;
  margin: 16px 0;
}

.radio-group label {
  display: flex;
  align-items: center;
  padding: 14px 18px;
  background: var(--input-bg);
  border: 2px solid var(--input-border);
  border-radius: 12px;
  cursor: pointer;
  transition: var(--transition);
  font-weight: 400;
  color: var(--text-secondary);
}

.radio-group label:hover {
  border-color: var(--input-focus);
  background: rgba(49, 130, 206, 0.05);
}

.radio-group input[type="radio"] {
  margin-right: 14px;
  accent-color: var(--btn-primary-bg);
  width: 18px;
  height: 18px;
  cursor: pointer;
}

.radio-group .coming-soon {
  margin-left: auto;
  font-size: 12px;
  color: var(--text-muted);
  background: var(--card-bg);
  padding: 2px 10px;
  border-radius: 20px;
}

/* ============================================
   Buttons
   ============================================ */
.btn {
  display: inline-block;
  width: 100%;
  padding: 14px;
  border: none;
  border-radius: 10px;
  font-size: 16px;
  font-weight: 600;
  background: var(--btn-primary-bg);
  color: var(--btn-primary-text);
  cursor: pointer;
  transition: background 0.3s, transform 0.2s, box-shadow 0.3s;
  box-shadow: 0 4px 12px rgba(43, 108, 176, 0.25);
}

.btn:hover {
  background: var(--btn-primary-hover);
  transform: scale(1.01);
  box-shadow: 0 6px 20px rgba(43, 108, 176, 0.35);
}

.btn:active {
  transform: scale(0.98);
}

/* Secondary link */
.link {
  display: inline-block;
  margin-top: 16px;
  color: var(--btn-primary-bg);
  text-decoration: none;
  font-weight: 500;
  transition: var(--transition);
}

.link:hover {
  text-decoration: underline;
  color: var(--btn-primary-hover);
}

/* ============================================
   Error & Success Messages
   ============================================ */
.alert {
  padding: 12px 16px;
  border-radius: 10px;
  margin-bottom: 18px;
  font-size: 14px;
  animation: shake 0.4s ease;
}

@keyframes shake {
  0%, 100% { transform: translateX(0); }
  20% { transform: translateX(-6px); }
  40% { transform: translateX(6px); }
  60% { transform: translateX(-4px); }
  80% { transform: translateX(4px); }
}

.alert.error {
  background: #fed7d7;
  color: #9b2c2c;
  border-left: 4px solid #e53e3e;
}

[data-theme="dark"] .alert.error {
  background: #742a2a;
  color: #feb2b2;
  border-left-color: #fc8181;
}

.alert.success {
  background: #c6f6d5;
  color: #22543d;
  border-left: 4px solid #38a169;
}

[data-theme="dark"] .alert.success {
  background: #2f855a;
  color: #c6f6d5;
  border-left-color: #68d391;
}

/* ============================================
   Responsive
   ============================================ */
@media (max-width: 480px) {
  .card {
    padding: 28px 20px;
  }
  .theme-toggle {
    top: 12px;
    right: 12px;
    padding: 4px 8px;
  }
  .theme-toggle button {
    font-size: 12px;
    padding: 4px 10px;
  }
}