/* ── Theme tokens ── */
:root {
  --bg: #f8f8f8;
  --surface: #ffffff;
  --header-bg: #ffffff;
  --text: #111111;
  --text-sub: #555555;
  --border: #e0e0e0;
  --accent: #4f46e5;
  --accent-hover: #4338ca;
  --error: #dc2626;
  --success: #16a34a;
  --switch-track: #d1d5db;
  --switch-thumb: #ffffff;
  --input-bg: #ffffff;
  --placeholder: #9ca3af;
  --shadow: 0 2px 12px rgba(0,0,0,0.08);
  --transition: 0.3s ease;
}

[data-theme="dark"] {
  --bg: #0d0d0d;
  --surface: #1a1a1a;
  --header-bg: #141414;
  --text: #f1f1f1;
  --text-sub: #9ca3af;
  --border: #2e2e2e;
  --accent: #818cf8;
  --accent-hover: #6366f1;
  --error: #f87171;
  --success: #4ade80;
  --switch-track: #4f46e5;
  --switch-thumb: #ffffff;
  --input-bg: #222222;
  --placeholder: #6b7280;
  --shadow: 0 2px 12px rgba(0,0,0,0.4);
}

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

body {
  background: var(--bg);
  color: var(--text);
  font-family: 'Segoe UI', 'Apple SD Gothic Neo', system-ui, sans-serif;
  min-height: 100vh;
  transition: background var(--transition), color var(--transition);
  display: flex;
  flex-direction: column;
}

/* ── Header ── */
header {
  position: sticky;
  top: 0;
  z-index: 100;
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 0.9rem 2rem;
  background: var(--header-bg);
  border-bottom: 1px solid var(--border);
  box-shadow: var(--shadow);
  transition: background var(--transition), border-color var(--transition);
}

.logo {
  font-size: 1.1rem;
  font-weight: 700;
  color: var(--accent);
  letter-spacing: -0.3px;
}

/* ── Toggle switch ── */
.switch {
  position: relative;
  display: inline-block;
  width: 60px;
  height: 30px;
  cursor: pointer;
}
.switch input { opacity: 0; width: 0; height: 0; }

.slider {
  position: absolute;
  inset: 0;
  background: var(--switch-track);
  border-radius: 999px;
  transition: background var(--transition);
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 0 5px;
}
.slider::after {
  content: '';
  position: absolute;
  width: 22px;
  height: 22px;
  left: 4px;
  border-radius: 50%;
  background: var(--switch-thumb);
  box-shadow: 0 1px 4px rgba(0,0,0,0.25);
  transition: transform var(--transition);
}
.switch input:checked + .slider::after { transform: translateX(30px); }
.icon { font-size: 12px; z-index: 1; pointer-events: none; user-select: none; }

/* ── Hero ── */
.hero {
  text-align: center;
  padding: 4rem 2rem 3rem;
}
.hero h1 {
  font-size: clamp(1.5rem, 4vw, 2.4rem);
  font-weight: 800;
  color: var(--accent);
  margin-bottom: 0.75rem;
  line-height: 1.3;
}
.hero p {
  font-size: 1rem;
  color: var(--text-sub);
}

/* ── Form section ── */
.form-section {
  flex: 1;
  display: flex;
  flex-direction: column;
  align-items: center;
  padding: 0 1.5rem 4rem;
}

form {
  width: 100%;
  max-width: 640px;
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 16px;
  padding: 2.5rem;
  box-shadow: var(--shadow);
  display: flex;
  flex-direction: column;
  gap: 1.25rem;
  transition: background var(--transition), border-color var(--transition);
}

.form-row { display: flex; flex-direction: column; gap: 1.25rem; }
.two-col { flex-direction: row; gap: 1rem; }
.two-col .field { flex: 1; min-width: 0; }

@media (max-width: 520px) {
  .two-col { flex-direction: column; }
  form { padding: 1.5rem; }
}

/* ── Fields ── */
.field { display: flex; flex-direction: column; gap: 0.35rem; }

label {
  font-size: 0.875rem;
  font-weight: 600;
  color: var(--text);
}
.req { color: var(--error); }

input, select, textarea {
  width: 100%;
  padding: 0.65rem 0.9rem;
  border: 1.5px solid var(--border);
  border-radius: 8px;
  background: var(--input-bg);
  color: var(--text);
  font-size: 0.95rem;
  font-family: inherit;
  transition: border-color var(--transition), background var(--transition), box-shadow var(--transition);
  outline: none;
}
input::placeholder, textarea::placeholder { color: var(--placeholder); }
input:focus, select:focus, textarea:focus {
  border-color: var(--accent);
  box-shadow: 0 0 0 3px color-mix(in srgb, var(--accent) 20%, transparent);
}
input.invalid, select.invalid, textarea.invalid {
  border-color: var(--error);
  box-shadow: 0 0 0 3px color-mix(in srgb, var(--error) 15%, transparent);
}

textarea { resize: vertical; min-height: 120px; }

.char-count {
  align-self: flex-end;
  font-size: 0.75rem;
  color: var(--placeholder);
}
.char-count.warn { color: var(--error); }

.err-msg {
  font-size: 0.78rem;
  color: var(--error);
  min-height: 1em;
  display: block;
}

/* ── Submit button ── */
button[type="submit"] {
  margin-top: 0.5rem;
  padding: 0.85rem 2rem;
  background: var(--accent);
  color: #fff;
  border: none;
  border-radius: 10px;
  font-size: 1rem;
  font-weight: 700;
  cursor: pointer;
  transition: background var(--transition), opacity var(--transition), transform 0.1s;
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 0.6rem;
  position: relative;
}
button[type="submit"]:hover:not(:disabled) { background: var(--accent-hover); }
button[type="submit"]:active:not(:disabled) { transform: scale(0.98); }
button[type="submit"]:disabled { opacity: 0.6; cursor: not-allowed; }

.spinner {
  display: none;
  width: 18px;
  height: 18px;
  border: 2.5px solid rgba(255,255,255,0.35);
  border-top-color: #fff;
  border-radius: 50%;
  animation: spin 0.7s linear infinite;
}
button.loading .spinner { display: inline-block; }
button.loading .btn-text { opacity: 0.7; }

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

/* ── Toast ── */
.toast {
  margin-top: 1.25rem;
  width: 100%;
  max-width: 640px;
  padding: 0;
  border-radius: 10px;
  font-size: 0.95rem;
  font-weight: 600;
  text-align: center;
  overflow: hidden;
  max-height: 0;
  opacity: 0;
  transition: max-height 0.4s ease, opacity 0.4s ease, padding 0.4s ease;
}
.toast.show {
  padding: 1rem 1.5rem;
  max-height: 80px;
  opacity: 1;
}
.toast.success { background: color-mix(in srgb, var(--success) 15%, transparent); color: var(--success); border: 1px solid var(--success); }
.toast.error   { background: color-mix(in srgb, var(--error) 12%, transparent);   color: var(--error);   border: 1px solid var(--error); }

/* ── Footer ── */
footer {
  text-align: center;
  padding: 1.5rem;
  font-size: 0.8rem;
  color: var(--placeholder);
  border-top: 1px solid var(--border);
  transition: border-color var(--transition);
}