/* ============================================================
   AI现场教学系统 · 登录页
   设计令牌沿用全站体系（brand #0d6471 / ink #172b3a）
   单文件交付，不依赖任何外部资源与构建流程
   ============================================================ */

:root {
  color-scheme: light;

  /* 品牌与语义色 —— 与全站 style.css 保持一致 */
  --ink: #172b3a;
  --ink-soft: #334a5c;
  --muted: #607181;
  --line: #dbe5eb;
  --line-strong: #c3d3db;
  --surface: #fff;
  --surface-soft: #f5f9fa;
  --surface-sunk: #eef3f6;
  --brand: #0d6471;
  --brand-deep: #084954;
  --brand-tint: rgb(13 100 113 / 12%);
  --accent: #d78a36;
  --danger: #a64040;
  --danger-tint: rgb(166 64 64 / 10%);

  --radius-sm: .5rem;
  --radius: .75rem;
  --radius-lg: 1.125rem;
  --shadow-card: 0 .0625rem .125rem rgb(23 43 58 / 6%), 0 1.25rem 2.5rem -1rem rgb(13 100 113 / 22%);
  --shadow-pop: 0 .125rem .5rem rgb(23 43 58 / 10%);
  --ring: 0 0 0 .1875rem rgb(13 100 113 / 18%);
  --ring-danger: 0 0 0 .1875rem rgb(166 64 64 / 16%);

  --ease: cubic-bezier(.4, 0, .2, 1);
}

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

html { -webkit-text-size-adjust: 100%; }

body {
  margin: 0;
  min-width: 320px;
  min-height: 100vh;
  min-height: 100dvh;
  font-family: Inter, system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", "Microsoft YaHei", "PingFang SC", sans-serif;
  font-size: 1rem;
  line-height: 1.6;
  color: var(--ink);
  background:
    radial-gradient(120% 80% at 50% -10%, rgb(13 100 113 / 10%) 0%, rgb(13 100 113 / 0%) 55%),
    radial-gradient(90% 60% at 100% 100%, rgb(215 138 54 / 8%) 0%, rgb(215 138 54 / 0%) 60%),
    linear-gradient(180deg, #f2f7f8 0%, var(--surface-sunk) 100%);
  background-attachment: fixed;
  -webkit-font-smoothing: antialiased;
}

/* ---------- 布局骨架 ---------- */
.container {
  display: grid;
  place-items: center;
  min-height: 100vh;
  min-height: 100dvh;
  width: min(72rem, calc(100% - 2rem));
  margin-inline: auto;
  padding: clamp(1.5rem, 4vw, 3rem) 0;
}

/* ---------- 登录卡片 ---------- */
.portal-card {
  width: min(30rem, 100%);
  padding: clamp(1.5rem, 4.5vw, 2.5rem);
  border: 1px solid var(--line);
  border-radius: var(--radius-lg);
  background: var(--surface);
  box-shadow: var(--shadow-card);
}

.portal-intro { text-align: center; }

.eyebrow {
  display: inline-flex;
  align-items: center;
  gap: .4rem;
  margin: 0 0 .85rem;
  padding: .25rem .7rem;
  border-radius: 999px;
  background: var(--brand-tint);
  color: var(--brand-deep);
  font-size: .75rem;
  font-weight: 700;
  letter-spacing: .08em;
}
.eyebrow::before {
  content: "";
  width: .375rem; height: .375rem;
  border-radius: 50%;
  background: var(--brand);
}

.portal-intro h1 {
  margin: 0 0 .6rem;
  font-size: clamp(1.5rem, 5.2vw, 1.9rem);
  line-height: 1.3;
  letter-spacing: -.02em;
  font-weight: 700;
  color: var(--ink);
}

.portal-intro .lead {
  margin: 0;
  color: var(--muted);
  font-size: clamp(.875rem, 2.4vw, .9375rem);
  line-height: 1.7;
  text-wrap: pretty;
}

/* ---------- 角色分段控件 ---------- */
.portal-tabs {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: .25rem;
  margin: clamp(1.5rem, 4vw, 2rem) 0 0;
  padding: .3125rem;
  border: 1px solid var(--line);
  border-radius: var(--radius);
  background: var(--surface-sunk);
}

.portal-tab {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: .45rem;
  min-height: 2.75rem;
  padding: .5rem .6rem;
  border: 0;
  border-radius: calc(var(--radius) - .2rem);
  background: transparent;
  color: var(--muted);
  font: inherit;
  font-size: .9rem;
  font-weight: 600;
  cursor: pointer;
  transition: background-color .18s var(--ease), color .18s var(--ease), box-shadow .18s var(--ease);
  -webkit-tap-highlight-color: transparent;
}
.portal-tab svg { width: 1.05rem; height: 1.05rem; flex: 0 0 auto; }
.portal-tab span { white-space: nowrap; overflow: hidden; text-overflow: ellipsis; }

.portal-tab:hover { color: var(--brand-deep); background: rgb(255 255 255 / 60%); }
.portal-tab:focus-visible { outline: 2px solid var(--brand); outline-offset: 2px; }

.portal-tab.is-active {
  background: var(--surface);
  color: var(--brand-deep);
  box-shadow: var(--shadow-pop);
}

/* ---------- 面板 ---------- */
.portal-panel { padding-top: 1.5rem; }
.portal-panel[hidden] { display: none; }
.portal-panel:not([hidden]) { animation: panel-in .28s var(--ease) both; }

@keyframes panel-in {
  from { opacity: 0; transform: translateY(.375rem); }
  to   { opacity: 1; transform: none; }
}

.portal-panel h2 {
  margin: 0 0 .35rem;
  font-size: 1.0625rem;
  font-weight: 700;
  letter-spacing: -.01em;
}

.panel-note {
  margin: 0 0 1.15rem;
  color: var(--muted);
  font-size: .85rem;
  line-height: 1.65;
  text-wrap: pretty;
}

/* ---------- 表单 ---------- */
.form-card { display: block; margin: 0; }

.field { margin-bottom: 1rem; }
.field:last-of-type { margin-bottom: 1.25rem; }

.field > label {
  display: block;
  margin-bottom: .375rem;
  font-size: .85rem;
  font-weight: 600;
  color: var(--ink-soft);
}
.field .optional {
  margin-left: .35rem;
  color: var(--muted);
  font-weight: 400;
}

.field-control { position: relative; display: flex; align-items: center; }

.field input {
  width: 100%;
  height: 2.875rem;
  padding: 0 .875rem;
  border: 1px solid var(--line-strong);
  border-radius: var(--radius-sm);
  background: var(--surface);
  color: var(--ink);
  font: inherit;
  font-size: 1rem; /* 保持 ≥16px，避免 iOS Safari 聚焦时自动缩放 */
  transition: border-color .16s var(--ease), box-shadow .16s var(--ease), background-color .16s var(--ease);
}
.field.has-icon input { padding-right: 2.875rem; }

.field input::placeholder { color: #94a5b1; }
.field input:hover:not(:focus) { border-color: #a9bcc5; }

.field input:focus {
  outline: none;
  border-color: var(--brand);
  box-shadow: var(--ring);
}

.field.has-error input {
  border-color: var(--danger);
  background: var(--danger-tint);
}
.field.has-error input:focus { box-shadow: var(--ring-danger); }

.field-error {
  display: none;
  align-items: center;
  gap: .3rem;
  margin: .375rem 0 0;
  color: var(--danger);
  font-size: .8125rem;
  line-height: 1.45;
}
.field.has-error .field-error { display: flex; }
.field-error svg { width: .875rem; height: .875rem; flex: 0 0 auto; }

/* 密码可见性切换 */
.reveal-btn {
  position: absolute;
  right: .25rem;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 2.375rem;
  height: 2.375rem;
  padding: 0;
  border: 0;
  border-radius: var(--radius-sm);
  background: transparent;
  color: var(--muted);
  cursor: pointer;
  transition: color .16s var(--ease), background-color .16s var(--ease);
}
.reveal-btn:hover { color: var(--brand-deep); background: var(--surface-sunk); }
.reveal-btn:focus-visible { outline: 2px solid var(--brand); outline-offset: 1px; }
.reveal-btn svg { width: 1.125rem; height: 1.125rem; }
.portal-shell .reveal-btn svg[hidden] { display: none !important; }

/* 提交区 */
.form-alert {
  display: none;
  margin: 0 0 1rem;
  padding: .625rem .75rem;
  border: 1px solid rgb(166 64 64 / 28%);
  border-radius: var(--radius-sm);
  background: var(--danger-tint);
  color: var(--danger);
  font-size: .85rem;
}
.form-alert.is-visible { display: block; }

.button {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: .5rem;
  width: 100%;
  min-height: 2.875rem;
  padding: 0 1.25rem;
  border: 0;
  border-radius: var(--radius-sm);
  background: linear-gradient(180deg, var(--brand) 0%, var(--brand-deep) 100%);
  color: #fff;
  font: inherit;
  font-size: .95rem;
  font-weight: 700;
  letter-spacing: .02em;
  cursor: pointer;
  transition: transform .16s var(--ease), box-shadow .16s var(--ease), filter .16s var(--ease);
  -webkit-tap-highlight-color: transparent;
}
.button:hover { filter: brightness(1.06); box-shadow: 0 .5rem 1.25rem -.375rem rgb(13 100 113 / 55%); }
.button:active { transform: translateY(.0625rem); }
.button:focus-visible { outline: 2px solid var(--brand-deep); outline-offset: 2px; }

.button[disabled] {
  cursor: progress;
  filter: none;
  opacity: .75;
  box-shadow: none;
  transform: none;
}

.button .spinner {
  display: none;
  width: 1rem; height: 1rem;
  border: 2px solid rgb(255 255 255 / 40%);
  border-top-color: #fff;
  border-radius: 50%;
  animation: spin .7s linear infinite;
}
.button.is-loading .spinner { display: block; }

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

.form-footnote {
  margin: 1rem 0 0;
  color: var(--muted);
  font-size: .8rem;
  line-height: 1.6;
  text-align: center;
}

/* ---------- 响应式 ---------- */
@media (min-width: 480px) {
  .portal-tabs { grid-template-columns: repeat(4, minmax(0, 1fr)); }
  .portal-tab { font-size: .85rem; padding: .5rem .35rem; }
}

@media (max-width: 640px) {
  .container { width: calc(100% - 1.5rem); }
}

@media (max-width: 400px) {
  .portal-card { padding: 1.25rem 1.125rem 1.5rem; }
  .portal-tab span { font-size: .82rem; }
}

/* 横屏矮屏：取消强制垂直居中，避免内容被裁切 */
@media (max-height: 620px) and (orientation: landscape) {
  .container { place-items: start center; padding-top: 1rem; }
}

/* ---------- 偏好与降级 ---------- */
@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after {
    animation-duration: .001ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: .001ms !important;
  }
}

@media (prefers-contrast: more) {
  .field input { border-color: var(--ink-soft); }
  .portal-tab { color: var(--ink-soft); }
}

@media (forced-colors: active) {
  .portal-card { border: 1px solid CanvasText; }
  .portal-tab.is-active { outline: 2px solid Highlight; }
}

/* Keep the shared header and footer while centering the supplied card. */
.portal-shell .container {
  min-height: calc(100dvh - 9rem);
  padding-inline: 0;
  border: 0;
  border-radius: 0;
  background: transparent;
  box-shadow: none;
}
.portal-shell .portal-card { margin-inline: auto; }