/* ==========================================================================
   在线计算器 · 样式
   无任何外部依赖（不引用字体/CDN），可离线加载
   ========================================================================== */

/* ---------- 主题变量 ---------- */
:root {
  --bg: #0b1220;
  --bg-soft: #111c33;
  --card: rgba(20, 32, 56, 0.72);
  --card-solid: #141f38;
  --border: rgba(120, 155, 220, 0.18);
  --text: #e8eefc;
  --text-dim: #93a4c6;
  --accent: #4f8cff;
  --accent-2: #22d3ee;
  --danger: #ff6b6b;
  --ok: #34d399;
  --warn: #fbbf24;
  --radius: 18px;
  --radius-sm: 12px;
  --shadow: 0 18px 50px rgba(0, 0, 0, 0.45);
}

html[data-theme="light"] {
  --bg: #f4f7fd;
  --bg-soft: #e8eefb;
  --card: rgba(255, 255, 255, 0.86);
  --card-solid: #ffffff;
  --border: rgba(30, 64, 130, 0.14);
  --text: #10203c;
  --text-dim: #5b6b8c;
  --accent: #2563eb;
  --accent-2: #0891b2;
  --shadow: 0 16px 40px rgba(30, 64, 130, 0.12);
}

/* ---------- 基础 ---------- */
* { box-sizing: border-box; }

html, body { height: 100%; }

body {
  margin: 0;
  min-height: 100%;
  background: var(--bg);
  color: var(--text);
  font-family: "Segoe UI", "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei",
               system-ui, -apple-system, Roboto, Helvetica, Arial, sans-serif;
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
  transition: background .3s ease, color .3s ease;
}

.wrap {
  width: min(1120px, 92vw);
  margin-inline: auto;
}

kbd {
  font-family: Consolas, monospace;
  font-size: .78em;
  border: 1px solid var(--border);
  border-bottom-width: 2px;
  border-radius: 5px;
  padding: 1px 5px;
  background: rgba(127, 155, 210, 0.12);
}

/* ---------- 背景光晕 ---------- */
.bg-glow {
  position: fixed;
  inset: 0;
  z-index: -1;
  background:
    radial-gradient(680px 380px at 12% -8%, rgba(79, 140, 255, 0.28), transparent 70%),
    radial-gradient(620px 360px at 88% 4%, rgba(34, 211, 238, 0.20), transparent 70%),
    radial-gradient(700px 420px at 50% 108%, rgba(99, 102, 241, 0.16), transparent 70%);
  pointer-events: none;
}

/* ---------- 页面布局 ----------
   login.html 与 index.html 是两个独立页面, 均整屏居中显示卡片:
   .login-wrap 用于登录页, .calc-wrap 用于计算器页。
   未登录时的跳转由 index.html 的 <head> 内联守卫完成, 这里不参与逻辑。 */
.login-wrap,
.calc-wrap {
  display: flex;
  align-items: center;
  justify-content: center;
  min-height: 100vh;
  padding: 40px 0;
}

/* ---------- 登录表单 ---------- */
.login-card {
  width: 100%;
  max-width: 380px;
  padding: 30px 26px 26px;
}

.login-title {
  margin: 0 0 6px;
  font-size: 1.3rem;
  text-align: center;
  letter-spacing: .2px;
}

.login-sub {
  margin: 0 0 22px;
  text-align: center;
  font-size: .84rem;
  color: var(--text-dim);
}

.field {
  display: block;
  margin-bottom: 14px;
}

.field-label {
  display: block;
  margin-bottom: 6px;
  font-size: .8rem;
  color: var(--text-dim);
}

.input {
  width: 100%;
  appearance: none;
  background: var(--bg-soft);
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  color: var(--text);
  font-family: inherit;
  font-size: .95rem;
  padding: 11px 13px;
  transition: border-color .18s ease, box-shadow .18s ease;
}

.input::placeholder { color: var(--text-dim); opacity: .75; }

.input:focus {
  outline: none;
  border-color: var(--accent);
  box-shadow: 0 0 0 3px color-mix(in srgb, var(--accent) 22%, transparent);
}

.login-error {
  min-height: 20px;
  margin: 2px 0 12px;
  font-size: .8rem;
  line-height: 1.45;
  color: var(--danger);
}

.btn-primary {
  width: 100%;
  appearance: none;
  border: none;
  border-radius: var(--radius-sm);
  background: linear-gradient(135deg, var(--accent), var(--accent-2));
  color: #fff;
  font-family: inherit;
  font-size: .96rem;
  font-weight: 600;
  letter-spacing: .5px;
  padding: 12px 16px;
  cursor: pointer;
  box-shadow: 0 10px 24px rgba(79, 140, 255, .34);
  transition: transform .08s ease, filter .18s ease, opacity .18s ease;
}

.btn-primary:hover   { filter: brightness(1.07); }
.btn-primary:active  { transform: scale(.985); }
.btn-primary:disabled { opacity: .6; cursor: default; box-shadow: none; }

/* ---------- 卡片 ---------- */
.card {
  background: var(--card);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  box-shadow: var(--shadow);
  padding: 22px;
  backdrop-filter: blur(10px);
}

.calc-card {
  width: 100%;
  max-width: 460px;
}

.card-head {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 12px;
  margin-bottom: 14px;
}

.card-title {
  margin: 0;
  font-size: 1.06rem;
  letter-spacing: .2px;
}

/* ---------- 计算器 ---------- */
.display {
  background: var(--bg-soft);
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  padding: 14px 16px 12px;
  margin-bottom: 16px;
  text-align: right;
  overflow: hidden;
}

.display-expr {
  min-height: 20px;
  font-size: .84rem;
  color: var(--text-dim);
  font-variant-numeric: tabular-nums;
  word-break: break-all;
}

.display-main {
  font-size: clamp(1.7rem, 6vw, 2.5rem);
  font-weight: 700;
  font-variant-numeric: tabular-nums;
  letter-spacing: -.5px;
  word-break: break-all;
  line-height: 1.25;
}

.keypad {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 10px;
}

.key {
  appearance: none;
  border: 1px solid var(--border);
  background: var(--card-solid);
  color: var(--text);
  font-size: 1.12rem;
  font-weight: 600;
  font-family: inherit;
  border-radius: 14px;
  padding: 15px 0;
  cursor: pointer;
  transition: transform .08s ease, background .18s ease, border-color .18s ease;
}

.key:hover  { border-color: var(--accent); }
.key:active { transform: scale(.955); }

.key:focus-visible {
  outline: 2px solid var(--accent);
  outline-offset: 2px;
}

.key-fn {
  color: var(--warn);
  font-size: 1rem;
}

.key-op {
  color: var(--accent-2);
  font-size: 1.25rem;
}

.key-eq {
  background: linear-gradient(135deg, var(--accent), var(--accent-2));
  color: #fff;
  border-color: transparent;
  box-shadow: 0 10px 24px rgba(79, 140, 255, .34);
}

.key.is-active {
  border-color: var(--accent);
  background: color-mix(in srgb, var(--accent) 18%, var(--card-solid));
}

.hint {
  margin: 14px 2px 0;
  font-size: .78rem;
  color: var(--text-dim);
}

/* ---------- 历史记录 ---------- */
.history-block {
  margin-top: 18px;
  border-top: 1px solid var(--border);
  padding-top: 14px;
}

.history-head {
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.history-title {
  margin: 0;
  font-size: .9rem;
  color: var(--text-dim);
  font-weight: 600;
}

.text-btn,
.icon-btn {
  appearance: none;
  background: transparent;
  border: 1px solid var(--border);
  color: var(--text-dim);
  border-radius: 9px;
  padding: 5px 11px;
  font-size: .78rem;
  font-family: inherit;
  cursor: pointer;
  transition: color .18s ease, border-color .18s ease;
}

.text-btn:hover,
.icon-btn:hover { color: var(--text); border-color: var(--accent); }

.history-list {
  list-style: none;
  margin: 10px 0 0;
  padding: 0;
  max-height: 172px;
  overflow-y: auto;
}

.history-list li {
  display: flex;
  justify-content: space-between;
  gap: 12px;
  padding: 7px 10px;
  border-radius: 9px;
  font-size: .86rem;
  font-variant-numeric: tabular-nums;
}

.history-list li:nth-child(odd) { background: rgba(127, 155, 210, 0.07); }

.history-list .h-expr { color: var(--text-dim); }
.history-list .h-res  { font-weight: 600; }

.history-empty {
  color: var(--text-dim);
  font-style: italic;
  justify-content: center !important;
  background: none !important;
}

/* ---------- 响应式 ---------- */
@media (max-width: 620px) {
  .login-wrap,
  .calc-wrap  { padding: 20px 0; align-items: flex-start; }
  .card { padding: 18px; }
  .key { padding: 13px 0; font-size: 1.04rem; }
}

@media (prefers-reduced-motion: reduce) {
  * { transition: none !important; animation: none !important; }
}