/* ============================================================
   設計系統｜繳費提醒 App
   風格：Swiss Modernism 系的乾淨網格 + 個人記帳工具慣用的
        信任藍（品牌色）＋ 沉穩綠（正向/金額強調），
        淺色／深色模式各自調校過對比度，不是簡單反轉顏色。
   數字（金額）沿用系統字體（San Francisco / PingFang），
   靠 font-variant-numeric: tabular-nums 對齊，不額外載入網路字體。
   ============================================================ */

:root {
  --font-sans: -apple-system, BlinkMacSystemFont, 'PingFang TC', 'Noto Sans TC', sans-serif;
  --font-number: var(--font-sans);

  /* 8px 間距節奏 */
  --space-1: 4px;
  --space-2: 8px;
  --space-3: 12px;
  --space-4: 16px;
  --space-5: 24px;
  --space-6: 32px;

  --radius-sm: 8px;
  --radius-md: 12px;
  --radius-lg: 16px;
  --radius-pill: 999px;

  --duration-fast: 150ms;
  --duration-normal: 250ms;
  --ease-standard: cubic-bezier(0.2, 0, 0, 1);

  /* 淺色模式（預設） */
  --color-bg: #F7F8FA;
  --color-surface: #FFFFFF;
  --color-surface-muted: #F1F3F6;
  --color-text: #0F172A;
  --color-text-muted: #64748B;
  --color-border: #E2E8F0;

  --color-primary: #1E40AF;
  --color-primary-contrast: #FFFFFF;
  --color-accent: #059669;
  --color-accent-contrast: #FFFFFF;

  --color-status-overdue: #DC2626;
  --color-status-dueSoon: #B45309;
  --color-status-normal: #059669;
  --color-status-paid: #94A3B8;

  --shadow-card: 0 1px 2px rgba(15, 23, 42, 0.04), 0 1px 6px rgba(15, 23, 42, 0.04);
  --shadow-float: 0 8px 20px rgba(15, 23, 42, 0.18);
}

@media (prefers-color-scheme: dark) {
  :root {
    --color-bg: #0F172A;
    --color-surface: #192134;
    --color-surface-muted: #141B2C;
    --color-text: #F1F5F9;
    --color-text-muted: #94A3B8;
    --color-border: rgba(255, 255, 255, 0.08);

    --color-primary: #3B82F6;
    --color-primary-contrast: #0F172A;
    --color-accent: #10B981;
    --color-accent-contrast: #0F172A;

    --color-status-overdue: #F87171;
    --color-status-dueSoon: #FBBF24;
    --color-status-normal: #10B981;
    --color-status-paid: #64748B;

    --shadow-card: 0 1px 2px rgba(0, 0, 0, 0.3), 0 2px 8px rgba(0, 0, 0, 0.25);
    --shadow-float: 0 10px 24px rgba(0, 0, 0, 0.45);
  }
}

* { box-sizing: border-box; }

@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after {
    animation-duration: 0.01ms !important;
    transition-duration: 0.01ms !important;
  }
}

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

body {
  margin: 0;
  min-height: 100dvh;
  font-family: var(--font-sans);
  background: var(--color-bg);
  color: var(--color-text);
  font-size: 16px;
  line-height: 1.55;
  padding-bottom: calc(64px + env(safe-area-inset-bottom));
  transition: background var(--duration-normal) var(--ease-standard);
}

a { color: inherit; }

:focus-visible {
  outline: 2px solid var(--color-primary);
  outline-offset: 2px;
}

.page {
  padding: var(--space-5);
  padding-top: calc(var(--space-6) + env(safe-area-inset-top));
  max-width: 480px;
  margin: 0 auto;
}

h1 {
  font-size: 22px;
  font-weight: 700;
  letter-spacing: -0.02em;
  margin: 0 0 var(--space-4);
}
h2 {
  font-size: 14px;
  font-weight: 600;
  color: var(--color-text-muted);
  text-transform: uppercase;
  letter-spacing: 0.04em;
  margin: var(--space-5) 0 var(--space-2);
}

/* ============ 帳單卡片 ============ */
.bill-list { display: flex; flex-direction: column; gap: var(--space-2); }

.bill-card {
  display: block;
  padding: var(--space-3) var(--space-4);
  border-radius: var(--radius-md);
  background: var(--color-surface);
  box-shadow: var(--shadow-card);
  text-decoration: none;
  color: inherit;
  transition: transform var(--duration-fast) var(--ease-standard), box-shadow var(--duration-fast) var(--ease-standard);
}
.bill-card:active { transform: scale(0.98); }

.bill-card.status-paid { opacity: 0.6; }

.bill-card-main { display: flex; justify-content: space-between; align-items: baseline; gap: var(--space-2); }
.bill-card-name { font-weight: 600; font-size: 15px; }
.bill-card-amount { font-family: var(--font-number); font-variant-numeric: tabular-nums; font-weight: 600; }

.bill-card-meta { display: flex; justify-content: space-between; font-size: 13px; color: var(--color-text-muted); margin-top: var(--space-1); }
.bill-card-status { font-weight: 500; display: inline-flex; align-items: center; gap: 6px; }
.bill-card-status::before { content: ''; width: 7px; height: 7px; border-radius: 50%; background: currentColor; }
.status-overdue .bill-card-status { color: var(--color-status-overdue); }
.status-dueSoon .bill-card-status { color: var(--color-status-dueSoon); }
.status-normal .bill-card-status { color: var(--color-status-normal); }

.empty-hint { color: var(--color-text-muted); text-align: center; padding: var(--space-6) 0; font-size: 14px; }

/* 新增按鈕（浮動） */
.fab {
  position: fixed;
  right: var(--space-4);
  bottom: calc(76px + env(safe-area-inset-bottom));
  width: 52px;
  height: 52px;
  border-radius: 50%;
  background: var(--color-primary);
  color: var(--color-primary-contrast);
  display: flex;
  align-items: center;
  justify-content: center;
  text-decoration: none;
  box-shadow: var(--shadow-float);
  transition: transform var(--duration-fast) var(--ease-standard);
}
.fab:active { transform: scale(0.94); }
.fab svg { width: 24px; height: 24px; }

/* ============ 底部導覽列 ============ */
.bottom-nav {
  position: fixed;
  bottom: 0; left: 0; right: 0;
  display: flex;
  background: var(--color-surface);
  border-top: 1px solid var(--color-border);
  padding-bottom: env(safe-area-inset-bottom);
}
.nav-tab {
  flex: 1;
  min-height: 56px;
  display: flex;
  align-items: center;
  justify-content: center;
  text-decoration: none;
  color: var(--color-text-muted);
  font-size: 13px;
  font-weight: 500;
  transition: color var(--duration-fast) var(--ease-standard);
}
.nav-tab.active { color: var(--color-primary); font-weight: 700; }

/* ============ 表單 ============ */
form { display: flex; flex-direction: column; gap: var(--space-4); }
label { display: flex; flex-direction: column; gap: var(--space-1); font-size: 13px; font-weight: 500; color: var(--color-text-muted); }

input, select {
  min-height: 44px;
  padding: 0 var(--space-3);
  border-radius: var(--radius-sm);
  border: 1px solid var(--color-border);
  background: var(--color-surface);
  color: var(--color-text);
  font-size: 16px;
  font-family: inherit;
}
input:focus, select:focus { border-color: var(--color-primary); }

button {
  min-height: 48px;
  padding: 0 var(--space-4);
  border-radius: var(--radius-sm);
  border: none;
  background: var(--color-primary);
  color: var(--color-primary-contrast);
  font-size: 16px;
  font-weight: 600;
  cursor: pointer;
  transition: opacity var(--duration-fast) var(--ease-standard), transform var(--duration-fast) var(--ease-standard);
}
button:active { transform: scale(0.98); opacity: 0.9; }
button.danger { background: var(--color-status-overdue); }
button.secondary { background: transparent; color: var(--color-text-muted); border: 1px solid var(--color-border); }

.error { color: var(--color-status-overdue); font-size: 13px; min-height: 1.2em; }
.hint { color: var(--color-text-muted); font-size: 13px; }

/* ============ PIN / Google 登入鎖畫面 ============ */
.pin-lock {
  min-height: 100dvh;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: var(--space-3);
  padding: var(--space-5);
  text-align: center;
}
.pin-lock input {
  width: 160px;
  text-align: center;
  letter-spacing: 0.5em;
  font-size: 20px;
}
.auth-hint { color: var(--color-text-muted); font-size: 14px; }

/* ============ 年度總覽 ============ */
.yearly-total {
  display: flex;
  justify-content: space-between;
  align-items: baseline;
  background: var(--color-surface);
  box-shadow: var(--shadow-card);
  padding: var(--space-4);
  border-radius: var(--radius-md);
}
.yearly-total span { color: var(--color-text-muted); font-size: 14px; }
.yearly-total strong { font-family: var(--font-number); font-variant-numeric: tabular-nums; font-size: 26px; color: var(--color-accent); }

.yearly-list { display: flex; flex-direction: column; gap: var(--space-1); }
.yearly-row {
  display: flex;
  justify-content: space-between;
  background: var(--color-surface);
  box-shadow: var(--shadow-card);
  padding: var(--space-3) var(--space-4);
  border-radius: var(--radius-sm);
  font-size: 14px;
}
.yearly-row span:last-child { font-family: var(--font-number); font-variant-numeric: tabular-nums; font-weight: 600; }

/* ============ 設定頁 ============ */
section { margin-bottom: var(--space-5); display: flex; flex-direction: column; gap: var(--space-3); }
.switch-row {
  flex-direction: row;
  justify-content: space-between;
  align-items: center;
  min-height: 44px;
  font-size: 15px;
  color: var(--color-text);
}
.switch-row input[type="checkbox"] { width: 44px; height: 26px; accent-color: var(--color-primary); }

/* 手機螢幕窄，4 欄擠在一起會太小、字被裁切，改成兩欄堆疊 */
.source-row {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: var(--space-2);
  margin-bottom: var(--space-3);
  padding: var(--space-3);
  background: var(--color-surface);
  border-radius: var(--radius-sm);
}
.source-row .source-sender { grid-column: 1 / -1; }
.source-row .remove-source-btn { grid-column: 1 / -1; }
.remove-source-btn { background: var(--color-surface-muted); color: var(--color-text-muted); min-height: 44px; }