/* 樹洞回聲：學生端。溫暖、像手寫信紙與午後樹蔭，不像表單。行動裝置優先。 */
:root {
  --bg: #f8efe1;          /* 奶茶色紙張 */
  --bg-glow: #fbe3c4;     /* 午後陽光 */
  --card: #fffaf2;
  --ink: #4a3a2e;         /* 深咖啡字 */
  --ink-soft: #7d6857;
  --line: #ead9c2;
  --rule: #f0e2cf;        /* 信紙橫線 */
  --accent: #c8714a;      /* 陶土橘 */
  --accent-ink: #fff8f0;
  --accent-soft: #f6dcc8;
  --moss: #7f9a6a;        /* 苔綠 */
  --moss-soft: #eef3ea;
  --on-moss: #fffdf6;
  --honey: #e8b562;
  --shadow: 0 1px 0 rgba(120, 84, 50, .06), 0 8px 24px -12px rgba(120, 84, 50, .28);
  --radius: 18px;
  --serif: "Noto Serif TC", "Source Han Serif TC", "Songti TC", "PMingLiU", serif;
  --sans: "Noto Sans TC", "PingFang TC", "Microsoft JhengHei", system-ui, sans-serif;
  color-scheme: light;
}
@media (prefers-color-scheme: dark) {
  :root {
    --bg: #2a211b;        /* 夜裡的樹洞，仍帶暖意 */
    --bg-glow: #3a2a1f;
    --card: #33281f;
    --ink: #f3e6d6;
    --ink-soft: #c8b39d;
    --line: #4a3a2d;
    --rule: #40332a;
    --accent: #e39a6f;
    --accent-ink: #2a1b12;
    --accent-soft: #4a3226;
    --moss: #a9c18f;
    --moss-soft: #34392a;
    --on-moss: #1f2617;
    --honey: #e8b562;
    --shadow: 0 8px 24px -14px rgba(0, 0, 0, .7);
    color-scheme: dark;
  }
}

* { box-sizing: border-box; }
html { -webkit-text-size-adjust: 100%; scroll-behavior: smooth; }
body {
  margin: 0;
  background:
    radial-gradient(120% 60% at 50% -10%, var(--bg-glow), transparent 70%),
    var(--bg);
  background-attachment: fixed;
  color: var(--ink);
  font: 17px/1.8 var(--sans);
  letter-spacing: .02em;
}
.page { max-width: 600px; margin: 0 auto; padding: 0 16px 48px; }
[hidden] { display: none !important; }
.visually-hidden { position: absolute; width: 1px; height: 1px; overflow: hidden; clip: rect(0 0 0 0); white-space: nowrap; }

/* ---------- 頁首 ---------- */
.masthead { text-align: center; padding: 12px 0 20px; }
.topbar { display: flex; align-items: center; justify-content: flex-end; gap: 12px; margin-bottom: 12px; }
.help-link {
  font-size: 14px; color: var(--ink-soft); text-decoration: none;
  padding: 4px 12px; border: 1px solid var(--line); border-radius: 999px; background: var(--card);
}
.help-link:hover { color: var(--accent); border-color: var(--accent); }
.mark { width: 150px; height: 125px; display: block; margin: 0 auto 4px; }
.mark .ground { fill: var(--line); opacity: .7; }
.mark .leaf { fill: var(--moss); }
.mark .l1 { opacity: .78; }
.mark .l2 { opacity: .85; }
.mark .l3 { fill: #98b07f; }
.mark .l4 { opacity: .92; }
.mark .fruit { fill: var(--honey); }
.mark .trunk { fill: #a8714e; }
.mark .hollow { fill: #4a2f20; }
.mark .echo { fill: none; stroke: var(--honey); stroke-width: 3; stroke-linecap: round; animation: echo 3.6s ease-in-out infinite; }
.mark .e2 { animation-delay: .5s; opacity: .7; }
.mark .e3 { animation-delay: 1s; opacity: .45; }
@keyframes echo { 0%, 100% { opacity: .15; } 40% { opacity: 1; } }
@media (prefers-reduced-motion: reduce) { .mark .echo { animation: none; } }
/* 橢圓形淡出：像從樹洞往外看；中心偏左下，讓女孩與兔子保持清楚 */
.hero { margin: 0 -16px 6px; --hero-mask: radial-gradient(ellipse 56% 63% at 45% 57%, #000 46%, rgba(0, 0, 0, .5) 72%, transparent 96%); }
.hero img {
  display: block; width: 100%; height: auto; aspect-ratio: 3 / 2; object-fit: cover; background: var(--bg-glow);
  -webkit-mask-image: var(--hero-mask);
  mask-image: var(--hero-mask);
}
@media (min-width: 632px) {
  .hero { margin: 0 0 6px; }
  .hero img { border-radius: 0; }
}
@media (prefers-color-scheme: dark) { .hero img { filter: brightness(.88) saturate(.95); } }
h1 { margin: 10px 0 14px; font: 600 26px/1.55 var(--serif); letter-spacing: .06em; }
.test-note {
  display: inline-block; margin: 0; padding: 6px 14px; font-size: 13px; line-height: 1.6;
  color: var(--ink-soft); background: var(--card); border: 1px dashed var(--line); border-radius: 12px;
}

/* ---------- 共用 ---------- */
.view, .help {
  background: var(--card); border: 1px solid var(--line); border-radius: var(--radius);
  box-shadow: var(--shadow); padding: 26px 22px; margin-top: 18px;
}
.title { margin: 0 0 12px; font: 600 21px/1.5 var(--serif); letter-spacing: .05em; }
.title.small { font-size: 18px; }
.prose p { margin: 0 0 12px; }
.prose ul { margin: 0 0 12px; padding: 0; list-style: none; }
.prose li { position: relative; padding-left: 22px; margin-bottom: 10px; }
.prose li::before {
  content: ""; position: absolute; left: 4px; top: .72em; width: 8px; height: 8px;
  border-radius: 50% 50% 50% 0; background: var(--moss); transform: rotate(-45deg);  /* 小葉子 */
}
.prose strong { color: var(--ink); font-weight: 700; background: linear-gradient(transparent 62%, var(--accent-soft) 62%); }
.prose a { color: var(--accent); font-weight: 700; text-underline-offset: 3px; }
.hint { color: var(--ink-soft); font-size: 14.5px; margin: 8px 0; }
.hint.small { font-size: 13.5px; }
.lede { margin: 0 0 16px; color: var(--ink-soft); }
.note { color: var(--ink-soft); font-size: 15px; }

.notice {
  margin: 16px 0 0; padding: 12px 16px; border-radius: 14px;
  background: var(--moss-soft); color: var(--ink); border: 1px solid var(--line); font-size: 15px;
}
.notice-pause { background: var(--accent-soft); border-color: var(--accent); }

/* ---------- 按鈕 ---------- */
.btn {
  font: 600 16px/1 var(--sans); letter-spacing: .06em; cursor: pointer;
  border-radius: 999px; padding: 14px 24px; border: 1.5px solid transparent;
  transition: transform .12s ease, background-color .2s ease, box-shadow .2s ease;
}
.btn:active { transform: translateY(1px) scale(.99); }
.btn:disabled { opacity: .45; cursor: not-allowed; transform: none; }
.btn-primary { background: var(--accent); color: var(--accent-ink); box-shadow: 0 6px 16px -8px var(--accent); }
.btn-primary:hover:not(:disabled) { filter: brightness(1.05); }
.btn-outline { background: transparent; color: var(--ink); border-color: var(--line); }
.btn-outline:hover { border-color: var(--accent); color: var(--accent); }
.btn-wide { display: block; width: 100%; margin-top: 14px; }
.btn-ceremony {
  display: block; width: 100%; padding: 16px; font-family: var(--serif); font-size: 17px;
  background: var(--moss); color: var(--on-moss); box-shadow: 0 6px 16px -8px var(--moss);
}
.btn-text {
  background: none; border: 0; padding: 4px 0; cursor: pointer; font: 15px/1.6 var(--sans);
  color: var(--ink-soft); text-decoration: underline; text-underline-offset: 4px; text-decoration-color: var(--line);
}
.btn-text:hover { color: var(--accent); }
button:focus-visible, a:focus-visible, input:focus-visible, textarea:focus-visible, summary:focus-visible {
  outline: 3px solid var(--honey); outline-offset: 2px;
}
.actions { display: flex; gap: 10px; flex-wrap: wrap; margin-top: 14px; }
.actions .btn { flex: 1 1 140px; }

/* ---------- 加入 ---------- */
.consent {
  display: flex; gap: 12px; align-items: flex-start; margin-top: 18px; padding: 14px 16px;
  background: var(--bg); border-radius: 14px; cursor: pointer; font-size: 16px;
}
.consent input { width: 20px; height: 20px; margin-top: 5px; accent-color: var(--accent); flex: none; }
.recover { margin-top: 20px; border-top: 1px dashed var(--line); padding-top: 14px; }
.recover summary { cursor: pointer; color: var(--ink-soft); font-size: 15px; }
.recover form { display: grid; gap: 8px; margin-top: 12px; }
.recover label { font-size: 14px; color: var(--ink-soft); }
input:not([type=checkbox]) {
  font: 18px/1.4 ui-monospace, "Cascadia Mono", Menlo, monospace; letter-spacing: .12em;
  padding: 12px 14px; border: 1.5px solid var(--line); border-radius: 12px; background: var(--bg); color: var(--ink);
}

/* ---------- 領信碼 ---------- */
.claim-code {
  margin: 18px 0 6px; padding: 18px 12px; text-align: center;
  font: 700 32px/1.2 ui-monospace, "Cascadia Mono", Menlo, monospace; letter-spacing: .18em;
  background: var(--bg); border: 2px dashed var(--accent); border-radius: 16px; color: var(--ink);
  user-select: all;
}

/* ---------- 分頁 ---------- */
.tabs {
  display: grid; grid-auto-flow: column; grid-auto-columns: 1fr; gap: 4px; padding: 5px; margin-bottom: 22px;
  background: var(--bg); border-radius: 999px; border: 1px solid var(--line);
}
.tabs button {
  position: relative; border: 0; background: none; cursor: pointer; padding: 10px 2px; border-radius: 999px; min-width: 0;
  white-space: nowrap; font: 600 14.5px/1.2 var(--serif); letter-spacing: 0; color: var(--ink-soft); transition: background-color .2s, color .2s;
}
.tabs button[aria-selected=true] { background: var(--card); color: var(--accent); box-shadow: 0 2px 8px -4px rgba(120, 84, 50, .45); }
.badge.dot { min-width: 8px; width: 8px; height: 8px; padding: 0; vertical-align: 6px; }
.btn-link { text-align: center; text-decoration: none; }
.badge {
  display: inline-block; min-width: 18px; height: 18px; margin-left: 4px; padding: 0 5px; border-radius: 9px;
  background: var(--accent); color: var(--accent-ink); font: 700 11px/18px var(--sans); vertical-align: 2px;
}

/* ---------- 信紙 ---------- */
textarea, .paper {
  display: block; width: 100%; min-height: 220px; resize: vertical; padding: 6px 16px 10px;
  font: 17px/34px var(--serif); color: var(--ink); letter-spacing: .03em;
  border: 1px solid var(--line); border-radius: 14px;
  background-color: var(--card);
  background-image: linear-gradient(var(--card) 33px, var(--rule) 33px, var(--rule) 34px);
  background-size: 100% 34px; background-attachment: local; background-position: 0 6px;
}
textarea::placeholder { color: var(--ink-soft); opacity: .6; }
.under-paper { display: flex; align-items: center; justify-content: space-between; gap: 12px; margin-top: 12px; flex-wrap: wrap; }
.count { font-size: 14px; color: var(--ink-soft); font-variant-numeric: tabular-nums; }
.count.warn { color: var(--accent); font-weight: 700; }

/* ---------- 心事、題目、回聲 ---------- */
.status {
  display: inline-block; margin: 0 0 10px; padding: 3px 12px; font-size: 14px; border-radius: 999px;
  background: var(--moss-soft); color: var(--ink);
}
.status.rejected, .status.needs_edit { background: var(--accent-soft); }
.quote {
  margin: 0 0 12px; padding: 14px 18px; font: 16.5px/1.85 var(--serif); white-space: pre-wrap;
  background: var(--bg); border-radius: 4px 14px 14px 14px; border-left: 3px solid var(--honey);
}
#assignments { margin-top: 18px; display: grid; gap: 18px; }
#assignments article { padding: 18px 16px; border-radius: 16px; background: var(--bg); border: 1px solid var(--line); }
#assignments article .quote { background: var(--card); }
#assignments h3 { margin: 0 0 10px; font: 600 17px/1.4 var(--serif); display: flex; gap: 10px; align-items: center; flex-wrap: wrap; }
.tag { font: 500 12.5px/1 var(--sans); padding: 5px 10px; border-radius: 999px; background: var(--moss-soft); color: var(--ink-soft); }
.deadline { font-size: 14px; color: var(--ink-soft); margin: 0 0 10px; }
.feedback { font-size: 15px; padding: 10px 14px; border-radius: 12px; background: var(--moss-soft); }
.task-actions { display: flex; align-items: center; justify-content: space-between; gap: 12px; margin-top: 12px; flex-wrap: wrap; }

#inbox { display: grid; gap: 16px; margin-bottom: 16px; }
.letter {
  position: relative; margin: 0; padding: 22px 20px 20px; white-space: pre-wrap;
  font: 17px/1.9 var(--serif); background: var(--card); border: 1px solid var(--line);
  border-radius: 6px 18px 18px 18px; box-shadow: var(--shadow);
}
.letter::before {
  content: "回聲"; position: absolute; top: -11px; left: 16px; padding: 2px 10px; border-radius: 999px;
  font: 600 12px/1.6 var(--serif); letter-spacing: .2em; background: var(--honey); color: #3b2a1a;
}

/* ---------- 離開 ---------- */
.leave { margin-top: 36px; padding-top: 24px; border-top: 1px dashed var(--line); text-align: center; }
.leave .hint { margin-bottom: 0; }
.regret { margin-top: 26px; padding-top: 16px; border-top: 1px solid var(--rule); }
.regret .hint { margin: 2px 0 0; }

/* ---------- 求助（固定在最後） ---------- */
.help { background: var(--moss-soft); border-color: transparent; scroll-margin-top: 16px; }
.help .prose { font-size: 16px; }

.signoff { margin: 28px 8px 0; text-align: center; font: 15px/1.9 var(--serif); color: var(--ink-soft); letter-spacing: .06em; }

/* ---------- 訊息 ---------- */
#msg {
  position: fixed; left: 50%; bottom: 20px; transform: translateX(-50%); z-index: 5;
  max-width: calc(100% - 32px); margin: 0; padding: 12px 20px; border-radius: 14px;
  background: var(--ink); color: var(--bg); font-size: 15px; box-shadow: var(--shadow);
}
#msg:empty { display: none; }

@media (min-width: 600px) {
  h1 { font-size: 30px; }
  .view, .help { padding: 32px 34px; }
}