/* Hle Solve · AI 解題室 — 自訂設計系統（手機優先，無框架相依）
   配色：深青綠 primary + 琥珀 accent + 暖中性色，避免 indigo/purple 範本感。 */

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

:root {
  --c-primary: #0f766e;
  --c-primary-dark: #115e59;
  --c-primary-light: #ccfbf1;
  --c-accent: #d97706;
  --c-accent-light: #fef3c7;
  --c-bg: #f8fafc;
  --c-surface: #ffffff;
  --c-text: #1e293b;
  --c-text-muted: #64748b;
  --c-border: #e2e8f0;
  --c-error: #dc2626;
  --c-error-bg: #fef2f2;
  --c-success: #15803d;
  --c-warning: #b45309;
  --radius: 14px;
  --radius-sm: 9px;
  --shadow: 0 1px 3px rgba(15, 23, 42, .08), 0 4px 14px rgba(15, 23, 42, .06);
  --shadow-lg: 0 8px 30px rgba(15, 23, 42, .14);
  --maxw: 720px;
  --header-h: 60px;
}

html, body {
  margin: 0;
  padding: 0;
  background: var(--c-bg);
  color: var(--c-text);
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "Noto Sans TC", "PingFang TC", "Microsoft JhengHei", sans-serif;
  font-size: 16px;
  line-height: 1.6;
  -webkit-text-size-adjust: 100%;
}

body {
  overflow-x: hidden; /* 防水平溢出 */
  min-height: 100vh;
  display: flex;
  flex-direction: column;
}

img, video, canvas { max-width: 100%; height: auto; display: block; }

button { font-family: inherit; cursor: pointer; }
input, textarea { font-family: inherit; font-size: 16px; }

.hidden { display: none !important; }
.muted { color: var(--c-text-muted); }
.small { font-size: .85rem; }

.skip-link {
  position: absolute; left: -9999px; top: 0; background: var(--c-primary); color: #fff;
  padding: 8px 14px; z-index: 100; border-radius: 0 0 8px 0;
}
.skip-link:focus { left: 0; }

/* ---------- Header ---------- */
.app-header {
  position: sticky; top: 0; z-index: 50;
  height: var(--header-h);
  display: flex; align-items: center; justify-content: space-between;
  padding: 0 16px;
  background: rgba(255,255,255,.92);
  backdrop-filter: saturate(180%) blur(10px);
  border-bottom: 1px solid var(--c-border);
}
.brand { display: flex; align-items: center; gap: 10px; }
.brand-text h1 { margin: 0; font-size: 1.15rem; line-height: 1.15; color: var(--c-primary-dark); letter-spacing: .02em; }
.brand-sub { font-size: .78rem; color: var(--c-text-muted); }
.header-right { display: flex; align-items: center; gap: 10px; }

.pill {
  font-size: .78rem; padding: 4px 10px; border-radius: 999px; font-weight: 600;
  border: 1px solid transparent; white-space: nowrap;
}
.pill-muted { background: #f1f5f9; color: var(--c-text-muted); }
.pill-ok { background: #dcfce7; color: var(--c-success); border-color: #bbf7d0; }
.pill-warn { background: var(--c-accent-light); color: var(--c-warning); border-color: #fde68a; }
.pill-bad { background: var(--c-error-bg); color: var(--c-error); border-color: #fecaca; }

.icon-btn {
  width: 38px; height: 38px; border-radius: 50%; border: 1px solid var(--c-border);
  background: var(--c-surface); color: var(--c-text); display: grid; place-items: center;
}
.icon-btn:hover { background: var(--c-primary-light); border-color: var(--c-primary); color: var(--c-primary-dark); }

/* ---------- Main / Views ---------- */
.app-main {
  flex: 1;
  width: 100%;
  max-width: var(--maxw);
  margin: 0 auto;
  padding: 18px 16px 40px;
}
.view { animation: fadeIn .25s ease; }
@keyframes fadeIn { from { opacity: 0; transform: translateY(6px); } to { opacity: 1; transform: none; } }

.view-head {
  display: flex; align-items: center; gap: 10px; margin-bottom: 14px; flex-wrap: wrap;
}
.view-head h2 { margin: 0; font-size: 1.3rem; flex: 1; min-width: 0; }

/* ---------- Buttons ---------- */
.btn-primary, .btn-secondary, .btn-ghost, .btn-danger, .btn-danger-outline {
  border: none; border-radius: var(--radius-sm); padding: 10px 18px;
  font-size: .95rem; font-weight: 600; transition: transform .08s ease, box-shadow .15s ease, background .15s;
}
.btn-primary { background: var(--c-primary); color: #fff; box-shadow: 0 2px 8px rgba(15,118,110,.3); }
.btn-primary:hover { background: var(--c-primary-dark); }
.btn-primary:active { transform: scale(.97); }
.btn-primary:disabled { background: #94a3b8; box-shadow: none; cursor: not-allowed; }
.btn-secondary { background: var(--c-primary-light); color: var(--c-primary-dark); border: 1px solid #99f6e4; }
.btn-secondary:hover { background: #99f6e4; }
.btn-ghost { background: transparent; color: var(--c-text-muted); border: 1px solid var(--c-border); }
.btn-ghost:hover { color: var(--c-text); border-color: #cbd5e1; }
.btn-danger { background: var(--c-error); color: #fff; }
.btn-danger-outline { background: transparent; color: var(--c-error); border: 1px solid #fecaca; }
.btn-danger-outline:hover { background: var(--c-error-bg); }
.btn-shutter { width: 64px; height: 64px; border-radius: 50%; padding: 0; font-size: .85rem; }

/* ---------- Home / Hero / Entries ---------- */
.hero { text-align: center; padding: 14px 4px 22px; }
.hero h2 { margin: 0 0 8px; font-size: 1.55rem; line-height: 1.35; color: var(--c-primary-dark); }
.hero-desc { margin: 0; color: var(--c-text-muted); font-size: .98rem; }

.entry-grid {
  display: grid; grid-template-columns: repeat(2, 1fr); gap: 12px; margin-bottom: 20px;
}
.entry-card {
  display: flex; flex-direction: column; align-items: flex-start; gap: 6px;
  background: var(--c-surface); border: 1px solid var(--c-border); border-radius: var(--radius);
  padding: 16px 14px; text-align: left; box-shadow: var(--shadow); transition: transform .1s, box-shadow .15s, border-color .15s;
  color: var(--c-text);
}
.entry-card:hover { transform: translateY(-2px); box-shadow: var(--shadow-lg); border-color: var(--c-primary); }
.entry-card:active { transform: translateY(0); }
.entry-icon {
  width: 44px; height: 44px; border-radius: 12px; display: grid; place-items: center;
  background: var(--c-primary-light); color: var(--c-primary-dark); margin-bottom: 4px;
}
.entry-title { font-weight: 700; font-size: 1rem; }
.entry-hint { font-size: .8rem; color: var(--c-text-muted); }

.home-note {
  background: var(--c-accent-light); border: 1px solid #fde68a; border-radius: var(--radius-sm);
  padding: 12px 14px; font-size: .85rem; color: var(--c-warning); margin: 0;
}

/* ---------- Capture ---------- */
.camera-stage { position: relative; border-radius: var(--radius); overflow: hidden; background: #0f172a; margin-bottom: 14px; }
.camera-stage video { width: 100%; aspect-ratio: 4/3; object-fit: cover; }
.camera-controls { position: absolute; bottom: 12px; left: 0; right: 0; display: flex; justify-content: center; align-items: center; gap: 14px; }

.drop-zone {
  border: 2px dashed #94a3b8; border-radius: var(--radius); padding: 28px 18px; text-align: center;
  color: var(--c-text-muted); background: var(--c-surface); cursor: pointer; transition: border-color .15s, background .15s;
}
.drop-zone:hover, .drop-zone.dragover, .drop-zone:focus { border-color: var(--c-primary); background: #f0fdfa; outline: none; }
.drop-zone p { margin: 6px 0; }
.drop-zone strong { color: var(--c-primary-dark); }

.preview-stage { margin-top: 14px; }
.preview-wrap { position: relative; border-radius: var(--radius); overflow: hidden; border: 1px solid var(--c-border); background: #0f172a; }
.preview-wrap img { width: 100%; max-height: 60vh; object-fit: contain; margin: 0 auto; background: #0f172a; }
.preview-actions { display: flex; flex-wrap: wrap; gap: 10px; margin-top: 12px; }
.preview-actions .btn-primary { margin-left: auto; }

.error-text { color: var(--c-error); background: var(--c-error-bg); border: 1px solid #fecaca; border-radius: var(--radius-sm); padding: 10px 12px; font-size: .9rem; margin: 10px 0 0; }

/* ---------- Review ---------- */
.review-layout { display: grid; grid-template-columns: 1fr; gap: 14px; }
.review-image { position: relative; border-radius: var(--radius); overflow: hidden; border: 1px solid var(--c-border); background: #0f172a; min-height: 140px; }
.review-image img { width: 100%; margin: 0 auto; }
.bbox-layer { position: absolute; inset: 0; pointer-events: none; }
.bbox-box {
  position: absolute; border: 2px solid #fbbf24; background: rgba(251,191,36,.18);
  border-radius: 4px; pointer-events: auto; cursor: pointer; transition: background .1s;
}
.bbox-box:hover, .bbox-box.active { background: rgba(20,184,166,.3); border-color: #14b8a6; }
.bbox-label { position: absolute; top: -10px; left: -2px; background: #fbbf24; color: #1c1917; font-size: .7rem; font-weight: 700; padding: 1px 6px; border-radius: 4px; }
#review-image-placeholder { padding: 26px 16px; text-align: center; margin: 0; }

.review-toolbar { display: flex; gap: 10px; margin-bottom: 10px; flex-wrap: wrap; }
.review-toolbar .btn-primary { margin-left: auto; }

.question-list { list-style: none; margin: 0; padding: 0; display: flex; flex-direction: column; gap: 10px; }
.question-card {
  background: var(--c-surface); border: 1px solid var(--c-border); border-radius: var(--radius-sm);
  padding: 12px; box-shadow: var(--shadow);
}
.question-card.active { border-color: var(--c-primary); box-shadow: 0 0 0 3px var(--c-primary-light); }
.qc-head { display: flex; align-items: center; gap: 8px; margin-bottom: 6px; flex-wrap: wrap; }
.qc-num { font-weight: 700; color: var(--c-primary-dark); background: var(--c-primary-light); border-radius: 6px; padding: 1px 8px; font-size: .85rem; }
.qc-conf { font-size: .75rem; color: var(--c-text-muted); }
.qc-conf.low { color: var(--c-warning); font-weight: 600; }
.qc-actions { margin-left: auto; display: flex; gap: 6px; }
.qc-actions button { border: 1px solid var(--c-border); background: #fff; border-radius: 6px; padding: 3px 8px; font-size: .78rem; color: var(--c-text-muted); }
.qc-actions button:hover { color: var(--c-error); border-color: #fecaca; }
.qc-text { width: 100%; border: 1px solid var(--c-border); border-radius: 6px; padding: 8px 10px; font-size: .95rem; resize: vertical; min-height: 44px; }
.qc-text:focus { outline: 2px solid var(--c-primary); border-color: transparent; }
.qc-solve-one { margin-top: 8px; }

/* ---------- Solutions ---------- */
.progress-bar-wrap { position: relative; height: 34px; background: #e2e8f0; border-radius: 999px; overflow: hidden; margin-bottom: 14px; }
.progress-bar { height: 100%; width: 0%; background: linear-gradient(90deg, var(--c-primary), #14b8a6); transition: width .3s ease; }
.progress-text { position: absolute; inset: 0; display: grid; place-items: center; font-size: .82rem; font-weight: 600; color: #0f172a; }

.solution-list { display: flex; flex-direction: column; gap: 14px; }
.solution-card { background: var(--c-surface); border: 1px solid var(--c-border); border-radius: var(--radius); padding: 14px; box-shadow: var(--shadow); }
.solution-card .s-head { display: flex; align-items: center; gap: 8px; margin-bottom: 8px; flex-wrap: wrap; }
.s-status { font-size: .75rem; font-weight: 700; padding: 2px 8px; border-radius: 999px; }
.s-status.pending { background: #f1f5f9; color: var(--c-text-muted); }
.s-status.loading { background: var(--c-accent-light); color: var(--c-warning); }
.s-status.done { background: #dcfce7; color: var(--c-success); }
.s-status.failed { background: var(--c-error-bg); color: var(--c-error); }
.s-question { font-weight: 600; margin: 0 0 8px; word-break: break-word; }
.s-steps { padding-left: 20px; margin: 8px 0; }
.s-steps li { margin-bottom: 6px; }
.s-final { background: var(--c-primary-light); border-left: 4px solid var(--c-primary); padding: 10px 12px; border-radius: 0 8px 8px 0; font-weight: 700; margin-top: 8px; }
.s-verify { font-size: .85rem; color: var(--c-text-muted); margin-top: 6px; }
.s-card-actions { display: flex; gap: 8px; margin-top: 10px; flex-wrap: wrap; }
.s-card-actions button { font-size: .82rem; padding: 6px 12px; }

/* ---------- Grade ---------- */
.grade-items { display: flex; flex-direction: column; gap: 12px; margin: 12px 0; }
.grade-item { background: var(--c-surface); border: 1px solid var(--c-border); border-radius: var(--radius-sm); padding: 12px; }
.grade-item label { display: block; font-size: .82rem; font-weight: 600; color: var(--c-text-muted); margin: 8px 0 4px; }
.grade-item textarea { width: 100%; border: 1px solid var(--c-border); border-radius: 6px; padding: 8px 10px; font-size: .92rem; resize: vertical; min-height: 40px; }
.grade-item textarea:focus { outline: 2px solid var(--c-primary); border-color: transparent; }
.grade-actions { display: flex; gap: 10px; flex-wrap: wrap; }
.grade-actions .btn-primary { margin-left: auto; }
.grade-results { margin-top: 14px; display: flex; flex-direction: column; gap: 10px; }
.g-result { background: var(--c-surface); border: 1px solid var(--c-border); border-radius: var(--radius-sm); padding: 12px; }
.g-verdict { font-weight: 700; }
.g-verdict.correct { color: var(--c-success); }
.g-verdict.partial { color: var(--c-warning); }
.g-verdict.wrong { color: var(--c-error); }
.g-verdict.manual { color: var(--c-text-muted); }

/* ---------- Calculator ---------- */
.calc-display {
  background: #0f172a; color: #f8fafc; border-radius: var(--radius-sm); padding: 14px 16px;
  font-size: 1.3rem; font-family: "SF Mono", ui-monospace, Menlo, Consolas, monospace;
  min-height: 54px; word-break: break-all; margin-bottom: 10px; text-align: right; overflow-wrap: anywhere;
}
.calc-input {
  width: 100%; border: 1px solid var(--c-border); border-radius: var(--radius-sm);
  padding: 10px 12px; font-size: 1.05rem; margin-bottom: 10px;
}
.calc-input:focus { outline: 2px solid var(--c-primary); border-color: transparent; }
.calc-keypad { display: grid; grid-template-columns: repeat(5, 1fr); gap: 8px; margin-bottom: 10px; }
.calc-key {
  border: 1px solid var(--c-border); background: var(--c-surface); border-radius: var(--radius-sm);
  padding: 12px 4px; font-size: 1.05rem; font-weight: 600; color: var(--c-text);
}
.calc-key:hover { background: var(--c-primary-light); border-color: var(--c-primary); color: var(--c-primary-dark); }
.calc-actions { display: flex; gap: 10px; flex-wrap: wrap; }
.calc-actions .btn-primary { margin-left: auto; }
.calc-result { margin-top: 12px; }

/* ---------- History ---------- */
.history-toolbar { display: flex; gap: 10px; margin-bottom: 12px; flex-wrap: wrap; }
.history-toolbar input[type="search"] { flex: 1; min-width: 160px; border: 1px solid var(--c-border); border-radius: var(--radius-sm); padding: 9px 12px; }
.history-list { list-style: none; margin: 0; padding: 0; display: flex; flex-direction: column; gap: 10px; }
.history-item { background: var(--c-surface); border: 1px solid var(--c-border); border-radius: var(--radius-sm); padding: 12px; display: flex; gap: 10px; align-items: flex-start; }
.history-item .h-text { flex: 1; min-width: 0; }
.history-item .h-q { font-weight: 600; margin: 0 0 4px; word-break: break-word; }
.history-item .h-meta { font-size: .78rem; color: var(--c-text-muted); }
.history-item button { border: 1px solid #fecaca; background: #fff; color: var(--c-error); border-radius: 6px; padding: 4px 10px; font-size: .8rem; flex-shrink: 0; }

/* ---------- Modal / Queue ---------- */
.modal-backdrop {
  position: fixed; inset: 0; background: rgba(15,23,42,.55); z-index: 200;
  display: grid; place-items: center; padding: 20px;
}
.modal-card {
  background: var(--c-surface); border-radius: var(--radius); padding: 26px 22px;
  max-width: 340px; width: 100%; text-align: center; box-shadow: var(--shadow-lg);
}
.modal-card h3 { margin: 0 0 14px; color: var(--c-primary-dark); }
.queue-position { font-size: 1.1rem; font-weight: 700; margin: 10px 0 4px; }
.spinner {
  width: 36px; height: 36px; margin: 0 auto; border-radius: 50%;
  border: 3px solid #e2e8f0; border-top-color: var(--c-primary);
  animation: spin 1s linear infinite;
}
@keyframes spin { to { transform: rotate(360deg); } }

/* ---------- Toast ---------- */
.toast {
  position: fixed; left: 50%; bottom: 24px; transform: translateX(-50%);
  background: #0f172a; color: #fff; padding: 10px 18px; border-radius: 999px;
  font-size: .9rem; z-index: 300; box-shadow: var(--shadow-lg); max-width: 90vw; text-align: center;
}

/* ---------- Footer ---------- */
.app-footer { text-align: center; padding: 18px 16px 28px; color: var(--c-text-muted); font-size: .8rem; border-top: 1px solid var(--c-border); }
.app-footer p { margin: 0; }

/* ---------- Responsive ---------- */
@media (min-width: 640px) {
  .entry-grid { grid-template-columns: repeat(3, 1fr); }
  .review-layout { grid-template-columns: 1.1fr 1fr; align-items: start; }
  .hero h2 { font-size: 1.9rem; }
}
@media (min-width: 900px) {
  :root { --maxw: 960px; }
  .entry-grid { grid-template-columns: repeat(6, 1fr); }
  .entry-card { padding: 14px 10px; }
  .entry-title { font-size: .92rem; }
  .entry-hint { font-size: .72rem; }
}

/* 觸控裝置：避免 hover 卡住 */
@media (hover: none) {
  .entry-card:hover { transform: none; }
}

.link-btn { background: none; border: none; color: var(--c-primary); text-decoration: underline; font-size: .82rem; padding: 0; cursor: pointer; }
.link-btn:hover { color: var(--c-primary-dark); }

/* 尊重減動效應偏好 */
@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after { animation-duration: .01ms !important; transition-duration: .01ms !important; }
}

/* ---------- 離線橫幅 ---------- */
.offline-banner {
  background: #7f1d1d; color: #fee2e2; text-align: center; padding: 8px 14px;
  font-size: .88rem; font-weight: 600; position: sticky; top: var(--header-h); z-index: 40;
}

/* ---------- 首頁：運作步驟 ---------- */
.how-section, .subjects-section { margin-top: 26px; }
.how-section h3, .subjects-section h3 { margin: 0 0 12px; font-size: 1.1rem; color: var(--c-primary-dark); }
.how-steps { list-style: none; margin: 0; padding: 0; display: flex; flex-direction: column; gap: 12px; }
.how-steps li { display: flex; gap: 12px; align-items: flex-start; background: var(--c-surface); border: 1px solid var(--c-border); border-radius: var(--radius-sm); padding: 12px 14px; }
.step-num { flex-shrink: 0; width: 30px; height: 30px; border-radius: 50%; background: var(--c-primary); color: #fff; display: grid; place-items: center; font-weight: 700; font-size: .95rem; }
.how-steps strong { display: block; font-size: .98rem; }
.how-steps p { margin: 2px 0 0; font-size: .85rem; color: var(--c-text-muted); }

.subject-chips { display: flex; flex-wrap: wrap; gap: 8px; margin-bottom: 8px; }
.subject-chips span { background: var(--c-surface); border: 1px solid var(--c-border); border-radius: 999px; padding: 5px 12px; font-size: .82rem; color: var(--c-text); }

/* ---------- 裁切覆層 ---------- */
.crop-overlay { position: absolute; inset: 0; background: rgba(15,23,42,.45); touch-action: none; }
.crop-box {
  position: absolute; left: 10%; top: 12%; width: 80%; height: 70%;
  border: 2px solid #fbbf24; background: rgba(0,0,0,0); cursor: move; touch-action: none;
}
.crop-handle { position: absolute; width: 22px; height: 22px; background: #fbbf24; border: 2px solid #fff; border-radius: 50%; z-index: 2; }
.crop-handle.tl { left: -11px; top: -11px; cursor: nwse-resize; }
.crop-handle.tr { right: -11px; top: -11px; cursor: nesw-resize; }
.crop-handle.bl { left: -11px; bottom: -11px; cursor: nesw-resize; }
.crop-handle.br { right: -11px; bottom: -11px; cursor: nwse-resize; }
.crop-hint { position: absolute; top: 8px; left: 50%; transform: translateX(-50%); background: rgba(15,23,42,.8); color: #fff; font-size: .78rem; padding: 4px 10px; border-radius: 999px; white-space: nowrap; }
.crop-actions { position: absolute; bottom: 10px; left: 0; right: 0; display: flex; justify-content: center; gap: 10px; }

@media (min-width: 640px) {
  .how-steps { display: grid; grid-template-columns: repeat(3, 1fr); }
}