/* 機器人學題庫練習 — 設計系統
 *
 * 不用 Bootstrap／FontAwesome CDN：PWA 離線時抓不到 CDN，整個介面會變成
 * 沒有樣式的裸 HTML，離線快取就白做了。字型用系統字，圖示用內嵌 SVG。
 */

/* ===== Design tokens ===== */

:root {
    /* 品牌色沿用原本的藍—青漸層，換皮但不換品牌識別 */
    --brand-1: #2f8bff;
    --brand-2: #00d2f0;
    --brand-gradient: linear-gradient(135deg, var(--brand-1), var(--brand-2));

    --success: #16a34a;
    --success-soft: #dcfce7;
    --danger: #dc2626;
    --danger-soft: #fee2e2;
    --warning: #d97706;
    --warning-soft: #fef3c7;

    /* 中性色。深色模式整組覆寫，元件不必各自處理 */
    --bg: #f4f6fa;
    --surface: #ffffff;
    --surface-2: #f8fafc;
    --border: #e3e8ef;
    --text: #16202e;
    --text-muted: #64748b;
    --shadow-sm: 0 1px 2px rgba(15, 30, 55, 0.06);
    --shadow: 0 4px 16px rgba(15, 30, 55, 0.08);
    --shadow-lg: 0 16px 48px rgba(15, 30, 55, 0.16);

    --radius-sm: 8px;
    --radius: 14px;
    --radius-lg: 22px;
    --radius-full: 999px;

    /* 4px 為基準的間距階梯 */
    --s1: 0.25rem; --s2: 0.5rem;  --s3: 0.75rem; --s4: 1rem;
    --s5: 1.5rem;  --s6: 2rem;    --s7: 3rem;

    --font: -apple-system, BlinkMacSystemFont, "Segoe UI", "Noto Sans TC",
            "PingFang TC", "Microsoft JhengHei", Roboto, sans-serif;

    /* iPhone 瀏海與底部橫條的安全區 */
    --safe-top: env(safe-area-inset-top, 0px);
    --safe-bottom: env(safe-area-inset-bottom, 0px);
}

@media (prefers-color-scheme: dark) {
    :root:not([data-theme="light"]) {
        --bg: #0e141b;
        --surface: #161e29;
        --surface-2: #1c2735;
        --border: #2a3646;
        --text: #e8eef6;
        --text-muted: #94a3b8;
        --success-soft: #14321f;
        --danger-soft: #3a1a1a;
        --warning-soft: #362a12;
        --shadow-sm: 0 1px 2px rgba(0, 0, 0, 0.4);
        --shadow: 0 4px 16px rgba(0, 0, 0, 0.45);
        --shadow-lg: 0 16px 48px rgba(0, 0, 0, 0.6);
    }
}

/* 使用者手動切換時，data-theme 必須蓋過系統偏好 */
:root[data-theme="dark"] {
    --bg: #0e141b;
    --surface: #161e29;
    --surface-2: #1c2735;
    --border: #2a3646;
    --text: #e8eef6;
    --text-muted: #94a3b8;
    --success-soft: #14321f;
    --danger-soft: #3a1a1a;
    --warning-soft: #362a12;
    --shadow-sm: 0 1px 2px rgba(0, 0, 0, 0.4);
    --shadow: 0 4px 16px rgba(0, 0, 0, 0.45);
    --shadow-lg: 0 16px 48px rgba(0, 0, 0, 0.6);
}

/* ===== Reset ===== */

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

body {
    margin: 0;
    font-family: var(--font);
    font-size: 16px;
    line-height: 1.6;
    color: var(--text);
    background: var(--bg);
    -webkit-font-smoothing: antialiased;
    -webkit-tap-highlight-color: transparent;
}

h1, h2, h3, h4 { margin: 0; line-height: 1.3; font-weight: 700; }
h1 { font-size: 1.6rem; }
h2 { font-size: 1.3rem; }
h3 { font-size: 1.1rem; }
p  { margin: 0 0 var(--s3); }
img { max-width: 100%; display: block; }
button, input, select, textarea { font: inherit; color: inherit; }

.icon { width: 1.15em; height: 1.15em; fill: currentColor; flex: none; }
.icon-lg { width: 1.6em; height: 1.6em; }

/* ===== Layout ===== */

.wrap { max-width: 720px; margin: 0 auto; padding: var(--s4); }
.wrap-wide { max-width: 1180px; }

.stack   { display: flex; flex-direction: column; gap: var(--s4); }
.row     { display: flex; align-items: center; gap: var(--s3); }
.row-between { display: flex; align-items: center; justify-content: space-between; gap: var(--s3); }
.grow    { flex: 1; min-width: 0; }
.muted   { color: var(--text-muted); }
.small   { font-size: 0.875rem; }
.tiny    { font-size: 0.78rem; }
.center  { text-align: center; }
.hidden  { display: none !important; }

/* ===== Card ===== */

.card {
    background: var(--surface);
    border: 1px solid var(--border);
    border-radius: var(--radius);
    box-shadow: var(--shadow-sm);
    padding: var(--s4);
}

.card-flush { padding: 0; overflow: hidden; }

/* ===== Button ===== */

.btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: var(--s2);
    padding: 0.7rem 1.15rem;
    border: 1px solid transparent;
    border-radius: var(--radius-sm);
    background: var(--surface-2);
    color: var(--text);
    font-weight: 600;
    cursor: pointer;
    transition: transform 0.12s ease, filter 0.15s ease, background 0.15s ease;
    text-decoration: none;
}

.btn:hover:not(:disabled) { filter: brightness(0.97); }
.btn:active:not(:disabled) { transform: scale(0.98); }
.btn:disabled { opacity: 0.45; cursor: not-allowed; }
.btn:focus-visible { outline: 3px solid var(--brand-1); outline-offset: 2px; }

.btn-primary { background: var(--brand-gradient); color: #fff; border: none; }
.btn-ghost   { background: transparent; border-color: var(--border); }
.btn-plain   { background: transparent; border: none; padding: var(--s2); }
.btn-block   { width: 100%; }
.btn-lg      { padding: 1rem 1.5rem; font-size: 1.05rem; }
.btn-sm      { padding: 0.4rem 0.7rem; font-size: 0.85rem; }
.btn-danger  { background: var(--danger); color: #fff; }

/* ===== Form ===== */

.field { display: flex; flex-direction: column; gap: var(--s2); }

.input, .textarea, .select {
    width: 100%;
    padding: 0.7rem 0.9rem;
    background: var(--surface-2);
    border: 1px solid var(--border);
    border-radius: var(--radius-sm);
    transition: border-color 0.15s ease;
}

.input:focus, .textarea:focus, .select:focus {
    outline: none;
    border-color: var(--brand-1);
    box-shadow: 0 0 0 3px rgba(47, 139, 255, 0.18);
}

.textarea { resize: vertical; min-height: 8rem; line-height: 1.6; }
.label { font-weight: 600; font-size: 0.9rem; }

/* ===== Badge / Pill ===== */

.badge {
    display: inline-flex;
    align-items: center;
    gap: 0.3em;
    padding: 0.2em 0.65em;
    border-radius: var(--radius-full);
    background: var(--surface-2);
    border: 1px solid var(--border);
    font-size: 0.8rem;
    font-weight: 600;
    white-space: nowrap;
}

.badge-success { background: var(--success-soft); color: var(--success); border-color: transparent; }
.badge-danger  { background: var(--danger-soft);  color: var(--danger);  border-color: transparent; }
.badge-warning { background: var(--warning-soft); color: var(--warning); border-color: transparent; }
.badge-brand   { background: var(--brand-gradient); color: #fff; border-color: transparent; }

/* ===== Progress ===== */

.progress {
    height: 8px;
    background: var(--border);
    border-radius: var(--radius-full);
    overflow: hidden;
}

.progress-bar {
    height: 100%;
    background: var(--brand-gradient);
    border-radius: inherit;
    transition: width 0.7s cubic-bezier(0.3, 1, 0.4, 1);
}

/* ===== Collapse（自製，取代 Bootstrap 的 collapse）===== */

.collapse-head {
    display: flex;
    align-items: center;
    justify-content: space-between;
    width: 100%;
    padding: var(--s4);
    background: none;
    border: none;
    cursor: pointer;
    font-weight: 600;
    text-align: left;
}

.collapse-head .chevron { transition: transform 0.25s ease; }
.collapse-head[aria-expanded="true"] .chevron { transform: rotate(180deg); }
.collapse-body { padding: 0 var(--s4) var(--s4); }

/* ===== Tabs ===== */

.tabs {
    display: flex;
    gap: var(--s1);
    border-bottom: 1px solid var(--border);
    margin-bottom: var(--s4);
    overflow-x: auto;
}

.tab {
    padding: 0.6rem 1rem;
    background: none;
    border: none;
    border-bottom: 2px solid transparent;
    color: var(--text-muted);
    font-weight: 600;
    cursor: pointer;
    white-space: nowrap;
}

.tab[aria-selected="true"] { color: var(--brand-1); border-bottom-color: var(--brand-1); }

/* ===== Modal ===== */

.modal {
    position: fixed;
    inset: 0;
    z-index: 900;
    display: flex;
    align-items: center;
    justify-content: center;
    padding: var(--s4);
    background: rgba(8, 15, 25, 0.55);
    backdrop-filter: blur(3px);
    animation: fade-in 0.2s ease;
}

.modal-card {
    background: var(--surface);
    border-radius: var(--radius-lg);
    box-shadow: var(--shadow-lg);
    width: min(640px, 100%);
    max-height: 88vh;
    display: flex;
    flex-direction: column;
    animation: pop-in 0.28s cubic-bezier(0.2, 1.2, 0.4, 1);
}

.modal-head, .modal-foot {
    padding: var(--s4);
    display: flex;
    align-items: center;
    gap: var(--s3);
}
.modal-head { border-bottom: 1px solid var(--border); }
.modal-foot { border-top: 1px solid var(--border); justify-content: flex-end; }
.modal-body { padding: var(--s4); overflow-y: auto; }

/* ===== 動畫 ===== */

@keyframes fade-in { from { opacity: 0; } to { opacity: 1; } }
@keyframes fade-out { to { opacity: 0; } }
@keyframes pop-in {
    from { transform: scale(0.92) translateY(10px); opacity: 0; }
    to   { transform: scale(1) translateY(0); opacity: 1; }
}
@keyframes slide-up {
    from { transform: translateY(16px); opacity: 0; }
    to   { transform: translateY(0); opacity: 1; }
}

.enter { animation: slide-up 0.35s cubic-bezier(0.2, 1, 0.4, 1) backwards; }

@media (prefers-reduced-motion: reduce) {
    *, *::before, *::after {
        animation-duration: 0.01ms !important;
        animation-iteration-count: 1 !important;
        transition-duration: 0.01ms !important;
    }
}

/* ===== 首頁：今日主行動 ===== */

.greeting { display: flex; align-items: baseline; justify-content: space-between; gap: var(--s3); }
.greeting h1 { font-size: 1.35rem; }

.streak {
    display: inline-flex;
    align-items: center;
    gap: 0.3em;
    font-weight: 700;
    color: var(--warning);
}
.streak-cold { color: var(--text-muted); }

/* 今天要複習什麼——整個首頁只有這一個主行動 */
.today-card {
    background: var(--brand-gradient);
    color: #fff;
    border: none;
    border-radius: var(--radius-lg);
    padding: var(--s6) var(--s5);
    text-align: center;
    box-shadow: 0 10px 30px rgba(47, 139, 255, 0.28);
}

.today-count {
    font-size: 3.6rem;
    font-weight: 800;
    line-height: 1;
    letter-spacing: -0.02em;
}

.today-label { opacity: 0.9; margin-bottom: var(--s4); }

.today-card .btn {
    background: #fff;
    color: var(--brand-1);
    font-size: 1.05rem;
    padding: 0.85rem 2.2rem;
    border-radius: var(--radius-full);
}

/* 今日目標 */
.goal { display: flex; flex-direction: column; gap: var(--s2); }

/* ===== 全螢幕作答 ===== */

.practice {
    position: fixed;
    inset: 0;
    z-index: 800;
    display: flex;
    flex-direction: column;
    background: var(--bg);
    padding-top: var(--safe-top);
    padding-bottom: var(--safe-bottom);
}

.practice-top {
    display: flex;
    align-items: center;
    gap: var(--s3);
    padding: var(--s3) var(--s4);
}

.practice-progress { flex: 1; }

/* 題目圖佔掉所有剩餘空間，這是學生真正在看的東西 */
.practice-stage {
    flex: 1;
    display: flex;
    align-items: center;
    justify-content: center;
    padding: var(--s3) var(--s4);
    overflow: auto;
    min-height: 0;
}

.question-frame {
    background: #fff;   /* 掃描圖是白底，深色模式也要維持白底才看得清楚 */
    border-radius: var(--radius);
    box-shadow: var(--shadow);
    padding: var(--s3);
    max-width: 100%;
    cursor: zoom-in;
}

.question-frame img { max-height: 52vh; width: auto; margin: 0 auto; object-fit: contain; }

/* 放大檢視 */
.zoomed {
    position: fixed;
    inset: 0;
    z-index: 950;
    background: rgba(0, 0, 0, 0.92);
    display: flex;
    align-items: center;
    justify-content: center;
    padding: var(--s3);
    cursor: zoom-out;
    overflow: auto;
}
.zoomed img { max-width: none; width: auto; min-width: 100%; }

/* 選項放在底部，拇指構得到 */
.practice-actions {
    padding: var(--s3) var(--s4) var(--s4);
    display: flex;
    flex-direction: column;
    gap: var(--s3);
    background: var(--surface);
    border-top: 1px solid var(--border);
    /* 解析可能很長（AI 產的通常有好幾段），底部區塊要能自己捲，
       不能把選項與「下一題」擠出畫面 */
    max-height: 70vh;
    overflow-y: auto;
    overscroll-behavior: contain;
}

/* 選項與下一題永遠留在視線內，捲動的是上面的解析 */
.practice-actions .options,
.practice-actions > .btn {
    flex: none;
}

.options { display: grid; grid-template-columns: repeat(4, 1fr); gap: var(--s2); }

.option {
    padding: 1.1rem 0;
    font-size: 1.25rem;
    font-weight: 700;
    background: var(--surface-2);
    border: 2px solid var(--border);
    border-radius: var(--radius);
    cursor: pointer;
    transition: all 0.15s ease;
}

.option:active { transform: scale(0.96); }
.option[aria-pressed="true"] { background: var(--brand-gradient); color: #fff; border-color: transparent; }
.option.is-correct { background: var(--success); color: #fff; border-color: transparent; }
.option.is-wrong   { background: var(--danger);  color: #fff; border-color: transparent; }
.option.is-dim     { opacity: 0.4; }
.option:disabled   { cursor: default; }

/* 把握度 */
.confidence { display: grid; grid-template-columns: repeat(3, 1fr); gap: var(--s2); }

.conf-btn {
    padding: 0.6rem 0.3rem;
    background: var(--surface-2);
    border: 2px solid var(--border);
    border-radius: var(--radius-sm);
    font-size: 0.9rem;
    font-weight: 600;
    cursor: pointer;
    transition: all 0.15s ease;
}

.conf-btn[aria-pressed="true"] { border-color: currentColor; }
.conf-sure[aria-pressed="true"]  { color: var(--success); background: var(--success-soft); }
.conf-unsure[aria-pressed="true"]{ color: var(--warning); background: var(--warning-soft); }
.conf-guess[aria-pressed="true"] { color: var(--danger);  background: var(--danger-soft); }

/* 作答結果 */
.result {
    padding: var(--s4);
    border-radius: var(--radius);
    animation: slide-up 0.3s ease;
}
.result-correct { background: var(--success-soft); }
.result-wrong   { background: var(--danger-soft); }

.result-title { display: flex; align-items: center; gap: var(--s2); font-size: 1.15rem; font-weight: 700; }
.result-correct .result-title { color: var(--success); }
.result-wrong   .result-title { color: var(--danger); }

/* combo */
.combo {
    display: inline-flex;
    align-items: center;
    gap: 0.3em;
    padding: 0.25rem 0.7rem;
    border-radius: var(--radius-full);
    background: linear-gradient(135deg, #fb7185, #fbbf24);
    color: #fff;
    font-weight: 700;
    font-size: 0.85rem;
    animation: pulse 0.5s ease;
}
.combo-hot { background: linear-gradient(135deg, #f43f5e, #f97316); box-shadow: 0 0 16px rgba(244, 63, 94, 0.5); }

@keyframes pulse {
    0% { transform: scale(1); } 40% { transform: scale(1.25); } 100% { transform: scale(1); }
}

/* 答對／答錯的整體反應 */
.flash-correct { animation: flash-ok 0.6s ease; }
.flash-wrong   { animation: shake 0.45s ease; }

@keyframes flash-ok {
    0%   { box-shadow: inset 0 0 0 0 rgba(22, 163, 74, 0.35); }
    30%  { box-shadow: inset 0 0 60px 0 rgba(22, 163, 74, 0.35); }
    100% { box-shadow: inset 0 0 0 0 rgba(22, 163, 74, 0); }
}
@keyframes shake {
    0%, 100% { transform: translateX(0); }
    20% { transform: translateX(-8px); } 40% { transform: translateX(7px); }
    60% { transform: translateX(-4px); } 80% { transform: translateX(2px); }
}

/* ===== Toast ===== */

#toasts {
    position: fixed;
    left: 50%;
    transform: translateX(-50%);
    top: calc(var(--safe-top) + var(--s3));
    z-index: 1000;
    display: flex;
    flex-direction: column;
    gap: var(--s2);
    pointer-events: none;
    width: min(420px, calc(100vw - 2rem));
}

.toast {
    display: flex;
    align-items: center;
    gap: var(--s2);
    padding: 0.7rem 1rem;
    background: var(--surface);
    border: 1px solid var(--border);
    border-radius: var(--radius-full);
    box-shadow: var(--shadow-lg);
    font-weight: 600;
    font-size: 0.9rem;
    animation: slide-up 0.3s cubic-bezier(0.2, 1.2, 0.4, 1);
}
.toast.leaving { animation: fade-out 0.35s ease forwards; }

/* ===== 里程碑慶祝 ===== */

.celebrate {
    position: fixed; inset: 0; z-index: 1001;
    display: flex; align-items: center; justify-content: center;
    background: rgba(8, 15, 25, 0.5);
    animation: fade-in 0.25s ease;
}
.celebrate.leaving { animation: fade-out 0.35s ease forwards; }

.celebrate-card {
    background: var(--surface);
    border-radius: var(--radius-lg);
    padding: var(--s6) var(--s7);
    text-align: center;
    box-shadow: var(--shadow-lg);
    animation: pop-in 0.45s cubic-bezier(0.2, 1.4, 0.4, 1);
}
.celebrate-emoji { font-size: 4rem; line-height: 1; animation: bounce 0.9s ease infinite; }
@keyframes bounce { 0%,100% { transform: translateY(0);} 50% { transform: translateY(-14px);} }

/* ===== 統計小方塊 ===== */

.tiles { display: grid; grid-template-columns: repeat(auto-fit, minmax(120px, 1fr)); gap: var(--s3); }

.tile {
    background: var(--surface);
    border: 1px solid var(--border);
    border-radius: var(--radius);
    padding: var(--s4);
    text-align: center;
}
.tile-value { font-size: 1.7rem; font-weight: 800; line-height: 1.1; }

/* ===== 手機調整 ===== */

@media (max-width: 560px) {
    .wrap { padding: var(--s3); }
    .today-count { font-size: 3rem; }
    .celebrate-card { padding: var(--s5); }
    .question-frame img { max-height: 44vh; }
    .option { font-size: 1.1rem; padding: 0.95rem 0; }
}

/* 橫向時題目圖給更多高度——很多學生會轉橫看電路圖 */
@media (orientation: landscape) and (max-height: 560px) {
    .question-frame img { max-height: 62vh; }
    .practice-top { padding: var(--s2) var(--s4); }
}