:root {
    --brand-blue: #1E40AF;
    --highlight-blue: #3B82F6;
    --success-green: #059669;
    --warning-orange: #D97706;
    --danger-red: #DC2626;
    --paper: #FDFBF7;
    --surface: #FFFFFF;
    --ink: #172033;
    --muted: #667085;
    --line: #D8DEE9;
    --noun: #E8F0FE;
    --verb: #E8F7EF;
    --adj: #FFF2E5;
    --adv: #F1ECFF;
}

* {
    box-sizing: border-box;
}

html,
body {
    margin: 0;
    min-height: 100%;
    color: var(--ink);
    background: #EEF2F7;
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
}

body {
    padding: env(safe-area-inset-top) 0 env(safe-area-inset-bottom);
}

button {
    min-height: 44px;
    font: inherit;
    touch-action: manipulation;
}

button:focus-visible,
.blank-slot:focus-visible {
    outline: 3px solid rgba(59, 130, 246, 0.38);
    outline-offset: 2px;
}

.app-shell {
    width: min(100%, 1180px);
    margin: 0 auto;
    min-height: 100vh;
    padding: 12px;
}

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

.brand-block h1 {
    margin: 0;
    font-size: clamp(20px, 5vw, 30px);
    color: var(--brand-blue);
}

.brand-block p {
    margin: 4px 0 0;
    color: var(--muted);
    font-size: 14px;
}

.viewport-nav {
    display: grid;
    grid-template-columns: repeat(4, minmax(0, 1fr));
    gap: 8px;
    margin-bottom: 12px;
    overflow-x: auto;
}

.viewport-nav button {
    min-width: 104px;
    min-height: 44px;
    border: 1px solid var(--line);
    border-radius: 10px;
    background: var(--surface);
    color: var(--ink);
    cursor: pointer;
}

.viewport-nav button.is-active {
    border-color: var(--brand-blue);
    background: var(--brand-blue);
    color: #FFFFFF;
}

.workspace-view {
    background: var(--surface);
    border: 1px solid var(--line);
    border-radius: 16px;
    box-shadow: 0 10px 30px rgba(30, 64, 175, 0.08);
    overflow: hidden;
}

.workspace-view[hidden] {
    display: none;
}

.view-header {
    padding: 16px;
    border-bottom: 1px solid var(--line);
}

.view-header h2 {
    margin: 0 0 6px;
    font-size: 20px;
}

.view-header p {
    margin: 0;
    color: var(--muted);
}

.dashboard-grid {
    display: grid;
    gap: 12px;
    padding: 16px;
}

.task-card,
.speaking-card,
.question-card {
    padding: 16px;
    border: 1px solid var(--line);
    border-radius: 14px;
    background: #FFFFFF;
}

.task-card strong {
    color: var(--brand-blue);
}

.task-card p {
    margin: 8px 0 0;
    color: var(--muted);
}

.status-pill {
    display: inline-flex;
    align-items: center;
    min-height: 28px;
    padding: 4px 10px;
    border-radius: 999px;
    background: #E8F7EF;
    color: var(--success-green);
    font-size: 12px;
    font-weight: 700;
}

.vocab-workspace {
    background: var(--paper);
}

.vocab-strip {
    position: sticky;
    top: 0;
    z-index: 10;
    display: grid;
    grid-auto-flow: column;
    grid-auto-columns: minmax(128px, 1fr);
    gap: 8px;
    overflow-x: auto;
    padding: 12px;
    background: rgba(253, 251, 247, 0.98);
    border-bottom: 1px solid var(--line);
    scrollbar-width: none;
}

.vocab-strip::-webkit-scrollbar {
    display: none;
}

.word-tile {
    min-height: 48px;
    display: grid;
    grid-template-columns: 1fr auto;
    align-items: center;
    gap: 8px;
    padding: 8px 10px;
    border: 1px solid transparent;
    border-radius: 10px;
    color: var(--ink);
    cursor: pointer;
    text-align: left;
}

.word-tile span {
    font-size: 12px;
    color: var(--muted);
}

.word-tile:active {
    transform: scale(0.98);
}

.word-tile.is-used {
    background: #E5E7EB;
    color: #8A8F98;
    text-decoration: line-through;
    opacity: 0.72;
    cursor: not-allowed;
}

.pos-noun {
    background: var(--noun);
}

.pos-verb {
    background: var(--verb);
}

.pos-adj {
    background: var(--adj);
}

.pos-adv {
    background: var(--adv);
}

.cloze-article {
    padding: 18px;
    background: var(--paper);
    font-size: 17px;
    line-height: 1.65;
}

.cloze-article p,
.reading-passage p {
    margin: 0 0 1.2em;
}

.blank-slot {
    min-height: 44px;
    min-width: 116px;
    margin: 4px;
    padding: 6px 10px;
    border: 2px solid transparent;
    border-bottom-color: var(--brand-blue);
    border-radius: 8px;
    background: #FFFFFF;
    color: var(--brand-blue);
    font-weight: 700;
    cursor: pointer;
}

.blank-slot.is-active {
    border-color: var(--highlight-blue);
    box-shadow: 0 0 0 3px rgba(59, 130, 246, 0.16);
}

.blank-slot.is-filled {
    color: #0F5132;
    border-color: var(--success-green);
    background: #ECFDF5;
}

.split-reading-container {
    min-height: 68vh;
    display: grid;
    grid-template-rows: minmax(240px, 58vh) 10px minmax(170px, 1fr);
    background: var(--surface);
}

.split-article-pane {
    overflow-y: auto;
    background: var(--paper);
    scroll-behavior: smooth;
}

.reading-passage {
    padding: 18px;
    font-size: 17px;
    line-height: 1.65;
}

.reading-passage p {
    padding: 8px 10px;
    border-radius: 10px;
}

.split-divider {
    min-height: 10px;
    background: linear-gradient(90deg, transparent, #AEB8C8, transparent);
    cursor: row-resize;
    touch-action: none;
}

.split-question-pane {
    overflow-y: auto;
    padding: 12px;
    border-top: 1px solid var(--line);
    background: #FFFFFF;
}

.question-grid {
    display: grid;
    gap: 8px;
}

.question-jump,
.answer-option,
.primary-action {
    min-height: 44px;
    border: 1px solid var(--line);
    border-radius: 10px;
    padding: 8px 12px;
    background: #FFFFFF;
    cursor: pointer;
}

.question-jump.is-active {
    border-color: var(--brand-blue);
    background: #EFF6FF;
    color: var(--brand-blue);
}

.evidence-highlight {
    background: #FFF4BF;
    animation: evidenceFadeIn 320ms ease-out;
}

@keyframes evidenceFadeIn {
    from {
        background: rgba(255, 244, 191, 0);
        transform: translateY(3px);
    }
    to {
        background: #FFF4BF;
        transform: translateY(0);
    }
}

.speaking-layout {
    display: grid;
    gap: 12px;
    padding: 16px;
}

.read-aloud-text {
    padding: 14px;
    border-radius: 12px;
    background: var(--paper);
    line-height: 1.65;
}

.wave-meter {
    height: 18px;
    overflow: hidden;
    border-radius: 999px;
    background: #E5E7EB;
}

.wave-meter > span {
    display: block;
    width: 42%;
    height: 100%;
    background: linear-gradient(90deg, var(--highlight-blue), var(--success-green));
}

.score-panel {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 8px;
}

.score-box {
    min-height: 76px;
    display: grid;
    place-items: center;
    border: 1px solid var(--line);
    border-radius: 12px;
    background: #FFFFFF;
}

.score-box strong {
    display: block;
    color: var(--brand-blue);
    font-size: 22px;
}

.primary-action {
    border-color: var(--brand-blue);
    background: var(--brand-blue);
    color: #FFFFFF;
    font-weight: 700;
}

.warning-text {
    color: var(--warning-orange);
}

.danger-text {
    color: var(--danger-red);
}

@media (min-width: 768px) {
    .dashboard-grid {
        grid-template-columns: repeat(3, 1fr);
    }

    .split-reading-container {
        grid-template-rows: minmax(560px, 1fr);
        grid-template-columns: minmax(320px, 58%) 10px minmax(280px, 42%);
    }

    .split-divider {
        min-width: 10px;
        min-height: auto;
        cursor: col-resize;
        background: linear-gradient(180deg, transparent, #AEB8C8, transparent);
    }

    .split-question-pane {
        border-top: 0;
        border-left: 1px solid var(--line);
    }

    .speaking-layout {
        grid-template-columns: 1.4fr 0.9fr;
    }
}