/* =========================================================
   Note Mentor — UI
   ========================================================= */

:root {
    --bg: #eef1f6;
    --bg-elevated: #ffffff;
    --bg-soft: #f5f7fb;
    --bg-muted: #e8edf5;
    --ink: #1a2332;
    --ink-soft: #4a5568;
    --ink-faint: #7a8699;
    --line: #d5dde8;
    --line-soft: #e6ebf2;
    --accent: #3b6fd4;
    --accent-hover: #2f5bb5;
    --accent-soft: #e8f0fc;
    --accent-deep: #1e4a9e;
    --good: #1f8f4e;
    --good-soft: #e6f6ec;
    --bad: #c62828;
    --bad-soft: #fdecea;
    --warn: #d97706;
    --warn-soft: #fff7ed;
    --target: #4a90d9;
    --shadow-sm: 0 1px 2px rgba(26, 35, 50, 0.05);
    --shadow: 0 4px 16px rgba(26, 35, 50, 0.07), 0 1px 3px rgba(26, 35, 50, 0.04);
    --shadow-lg: 0 12px 40px rgba(26, 35, 50, 0.1);
    --radius: 12px;
    --radius-sm: 8px;
    --radius-pill: 999px;
    --font: "Segoe UI", system-ui, -apple-system, BlinkMacSystemFont, "Helvetica Neue", sans-serif;
    --mono: ui-monospace, "Cascadia Code", "Segoe UI Mono", Consolas, monospace;
    --max: 1120px;
    --header-h: auto;
}

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

html {
    scroll-behavior: smooth;
}

body {
    margin: 0;
    min-height: 100vh;
    font-family: var(--font);
    font-size: 15.5px;
    line-height: 1.5;
    color: var(--ink);
    background:
        radial-gradient(1200px 500px at 10% -10%, #dfe9ff 0%, transparent 55%),
        radial-gradient(900px 420px at 100% 0%, #e8f4ef 0%, transparent 50%),
        var(--bg);
    -webkit-font-smoothing: antialiased;
}

.hidden {
    display: none !important;
}

/* ---------- App shell ---------- */

.app {
    max-width: var(--max);
    margin: 0 auto;
    padding: 1.25rem 1.1rem 3rem;
}

/* ---------- Header ---------- */

.app-header {
    display: flex;
    flex-wrap: wrap;
    align-items: center;
    justify-content: space-between;
    gap: 1rem 1.25rem;
    margin-bottom: 1.1rem;
    padding: 1rem 1.15rem;
    background: linear-gradient(135deg, #1e3a6e 0%, #2a4f8f 48%, #3a6cb5 100%);
    color: #fff;
    border-radius: calc(var(--radius) + 2px);
    box-shadow: var(--shadow-lg);
}

.brand {
    display: flex;
    align-items: center;
    gap: 0.85rem;
    min-width: 0;
}

.brand-mark {
    flex-shrink: 0;
    width: 3rem;
    height: 3rem;
    display: grid;
    place-items: center;
    border-radius: 14px;
    background: rgba(255, 255, 255, 0.14);
    border: 1px solid rgba(255, 255, 255, 0.22);
    font-size: 1.45rem;
    line-height: 1;
    box-shadow: inset 0 1px 0 rgba(255, 255, 255, 0.2);
}

.brand h1 {
    margin: 0;
    font-size: clamp(1.35rem, 2.5vw, 1.7rem);
    font-weight: 700;
    letter-spacing: -0.02em;
    line-height: 1.15;
}

.tagline {
    margin: 0.2rem 0 0;
    font-size: 0.9rem;
    opacity: 0.88;
    font-weight: 400;
}

.header-actions {
    display: flex;
    flex-wrap: wrap;
    gap: 0.5rem;
    align-items: center;
}

/* Language switcher */
.lang-switch {
    position: relative;
}

#lang-toggle {
    display: inline-flex;
    align-items: center;
    gap: 0.35rem;
    margin: 0;
    padding: 0.5rem 0.75rem;
    background: rgba(255, 255, 255, 0.14);
    color: #fff;
    border: 1px solid rgba(255, 255, 255, 0.28);
    box-shadow: none;
    font-weight: 600;
    border-radius: var(--radius-sm);
}

#lang-toggle:hover:not(:disabled) {
    background: rgba(255, 255, 255, 0.22);
    border-color: rgba(255, 255, 255, 0.4);
    color: #fff;
}

#lang-toggle .lang-globe {
    font-size: 1.05rem;
    line-height: 1;
}

#lang-current-code {
    font-variant-numeric: tabular-nums;
    letter-spacing: 0.04em;
    min-width: 1.5rem;
}

.lang-menu {
    position: absolute;
    right: 0;
    top: calc(100% + 0.35rem);
    z-index: 50;
    min-width: 10.5rem;
    margin: 0;
    padding: 0.35rem 0;
    list-style: none;
    background: var(--bg-elevated);
    color: var(--ink);
    border: 1px solid var(--line-soft);
    border-radius: var(--radius-sm);
    box-shadow: var(--shadow-lg);
}

.lang-menu li {
    padding: 0.5rem 0.85rem;
    cursor: pointer;
    font-weight: 600;
    font-size: 0.92rem;
}

.lang-menu li:hover {
    background: var(--accent-soft);
    color: var(--accent-deep);
}

.lang-menu li.is-active {
    color: var(--accent-deep);
}

.lang-menu li.is-active::before {
    content: "✓ ";
    font-weight: 700;
}

/* ---------- Buttons ---------- */

button {
    appearance: none;
    font-family: inherit;
    font-size: 0.95rem;
    font-weight: 600;
    line-height: 1.2;
    padding: 0.55rem 1.05rem;
    margin: 0.2rem;
    border-radius: var(--radius-sm);
    border: 1px solid transparent;
    cursor: pointer;
    background: var(--bg-elevated);
    color: var(--ink);
    border-color: var(--line);
    box-shadow: var(--shadow-sm);
    transition: background 0.15s ease, border-color 0.15s ease, transform 0.1s ease, box-shadow 0.15s ease;
}

button:hover:not(:disabled) {
    background: var(--bg-soft);
    border-color: #c5d0e0;
}

button:active:not(:disabled) {
    transform: translateY(1px);
}

button:disabled {
    opacity: 0.5;
    cursor: not-allowed;
    box-shadow: none;
}

button:focus-visible,
select:focus-visible,
input:focus-visible {
    outline: 2px solid var(--accent);
    outline-offset: 2px;
}

.btn-primary,
.header-actions button {
    background: #fff;
    color: var(--accent-deep);
    border-color: transparent;
    box-shadow: 0 2px 8px rgba(0, 0, 0, 0.12);
}

.btn-primary:hover:not(:disabled),
.header-actions button:hover:not(:disabled) {
    background: #f4f7ff;
    border-color: transparent;
}

.btn-accent {
    background: var(--accent);
    color: #fff;
    border-color: var(--accent-hover);
}

.btn-accent:hover:not(:disabled) {
    background: var(--accent-hover);
    border-color: var(--accent-deep);
    color: #fff;
}

.btn-good {
    background: var(--good);
    color: #fff;
    border-color: #187a42;
}

.btn-good:hover:not(:disabled) {
    background: #1a7a43;
    color: #fff;
}

.btn-warn {
    background: var(--warn);
    color: #fff;
    border-color: #b45309;
}

.btn-warn:hover:not(:disabled) {
    background: #b45309;
    color: #fff;
}

.btn-ghost {
    background: transparent;
    border-color: var(--line);
    box-shadow: none;
}

.tempo-reset {
    padding: 0.35rem 0.75rem;
    font-size: 0.88rem;
    margin: 0;
    border-radius: var(--radius-pill);
}

/* ---------- Status ---------- */

#status {
    margin: 0 0 1rem;
    padding: 0.75rem 1rem;
    background: var(--bg-elevated);
    border: 1px solid var(--line-soft);
    border-left: 4px solid var(--accent);
    border-radius: var(--radius-sm);
    box-shadow: var(--shadow-sm);
    color: var(--ink-soft);
    font-size: 0.95rem;
}

/* ---------- Transport + settings ---------- */

#controls {
    margin-bottom: 1.15rem;
}

.transport-bar {
    display: flex;
    flex-wrap: wrap;
    align-items: center;
    gap: 0.35rem;
    padding: 0.65rem 0.75rem;
    margin-bottom: 0.85rem;
    background: var(--bg-elevated);
    border: 1px solid var(--line-soft);
    border-radius: var(--radius);
    box-shadow: var(--shadow);
}

.transport-bar button {
    margin: 0.15rem;
}

.btn-settings {
    margin-left: auto !important;
    background: var(--bg-soft);
    border-color: var(--line);
    color: var(--accent-deep);
    font-weight: 600;
}

.btn-settings:hover:not(:disabled) {
    background: var(--accent-soft);
    border-color: #b8c9e8;
}

.btn-settings .settings-chevron {
    display: inline-block;
    transition: transform 0.25s ease;
    font-size: 0.85em;
}

.btn-settings[aria-expanded="false"] .settings-chevron {
    transform: rotate(180deg);
}

/* Collapsible options drawer */
.settings-drawer {
    display: grid;
    grid-template-rows: 1fr;
    transition: grid-template-rows 0.38s ease, opacity 0.28s ease;
    opacity: 1;
}

.settings-drawer.is-collapsed {
    grid-template-rows: 0fr;
    opacity: 0;
    pointer-events: none;
}

.settings-drawer-inner {
    overflow: hidden;
    min-height: 0;
}

.settings-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: 0.75rem;
    padding-bottom: 0.15rem;
}

.playback-options {
    margin: 0;
    padding: 0.85rem 1rem;
    background: var(--bg-elevated);
    border: 1px solid var(--line-soft);
    border-radius: var(--radius);
    box-shadow: var(--shadow-sm);
}

.playback-options label {
    font-weight: 600;
    margin-right: 0.45rem;
    color: var(--ink);
    font-size: 0.92rem;
}

.playback-options select,
.playback-options input[type="number"] {
    font-family: inherit;
    font-size: 0.92rem;
    padding: 0.4rem 0.55rem;
    border: 1px solid var(--line);
    border-radius: 7px;
    background: var(--bg-soft);
    color: var(--ink);
    max-width: 100%;
}

.playback-options input[type="number"] {
    width: 4.75rem;
}

.playback-options .hint {
    display: block;
    margin-top: 0.4rem;
    color: var(--ink-faint);
    font-size: 0.84rem;
    line-height: 1.4;
}

.playback-options .hint a {
    color: var(--accent);
    text-decoration: none;
    font-weight: 600;
}

.playback-options .hint a:hover {
    text-decoration: underline;
}

.playback-options .tempo-row {
    display: flex;
    flex-wrap: wrap;
    align-items: center;
    gap: 0.5rem 0.75rem;
}

.playback-options input[type="range"] {
    flex: 1 1 160px;
    min-width: 120px;
    max-width: 320px;
    accent-color: var(--accent);
    vertical-align: middle;
}

.playback-options #tempo-value,
.playback-options #zoom-value {
    font-variant-numeric: tabular-nums;
    min-width: 4.5rem;
    font-weight: 600;
    color: var(--accent-deep);
    font-family: var(--mono);
    font-size: 0.9rem;
}

.field-gap {
    margin-top: 0.55rem;
}

.option-divider {
    height: 1px;
    background: var(--line-soft);
    margin: 0.65rem 0;
    border: 0;
}

/* ---------- Score stage ---------- */

.score-stage {
    margin: 0 0 1rem;
    padding: 0.85rem 0.85rem 0.5rem;
    background: var(--bg-elevated);
    border: 1px solid var(--line-soft);
    border-radius: var(--radius);
    box-shadow: var(--shadow);
}

#osmd-container {
    margin: 0;
    border: 1px solid var(--line-soft);
    border-radius: var(--radius-sm);
    padding: 0.85rem 0.75rem;
    background:
        linear-gradient(180deg, #fbfcfe 0%, #ffffff 40%);
    overflow: hidden;
    min-height: 200px;
    position: relative;
    box-shadow: inset 0 1px 0 rgba(255, 255, 255, 0.9);
}

.osmd-slide-layer {
    position: absolute;
    left: 0;
    right: 0;
    top: 0;
    width: 100%;
    will-change: transform, opacity;
    pointer-events: none;
}

.osmd-slide-layer.osmd-slide-live {
    position: relative;
    pointer-events: auto;
}

.osmd-slide-layer.osmd-animating {
    transition: transform 0.42s cubic-bezier(0.22, 0.61, 0.36, 1),
                opacity 0.38s ease;
}

#measure-window-label {
    color: var(--ink-faint);
    font-size: 0.88rem;
    margin: 0.55rem 0 0.35rem;
    padding: 0 0.15rem;
    font-weight: 500;
}

/* Staff space guides (FACE / ACEG) */
#staff-space-guides-overlay {
    position: absolute;
    left: 0;
    top: 0;
    right: 0;
    bottom: 0;
    pointer-events: none;
    overflow: hidden;
    z-index: 5;
}

#staff-space-guides-overlay .ssg-letter {
    position: absolute;
    transform: translate(-50%, -50%);
    color: #3d5a80;
    font-family: var(--font);
    font-weight: 600;
    opacity: 0.9;
    user-select: none;
    line-height: 1;
    text-shadow: 0 0 2px #fff, 0 0 3px #fff;
    z-index: 6;
}

/* ---------- Practice panel ---------- */

#practice {
    margin: 0 0 1rem;
    padding: 1rem 1.1rem;
    background: linear-gradient(180deg, #f8fbff 0%, var(--bg-elevated) 100%);
    border: 1px solid var(--line-soft);
    border-radius: var(--radius);
    box-shadow: var(--shadow);
}

#practice p {
    margin: 0.4rem 0;
}

#practice-instruction {
    color: var(--ink-soft);
}

#practice-instruction .note-target {
    color: var(--target);
    font-weight: 700;
}

#current-note {
    font-size: 1.35rem;
    font-weight: 700;
    margin: 0.65rem 0;
    min-height: 2rem;
    padding: 0.55rem 0.75rem;
    background: var(--bg-soft);
    border-radius: var(--radius-sm);
    border: 1px solid var(--line-soft);
    font-variant-numeric: tabular-nums;
}

#feedback {
    min-height: 1.25rem;
    margin: 0.35rem 0;
}

.practice-meta {
    display: flex;
    flex-wrap: wrap;
    align-items: center;
    gap: 0.75rem 1.25rem;
    margin-top: 0.5rem;
}

.progress-pill {
    display: inline-flex;
    align-items: center;
    gap: 0.35rem;
    padding: 0.35rem 0.75rem;
    background: var(--accent-soft);
    color: var(--accent-deep);
    border-radius: var(--radius-pill);
    font-weight: 600;
    font-size: 0.9rem;
    font-variant-numeric: tabular-nums;
}

.goed {
    color: var(--good);
}

.fout {
    color: var(--bad);
}

/* ---------- Piano ---------- */

#piano-section {
    margin: 0.65rem 0 0.35rem;
    border: 1px solid var(--line-soft);
    border-radius: var(--radius-sm);
    background: linear-gradient(180deg, #f3f5f9 0%, #e9edf4 100%);
    padding: 0.65rem 0.75rem 0.85rem;
}

#piano-section.hidden {
    display: none !important;
}

#piano-caption {
    font-size: 0.88rem;
    color: var(--ink-soft);
    margin: 0 0 0.5rem;
}

#piano-caption .legend-target {
    color: var(--target);
    font-weight: 700;
}

#piano-caption .legend-good {
    color: var(--good);
    font-weight: 700;
}

#piano-caption .legend-bad {
    color: var(--bad);
    font-weight: 700;
}

#piano-scroll {
    overflow-x: auto;
    padding-bottom: 0.25rem;
    border-radius: 6px;
}

#piano-label-row {
    position: relative;
    height: 1.4rem;
    margin-bottom: 0.15rem;
    min-width: 100%;
}

#piano-label-row .pk-label {
    position: absolute;
    transform: translateX(-50%);
    font-size: 0.78rem;
    font-weight: 700;
    color: var(--accent-deep);
    white-space: nowrap;
    pointer-events: none;
}

#piano {
    position: relative;
    height: 132px;
    display: flex;
    width: max-content;
    min-width: 100%;
    user-select: none;
    touch-action: manipulation;
    filter: drop-shadow(0 4px 8px rgba(0, 0, 0, 0.08));
}

.piano-key {
    box-sizing: border-box;
    cursor: pointer;
    position: relative;
}

.piano-key.white {
    flex: 1 0 0;
    min-width: 26px;
    height: 132px;
    background: linear-gradient(#ffffff, #f2f2f2 70%, #e8e8e8);
    border: 1px solid #5a6270;
    border-radius: 0 0 5px 5px;
    z-index: 1;
}

.piano-key.white:active {
    background: #e4e4e4;
}

.piano-key.black {
    position: absolute;
    top: 0;
    width: 18px;
    height: 84px;
    background: linear-gradient(#3a3a3a, #111 80%);
    border: 1px solid #000;
    border-radius: 0 0 3px 3px;
    z-index: 2;
    margin-left: -9px;
}

.piano-key.black:active {
    background: #222;
}

.piano-key.white.target {
    background: linear-gradient(#9ec7f0, #4a90d9);
    border-color: #2a6cb0;
}

.piano-key.black.target {
    background: linear-gradient(#5a9ad4, #2f6fad);
    border-color: #1a4a80;
}

.piano-key.white.correct {
    background: linear-gradient(#a8e0b2, #3cb043);
    border-color: #2a7a32;
}

.piano-key.black.correct {
    background: linear-gradient(#4caf50, #2e7d32);
}

.piano-key.white.wrong {
    background: linear-gradient(#f5a5a5, #e53935);
    border-color: #b71c1c;
}

.piano-key.black.wrong {
    background: linear-gradient(#e57373, #c62828);
}

.piano-key .key-dot {
    position: absolute;
    left: 50%;
    bottom: 12px;
    width: 10px;
    height: 10px;
    margin-left: -5px;
    border-radius: 50%;
    background: rgba(255, 255, 255, 0.9);
    box-shadow: 0 0 0 1px rgba(0, 0, 0, 0.15);
    display: none;
    pointer-events: none;
    z-index: 3;
}

.piano-key.target .key-dot,
.piano-key.correct .key-dot,
.piano-key.wrong .key-dot {
    display: block;
}

.piano-key.black .key-dot {
    bottom: 10px;
}

.piano-key.key-flash-off {
    filter: brightness(1.35) !important;
    background: #fff !important;
    transition: none !important;
}

.piano-key.black.key-flash-off {
    background: #555 !important;
    filter: brightness(1.5) !important;
}

@keyframes key-retrigger-pulse {
    0%   { transform: scale(1);    box-shadow: none; }
    25%  { transform: scale(0.94); box-shadow: 0 0 0 3px rgba(74, 144, 217, 0.85); }
    55%  { transform: scale(1.03); box-shadow: 0 0 14px 4px rgba(74, 144, 217, 0.55); }
    100% { transform: scale(1);    box-shadow: none; }
}

.piano-key.retrigger {
    animation: key-retrigger-pulse 0.4s ease-out;
    z-index: 4;
}

#piano-octave-row {
    display: flex;
    font-size: 0.7rem;
    color: var(--ink-faint);
    margin-top: 0.25rem;
    min-width: 100%;
    width: max-content;
}

#piano-octave-row span {
    flex: 1 0 0;
    min-width: 26px;
    text-align: left;
    padding-left: 2px;
}

/* ---------- Input section (MIDI / mic) ---------- */

.input-section {
    margin-top: 1.25rem;
    padding: 1rem 1.1rem 1.15rem;
    background: var(--bg-elevated);
    border: 1px solid var(--line-soft);
    border-radius: var(--radius);
    box-shadow: var(--shadow-sm);
}

.input-section h2 {
    margin: 0 0 0.65rem;
    font-size: 1.05rem;
    font-weight: 700;
    color: var(--ink);
    letter-spacing: -0.01em;
}

#midi-status,
#mic-status {
    color: var(--ink-soft);
    font-size: 0.92rem;
    margin: 0.25rem 0;
}

.input-section .playback-options {
    margin-top: 0.85rem;
    background: var(--bg-soft);
}

/* ---------- Count-in overlay ---------- */

#count-in-overlay {
    position: fixed;
    inset: 0;
    background: rgba(15, 23, 42, 0.55);
    backdrop-filter: blur(3px);
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    z-index: 1000;
    pointer-events: none;
}

#count-in-overlay.hidden {
    display: none !important;
}

#count-in-number {
    font-size: clamp(4.5rem, 14vw, 7rem);
    font-weight: 800;
    color: #fff;
    line-height: 1;
    text-shadow: 0 4px 28px rgba(0, 0, 0, 0.45);
    font-variant-numeric: tabular-nums;
}

#count-in-sub {
    margin-top: 0.75rem;
    font-size: 1.2rem;
    color: #f0f0f0;
    letter-spacing: 0.02em;
}

#count-in-overlay.downbeat #count-in-number {
    color: #ffd54f;
}

/* ---------- Responsive ---------- */

@media (max-width: 640px) {
    .app {
        padding: 0.75rem 0.7rem 2rem;
    }

    .app-header {
        padding: 0.9rem 1rem;
    }

    .brand-mark {
        width: 2.5rem;
        height: 2.5rem;
        font-size: 1.2rem;
    }

    .transport-bar {
        justify-content: stretch;
    }

    .transport-bar button {
        flex: 1 1 auto;
        text-align: center;
    }

    .btn-settings {
        margin-left: 0.15rem !important;
        flex: 1 1 100%;
    }

    .settings-grid {
        grid-template-columns: 1fr;
    }
}