:root {
    --font-sans: 'Inter', -apple-system, BlinkMacSystemFont, sans-serif;
    --font-mono: 'JetBrains Mono', monospace;
    --font-display: 'Playfair Display', serif;

    --space-xs: 4px;
    --space-sm: 8px;
    --space-md: 16px;
    --space-lg: 24px;
    --space-xl: 32px;
    --space-2xl: 48px;
    --space-3xl: 64px;

    --radius-sm: 6px;
    --radius-md: 10px;
    --radius-lg: 16px;
    --radius-xl: 24px;

    --transition: 0.3s cubic-bezier(0.4, 0, 0.2, 1);
    --transition-slow: 0.6s cubic-bezier(0.4, 0, 0.2, 1);

    --shadow-sm: 0 1px 3px rgba(0,0,0,0.08);
    --shadow-md: 0 4px 12px rgba(0,0,0,0.1);
    --shadow-lg: 0 8px 32px rgba(0,0,0,0.12);
    --shadow-xl: 0 16px 48px rgba(0,0,0,0.15);
}

[data-theme="light"] {
    --bg-primary: #fafafa;
    --bg-secondary: #ffffff;
    --bg-tertiary: #f2f2f2;
    --bg-elevated: #ffffff;
    --bg-overlay: rgba(0,0,0,0.4);

    --text-primary: #1a1a1a;
    --text-secondary: #6b6b6b;
    --text-tertiary: #a0a0a0;
    --text-inverse: #ffffff;

    --border-primary: #e5e5e5;
    --border-secondary: #f0f0f0;
    --border-focus: #1a1a1a;

    --accent: #1a1a1a;
    --accent-hover: #333;
    --accent-soft: #e8e8e8;

    --success: #2e7d32;
    --warning: #f57c00;
    --error: #d32f2f;
    --perfect: #1565c0;

    --slider-bg: #ddd;
    --slider-fill: #1a1a1a;
    --slider-thumb: #1a1a1a;

    --letter-color: #1a1a1a;
    --grid-color: rgba(0,0,0,0.08);

    --mode-bg: #f5f5f5;
    --mode-hover: #eee;
    --mode-active: #1a1a1a;
    --mode-text: #1a1a1a;
    --mode-text-active: #fff;

    --modal-overlay: rgba(0,0,0,0.5);
    --modal-bg: #ffffff;

    --quote-bg: #f5f5f5;
    --quote-text: #6b6b6b;

    --progress-bg: #e5e5e5;
    --progress-fill: #1a1a1a;

    --grade-s: #1565c0;
    --grade-a: #2e7d32;
    --grade-b: #f57c00;
    --grade-c: #d32f2f;
    --grade-d: #c62828;
    --grade-f: #b71c1c;
}

[data-theme="dark"] {
    --bg-primary: #0d0d0d;
    --bg-secondary: #1a1a1a;
    --bg-tertiary: #252525;
    --bg-elevated: #222;
    --bg-overlay: rgba(0,0,0,0.7);

    --text-primary: #f0f0f0;
    --text-secondary: #999;
    --text-tertiary: #666;
    --text-inverse: #0d0d0d;

    --border-primary: #333;
    --border-secondary: #2a2a2a;
    --border-focus: #f0f0f0;

    --accent: #f0f0f0;
    --accent-hover: #ddd;
    --accent-soft: #2a2a2a;

    --success: #66bb6a;
    --warning: #ffa726;
    --error: #ef5350;
    --perfect: #42a5f5;

    --slider-bg: #333;
    --slider-fill: #f0f0f0;
    --slider-thumb: #f0f0f0;

    --letter-color: #f0f0f0;
    --grid-color: rgba(255,255,255,0.08);

    --mode-bg: #252525;
    --mode-hover: #333;
    --mode-active: #f0f0f0;
    --mode-text: #f0f0f0;
    --mode-text-active: #0d0d0d;

    --modal-overlay: rgba(0,0,0,0.7);
    --modal-bg: #1a1a1a;

    --quote-bg: #252525;
    --quote-text: #999;

    --progress-bg: #333;
    --progress-fill: #f0f0f0;

    --grade-s: #42a5f5;
    --grade-a: #66bb6a;
    --grade-b: #ffa726;
    --grade-c: #ef5350;
    --grade-d: #e53935;
    --grade-f: #c62828;
}

*, *::before, *::after {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
}

html {
    font-size: 16px;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}

body {
    font-family: var(--font-sans);
    background: var(--bg-primary);
    color: var(--text-primary);
    line-height: 1.5;
    min-height: 100vh;
    transition: background var(--transition), color var(--transition);
    overflow-x: hidden;
}

a { color: inherit; text-decoration: none; }
button { cursor: pointer; font-family: inherit; border: none; background: none; color: inherit; }
input[type="range"] { -webkit-appearance: none; appearance: none; background: transparent; cursor: pointer; width: 100%; }

::-webkit-scrollbar { width: 6px; }
::-webkit-scrollbar-track { background: var(--bg-tertiary); }
::-webkit-scrollbar-thumb { background: var(--border-primary); border-radius: 3px; }

.site-header {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    z-index: 100;
    background: var(--bg-secondary);
    border-bottom: 1px solid var(--border-primary);
    padding: 0 var(--space-lg);
    height: 56px;
    display: flex;
    align-items: center;
    transition: background var(--transition), border-color var(--transition);
}

.header-inner {
    max-width: 1440px;
    width: 100%;
    margin: 0 auto;
    display: flex;
    align-items: center;
    justify-content: space-between;
}

.logo {
    display: flex;
    align-items: baseline;
    gap: 1px;
    font-size: 1.25rem;
    font-weight: 800;
    letter-spacing: -0.02em;
}

.logo-ks { color: var(--text-primary); }
.logo-ks.accent {
    color: var(--text-primary);
    font-style: italic;
    transform: scaleX(-1);
    display: inline-block;
}
.logo-divider {
    margin: 0 var(--space-sm);
    color: var(--text-tertiary);
    font-weight: 300;
}
.logo-sub {
    font-weight: 400;
    font-size: 0.85rem;
    color: var(--text-secondary);
    letter-spacing: 0.05em;
    text-transform: uppercase;
}

.header-controls {
    display: flex;
    align-items: center;
    gap: var(--space-md);
}

.theme-toggle {
    display: flex;
    align-items: center;
    gap: var(--space-sm);
    cursor: pointer;
    user-select: none;
}

.theme-track {
    width: 44px;
    height: 22px;
    background: var(--slider-bg);
    border-radius: 11px;
    position: relative;
    transition: background var(--transition);
}

.theme-thumb {
    position: absolute;
    top: 2px;
    left: 2px;
    width: 18px;
    height: 18px;
    background: var(--text-primary);
    border-radius: 50%;
    transition: transform var(--transition), background var(--transition);
}

[data-theme="dark"] .theme-thumb {
    transform: translateX(22px);
}

.theme-label {
    font-size: 0.85rem;
    color: var(--text-secondary);
}

.btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: var(--space-sm);
    padding: var(--space-sm) var(--space-lg);
    font-size: 0.85rem;
    font-weight: 600;
    border-radius: var(--radius-sm);
    transition: all var(--transition);
    border: 1px solid var(--border-primary);
    background: var(--bg-secondary);
    color: var(--text-primary);
    letter-spacing: 0.01em;
}

.btn:hover { border-color: var(--border-focus); background: var(--accent-soft); }
.btn-sm { padding: var(--space-xs) var(--space-md); font-size: 0.8rem; }
.btn-primary {
    background: var(--accent);
    color: var(--text-inverse);
    border-color: var(--accent);
}
.btn-primary:hover { background: var(--accent-hover); border-color: var(--accent-hover); }
.btn-submit {
    background: var(--accent);
    color: var(--text-inverse);
    border-color: var(--accent);
    padding: var(--space-md) var(--space-xl);
    font-size: 0.95rem;
    font-weight: 700;
}
.btn-submit:hover { background: var(--accent-hover); }
.btn-preview, .btn-zoom, .btn-slowmo {
    font-size: 0.8rem;
    padding: var(--space-sm) var(--space-md);
}

.game-container {
    display: grid;
    grid-template-columns: 240px 1fr 240px;
    gap: 0;
    max-width: 1440px;
    margin: 0 auto;
    padding-top: 56px;
    min-height: 100vh;
}

.sidebar-left, .sidebar-right {
    padding: var(--space-lg);
    background: var(--bg-secondary);
    border-color: var(--border-primary);
    transition: background var(--transition), border-color var(--transition);
}

.sidebar-left {
    border-right: 1px solid var(--border-primary);
}

.sidebar-right {
    border-left: 1px solid var(--border-primary);
    display: flex;
    flex-direction: column;
    gap: var(--space-lg);
}

.sidebar-title {
    font-size: 0.65rem;
    font-weight: 700;
    text-transform: uppercase;
    letter-spacing: 0.15em;
    color: var(--text-tertiary);
    margin-bottom: var(--space-md);
    padding-bottom: var(--space-sm);
    border-bottom: 1px solid var(--border-primary);
}

.game-main {
    padding: var(--space-xl);
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    min-height: calc(100vh - 56px);
}

.game-stage {
    width: 100%;
    max-width: 640px;
    position: relative;
}

.progress-bar {
    width: 100%;
    height: 3px;
    background: var(--progress-bg);
    border-radius: 2px;
    margin-bottom: var(--space-2xl);
    overflow: hidden;
}

.progress-fill {
    height: 100%;
    background: var(--progress-fill);
    width: 0%;
    transition: width var(--transition-slow);
    border-radius: 2px;
}

.pair-display {
    display: flex;
    justify-content: center;
    align-items: center;
    margin-bottom: var(--space-xl);
    min-height: 240px;
    position: relative;
}

.pair-container {
    display: flex;
    align-items: baseline;
    position: relative;
    font-family: var(--font-display);
}

.letter {
    font-size: 10rem;
    font-weight: 700;
    line-height: 1;
    color: var(--letter-color);
    transition: color var(--transition);
    user-select: none;
}

.letter-gap {
    width: 0px;
    display: inline-block;
    transition: width 0.1s ease;
}

.grid-overlay {
    position: absolute;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
    width: 100%;
    height: 200px;
    pointer-events: none;
    opacity: 0.3;
    transition: opacity var(--transition);
}

.grid-overlay.hidden {
    opacity: 0;
}

.grid-line {
    position: absolute;
    background: var(--grid-color);
}

.grid-line-v {
    left: 50%;
    top: 0;
    bottom: 0;
    width: 1px;
}

.grid-line-h {
    top: 50%;
    left: 0;
    right: 0;
    height: 1px;
}

.grid-metric {
    position: absolute;
    bottom: -24px;
    left: 50%;
    transform: translateX(-50%);
    font-family: var(--font-mono);
    font-size: 0.75rem;
    color: var(--text-tertiary);
    letter-spacing: 0.05em;
}

.controls-area {
    margin-top: var(--space-xl);
}

.slider-container {
    margin-bottom: var(--space-lg);
}

.slider-label {
    display: flex;
    justify-content: space-between;
    font-size: 0.85rem;
    font-weight: 500;
    margin-bottom: var(--space-sm);
    color: var(--text-secondary);
}

.slider-value {
    font-family: var(--font-mono);
    font-weight: 700;
    color: var(--text-primary);
    min-width: 48px;
    text-align: right;
}

.slider-track {
    position: relative;
    padding: var(--space-sm) 0;
}

.slider {
    width: 100%;
    height: 4px;
    background: var(--slider-bg);
    border-radius: 2px;
    outline: none;
    position: relative;
    z-index: 2;
}

.slider::-webkit-slider-thumb {
    -webkit-appearance: none;
    appearance: none;
    width: 20px;
    height: 20px;
    background: var(--slider-thumb);
    border-radius: 50%;
    border: 3px solid var(--bg-secondary);
    box-shadow: var(--shadow-md);
    transition: transform 0.15s ease;
}

.slider::-webkit-slider-thumb:hover {
    transform: scale(1.15);
}

.slider::-moz-range-thumb {
    width: 20px;
    height: 20px;
    background: var(--slider-thumb);
    border-radius: 50%;
    border: 3px solid var(--bg-secondary);
    box-shadow: var(--shadow-md);
    cursor: pointer;
}

.slider-ticks {
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    height: 100%;
    pointer-events: none;
}

.tick {
    position: absolute;
    top: 50%;
    transform: translate(-50%, -50%);
    width: 1px;
    height: 12px;
    background: var(--border-primary);
}

.tick-label {
    position: absolute;
    top: 16px;
    left: 50%;
    transform: translateX(-50%);
    font-family: var(--font-mono);
    font-size: 0.6rem;
    color: var(--text-tertiary);
    white-space: nowrap;
}

.action-buttons {
    display: flex;
    gap: var(--space-sm);
    flex-wrap: wrap;
    justify-content: center;
}

.action-buttons .btn-submit {
    flex: 1;
    min-width: 160px;
}

.timer {
    text-align: center;
    font-family: var(--font-mono);
    font-size: 1.5rem;
    font-weight: 700;
    color: var(--text-primary);
    margin-top: var(--space-lg);
    min-height: 2rem;
    letter-spacing: 0.05em;
}

.timer.warning { color: var(--warning); }
.timer.danger { color: var(--error); animation: pulse 0.5s ease infinite; }

.tip-box {
    text-align: center;
    margin-top: var(--space-md);
    padding: var(--space-sm) var(--space-md);
    background: var(--accent-soft);
    border-radius: var(--radius-sm);
    font-size: 0.85rem;
    color: var(--text-secondary);
    display: flex;
    align-items: center;
    justify-content: center;
    gap: var(--space-sm);
    transition: opacity var(--transition);
}

.tip-box.hidden { opacity: 0; }

.mode-selector { margin-bottom: var(--space-xl); }

.mode-list {
    display: flex;
    flex-direction: column;
    gap: var(--space-sm);
}

.mode-btn {
    text-align: left;
    padding: var(--space-md);
    border-radius: var(--radius-sm);
    background: var(--mode-bg);
    border: 1px solid transparent;
    transition: all var(--transition);
}

.mode-btn:hover {
    background: var(--mode-hover);
    border-color: var(--border-primary);
}

.mode-btn.active {
    background: var(--mode-active);
    color: var(--mode-text-active);
    border-color: var(--mode-active);
}

.mode-btn.active .mode-desc {
    color: rgba(255,255,255,0.6);
}

.mode-btn.active:hover {
    opacity: 0.9;
}

.mode-name {
    display: block;
    font-size: 0.8rem;
    font-weight: 700;
    margin-bottom: 2px;
}

.mode-desc {
    display: block;
    font-size: 0.7rem;
    color: var(--text-tertiary);
    line-height: 1.3;
}

.scoreboard { margin-bottom: var(--space-xl); }

.score-grid {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: var(--space-sm);
}

.score-item {
    background: var(--bg-tertiary);
    padding: var(--space-sm) var(--space-md);
    border-radius: var(--radius-sm);
}

.score-label {
    display: block;
    font-size: 0.6rem;
    font-weight: 600;
    text-transform: uppercase;
    letter-spacing: 0.1em;
    color: var(--text-tertiary);
    margin-bottom: 2px;
}

.score-value {
    display: block;
    font-family: var(--font-mono);
    font-size: 1rem;
    font-weight: 700;
    color: var(--text-primary);
}

.history-panel { }

.history-list {
    display: flex;
    flex-direction: column;
    gap: var(--space-xs);
    max-height: 200px;
    overflow-y: auto;
}

.history-empty {
    font-size: 0.75rem;
    color: var(--text-tertiary);
    text-align: center;
    padding: var(--space-md);
}

.history-item {
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: var(--space-xs) var(--space-sm);
    background: var(--bg-tertiary);
    border-radius: var(--radius-sm);
    font-size: 0.75rem;
    font-family: var(--font-mono);
}

.history-item .h-pair {
    font-weight: 700;
}

.history-item .h-score {
    color: var(--text-secondary);
}

.history-item.perfect {
    border-left: 2px solid var(--perfect);
}

.preview-panel {
    margin-bottom: var(--space-lg);
}

.preview-box {
    background: var(--bg-tertiary);
    border-radius: var(--radius-sm);
    padding: var(--space-md);
    text-align: center;
}

.preview-section {
    padding: var(--space-sm) 0;
}

.preview-label {
    font-size: 0.6rem;
    font-weight: 700;
    text-transform: uppercase;
    letter-spacing: 0.15em;
    color: var(--text-tertiary);
    display: block;
    margin-bottom: var(--space-xs);
}

.preview-text {
    font-family: var(--font-display);
    font-size: 2rem;
    font-weight: 700;
    color: var(--text-primary);
    line-height: 1.2;
    transition: all var(--transition);
}

.preview-text.before-text {
    color: var(--text-tertiary);
    letter-spacing: 0.2em;
}

.preview-divider {
    height: 1px;
    background: var(--border-primary);
    margin: var(--space-sm) 0;
}

.reference-panel {
    margin-bottom: var(--space-lg);
}

.tip-list {
    list-style: none;
    font-size: 0.75rem;
    display: flex;
    flex-direction: column;
    gap: var(--space-sm);
}

.tip-list li {
    padding: var(--space-xs) 0;
    padding-left: var(--space-md);
    position: relative;
    color: var(--text-secondary);
    line-height: 1.4;
}

.tip-list li::before {
    content: "→";
    position: absolute;
    left: 0;
    color: var(--text-tertiary);
    font-family: var(--font-mono);
}

.tip-list li strong {
    color: var(--text-primary);
    font-weight: 600;
}

.quote-bar {
    margin-top: auto;
    padding: var(--space-md);
    background: var(--quote-bg);
    border-radius: var(--radius-sm);
    text-align: center;
    font-family: var(--font-display);
    font-size: 0.85rem;
    font-style: italic;
    color: var(--quote-text);
    line-height: 1.4;
}

.quote-icon {
    display: block;
    margin-bottom: var(--space-xs);
    font-size: 0.6rem;
    color: var(--text-tertiary);
    font-style: normal;
}

.modal-overlay {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: var(--modal-overlay);
    display: flex;
    align-items: center;
    justify-content: center;
    z-index: 1000;
    opacity: 0;
    pointer-events: none;
    transition: opacity 0.3s ease;
    backdrop-filter: blur(4px);
}

.modal-overlay.active {
    opacity: 1;
    pointer-events: all;
}

.modal {
    background: var(--modal-bg);
    border-radius: var(--radius-lg);
    width: 90%;
    max-width: 480px;
    box-shadow: var(--shadow-xl);
    transform: scale(0.9) translateY(20px);
    transition: transform 0.4s cubic-bezier(0.34, 1.56, 0.64, 1);
    max-height: 90vh;
    overflow-y: auto;
}

.modal-lg { max-width: 560px; }

.modal-overlay.active .modal {
    transform: scale(1) translateY(0);
}

.modal-header {
    padding: var(--space-lg) var(--space-xl);
    border-bottom: 1px solid var(--border-primary);
    display: flex;
    align-items: center;
    justify-content: space-between;
}

.modal-header h2 {
    font-size: 1.25rem;
    font-weight: 700;
}

.modal-close {
    width: 32px;
    height: 32px;
    display: flex;
    align-items: center;
    justify-content: center;
    border-radius: 50%;
    font-size: 1.25rem;
    transition: background var(--transition);
}

.modal-close:hover {
    background: var(--accent-soft);
}

.modal-body {
    padding: var(--space-xl);
}

.result-pair {
    text-align: center;
    font-family: var(--font-display);
    font-size: 5rem;
    font-weight: 700;
    color: var(--text-primary);
    margin-bottom: var(--space-md);
    line-height: 1;
}

.result-verdict {
    text-align: center;
    font-size: 1.1rem;
    font-weight: 700;
    margin-bottom: var(--space-lg);
}

.verdict-perfect { color: var(--perfect); }
.verdict-great { color: var(--success); }
.verdict-good { color: var(--warning); }
.verdict-bad { color: var(--error); }

.result-details {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: var(--space-sm);
    margin-bottom: var(--space-lg);
}

.result-stat {
    background: var(--bg-tertiary);
    padding: var(--space-md);
    border-radius: var(--radius-sm);
    text-align: center;
}

.stat-label {
    display: block;
    font-size: 0.6rem;
    font-weight: 600;
    text-transform: uppercase;
    letter-spacing: 0.1em;
    color: var(--text-tertiary);
    margin-bottom: var(--space-xs);
}

.stat-value {
    display: block;
    font-family: var(--font-mono);
    font-size: 1.4rem;
    font-weight: 700;
    color: var(--text-primary);
}

.result-tip {
    text-align: center;
    font-size: 0.85rem;
    color: var(--text-secondary);
    font-style: italic;
}

.modal-footer {
    padding: var(--space-lg) var(--space-xl);
    border-top: 1px solid var(--border-primary);
    display: flex;
    justify-content: center;
    gap: var(--space-md);
}

.modal-footer .btn {
    min-width: 160px;
}

.final-grade {
    text-align: center;
    font-size: 6rem;
    font-weight: 900;
    line-height: 1;
    margin-bottom: var(--space-lg);
    font-family: var(--font-display);
}

.final-grade.grade-s { color: var(--grade-s); }
.final-grade.grade-a { color: var(--grade-a); }
.final-grade.grade-b { color: var(--grade-b); }
.final-grade.grade-c { color: var(--grade-c); }
.final-grade.grade-d { color: var(--grade-d); }
.final-grade.grade-f { color: var(--grade-f); }

.final-stats {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: var(--space-sm);
    margin-bottom: var(--space-lg);
}

.final-stat {
    text-align: center;
    padding: var(--space-md);
    background: var(--bg-tertiary);
    border-radius: var(--radius-sm);
}

.final-stat-label {
    display: block;
    font-size: 0.65rem;
    font-weight: 600;
    text-transform: uppercase;
    letter-spacing: 0.1em;
    color: var(--text-tertiary);
    margin-bottom: 2px;
}

.final-stat-value {
    display: block;
    font-family: var(--font-mono);
    font-size: 1.5rem;
    font-weight: 700;
    color: var(--text-primary);
}

.final-quote {
    text-align: center;
    font-family: var(--font-display);
    font-size: 1rem;
    font-style: italic;
    color: var(--text-secondary);
    padding: var(--space-md);
    background: var(--bg-tertiary);
    border-radius: var(--radius-sm);
}

@keyframes pulse {
    0%, 100% { opacity: 1; }
    50% { opacity: 0.5; }
}

@keyframes float {
    0%, 100% { transform: translateY(0); }
    50% { transform: translateY(-8px); }
}

@keyframes slideIn {
    from { opacity: 0; transform: translateY(10px); }
    to { opacity: 1; transform: translateY(0); }
}

.letter { animation: float 4s ease-in-out infinite; }
.letter-first { animation-delay: 0s; }
.letter-second { animation-delay: 0.2s; }

.slowmo-active .letter {
    animation-duration: 8s !important;
}

.slowmo-active .letter-gap {
    transition-duration: 0.5s !important;
}

.zoomed .letter {
    font-size: 14rem !important;
}

@media (max-width: 1024px) {
    .game-container {
        grid-template-columns: 1fr;
    }
    .sidebar-left, .sidebar-right {
        display: none;
    }
    .game-main {
        padding: var(--space-lg);
    }
    .letter {
        font-size: 6rem;
    }
    .zoomed .letter {
        font-size: 8rem !important;
    }
}