:root {
    --bg-main: #ffffff;
    --bg-container: #ffffff;
    --bg-meta: #f5f5f5;
    --text-primary: #1a1a1a;
    --text-secondary: #666666;
    --accent: #ff1493;
    --border: #e0e0e0;
    --card-front-bg: #ffffff;
    --card-back-bg: #fef5fb;
    --card-border: #ff1493;
    --tooltip-bg: #2c3e50;
}

[data-theme="dark"] {
    --bg-main: #0a0a0a;
    --bg-container: #121212;
    --bg-meta: #1a1a1a;
    --text-primary: #f5f5f5;
    --text-secondary: #999999;
    --accent: #ff1493;
    --border: #2a2a2a;
    --card-front-bg: #121212;
    --card-back-bg: #1a0a15;
    --card-border: #ff1493;
    --tooltip-bg: #1a1a1a;
}

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

body {
    font-family: -apple-system, BlinkMacSystemFont, 'SF Pro Text', 'Segoe UI', 'Roboto', 'Helvetica Neue', Arial, sans-serif;
    line-height: 1.65;
    color: var(--text-primary);
    background: var(--bg-main);
    padding: 20px;
    transition: background-color 0.3s ease, color 0.3s ease;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
    text-rendering: optimizeLegibility;
}

.container {
    max-width: 700px;
    margin: 0 auto;
    background: var(--bg-container);
    padding: clamp(40px, 5vw, 60px) clamp(24px, 4vw, 50px);
    transition: background-color 0.3s ease;
}

header {
    position: relative;
    text-align: center;
    margin-bottom: 60px;
    padding-bottom: 30px;
    border-bottom: 3px solid var(--accent);
    transition: border-color 0.3s ease;
}

.theme-toggle {
    position: fixed;
    top: calc(env(safe-area-inset-top, 0px) + clamp(12px, 2vw, 20px));
    right: calc(env(safe-area-inset-right, 0px) + clamp(12px, 2vw, 20px));
    background: var(--accent);
    border: none;
    width: 44px;
    height: 44px;
    border-radius: 50%;
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
    transition: all 0.3s ease;
    box-shadow: 0 2px 8px rgba(0,0,0,0.2);
}

.theme-toggle:hover {
    transform: scale(1.1);
}

.theme-toggle svg {
    width: 24px;
    height: 24px;
    color: white;
}

.language-switcher {
    position: fixed;
    top: calc(env(safe-area-inset-top, 0px) + clamp(12px, 2vw, 20px));
    left: calc(env(safe-area-inset-left, 0px) + clamp(12px, 2vw, 20px));
    background: var(--bg-container);
    border: 1px solid var(--border);
    border-radius: 999px;
    padding: 6px 14px;
    display: flex;
    align-items: center;
    gap: 8px;
    font-size: 0.9rem;
    color: var(--text-primary);
    box-shadow: 0 2px 10px rgba(0, 0, 0, 0.08);
}

.language-switcher label {
    font-weight: 600;
}

.language-switcher select {
    border: none;
    background: transparent;
    font-size: 0.9rem;
    color: var(--text-primary);
    outline: none;
    padding: 4px 6px;
    border-radius: 8px;
}

[data-theme="dark"] .language-switcher {
    background: var(--bg-meta);
}

.sun-icon { display: block; }
.moon-icon { display: none; }

[data-theme="dark"] .sun-icon { display: none; }
[data-theme="dark"] .moon-icon { display: block; }

h1 {
    font-family: -apple-system, BlinkMacSystemFont, 'SF Pro Display', 'Segoe UI', 'Roboto', 'Helvetica Neue', Arial, sans-serif;
    font-size: clamp(2rem, 4vw, 2.8rem);
    font-weight: 700;
    color: var(--text-primary);
    margin-bottom: 15px;
    line-height: 1.2;
    transition: color 0.3s ease;
    letter-spacing: -0.02em;
}

.subtitle {
    font-size: 1em;
    color: var(--text-secondary);
    font-style: italic;
    font-weight: 400;
    transition: color 0.3s ease;
}

h2 {
    font-family: -apple-system, BlinkMacSystemFont, 'SF Pro Display', 'Segoe UI', 'Roboto', 'Helvetica Neue', Arial, sans-serif;
    font-size: clamp(1.3rem, 2.5vw, 1.7rem);
    font-weight: 600;
    color: var(--text-primary);
    margin: 40px 0 20px 0;
    padding-bottom: 10px;
    border-bottom: 2px solid var(--border);
    transition: color 0.3s ease, border-color 0.3s ease;
    letter-spacing: -0.01em;
}

p {
    margin-bottom: 15px;
    font-size: 1.0em;
}

.tappable {
    cursor: pointer;
    transition: background-color 0.2s ease, border-color 0.2s ease, color 0.2s ease;
    padding: 2px 1px;
    border-bottom: 1px dashed rgba(255, 20, 147, 0.35);
    border-radius: 2px;
}

.tappable:hover,
.tappable.active,
.tappable:focus-visible {
    background-color: rgba(255, 20, 147, 0.12);
    border-bottom-color: rgba(255, 20, 147, 0.7);
    outline: none;
}

[data-theme="dark"] .tappable {
    border-bottom-color: rgba(255, 20, 147, 0.45);
}

[data-theme="dark"] .tappable:hover,
[data-theme="dark"] .tappable.active,
[data-theme="dark"] .tappable:focus-visible {
    background-color: rgba(255, 20, 147, 0.2);
    border-bottom-color: rgba(255, 20, 147, 0.85);
}

.tooltip {
    display: none;
    position: fixed;
    background: var(--tooltip-bg);
    color: white;
    padding: 12px 16px;
    border-radius: 6px;
    font-size: 0.95em;
    max-width: 80vw;
    z-index: 1000;
    box-shadow: 0 4px 12px rgba(0,0,0,0.3);
    line-height: 1.4;
    transition: background-color 0.3s ease;
}

[data-theme="dark"] .tooltip {
    border: 1px solid var(--accent);
}

.tooltip::before {
    content: '';
    position: absolute;
    top: -8px;
    left: 50%;
    transform: translateX(-50%);
    border-left: 8px solid transparent;
    border-right: 8px solid transparent;
    border-bottom: 8px solid var(--tooltip-bg);
}

.tooltip.tooltip--above::before {
    top: auto;
    bottom: -8px;
    border-bottom: none;
    border-top: 8px solid var(--tooltip-bg);
}

.tooltip.visible {
    display: block;
}

.quote {
    font-style: italic;
    color: var(--text-secondary);
    padding-left: 20px;
    border-left: 4px solid var(--accent);
    margin: 20px 0;
}

hr {
    border: none;
    border-top: 1px solid var(--border);
    margin: 30px 0;
}

.story {
    background: var(--bg-container);
}

.meta-section {
    background: var(--bg-meta);
    margin-top: clamp(40px, 6vw, 60px);
    margin-right: clamp(-60px, -7vw, -10px);
    margin-bottom: 0;
    margin-left: clamp(-60px, -7vw, -10px);
    padding: clamp(30px, 5vw, 40px) clamp(24px, 6vw, 50px);
    border-top: 3px solid var(--accent);
    border-radius: 18px;
    transition: background-color 0.3s ease, border-color 0.3s ease;
}

.flashcard {
    position: relative;
    perspective: 1000px;
    margin: 40px 0 60px 0;
    z-index: 0;
    transform: translateZ(0);
    overflow: visible;
}

.flashcard-inner {
    position: relative;
    width: 100%;
    min-height: 240px;
    transition: transform 0.6s;
    transform-style: preserve-3d;
    z-index: 1;
}

.flashcard-inner.flipped {
    transform: rotateY(180deg);
}

.flashcard-front,
.flashcard-back {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    min-height: 240px;
    backface-visibility: hidden;
    border: 2px solid var(--card-border);
    border-radius: 8px;
    padding: 25px;
    display: flex;
    flex-direction: column;
    justify-content: space-between;
    transition: background-color 0.3s ease, border-color 0.3s ease;
}

.flashcard-front {
    background: var(--card-front-bg);
    z-index: 2;
}

.flashcard-back {
    transform: rotateY(180deg);
    background: var(--card-back-bg);
    z-index: 3;
}

.flashcard-content {
    flex: 1;
}

.flip-btn {
    margin-top: 15px;
    padding: 10px 20px;
    background: var(--accent);
    color: white;
    border: none;
    border-radius: 5px;
    cursor: pointer;
    font-size: 0.9em;
    font-family: -apple-system, BlinkMacSystemFont, 'SF Pro Text', 'Segoe UI', 'Roboto', 'Helvetica Neue', Arial, sans-serif;
    font-weight: 500;
    transition: all 0.3s ease;
}

.flip-btn:hover {
    filter: brightness(1.1);
    transform: translateY(-2px);
}

.metrics {
    background: var(--bg-container);
    padding: 20px;
    border-radius: 6px;
    margin-top: 20px;
    border: 1px solid var(--border);
}

.metrics ul {
    list-style: none;
    margin: 10px 0 0 0;
}

.metrics li {
    margin: 8px 0;
}

@media (max-width: 768px) {
    .meta-section {
        margin-left: clamp(-18px, -2vw, -6px);
        margin-right: clamp(-18px, -2vw, -6px);
        border-radius: 16px;
    }

    .theme-toggle {
        width: 40px;
        height: 40px;
    }
}