:root {
    --bg-primary: #0a0e1a;
    --bg-secondary: #1a2035;
    --bg-card: #151b2e;
    --gold: #e8a838;
    --gold-dark: #c47f1a;
    --gold-light: #f5c563;
    --white: #ffffff;
    --white-soft: #e8eaf0;
    --gray: #7a8599;
    --error: #ff6b6b;
    --success: #4ecdc4;
    --eve-blue: #a8d8ea;
    --space-blue: #1e3a5f;

    --font-main: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
    --font-serif: "Georgia", "Songti SC", serif;

    --transition-fast: 200ms ease;
    --transition-normal: 400ms ease;
    --transition-slow: 600ms ease;

    --safe-top: env(safe-area-inset-top, 0px);
    --safe-bottom: env(safe-area-inset-bottom, 0px);
}

* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
    -webkit-tap-highlight-color: transparent;
}

html, body {
    height: 100%;
    overflow: hidden;
    font-family: var(--font-main);
    background: linear-gradient(180deg, #0a0e1a 0%, #0f1628 50%, #0a0e1a 100%);
    color: var(--white);
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}

body {
    touch-action: pan-y;
}

#app {
    width: 100%;
    height: 100%;
    position: relative;
    overflow: hidden;
}

.slide {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    display: flex;
    align-items: center;
    justify-content: center;
    opacity: 0;
    visibility: hidden;
    transition: opacity var(--transition-normal), transform var(--transition-normal);
    transform: translateY(20px);
    padding: var(--safe-top) 24px var(--safe-bottom);
    overflow-y: auto;
}

.slide.active {
    opacity: 1;
    visibility: visible;
    transform: translateY(0);
}

.slide.exit-up {
    opacity: 0;
    transform: translateY(-20px);
}

.slide-content {
    width: 100%;
    max-width: 400px;
    display: flex;
    flex-direction: column;
    align-items: center;
    text-align: center;
}

/* Cover */
.cover {
    animation: fadeInUp 0.8s ease 0.3s both;
    position: relative;
    z-index: 2;
}

.starfield {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    overflow: hidden;
    z-index: 1;
}

.star {
    position: absolute;
    background: #fff;
    border-radius: 50%;
    animation: twinkle var(--duration, 3s) ease-in-out infinite;
    opacity: 0;
}

@keyframes twinkle {
    0%, 100% { opacity: 0.2; }
    50% { opacity: 1; }
}

.cover-decoration {
    font-size: 2.5rem;
    margin-bottom: 2rem;
    animation: float 3s ease-in-out infinite;
}

.cover-title {
    font-size: 1.75rem;
    font-weight: 300;
    letter-spacing: 0.1em;
    color: var(--gold);
    margin-bottom: 0.75rem;
}

.cover-subtitle {
    font-size: 0.9rem;
    color: var(--eve-blue);
    font-weight: 300;
    margin-bottom: 2rem;
    letter-spacing: 0.05em;
}

.cover-divider {
    width: 40px;
    height: 1px;
    background: var(--gold-dark);
    margin-bottom: 2.5rem;
}

.btn-start {
    animation: goldGlow 2.5s ease-in-out infinite;
}

.btn-start,
.btn-next,
.btn-play {
    background: transparent;
    border: 1px solid var(--gold);
    color: var(--gold);
    padding: 12px 32px;
    font-size: 0.9rem;
    letter-spacing: 0.1em;
    cursor: pointer;
    transition: all var(--transition-fast);
    border-radius: 2px;
}

.btn-start:active,
.btn-next:active,
.btn-play:active {
    background: var(--gold);
    color: var(--bg-primary);
    transform: scale(0.97);
}

.cover-hint {
    margin-top: 1.5rem;
    font-size: 0.75rem;
    color: var(--gray);
    opacity: 0.6;
}

/* Puzzle common */
.puzzle-header {
    margin-bottom: 2rem;
}

.puzzle-step {
    font-size: 0.75rem;
    color: var(--gold-dark);
    letter-spacing: 0.2em;
    text-transform: uppercase;
}

.puzzle-title {
    font-size: 1.5rem;
    font-weight: 300;
    color: var(--white);
    margin-top: 0.5rem;
}

.puzzle-hint {
    font-size: 0.95rem;
    color: var(--gray);
    margin-bottom: 2rem;
    line-height: 1.6;
}

.puzzle-reward {
    margin-top: 2rem;
    animation: fadeInUp var(--transition-normal) ease forwards;
}

.puzzle-reward .reward-text {
    font-size: 0.9rem;
    color: var(--white-soft);
    line-height: 1.8;
    margin-bottom: 1.5rem;
}

/* Letter */
.letter {
    max-width: 360px;
    padding: 2rem 0;
}

.letter-greeting {
    font-family: var(--font-serif);
    font-size: 1.3rem;
    font-weight: 400;
    color: var(--gold);
    margin-bottom: 1.5rem;
    align-self: flex-start;
}

.letter-body {
    text-align: left;
    line-height: 2;
    font-size: 0.9rem;
    color: var(--white-soft);
    margin-bottom: 2rem;
}

.letter-body p {
    margin-bottom: 1em;
}

.letter-signature {
    align-self: flex-end;
    font-family: var(--font-serif);
    font-size: 0.9rem;
    color: var(--gold-dark);
    margin-bottom: 2rem;
}

/* Stats */
.stats-title {
    font-size: 1.3rem;
    font-weight: 300;
    color: var(--gold);
    margin-bottom: 2.5rem;
}

.stats-grid {
    display: grid;
    grid-template-columns: 1fr;
    gap: 2rem;
    margin-bottom: 2.5rem;
    width: 100%;
}

.stat-item {
    display: flex;
    flex-direction: column;
    align-items: center;
}

.stat-number {
    font-size: 3rem;
    font-weight: 200;
    color: var(--white);
    line-height: 1;
}

.stat-label {
    font-size: 0.85rem;
    color: var(--gold);
    margin-top: 0.25rem;
}

.stat-desc {
    font-size: 0.75rem;
    color: var(--gray);
    margin-top: 0.25rem;
}

/* Reward page */
.reward-page {
    justify-content: center;
}

.gift-box {
    cursor: pointer;
    transition: transform var(--transition-fast);
}

.gift-box:active {
    transform: scale(0.95);
}

.gift-icon {
    font-size: 4rem;
    margin-bottom: 1.5rem;
}

.gift-box h2 {
    font-size: 1.1rem;
    font-weight: 300;
    color: var(--white-soft);
    margin-bottom: 0.75rem;
}

.gift-desc {
    font-size: 0.8rem;
    color: var(--gray);
}

.gift-message {
    font-size: 1.1rem;
    color: var(--gold);
    margin-bottom: 2rem;
}

/* Utility */
.hidden {
    display: none !important;
}

/* Audio toggle */
.audio-toggle {
    position: fixed;
    top: calc(var(--safe-top) + 16px);
    right: 16px;
    width: 36px;
    height: 36px;
    border-radius: 50%;
    background: var(--bg-secondary);
    border: 1px solid var(--gold-dark);
    color: var(--gold);
    font-size: 1rem;
    cursor: pointer;
    z-index: 100;
    display: flex;
    align-items: center;
    justify-content: center;
    transition: opacity var(--transition-fast);
}

.audio-toggle.muted {
    opacity: 0.4;
}

/* Progress bar */
.progress-bar {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 2px;
    background: var(--bg-secondary);
    z-index: 90;
}

.progress-fill {
    height: 100%;
    background: var(--gold);
    width: 0%;
    transition: width var(--transition-normal);
}

/* FX Canvas */
.fx-canvas {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    pointer-events: none;
    z-index: 1000;
}