/* CSS Variables - Design System */
:root {
    /* Colors */
    --bg-primary: #0a0a0a;
    --bg-secondary: #1a1a1a;
    --bg-tertiary: #2a2a2a;
    --text-primary: #ffffff;
    --text-secondary: #a0a0a0;
    --text-tertiary: #666666;

    /* Tone Colors */
    --tone-1: #FF6B6B;  /* Flat tone - Red */
    --tone-2: #4ECDC4;  /* Rising tone - Teal */
    --tone-3: #45B7D1;  /* Dipping tone - Blue */
    --tone-4: #96CEB4;  /* Falling tone - Green */
    --tone-5: #FFEAA7;  /* Neutral tone - Yellow */

    /* UI Colors */
    --accent: #6366F1;
    --success: #10B981;
    --error: #EF4444;
    --warning: #F59E0B;

    /* Typography */
    --font-ui: 'Inter', -apple-system, BlinkMacSystemFont, sans-serif;
    --font-chinese: 'Noto Sans SC', sans-serif;
    --font-mono: 'JetBrains Mono', monospace;

    /* Spacing */
    --spacing-xs: 0.25rem;
    --spacing-sm: 0.5rem;
    --spacing-md: 1rem;
    --spacing-lg: 1.5rem;
    --spacing-xl: 2rem;
    --spacing-2xl: 3rem;

    /* Border Radius */
    --radius-sm: 0.25rem;
    --radius-md: 0.5rem;
    --radius-lg: 1rem;
    --radius-full: 9999px;
}

/* Reset & Base */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

body {
    font-family: var(--font-ui);
    background: var(--bg-primary);
    color: var(--text-primary);
    line-height: 1.6;
    min-height: 100vh;
    overflow-x: hidden;
}

/* App Container */
.app-container {
    max-width: 768px;
    margin: 0 auto;
    padding: var(--spacing-md);
    min-height: 100vh;
    display: flex;
    flex-direction: column;
}

/* Header */
.app-header {
    text-align: center;
    padding: var(--spacing-xl) 0;
}

.app-title {
    font-size: 2.5rem;
    font-weight: 700;
    background: linear-gradient(135deg, var(--accent) 0%, var(--tone-2) 100%);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
    margin-bottom: var(--spacing-sm);
}

.app-subtitle {
    color: var(--text-secondary);
    font-size: 1.125rem;
}

/* Mode Tabs */
.mode-tabs {
    display: flex;
    gap: var(--spacing-sm);
    background: var(--bg-secondary);
    padding: var(--spacing-sm);
    border-radius: var(--radius-lg);
    margin-bottom: var(--spacing-xl);
}

.tab-btn {
    flex: 1;
    padding: var(--spacing-md) var(--spacing-lg);
    background: transparent;
    color: var(--text-secondary);
    border: none;
    border-radius: var(--radius-md);
    font-size: 1rem;
    font-weight: 500;
    cursor: pointer;
    transition: all 0.3s ease;
}

.tab-btn.active {
    background: var(--bg-tertiary);
    color: var(--text-primary);
}

.tab-btn:hover:not(.active) {
    color: var(--text-primary);
}

/* Mode Content */
.mode-content {
    display: none;
    flex: 1;
}

.mode-content.active {
    display: block;
}

/* Practice Mode */
.practice-container {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: var(--spacing-2xl);
}

.practice-phrase {
    text-align: center;
    background: var(--bg-secondary);
    padding: var(--spacing-xl);
    border-radius: var(--radius-lg);
    width: 100%;
}

.phrase-label {
    color: var(--text-secondary);
    font-size: 0.875rem;
    text-transform: uppercase;
    letter-spacing: 0.05em;
    margin-bottom: var(--spacing-md);
}

.phrase-chinese {
    font-family: var(--font-chinese);
    font-size: 3rem;
    font-weight: 500;
    margin-bottom: var(--spacing-sm);
    line-height: 1.2;
}

.phrase-pinyin {
    font-family: var(--font-mono);
    font-size: 1.25rem;
    color: var(--text-secondary);
}

/* Recording Button */
.record-container {
    position: relative;
}

.record-btn {
    position: relative;
    width: 120px;
    height: 120px;
    border-radius: 50%;
    background: linear-gradient(135deg, var(--accent), var(--tone-2));
    border: none;
    color: white;
    cursor: pointer;
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    gap: var(--spacing-sm);
    transition: all 0.3s ease;
    box-shadow: 0 10px 40px rgba(99, 102, 241, 0.3);
}

.record-btn:hover {
    transform: scale(1.05);
    box-shadow: 0 15px 50px rgba(99, 102, 241, 0.4);
}

.record-btn:active {
    transform: scale(0.95);
}

.record-btn.recording {
    animation: pulse 1.5s infinite;
    background: linear-gradient(135deg, var(--error), var(--tone-1));
}

.record-btn.processing {
    background: linear-gradient(135deg, var(--warning), var(--tone-5));
    animation: spin 1s linear infinite;
}

@keyframes pulse {
    0% {
        box-shadow: 0 0 0 0 rgba(239, 68, 68, 0.7);
    }
    70% {
        box-shadow: 0 0 0 30px rgba(239, 68, 68, 0);
    }
    100% {
        box-shadow: 0 0 0 0 rgba(239, 68, 68, 0);
    }
}

@keyframes spin {
    from {
        transform: rotate(0deg);
    }
    to {
        transform: rotate(360deg);
    }
}

.mic-icon {
    width: 32px;
    height: 32px;
}

.record-text {
    font-size: 0.875rem;
    font-weight: 500;
}

/* Feedback Display */
.feedback-container {
    width: 100%;
    background: var(--bg-secondary);
    border-radius: var(--radius-lg);
    padding: var(--spacing-xl);
    animation: slideUp 0.5s ease;
}

.feedback-container.hidden {
    display: none;
}

@keyframes slideUp {
    from {
        opacity: 0;
        transform: translateY(20px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

.feedback-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: var(--spacing-lg);
}

.feedback-header h3 {
    font-size: 1.125rem;
    font-weight: 600;
}

.accuracy-badge {
    background: var(--bg-tertiary);
    padding: var(--spacing-sm) var(--spacing-md);
    border-radius: var(--radius-full);
    font-weight: 500;
}

.accuracy-value {
    color: var(--success);
    font-size: 1.25rem;
    font-weight: 700;
}

/* Syllable Feedback */
.syllable-feedback {
    display: flex;
    flex-wrap: wrap;
    gap: var(--spacing-md);
}

.syllable-card {
    flex: 1;
    min-width: 80px;
    background: var(--bg-tertiary);
    border-radius: var(--radius-md);
    padding: var(--spacing-md);
    text-align: center;
    border: 2px solid transparent;
    transition: all 0.3s ease;
}

.syllable-card.correct {
    border-color: var(--success);
}

.syllable-card.incorrect {
    border-color: var(--error);
    animation: shake 0.5s ease;
}

@keyframes shake {
    0%, 100% { transform: translateX(0); }
    25% { transform: translateX(-5px); }
    75% { transform: translateX(5px); }
}

.syllable-character {
    font-family: var(--font-chinese);
    font-size: 2rem;
    font-weight: 500;
    margin-bottom: var(--spacing-xs);
}

.syllable-pinyin {
    font-family: var(--font-mono);
    font-size: 1rem;
    margin-bottom: var(--spacing-sm);
}

.tone-indicator {
    display: inline-block;
    width: 40px;
    height: 20px;
    border-radius: var(--radius-sm);
    position: relative;
    overflow: hidden;
}

.tone-curve {
    position: absolute;
    width: 100%;
    height: 2px;
    background: currentColor;
    top: 50%;
    transform: translateY(-50%);
}

/* Tone curves */
.tone-curve.tone-1 { /* Flat */
    background: var(--tone-1);
}

.tone-curve.tone-2 { /* Rising */
    background: var(--tone-2);
    transform: rotate(-15deg);
    transform-origin: left center;
}

.tone-curve.tone-3 { /* Dipping */
    background: var(--tone-3);
    height: 20px;
    border-radius: 0 0 50% 50%;
    top: 0;
    transform: none;
}

.tone-curve.tone-4 { /* Falling */
    background: var(--tone-4);
    transform: rotate(15deg);
    transform-origin: left center;
}

.tone-curve.tone-5 { /* Neutral */
    background: var(--tone-5);
    opacity: 0.5;
}

.syllable-status {
    margin-top: var(--spacing-sm);
    font-size: 1.5rem;
}

/* New Phrase Button */
.new-phrase-btn {
    padding: var(--spacing-md) var(--spacing-xl);
    background: var(--bg-secondary);
    color: var(--text-primary);
    border: 1px solid var(--bg-tertiary);
    border-radius: var(--radius-md);
    font-size: 1rem;
    font-weight: 500;
    cursor: pointer;
    transition: all 0.3s ease;
}

.new-phrase-btn:hover {
    background: var(--bg-tertiary);
}

/* Conversation Mode */
.chat-container {
    height: calc(100vh - 350px);
    overflow-y: auto;
    padding: var(--spacing-md);
    background: var(--bg-secondary);
    border-radius: var(--radius-lg);
    margin-bottom: var(--spacing-xl);
}

.chat-messages {
    display: flex;
    flex-direction: column;
    gap: var(--spacing-md);
}

.message {
    max-width: 70%;
    padding: var(--spacing-md) var(--spacing-lg);
    border-radius: var(--radius-lg);
    animation: slideUp 0.3s ease;
}

.message.assistant {
    align-self: flex-start;
    background: var(--bg-tertiary);
    border-bottom-left-radius: var(--radius-sm);
}

.message.user {
    align-self: flex-end;
    background: linear-gradient(135deg, var(--accent), var(--tone-2));
    border-bottom-right-radius: var(--radius-sm);
}

.message-content {
    font-family: var(--font-chinese);
    font-size: 1.125rem;
    margin-bottom: var(--spacing-sm);
}

.message-pinyin {
    font-family: var(--font-mono);
    font-size: 0.875rem;
    color: var(--text-secondary);
    opacity: 0.8;
}

.message-feedback {
    margin-top: var(--spacing-md);
    padding-top: var(--spacing-md);
    border-top: 1px solid rgba(255, 255, 255, 0.1);
}

.conversation-controls {
    display: flex;
    justify-content: center;
    padding: var(--spacing-lg);
}

/* Mobile Optimizations */
@media (max-width: 640px) {
    .app-title {
        font-size: 2rem;
    }

    .phrase-chinese {
        font-size: 2.5rem;
    }

    .chat-container {
        height: calc(100vh - 300px);
    }

    .message {
        max-width: 85%;
    }
}

/* Loading State */
.loading {
    display: inline-block;
    width: 20px;
    height: 20px;
    border: 3px solid rgba(255, 255, 255, 0.3);
    border-radius: 50%;
    border-top-color: white;
    animation: spin 1s ease infinite;
}

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

.text-center {
    text-align: center;
}

.mt-1 { margin-top: var(--spacing-sm); }
.mt-2 { margin-top: var(--spacing-md); }
.mt-3 { margin-top: var(--spacing-lg); }