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

:root {
    --primary-color: #4a90e2;
    --primary-dark: #357abd;
    --secondary-color: #64b5f6;
    --success-color: #66bb6a;
    --danger-color: #ef5350;
    --bg-color: #f5f7fa;
    --card-bg: #ffffff;
    --text-color: #333333;
    --text-light: #666666;
    --border-color: #e0e0e0;
    --shadow: 0 2px 8px rgba(0, 0, 0, 0.1);
    --shadow-lg: 0 4px 16px rgba(0, 0, 0, 0.15);
}

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Oxygen, Ubuntu, Cantarell, sans-serif;
    background: linear-gradient(to bottom, #f8f9fa 0%, #e9ecef 100%);
    color: var(--text-color);
    line-height: 1.6;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
    overflow-x: hidden;
    min-height: 100vh;
}

.screen {
    min-height: 100vh;
}

.hidden {
    display: none !important;
}

/* ============= AUTH SCREEN ============= */

#auth-screen {
    display: flex;
    align-items: center;
    justify-content: center;
    padding: 20px;
    background: linear-gradient(135deg, var(--primary-color), var(--secondary-color));
}

.auth-container {
    background: var(--card-bg);
    border-radius: 16px;
    padding: 40px;
    width: 100%;
    max-width: 400px;
    box-shadow: var(--shadow-lg);
}

.auth-container h1 {
    text-align: center;
    color: var(--primary-color);
    margin-bottom: 30px;
    font-size: 28px;
}

.tabs {
    display: flex;
    gap: 10px;
    margin-bottom: 30px;
}

.tab-btn {
    flex: 1;
    padding: 12px;
    border: 2px solid var(--border-color);
    background: white;
    border-radius: 8px;
    font-size: 16px;
    cursor: pointer;
    transition: all 0.3s;
    font-weight: 500;
}

.tab-btn.active {
    background: var(--primary-color);
    color: white;
    border-color: var(--primary-color);
}

.auth-form {
    display: none;
}

.auth-form.active {
    display: block;
}

.form-group {
    margin-bottom: 20px;
}

.form-group label {
    display: block;
    margin-bottom: 8px;
    font-weight: 500;
    color: var(--text-color);
}

.form-group input {
    width: 100%;
    padding: 12px;
    border: 2px solid var(--border-color);
    border-radius: 8px;
    font-size: 16px;
    transition: border-color 0.3s;
}

.form-group input:focus {
    outline: none;
    border-color: var(--primary-color);
}

.btn {
    padding: 12px 24px;
    border: none;
    border-radius: 8px;
    font-size: 16px;
    font-weight: 600;
    cursor: pointer;
    transition: all 0.3s;
    text-align: center;
}

.btn-primary {
    background: var(--primary-color);
    color: white;
    width: 100%;
}

.btn-primary:hover {
    background: var(--primary-dark);
    transform: translateY(-2px);
    box-shadow: var(--shadow);
}

.btn-primary:active {
    transform: translateY(0);
}

.error-message {
    color: var(--danger-color);
    margin-top: 10px;
    font-size: 14px;
    text-align: center;
    min-height: 20px;
}

/* ============= MAIN APP ============= */

.header {
    background: white;
    padding: 20px;
    display: flex;
    justify-content: space-between;
    align-items: center;
    box-shadow: 0 2px 12px rgba(0, 0, 0, 0.08);
    position: sticky;
    top: 0;
    z-index: 100;
    border-bottom: 1px solid #f0f2f5;
}

.header h1 {
    font-size: 24px;
    font-weight: 700;
    background: linear-gradient(135deg, var(--primary-color), var(--secondary-color));
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.btn-secondary {
    background: white;
    color: var(--text-color);
    padding: 10px 20px;
    border: 2px solid var(--border-color);
}

.btn-secondary:hover {
    background: var(--bg-color);
    border-color: var(--text-color);
}

/* Stats Dashboard */

.stats-dashboard {
    display: flex;
    align-items: flex-start;
    justify-content: flex-end;
    gap: 48px;
    padding: 20px;
    max-width: 1200px;
    margin: 20px auto;
    background: var(--card-bg);
    border-radius: 12px;
    box-shadow: var(--shadow);
    flex-wrap: wrap;
}

.stat-item-vertical {
    display: flex;
    flex-direction: column;
    align-items: flex-end;
    gap: 8px;
    text-align: right;
}

.stat-label-top {
    font-size: 12px;
    color: var(--text-light);
    font-weight: 600;
    text-transform: uppercase;
    letter-spacing: 0.5px;
}

.stat-value-large {
    font-size: 18px;
    font-weight: 700;
    color: var(--primary-color);
    line-height: 1.2;
}

/* Mode icon and text */
.mode-icon {
    font-size: 24px;
}

.mode-text {
    font-weight: 500;
}

/* Player Section */

.player-section {
    max-width: 900px;
    margin: 20px auto;
    padding: 0 20px;
}

.player-container {
    background: linear-gradient(145deg, #ffffff, #f8f9fa);
    border-radius: 24px;
    padding: 32px;
    box-shadow: 0 8px 32px rgba(0, 0, 0, 0.12);
    border: 1px solid rgba(74, 144, 226, 0.1);
}

.player-header {
    text-align: center;
    margin-bottom: 24px;
}

.player-header h2 {
    font-size: 22px;
    color: var(--text-color);
    margin-bottom: 12px;
    font-weight: 700;
}

.player-info-badges {
    display: flex;
    justify-content: center;
    align-items: center;
    gap: 12px;
    flex-wrap: wrap;
}

.audio-badge {
    background: linear-gradient(135deg, var(--primary-color), var(--secondary-color));
    color: white;
    padding: 8px 16px;
    border-radius: 24px;
    font-size: 13px;
    font-weight: 600;
    box-shadow: 0 2px 8px rgba(74, 144, 226, 0.3);
}

.listen-badge {
    background: var(--bg-color);
    color: var(--text-color);
    padding: 8px 16px;
    border-radius: 24px;
    font-size: 13px;
    font-weight: 600;
    border: 2px solid var(--border-color);
}

#audio-player {
    display: none;
}

/* Audio Loading Indicator */

.audio-loading {
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    padding: 32px 20px;
    gap: 12px;
}

.audio-loading.hidden {
    display: none;
}

.audio-spinner {
    width: 36px;
    height: 36px;
    border: 3px solid #e3e8ef;
    border-top-color: var(--primary-color);
    border-radius: 50%;
    animation: spin 0.7s linear infinite;
}

.audio-loading p {
    color: var(--text-light);
    font-size: 13px;
    font-weight: 500;
    margin: 0;
}

.progress-container {
    margin: 24px 0;
}

.progress-bar {
    width: 100%;
    height: 6px;
    -webkit-appearance: none;
    appearance: none;
    background: #e3e8ef;
    border-radius: 10px;
    outline: none;
    cursor: pointer;
    margin-bottom: 8px;
    position: relative;
}

.progress-bar::-webkit-slider-thumb {
    -webkit-appearance: none;
    appearance: none;
    width: 16px;
    height: 16px;
    background: linear-gradient(135deg, var(--primary-color), var(--secondary-color));
    border-radius: 50%;
    cursor: pointer;
    transition: all 0.2s;
    box-shadow: 0 2px 6px rgba(74, 144, 226, 0.4);
}

.progress-bar::-webkit-slider-thumb:hover {
    transform: scale(1.3);
    box-shadow: 0 3px 10px rgba(74, 144, 226, 0.6);
}

.progress-bar::-webkit-slider-thumb:active {
    transform: scale(1.1);
}

.progress-bar::-moz-range-thumb {
    width: 16px;
    height: 16px;
    background: linear-gradient(135deg, var(--primary-color), var(--secondary-color));
    border-radius: 50%;
    cursor: pointer;
    border: none;
    transition: all 0.2s;
    box-shadow: 0 2px 6px rgba(74, 144, 226, 0.4);
}

.progress-bar::-moz-range-thumb:hover {
    transform: scale(1.3);
    box-shadow: 0 3px 10px rgba(74, 144, 226, 0.6);
}

.progress-bar::-moz-range-thumb:active {
    transform: scale(1.1);
}

.time-display {
    display: flex;
    justify-content: space-between;
    font-size: 12px;
    color: var(--text-light);
    font-weight: 500;
}

.player-controls {
    display: flex;
    justify-content: center;
    align-items: center;
    gap: 8px;
    margin: 28px 0;
}

.control-btn {
    background: white;
    border: 2px solid var(--border-color);
    border-radius: 50%;
    width: 52px;
    height: 52px;
    display: flex;
    align-items: center;
    justify-content: center;
    cursor: pointer;
    transition: all 0.25s;
    font-size: 20px;
    color: var(--text-color);
}

.control-btn:hover:not(:disabled) {
    transform: translateY(-2px);
    border-color: var(--primary-color);
    color: var(--primary-color);
    box-shadow: 0 4px 12px rgba(74, 144, 226, 0.2);
}

.control-btn:active:not(:disabled) {
    transform: translateY(0);
}

.control-btn.play-btn {
    width: 68px;
    height: 68px;
    background: linear-gradient(135deg, var(--primary-color), var(--secondary-color));
    border: none;
    box-shadow: 0 4px 16px rgba(74, 144, 226, 0.4);
}

.control-btn.play-btn:hover:not(:disabled) {
    transform: translateY(-3px);
    box-shadow: 0 6px 20px rgba(74, 144, 226, 0.5);
}

.control-btn.play-btn .control-icon {
    font-size: 28px;
    color: white;
    display: inline-block;
    line-height: 1;
}

.control-btn:disabled {
    opacity: 0.3;
    cursor: not-allowed;
    transform: none;
}

.playback-settings {
    display: flex;
    justify-content: center;
    align-items: center;
    gap: 32px;
    margin-top: 24px;
    padding-top: 24px;
    border-top: 2px solid #f0f2f5;
    flex-wrap: wrap;
}

.setting-group {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 8px;
}

.setting-group label {
    font-weight: 600;
    color: var(--text-light);
    font-size: 12px;
    text-transform: uppercase;
    letter-spacing: 0.5px;
}

.speed-select {
    background: white;
    border: 2px solid var(--border-color);
    border-radius: 10px;
    padding: 10px 20px;
    cursor: pointer;
    transition: all 0.3s;
    font-weight: 600;
    font-size: 15px;
    color: var(--text-color);
    outline: none;
    min-width: 100px;
    text-align: center;
}

.speed-select:hover {
    border-color: var(--primary-color);
    background: #f8fafc;
}

.speed-select:focus {
    border-color: var(--primary-color);
    box-shadow: 0 0 0 3px rgba(74, 144, 226, 0.15);
}

.mode-toggle-btn-compact {
    background: linear-gradient(135deg, var(--primary-color), var(--secondary-color));
    color: white;
    border: none;
    border-radius: 10px;
    padding: 10px 24px;
    cursor: pointer;
    transition: all 0.3s;
    font-size: 15px;
    font-weight: 700;
    min-width: 100px;
    box-shadow: 0 2px 8px rgba(74, 144, 226, 0.3);
}

.mode-toggle-btn-compact:hover {
    transform: translateY(-2px);
    box-shadow: 0 4px 12px rgba(74, 144, 226, 0.4);
}

.mode-toggle-btn-compact:active {
    transform: translateY(0);
}

.mode-toggle-btn-compact[data-mode="repeat"] {
    background: linear-gradient(135deg, var(--success-color), #81c784);
    box-shadow: 0 2px 8px rgba(102, 187, 106, 0.3);
}

.mode-toggle-btn-compact[data-mode="repeat"]:hover {
    box-shadow: 0 4px 12px rgba(102, 187, 106, 0.4);
}

/* Sessions List */

.sessions-container {
    max-width: 1200px;
    margin: 32px auto;
    padding: 0 20px 40px;
}

.sessions-container h2 {
    margin-bottom: 20px;
    color: var(--text-color);
    font-size: 22px;
    font-weight: 700;
}

.sessions-list {
    display: grid;
    grid-template-columns: 1fr; /* Mobile: Full width */
    gap: 16px;
}

.session-btn {
    background: white;
    border: 2px solid #e3e8ef;
    border-radius: 14px;
    padding: 20px;
    cursor: pointer;
    transition: all 0.25s;
    text-align: left;
    font-weight: 600;
    font-size: 16px;
    width: 100%;
    display: flex;
    align-items: center;
    justify-content: space-between;
    min-height: 70px;
    box-shadow: 0 1px 3px rgba(0, 0, 0, 0.06);
}

.session-btn:hover {
    border-color: var(--primary-color);
    transform: translateY(-3px);
    box-shadow: 0 4px 12px rgba(74, 144, 226, 0.15);
}

.session-btn.completed {
    background: linear-gradient(135deg, var(--success-color), #81c784);
    color: white;
    border-color: var(--success-color);
    box-shadow: 0 2px 8px rgba(102, 187, 106, 0.2);
}

.session-btn.completed:hover {
    background: linear-gradient(135deg, #5cb860, var(--success-color));
    box-shadow: 0 4px 12px rgba(102, 187, 106, 0.3);
}

.session-btn.current {
    background: linear-gradient(135deg, var(--primary-color), var(--secondary-color));
    color: white;
    border-color: var(--primary-color);
    box-shadow: 0 4px 12px rgba(74, 144, 226, 0.3);
}

.session-btn.current:hover {
    background: linear-gradient(135deg, var(--primary-dark), var(--primary-color));
    box-shadow: 0 6px 16px rgba(74, 144, 226, 0.4);
}

/* Desktop: 3 columns */
@media (min-width: 769px) {
    .sessions-list {
        grid-template-columns: repeat(3, 1fr);
        gap: 20px;
    }
    
    .session-btn {
        font-size: 15px;
    }
}

/* Loading Overlay */

.loading-overlay {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: rgba(0, 0, 0, 0.5);
    display: flex;
    align-items: center;
    justify-content: center;
    z-index: 9999;
}

.spinner {
    width: 50px;
    height: 50px;
    border: 4px solid rgba(255, 255, 255, 0.3);
    border-top-color: white;
    border-radius: 50%;
    animation: spin 1s linear infinite;
}

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

/* Responsive Design */

@media (max-width: 768px) {
    .auth-container {
        padding: 30px 20px;
    }

    .header h1 {
        font-size: 18px;
    }

    .stats-dashboard {
        margin: 15px;
        padding: 16px;
        gap: 32px;
        justify-content: space-around;
    }

    .stat-label-top {
        font-size: 11px;
    }

    .stat-value-large {
        font-size: 16px;
    }

    .player-container {
        padding: 24px 20px;
        border-radius: 20px;
    }

    .player-header h2 {
        font-size: 18px;
    }

    .control-btn {
        width: 46px;
        height: 46px;
        font-size: 18px;
    }

    .control-btn.play-btn {
        width: 62px;
        height: 62px;
    }
    
    .control-btn.play-btn .control-icon {
        font-size: 26px;
    }

    .session-btn {
        padding: 16px;
        font-size: 14px;
        min-height: 60px;
    }
    
    .playback-settings {
        gap: 24px;
    }
    
    .mode-toggle-btn-compact {
        min-width: 90px;
        padding: 10px 20px;
        font-size: 14px;
    }
    
    .speed-select {
        font-size: 14px;
        min-width: 90px;
        padding: 10px 16px;
    }
}

/* iOS Safari specific fixes */

@supports (-webkit-touch-callout: none) {
    .progress-bar {
        height: 28px;
        border-radius: 14px;
    }

    .progress-bar::-webkit-slider-thumb {
        width: 20px;
        height: 20px;
    }
    
    .control-btn {
        -webkit-tap-highlight-color: transparent;
    }
}

/* PWA Standalone mode adjustments */

@media all and (display-mode: standalone) {
    body {
        padding-top: env(safe-area-inset-top);
        padding-bottom: env(safe-area-inset-bottom);
    }
    
    .header {
        padding-top: calc(20px + env(safe-area-inset-top));
    }
}

/* iOS PWA status bar adjustment */

@supports (-webkit-touch-callout: none) {
    @media all and (display-mode: standalone) {
        .header {
            padding-top: calc(20px + 44px); /* Status bar height */
        }
    }
}