:root {
    --primary: #667eea;
    --primary-dark: #5a67d8;
    --primary-light: #a3bffa;
    --secondary: #764ba2;
    --accent: #48bb78;
    --bg-primary: #f7fafc;
    --bg-secondary: #ffffff;
    --bg-dark: #1a202c;
    --text-primary: #2d3748;
    --text-secondary: #718096;
    --text-light: #a0aec0;
    --border: #e2e8f0;
    --shadow: 0 4px 6px -1px rgba(0, 0, 0, 0.1), 0 2px 4px -1px rgba(0, 0, 0, 0.06);
    --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.1), 0 4px 6px -2px rgba(0, 0, 0, 0.05);
    --radius: 12px;
    --radius-lg: 20px;
    --transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
}

[data-theme="dark"] {
    --bg-primary: #1a202c;
    --bg-secondary: #2d3748;
    --text-primary: #f7fafc;
    --text-secondary: #a0aec0;
    --text-light: #718096;
    --border: #4a5568;
}

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

html {
    font-size: 16px;
}

body {
    font-family: 'Noto Sans SC', -apple-system, BlinkMacSystemFont, sans-serif;
    background: var(--bg-primary);
    color: var(--text-primary);
    line-height: 1.6;
    min-height: 100vh;
}

.app {
    display: flex;
    min-height: 100vh;
}

/* ===== 侧边栏 ===== */
.sidebar {
    width: 260px;
    background: var(--bg-secondary);
    border-right: 1px solid var(--border);
    display: flex;
    flex-direction: column;
    position: fixed;
    height: 100vh;
    z-index: 100;
    transition: var(--transition);
}

.logo {
    padding: 24px;
    display: flex;
    align-items: center;
    gap: 12px;
    border-bottom: 1px solid var(--border);
}

.logo-icon {
    font-size: 28px;
}

.logo-text {
    font-size: 20px;
    font-weight: 700;
    background: linear-gradient(135deg, var(--primary) 0%, var(--secondary) 100%);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.nav-links {
    list-style: none;
    padding: 16px 12px;
    flex: 1;
}

.nav-links li {
    display: flex;
    align-items: center;
    gap: 12px;
    padding: 14px 16px;
    margin-bottom: 4px;
    border-radius: var(--radius);
    cursor: pointer;
    transition: var(--transition);
    color: var(--text-secondary);
    font-weight: 500;
}

.nav-links li:hover {
    background: var(--bg-primary);
    color: var(--text-primary);
}

.nav-links li.active {
    background: linear-gradient(135deg, var(--primary) 0%, var(--secondary) 100%);
    color: white;
    box-shadow: var(--shadow);
}

.nav-icon {
    font-size: 20px;
    width: 24px;
    text-align: center;
}

.sidebar-footer {
    padding: 20px;
    border-top: 1px solid var(--border);
}

.daily-goal {
    background: var(--bg-primary);
    padding: 16px;
    border-radius: var(--radius);
}

.goal-label {
    display: block;
    font-size: 12px;
    color: var(--text-secondary);
    margin-bottom: 8px;
    text-transform: uppercase;
    letter-spacing: 0.5px;
}

.goal-progress {
    height: 6px;
    background: var(--border);
    border-radius: 3px;
    overflow: hidden;
    margin-bottom: 8px;
}

.goal-bar {
    height: 100%;
    background: linear-gradient(90deg, var(--primary) 0%, var(--accent) 100%);
    border-radius: 3px;
    transition: width 0.5s ease;
}

.goal-text {
    font-size: 13px;
    color: var(--text-secondary);
}

/* ===== 主内容区 ===== */
.main-content {
    flex: 1;
    margin-left: 260px;
    padding: 32px;
    max-width: calc(100% - 260px);
}

.tab-content {
    display: none;
    animation: fadeIn 0.4s ease;
}

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

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

/* ===== 模式选择 ===== */
.mode-selector {
    margin-bottom: 40px;
}

.mode-selector h2 {
    font-size: 24px;
    margin-bottom: 20px;
    font-weight: 600;
}

.mode-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
    gap: 16px;
}

.mode-card {
    background: var(--bg-secondary);
    border: 2px solid var(--border);
    border-radius: var(--radius-lg);
    padding: 24px;
    cursor: pointer;
    transition: var(--transition);
}

.mode-card:hover {
    border-color: var(--primary-light);
    transform: translateY(-2px);
    box-shadow: var(--shadow);
}

.mode-card.active {
    border-color: var(--primary);
    background: linear-gradient(135deg, rgba(102, 126, 234, 0.05) 0%, rgba(118, 75, 162, 0.05) 100%);
    box-shadow: var(--shadow-lg);
}

.mode-icon {
    font-size: 36px;
    margin-bottom: 12px;
}

.mode-card h3 {
    font-size: 18px;
    margin-bottom: 8px;
    font-weight: 600;
}

.mode-desc {
    font-size: 14px;
    color: var(--text-secondary);
    margin-bottom: 12px;
}

.mode-meta {
    display: flex;
    gap: 8px;
    flex-wrap: wrap;
}

.tag {
    background: linear-gradient(135deg, var(--primary) 0%, var(--secondary) 100%);
    color: white;
    font-size: 11px;
    padding: 4px 10px;
    border-radius: 20px;
    font-weight: 500;
}

.duration {
    background: var(--bg-primary);
    color: var(--text-secondary);
    font-size: 11px;
    padding: 4px 10px;
    border-radius: 20px;
}

/* ===== 呼吸练习界面 ===== */
.breathing-interface {
    background: var(--bg-secondary);
    border-radius: var(--radius-lg);
    padding: 40px;
    box-shadow: var(--shadow);
}

.breathing-bg {
    position: relative;
    height: 400px;
    display: flex;
    align-items: center;
    justify-content: center;
    margin-bottom: 40px;
}

.breathing-circle {
    width: 200px;
    height: 200px;
    border-radius: 50%;
    background: linear-gradient(135deg, var(--primary) 0%, var(--secondary) 100%);
    display: flex;
    align-items: center;
    justify-content: center;
    position: relative;
    z-index: 10;
    box-shadow: 0 0 60px rgba(102, 126, 234, 0.4);
    transition: transform 0.1s linear;
}

.breathing-circle.inhale {
    animation: inhale var(--inhale-duration, 4s) ease-in-out forwards;
}

.breathing-circle.hold {
    animation: hold var(--hold-duration, 4s) ease-in-out forwards;
}

.breathing-circle.exhale {
    animation: exhale var(--exhale-duration, 4s) ease-in-out forwards;
}

.breathing-circle.wait {
    animation: wait var(--wait-duration, 4s) ease-in-out forwards;
}

@keyframes inhale {
    from { transform: scale(1); }
    to { transform: scale(1.5); }
}

@keyframes hold {
    from, to { transform: scale(1.5); }
}

@keyframes exhale {
    from { transform: scale(1.5); }
    to { transform: scale(1); }
}

@keyframes wait {
    from, to { transform: scale(1); }
}

.circle-inner {
    text-align: center;
    color: white;
}

.breath-text {
    display: block;
    font-size: 28px;
    font-weight: 600;
    margin-bottom: 8px;
}

.breath-timer {
    display: block;
    font-size: 48px;
    font-weight: 300;
    opacity: 0.9;
}

.breathing-rings {
    position: absolute;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
    width: 100%;
    height: 100%;
    pointer-events: none;
}

.ring {
    position: absolute;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
    border-radius: 50%;
    border: 2px solid var(--primary);
    opacity: 0;
}

.ring-1 { width: 250px; height: 250px; }
.ring-2 { width: 320px; height: 320px; }
.ring-3 { width: 400px; height: 400px; }

.breathing-rings.active .ring {
    animation: ripple 4s ease-out infinite;
}

.ring-2 { animation-delay: 0.5s !important; }
.ring-3 { animation-delay: 1s !important; }

@keyframes ripple {
    0% { transform: translate(-50%, -50%) scale(0.8); opacity: 0.6; }
    100% { transform: translate(-50%, -50%) scale(1.5); opacity: 0; }
}

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

.mode-info {
    margin-bottom: 30px;
}

.mode-info h3 {
    font-size: 22px;
    margin-bottom: 8px;
}

.mode-info p {
    color: var(--text-secondary);
}

.control-buttons {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 20px;
    margin-bottom: 24px;
    position: relative;
}

.btn-control {
    width: 50px;
    height: 50px;
    border-radius: 50%;
    border: 2px solid var(--border);
    background: var(--bg-secondary);
    cursor: pointer;
    font-size: 20px;
    transition: var(--transition);
    display: flex;
    align-items: center;
    justify-content: center;
}

.btn-control:hover {
    border-color: var(--primary);
    transform: scale(1.1);
}

.btn-control.active {
    background: linear-gradient(135deg, var(--primary) 0%, var(--secondary) 100%);
    border-color: transparent;
    color: white;
}

.btn-primary {
    background: linear-gradient(135deg, var(--primary) 0%, var(--secondary) 100%);
    color: white;
    border: none;
    padding: 16px 40px;
    border-radius: 50px;
    font-size: 16px;
    font-weight: 600;
    cursor: pointer;
    transition: var(--transition);
    box-shadow: 0 4px 15px rgba(102, 126, 234, 0.4);
}

.btn-primary:hover {
    transform: translateY(-2px);
    box-shadow: 0 6px 20px rgba(102, 126, 234, 0.5);
}

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

.btn-large {
    padding: 20px 60px;
    font-size: 18px;
}

.btn-secondary {
    background: var(--bg-primary);
    color: var(--text-primary);
    border: 1px solid var(--border);
    padding: 12px 24px;
    border-radius: 8px;
    font-size: 14px;
    cursor: pointer;
    transition: var(--transition);
}

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

.btn-danger {
    background: #fc8181;
    color: white;
    border: none;
    padding: 12px 24px;
    border-radius: 8px;
    font-size: 14px;
    cursor: pointer;
    transition: var(--transition);
    margin-left: 12px;
}

.btn-danger:hover {
    background: #f56565;
}

/* 背景音效选择器 */
.ambient-selector {
    background: var(--bg-primary);
    border-radius: var(--radius);
    padding: 20px;
    margin: 20px auto;
    max-width: 500px;
    display: none;
}

.ambient-selector.show {
    display: block;
    animation: slideDown 0.3s ease;
}

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

.ambient-selector h4 {
    margin-bottom: 12px;
    font-size: 14px;
    color: var(--text-secondary);
}

.ambient-options {
    display: flex;
    gap: 10px;
    flex-wrap: wrap;
    margin-bottom: 16px;
}

.ambient-btn {
    background: var(--bg-secondary);
    border: 1px solid var(--border);
    padding: 10px 16px;
    border-radius: 20px;
    cursor: pointer;
    font-size: 14px;
    transition: var(--transition);
    display: flex;
    align-items: center;
    gap: 6px;
}

.ambient-btn:hover, .ambient-btn.active {
    border-color: var(--primary);
    background: linear-gradient(135deg, rgba(102, 126, 234, 0.1) 0%, rgba(118, 75, 162, 0.1) 100%);
}

.ambient-btn.active {
    color: var(--primary);
    font-weight: 500;
}

.volume-control {
    display: flex;
    align-items: center;
    gap: 12px;
}

.volume-control span {
    font-size: 13px;
    color: var(--text-secondary);
    min-width: 40px;
}

input[type="range"] {
    flex: 1;
    -webkit-appearance: none;
    height: 6px;
    background: var(--border);
    border-radius: 3px;
    outline: none;
}

input[type="range"]::-webkit-slider-thumb {
    -webkit-appearance: none;
    width: 18px;
    height: 18px;
    background: linear-gradient(135deg, var(--primary) 0%, var(--secondary) 100%);
    border-radius: 50%;
    cursor: pointer;
    box-shadow: 0 2px 6px rgba(0, 0, 0, 0.2);
}

/* 练习进度 */
.session-progress {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 16px;
    margin-top: 24px;
}

.progress-ring {
    width: 60px;
    height: 60px;
}

.progress-ring svg {
    transform: rotate(-90deg);
}

#sessionProgress {
    transition: stroke-dashoffset 1s linear;
}

.session-time {
    font-size: 18px;
    font-weight: 500;
    color: var(--text-secondary);
    font-variant-numeric: tabular-nums;
}

/* ===== 统计页面 ===== */
.stats-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 24px;
}

.stats-header h2 {
    font-size: 24px;
}

.period-selector {
    display: flex;
    gap: 8px;
}

.period-btn {
    background: var(--bg-secondary);
    border: 1px solid var(--border);
    padding: 8px 16px;
    border-radius: 20px;
    font-size: 14px;
    cursor: pointer;
    transition: var(--transition);
}

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

.stats-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
    gap: 20px;
    margin-bottom: 32px;
}

.stat-card {
    background: var(--bg-secondary);
    padding: 24px;
    border-radius: var(--radius);
    box-shadow: var(--shadow);
    text-align: center;
}

.stat-icon {
    font-size: 32px;
    margin-bottom: 12px;
}

.stat-value {
    font-size: 36px;
    font-weight: 700;
    background: linear-gradient(135deg, var(--primary) 0%, var(--secondary) 100%);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.stat-label {
    font-size: 14px;
    color: var(--text-secondary);
    margin-top: 4px;
}

.chart-container {
    background: var(--bg-secondary);
    padding: 24px;
    border-radius: var(--radius);
    box-shadow: var(--shadow);
    margin-bottom: 32px;
}

.chart-container h3 {
    margin-bottom: 20px;
    font-size: 18px;
}

.chart {
    height: 200px;
    display: flex;
    align-items: flex-end;
    justify-content: space-around;
    gap: 8px;
    padding: 20px 0;
}

.chart-bar {
    flex: 1;
    background: linear-gradient(180deg, var(--primary) 0%, var(--secondary) 100%);
    border-radius: 4px 4px 0 0;
    min-height: 20px;
    position: relative;
    transition: var(--transition);
    cursor: pointer;
}

.chart-bar:hover {
    opacity: 0.8;
}

.chart-bar::after {
    content: attr(data-label);
    position: absolute;
    bottom: -24px;
    left: 50%;
    transform: translateX(-50%);
    font-size: 11px;
    color: var(--text-secondary);
    white-space: nowrap;
}

.chart-bar::before {
    content: attr(data-value);
    position: absolute;
    top: -20px;
    left: 50%;
    transform: translateX(-50%);
    font-size: 11px;
    color: var(--text-primary);
    font-weight: 500;
    opacity: 0;
    transition: opacity 0.3s;
}

.chart-bar:hover::before {
    opacity: 1;
}

/* 历史记录 */
.history-section {
    background: var(--bg-secondary);
    padding: 24px;
    border-radius: var(--radius);
    box-shadow: var(--shadow);
}

.history-section h3 {
    margin-bottom: 20px;
    font-size: 18px;
}

.history-list {
    display: flex;
    flex-direction: column;
    gap: 12px;
}

.history-item {
    display: flex;
    align-items: center;
    padding: 16px;
    background: var(--bg-primary);
    border-radius: var(--radius);
    transition: var(--transition);
}

.history-item:hover {
    transform: translateX(4px);
}

.history-icon {
    width: 48px;
    height: 48px;
    border-radius: 50%;
    background: linear-gradient(135deg, var(--primary) 0%, var(--secondary) 100%);
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 24px;
    margin-right: 16px;
}

.history-info {
    flex: 1;
}

.history-title {
    font-weight: 600;
    margin-bottom: 4px;
}

.history-meta {
    font-size: 13px;
    color: var(--text-secondary);
}

.history-duration {
    font-size: 16px;
    font-weight: 600;
    color: var(--primary);
}

.empty-state {
    text-align: center;
    padding: 48px;
    color: var(--text-secondary);
}

.empty-state-icon {
    font-size: 48px;
    margin-bottom: 16px;
}

/* ===== 设置页面 ===== */
.settings-section {
    background: var(--bg-secondary);
    padding: 24px;
    border-radius: var(--radius);
    box-shadow: var(--shadow);
    margin-bottom: 24px;
}

.settings-section h3 {
    font-size: 18px;
    margin-bottom: 20px;
    padding-bottom: 12px;
    border-bottom: 1px solid var(--border);
}

.setting-item {
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: 16px 0;
    border-bottom: 1px solid var(--border);
}

.setting-item:last-child {
    border-bottom: none;
}

.setting-item label {
    font-size: 15px;
}

.setting-value {
    font-weight: 600;
    color: var(--primary);
    margin-left: 12px;
}

/* Switch Toggle */
.switch {
    position: relative;
    display: inline-block;
    width: 50px;
    height: 28px;
}

.switch input {
    opacity: 0;
    width: 0;
    height: 0;
}

.slider {
    position: absolute;
    cursor: pointer;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background-color: var(--border);
    transition: 0.3s;
    border-radius: 28px;
}

.slider:before {
    position: absolute;
    content: "";
    height: 22px;
    width: 22px;
    left: 3px;
    bottom: 3px;
    background-color: white;
    transition: 0.3s;
    border-radius: 50%;
    box-shadow: 0 2px 4px rgba(0, 0, 0, 0.2);
}

input:checked + .slider {
    background: linear-gradient(135deg, var(--primary) 0%, var(--secondary) 100%);
}

input:checked + .slider:before {
    transform: translateX(22px);
}

select {
    padding: 10px 16px;
    border: 1px solid var(--border);
    border-radius: 8px;
    background: var(--bg-primary);
    font-size: 14px;
    cursor: pointer;
    min-width: 120px;
}

/* ===== 弹窗 ===== */
.modal {
    display: none;
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: rgba(0, 0, 0, 0.5);
    z-index: 1000;
    align-items: center;
    justify-content: center;
}

.modal.show {
    display: flex;
}

.modal-content {
    background: var(--bg-secondary);
    padding: 32px;
    border-radius: var(--radius-lg);
    width: 90%;
    max-width: 500px;
    animation: modalSlide 0.3s ease;
}

@keyframes modalSlide {
    from { opacity: 0; transform: translateY(-30px); }
    to { opacity: 1; transform: translateY(0); }
}

.modal-content h3 {
    margin-bottom: 20px;
    font-size: 20px;
}

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

.form-group label {
    display: block;
    margin-bottom: 8px;
    font-size: 14px;
    color: var(--text-secondary);
}

.form-group input, .form-group select {
    width: 100%;
    padding: 12px 16px;
    border: 1px solid var(--border);
    border-radius: 8px;
    font-size: 15px;
    background: var(--bg-primary);
}

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

.form-row {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 12px;
}

.modal-buttons {
    display: flex;
    justify-content: flex-end;
    gap: 12px;
    margin-top: 24px;
}

/* ===== 响应式设计 ===== */
@media (max-width: 768px) {
    .sidebar {
        width: 70px;
    }
    
    .sidebar .logo-text,
    .sidebar .nav-links li span:last-child,
    .sidebar .sidebar-footer {
        display: none;
    }
    
    .nav-links {
        padding: 16px 8px;
    }
    
    .nav-links li {
        justify-content: center;
        padding: 14px;
    }
    
    .main-content {
        margin-left: 70px;
        max-width: calc(100% - 70px);
        padding: 20px;
    }
    
    .mode-grid {
        grid-template-columns: 1fr;
    }
    
    .breathing-bg {
        height: 300px;
    }
    
    .breathing-circle {
        width: 160px;
        height: 160px;
    }
    
    .breath-text {
        font-size: 22px;
    }
    
    .breath-timer {
        font-size: 36px;
    }
    
    .stats-grid {
        grid-template-columns: repeat(2, 1fr);
    }
    
    .stats-header {
        flex-direction: column;
        gap: 16px;
        align-items: flex-start;
    }
    
    .form-row {
        grid-template-columns: repeat(2, 1fr);
    }
}

@media (max-width: 480px) {
    .main-content {
        padding: 16px;
    }
    
    .breathing-interface {
        padding: 24px;
    }
    
    .control-buttons {
        gap: 12px;
    }
    
    .btn-large {
        padding: 16px 40px;
        font-size: 16px;
    }
    
    .ambient-options {
        grid-template-columns: repeat(2, 1fr);
    }
}

/* ===== 动画状态类 ===== */
.pulsing {
    animation: pulse 2s ease-in-out infinite;
}

@keyframes pulse {
    0%, 100% { opacity: 1; }
    50% { opacity: 0.7; }
}

.glow {
    box-shadow: 0 0 80px rgba(102, 126, 234, 0.6);
}

/* 练习完成动画 */
.completion-animation {
    animation: completeBounce 0.6s ease;
}

@keyframes completeBounce {
    0% { transform: scale(1); }
    50% { transform: scale(1.2); }
    100% { transform: scale(1); }
}

/* 呼吸文字过渡 */
.breath-text {
    transition: opacity 0.3s ease;
}

.breath-text.fade {
    opacity: 0;
}