/* CSS Reset */
*,
*::before,
*::after {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
}

html {
    font-size: 16px;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', 'PingFang SC', 'Hiragino Sans GB', 'Microsoft YaHei', 'Helvetica Neue', Helvetica, Arial, sans-serif;
    line-height: 1.6;
    color: var(--text-color);
    background-color: var(--bg-color);
}

ul, ol {
    list-style: none;
}

a {
    text-decoration: none;
    color: inherit;
}

img {
    max-width: 100%;
    height: auto;
    display: block;
}

button {
    border: none;
    background: none;
    cursor: pointer;
    font-family: inherit;
}

input, textarea, select {
    font-family: inherit;
    font-size: inherit;
}

/* CSS Variables */
:root {
    /* Primary Colors - Blue Theme */
    --primary-color: #1890ff;
    --primary-hover: #40a9ff;
    --primary-active: #096dd9;
    --primary-light: #e6f7ff;
    
    /* Text Colors */
    --text-color: #262626;
    --text-secondary: #595959;
    --text-muted: #8c8c8c;
    --text-white: #ffffff;
    
    /* Background Colors */
    --bg-color: #f0f2f5;
    --bg-white: #ffffff;
    --bg-gray: #fafafa;
    
    /* Border Colors */
    --border-color: #d9d9d9;
    --border-light: #f0f0f0;
    
    /* Status Colors */
    --success-color: #52c41a;
    --warning-color: #faad14;
    --error-color: #ff4d4f;
    --info-color: #1890ff;
    
    /* Shadow */
    --shadow-sm: 0 2px 8px rgba(0, 0, 0, 0.08);
    --shadow-md: 0 4px 16px rgba(0, 0, 0, 0.12);
    --shadow-lg: 0 8px 32px rgba(0, 0, 0, 0.16);
    
    /* Border Radius */
    --radius-sm: 4px;
    --radius-md: 8px;
    --radius-lg: 16px;
    
    /* Spacing */
    --spacing-xs: 4px;
    --spacing-sm: 8px;
    --spacing-md: 16px;
    --spacing-lg: 24px;
    --spacing-xl: 32px;
    
    /* Container */
    --container-max-width: 1200px;
    --container-padding: 24px;
}

/* Layout */
.container {
    max-width: var(--container-max-width);
    margin: 0 auto;
    padding: 0 var(--container-padding);
}

/* Header */
.header {
    background-color: var(--bg-white);
    box-shadow: var(--shadow-sm);
    padding: var(--spacing-md) 0;
}

.logo {
    font-size: 1.5rem;
    font-weight: 600;
    color: var(--primary-color);
}

/* Main */
.main {
    min-height: calc(100vh - 140px);
    padding: var(--spacing-xl) 0;
}

.hero {
    text-align: center;
    padding: var(--spacing-xl) 0;
}

.hero h2 {
    font-size: 2rem;
    font-weight: 600;
    color: var(--text-color);
    margin-bottom: var(--spacing-md);
}

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

/* Recharge Section */
.recharge-section {
    max-width: 900px;
    margin: 0 auto;
    padding: var(--spacing-xl) 0;
}

.section-title {
    font-size: 1.25rem;
    font-weight: 600;
    color: var(--text-color);
    margin-bottom: var(--spacing-lg);
    text-align: center;
}

/* Recharge Options */
.recharge-options {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: var(--spacing-lg);
    margin-bottom: var(--spacing-xl);
}

.recharge-options.two-options {
    grid-template-columns: repeat(2, 1fr);
    max-width: 700px;
    margin-left: auto;
    margin-right: auto;
}

.recharge-options.three-options {
    grid-template-columns: repeat(3, 1fr);
    max-width: 900px;
    margin-left: auto;
    margin-right: auto;
}

.recharge-card {
    background-color: var(--bg-white);
    border: 2px solid var(--border-light);
    border-radius: var(--radius-lg);
    padding: var(--spacing-lg);
    cursor: pointer;
    transition: all 0.3s ease;
    position: relative;
    display: flex;
    flex-direction: column;
}

.recharge-card:hover {
    border-color: var(--primary-color);
    box-shadow: var(--shadow-md);
    transform: translateY(-4px);
}

.recharge-card.selected {
    border-color: var(--primary-color);
    background-color: var(--primary-light);
    box-shadow: var(--shadow-md);
}

.recharge-card.recommended {
    border-color: var(--warning-color);
}

.recharge-card.recommended:hover,
.recharge-card.recommended.selected {
    border-color: var(--warning-color);
    background-color: #fffbe6;
}

.recommend-badge {
    position: absolute;
    top: -10px;
    right: var(--spacing-md);
    background-color: var(--warning-color);
    color: var(--text-white);
    font-size: 0.75rem;
    font-weight: 600;
    padding: 4px 12px;
    border-radius: 12px;
}

.card-header {
    display: flex;
    align-items: center;
    gap: var(--spacing-sm);
    margin-bottom: var(--spacing-md);
}

.card-icon {
    width: 32px;
    height: 32px;
    background-color: var(--primary-color);
    color: var(--text-white);
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    font-weight: 600;
    font-size: 0.875rem;
}

.recharge-card.recommended .card-icon {
    background-color: var(--warning-color);
}

.card-header h4 {
    font-size: 1rem;
    font-weight: 600;
    color: var(--text-color);
}

.card-body {
    flex: 1;
    text-align: center;
    padding: var(--spacing-md) 0;
}

.price {
    display: flex;
    align-items: flex-start;
    justify-content: center;
    gap: 2px;
    margin-bottom: var(--spacing-sm);
}

.price .currency {
    font-size: 1.25rem;
    font-weight: 600;
    color: var(--primary-color);
    margin-top: 4px;
}

.price .amount {
    font-size: 2.5rem;
    font-weight: 700;
    color: var(--primary-color);
    line-height: 1;
}

.recharge-card.recommended .price .currency,
.recharge-card.recommended .price .amount {
    color: var(--warning-color);
}

.price-detail {
    font-size: 0.875rem;
    color: var(--text-muted);
}

.original-price {
    font-size: 0.875rem;
    color: var(--text-muted);
    text-decoration: line-through;
    margin-bottom: var(--spacing-xs);
}

.save-tag {
    display: inline-block;
    background-color: var(--error-color);
    color: var(--text-white);
    font-size: 0.75rem;
    padding: 2px 8px;
    border-radius: var(--radius-sm);
}

.custom-input-wrapper {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 4px;
    margin-bottom: var(--spacing-sm);
}

.custom-input-wrapper .currency {
    font-size: 1.5rem;
    font-weight: 600;
    color: var(--primary-color);
}

.custom-amount-input {
    width: 120px;
    height: 48px;
    font-size: 1.5rem;
    font-weight: 600;
    color: var(--text-color);
    border: 2px solid var(--border-color);
    border-radius: var(--radius-md);
    text-align: center;
    outline: none;
    transition: border-color 0.3s ease;
}

.custom-amount-input:focus {
    border-color: var(--primary-color);
}

.custom-amount-input.error {
    border-color: var(--error-color);
}

/* Custom Feature */
.custom-feature-wrapper {
    margin-bottom: var(--spacing-md);
}

.custom-feature-select {
    width: 100%;
    height: 48px;
    padding: 0 var(--spacing-md);
    font-size: 1rem;
    color: var(--text-color);
    border: 2px solid var(--border-color);
    border-radius: var(--radius-md);
    outline: none;
    transition: border-color 0.3s ease;
    background-color: var(--bg-white);
}

.custom-feature-select:focus {
    border-color: var(--primary-color);
}

.feature-info {
    margin-top: var(--spacing-md);
}

.feature-description {
    font-size: 0.875rem;
    color: var(--text-secondary);
    margin-bottom: var(--spacing-sm);
    line-height: 1.4;
}

/* Month Input */
.month-input-wrapper {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 8px;
    margin-bottom: var(--spacing-md);
}

.month-input {
    width: 80px;
    height: 48px;
    font-size: 1.5rem;
    font-weight: 600;
    color: var(--text-color);
    border: 2px solid var(--border-color);
    border-radius: var(--radius-md);
    text-align: center;
    outline: none;
    transition: border-color 0.3s ease;
}

.month-input:focus {
    border-color: var(--primary-color);
}

.month-label {
    font-size: 1rem;
    color: var(--text-secondary);
}

.card-footer {
    margin-top: var(--spacing-md);
    text-align: center;
}

.select-btn {
    display: inline-block;
    padding: 8px 24px;
    background-color: var(--primary-color);
    color: var(--text-white);
    border-radius: var(--radius-md);
    font-size: 0.875rem;
    font-weight: 500;
    transition: background-color 0.3s ease;
}

.recharge-card.recommended .select-btn {
    background-color: var(--warning-color);
}

.recharge-card:hover .select-btn {
    background-color: var(--primary-hover);
}

.recharge-card.recommended:hover .select-btn {
    background-color: #ffc53d;
}

.recharge-card.selected .select-btn {
    background-color: var(--success-color);
}

.recharge-card.selected .select-btn::after {
    content: ' ✓';
}

/* Account Section */
.account-section {
    background-color: var(--bg-white);
    border-radius: var(--radius-lg);
    padding: var(--spacing-xl);
    margin-bottom: var(--spacing-xl);
    box-shadow: var(--shadow-sm);
    max-width: 900px;
    margin-left: auto;
    margin-right: auto;
}

.input-group {
    position: relative;
}

.account-input {
    width: 100%;
    height: 48px;
    padding: 0 var(--spacing-md);
    font-size: 1rem;
    border: 2px solid var(--border-color);
    border-radius: var(--radius-md);
    outline: none;
    transition: border-color 0.3s ease;
}

.account-input:focus {
    border-color: var(--primary-color);
}

.account-input.error {
    border-color: var(--error-color);
}

.error-msg {
    display: block;
    color: var(--error-color);
    font-size: 0.875rem;
    margin-top: var(--spacing-sm);
    min-height: 20px;
}

/* Submit Section */
.submit-section {
    text-align: center;
}

.submit-btn {
    display: inline-flex;
    align-items: center;
    gap: var(--spacing-sm);
    padding: 16px 48px;
    background-color: var(--primary-color);
    color: var(--text-white);
    border-radius: var(--radius-md);
    font-size: 1.125rem;
    font-weight: 600;
    transition: all 0.3s ease;
    box-shadow: var(--shadow-sm);
}

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

.submit-btn:active {
    background-color: var(--primary-active);
    transform: translateY(0);
}

.submit-btn:disabled {
    background-color: var(--border-color);
    cursor: not-allowed;
    box-shadow: none;
    transform: none;
}

.btn-price {
    font-size: 1rem;
    font-weight: 500;
    opacity: 0.9;
}

.btn-price::before {
    content: '(';
}

.btn-price::after {
    content: ')';
}

.btn-price:empty {
    display: none;
}

/* Footer */
.footer {
    background-color: var(--bg-white);
    border-top: 1px solid var(--border-light);
    padding: var(--spacing-lg) 0;
    text-align: center;
}

.footer p {
    color: var(--text-muted);
    font-size: 0.875rem;
}

/* Confirm Page Styles */
.confirm-section {
    max-width: 600px;
    margin: 0 auto;
    padding: var(--spacing-xl) 0;
}

.confirm-card {
    background-color: var(--bg-white);
    border-radius: var(--radius-lg);
    padding: var(--spacing-xl);
    box-shadow: var(--shadow-md);
}

.confirm-header {
    text-align: center;
    margin-bottom: var(--spacing-xl);
    padding-bottom: var(--spacing-lg);
    border-bottom: 1px solid var(--border-light);
}

.confirm-header h2 {
    font-size: 1.5rem;
    font-weight: 600;
    color: var(--text-color);
    margin-bottom: var(--spacing-sm);
}

.confirm-header p {
    color: var(--text-secondary);
}

.confirm-body {
    margin-bottom: var(--spacing-xl);
}

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

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

.confirm-label {
    color: var(--text-secondary);
    font-size: 0.875rem;
}

.confirm-value {
    font-weight: 600;
    color: var(--text-color);
}

.confirm-value.price {
    color: var(--primary-color);
    font-size: 1.25rem;
}

.confirm-value.highlight {
    color: var(--error-color);
    font-size: 1.125rem;
    background-color: #fff2f0;
    padding: 4px 12px;
    border-radius: var(--radius-sm);
    border: 1px solid var(--error-color);
}

.confirm-footer {
    display: flex;
    gap: var(--spacing-md);
}

.confirm-footer .btn {
    flex: 1;
    padding: 14px 24px;
    border-radius: var(--radius-md);
    font-size: 1rem;
    font-weight: 500;
    text-align: center;
    transition: all 0.3s ease;
}

.btn-secondary {
    background-color: var(--bg-gray);
    color: var(--text-color);
    border: 1px solid var(--border-color);
}

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

.btn-primary {
    background-color: var(--primary-color);
    color: var(--text-white);
}

.btn-primary:hover {
    background-color: var(--primary-hover);
}

/* Responsive */
@media (max-width: 768px) {
    :root {
        --container-padding: 16px;
    }
    
    .hero h2 {
        font-size: 1.5rem;
    }
    
    .hero p {
        font-size: 1rem;
    }
    
    .recharge-options,
    .recharge-options.two-options {
        grid-template-columns: 1fr;
        gap: var(--spacing-md);
        max-width: 100%;
    }
    
    .recharge-card {
        padding: var(--spacing-md);
    }
    
    .price .amount {
        font-size: 2rem;
    }
    
    .submit-btn {
        width: 100%;
        justify-content: center;
    }
    
    .confirm-footer {
        flex-direction: column;
    }
}

@media (max-width: 480px) {
    .hero {
        padding: var(--spacing-lg) 0;
    }
    
    .hero h2 {
        font-size: 1.25rem;
    }
    
    .section-title {
        font-size: 1.125rem;
    }
    
    .account-section {
        padding: var(--spacing-lg);
    }
    
    .confirm-card {
        padding: var(--spacing-lg);
    }
}