/* ComAssistant 拉新活动 — mobile-first, system color scheme */

:root {
    color-scheme: light dark;
    --color-bg: #f0f4f8;
    --color-surface: #ffffff;
    --color-surface-2: #f8fafc;
    --color-text: #0f172a;
    --color-text-muted: #475569;
    --color-primary: #0369a1;
    --color-primary-hover: #0284c7;
    --color-primary-text: #ffffff;
    --color-border: #e2e8f0;
    --color-success-bg: #ecfdf5;
    --color-success-border: #6ee7b7;
    --color-success-text: #065f46;
    --color-error-bg: #fef2f2;
    --color-error-border: #fca5a5;
    --color-error-text: #991b1b;
    --shadow-card: 0 1px 3px rgba(15, 23, 42, 0.08), 0 4px 12px rgba(15, 23, 42, 0.06);
    --radius: 12px;
    --space-xs: 0.5rem;
    --space-sm: 0.75rem;
    --space-md: 1rem;
    --space-lg: 1.5rem;
    --space-xl: 2rem;
    --font: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "PingFang SC", "Microsoft YaHei", sans-serif;
    --transition: 200ms ease;
}

@media (prefers-color-scheme: dark) {
    :root {
        --color-bg: #0f172a;
        --color-surface: #1e293b;
        --color-surface-2: #334155;
        --color-text: #f1f5f9;
        --color-text-muted: #94a3b8;
        --color-primary: #38bdf8;
        --color-primary-hover: #7dd3fc;
        --color-primary-text: #0f172a;
        --color-border: #475569;
        --color-success-bg: #064e3b;
        --color-success-border: #34d399;
        --color-success-text: #d1fae5;
        --color-error-bg: #7f1d1d;
        --color-error-border: #f87171;
        --color-error-text: #fecaca;
        --shadow-card: 0 4px 16px rgba(0, 0, 0, 0.35);
    }
}

*,
*::before,
*::after {
    box-sizing: border-box;
}

html {
    font-size: 16px;
    -webkit-text-size-adjust: 100%;
}

body {
    margin: 0;
    min-height: 100dvh;
    font-family: var(--font);
    font-size: 1rem;
    line-height: 1.6;
    color: var(--color-text);
    background: var(--color-bg);
    padding: env(safe-area-inset-top) env(safe-area-inset-right) env(safe-area-inset-bottom) env(safe-area-inset-left);
}

.page {
    max-width: 42rem;
    margin: 0 auto;
    padding: var(--space-lg) var(--space-md);
}

@media (min-width: 768px) {
    .page {
        max-width: 56rem;
    }
}

.page-header {
    text-align: center;
    margin-bottom: var(--space-xl);
}

.page-header h1 {
    margin: 0 0 var(--space-xs);
    font-size: 1.5rem;
    font-weight: 700;
    line-height: 1.3;
}

.page-header p {
    margin: 0;
    color: var(--color-text-muted);
    font-size: 0.9375rem;
}

.layout {
    display: flex;
    flex-direction: column;
    gap: var(--space-lg);
}

.card {
    background: var(--color-surface);
    border: 1px solid var(--color-border);
    border-radius: var(--radius);
    box-shadow: var(--shadow-card);
    padding: var(--space-lg);
}

/* 双栏等高：Grid 保证两列同一行高度一致 */
@media (min-width: 768px) {
    .layout {
        display: grid;
        grid-template-columns: 1fr 1fr;
        gap: var(--space-lg);
        align-items: stretch;
    }

    .layout > .card {
        display: flex;
        flex-direction: column;
        min-height: 100%;
        height: auto;
    }

    .layout__rules .rules-list {
        flex: 1 1 auto;
    }

    .layout__form #invite-form {
        flex: 1 1 auto;
        display: flex;
        flex-direction: column;
        min-height: 0;
    }

    .layout__form .form-actions {
        margin-top: auto;
        padding-top: var(--space-sm);
    }
}

.card h2 {
    margin: 0 0 var(--space-md);
    font-size: 1.125rem;
    font-weight: 600;
}

.rules-list {
    margin: 0;
    padding-left: 1.25rem;
    color: var(--color-text-muted);
}

.rules-list li {
    margin-bottom: var(--space-sm);
}

.rules-list li:last-child {
    margin-bottom: 0;
}

.form-group {
    margin-bottom: var(--space-md);
}

.form-group label {
    display: block;
    margin-bottom: var(--space-xs);
    font-weight: 500;
    font-size: 0.9375rem;
}

.form-group .required {
    color: var(--color-error-text);
}

.form-group input {
    width: 100%;
    min-height: 44px;
    padding: var(--space-sm) var(--space-md);
    font-size: 16px;
    font-family: inherit;
    color: var(--color-text);
    background: var(--color-surface-2);
    border: 1px solid var(--color-border);
    border-radius: 8px;
    touch-action: manipulation;
    transition: border-color var(--transition), box-shadow var(--transition);
}

.form-group input:focus {
    outline: none;
    border-color: var(--color-primary);
    box-shadow: 0 0 0 3px color-mix(in srgb, var(--color-primary) 25%, transparent);
}

.form-group input[aria-invalid="true"] {
    border-color: var(--color-error-border);
}

.field-error {
    margin-top: var(--space-xs);
    font-size: 0.875rem;
    color: var(--color-error-text);
    min-height: 1.25rem;
}

.btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: var(--space-xs);
    width: 100%;
    min-height: 48px;
    padding: var(--space-sm) var(--space-lg);
    font-size: 1rem;
    font-weight: 600;
    font-family: inherit;
    color: var(--color-primary-text);
    background: var(--color-primary);
    border: none;
    border-radius: 8px;
    cursor: pointer;
    touch-action: manipulation;
    transition: background var(--transition), opacity var(--transition), transform var(--transition);
}

.btn:hover:not(:disabled) {
    background: var(--color-primary-hover);
}

.btn:focus-visible {
    outline: 2px solid var(--color-primary);
    outline-offset: 2px;
}

.btn:disabled {
    opacity: 0.6;
    cursor: not-allowed;
}

.btn:active:not(:disabled) {
    transform: scale(0.98);
}

@media (prefers-reduced-motion: reduce) {
    .btn,
    .form-group input,
    .spinner {
        transition: none;
    }

    .btn:active:not(:disabled) {
        transform: none;
    }
}

.spinner {
    width: 1.125rem;
    height: 1.125rem;
    border: 2px solid color-mix(in srgb, var(--color-primary-text) 35%, transparent);
    border-top-color: var(--color-primary-text);
    border-radius: 50%;
    animation: spin 0.7s linear infinite;
}

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

.alert {
    margin-top: var(--space-md);
    padding: var(--space-md);
    border-radius: 8px;
    font-size: 0.9375rem;
    border: 1px solid;
}

.alert--success {
    background: var(--color-success-bg);
    border-color: var(--color-success-border);
    color: var(--color-success-text);
}

.alert--error {
    background: var(--color-error-bg);
    border-color: var(--color-error-border);
    color: var(--color-error-text);
}

.alert[hidden] {
    display: none !important;
}

.page-footer {
    margin-top: var(--space-xl);
    text-align: center;
    font-size: 0.875rem;
    color: var(--color-text-muted);
}

.page-footer a {
    color: var(--color-primary);
    text-decoration: none;
}

.page-footer a:hover {
    text-decoration: underline;
}

.back-link {
    margin-top: var(--space-lg);
    text-align: center;
}

.back-link a {
    color: var(--color-primary);
}