:root {
    color-scheme: light;
    --bg-gradient: linear-gradient(135deg, #eef2ff 0%, #f8f9ff 100%);
    --surface: rgba(255, 255, 255, 0.9);
    --surface-secondary: #ffffff;
    --text-primary: #1f2937;
    --text-secondary: #4b5563;
    --accent: #4f46e5;
    --accent-contrast: #ffffff;
    --border: rgba(99, 102, 241, 0.15);
    --shadow: 0 20px 40px rgba(15, 23, 42, 0.08);
    --badge-good: #16a34a;
    --badge-error: #ef4444;
    --badge-info: #0ea5e9;
    --badge-warning: #f97316;
}

:root[data-theme="dark"] {
    color-scheme: dark;
    --bg-gradient: linear-gradient(135deg, #0f172a 0%, #1e1b4b 100%);
    --surface: rgba(15, 23, 42, 0.85);
    --surface-secondary: rgba(30, 41, 59, 0.9);
    --text-primary: #e2e8f0;
    --text-secondary: #94a3b8;
    --accent: #6366f1;
    --accent-contrast: #ffffff;
    --border: rgba(99, 102, 241, 0.35);
    --shadow: 0 20px 50px rgba(8, 47, 73, 0.4);
    --badge-good: #34d399;
    --badge-error: #f87171;
    --badge-info: #38bdf8;
    --badge-warning: #fb923c;
}

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

body {
    font-family: 'Inter', 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    background: var(--bg-gradient);
    color: var(--text-primary);
    min-height: 100vh;
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    padding: 32px;
    transition: background 0.4s ease, color 0.4s ease;
}

.theme-toggle {
    position: fixed;
    top: 16px;
    right: 16px;
    display: inline-flex;
    align-items: center;
    gap: 6px;
    background: var(--surface);
    border: 1px solid var(--border);
    border-radius: 10px;
    padding: 8px 14px;
    cursor: pointer;
    color: var(--text-secondary);
    font-size: 13px;
    font-weight: 500;
    z-index: 10;
    transition: color 0.15s ease, background 0.15s ease, border-color 0.15s ease;
}

.theme-toggle:hover {
    color: var(--text-primary);
    background: rgba(99, 102, 241, 0.08);
    border-color: var(--accent);
}

.auth-container {
    width: 100%;
    max-width: 460px;
}

.auth-header {
    text-align: center;
    margin-bottom: 28px;
}

.auth-header img {
    height: 40px;
    width: auto;
    margin-bottom: 12px;
}

.auth-header h1 {
    font-size: 1.6em;
    font-weight: 700;
    letter-spacing: -0.02em;
    margin-bottom: 6px;
}

.auth-header p {
    color: var(--text-secondary);
    font-size: 0.95em;
}

.auth-card {
    background: var(--surface);
    border-radius: 16px;
    padding: 32px;
    box-shadow: var(--shadow);
    border: 1px solid var(--border);
    backdrop-filter: blur(10px);
}

.tab-bar {
    display: flex;
    gap: 4px;
    background: var(--surface-secondary);
    border: 1px solid var(--border);
    border-radius: 10px;
    padding: 4px;
    margin-bottom: 24px;
}

.tab-btn {
    flex: 1;
    padding: 10px 16px;
    border: none;
    border-radius: 8px;
    background: transparent;
    color: var(--text-secondary);
    font-size: 14px;
    font-weight: 600;
    cursor: pointer;
    transition: all 0.15s ease;
}

.tab-btn.active {
    background: var(--accent);
    color: var(--accent-contrast);
    box-shadow: 0 4px 12px rgba(79, 70, 229, 0.25);
}

.tab-btn:not(.active):hover {
    color: var(--text-primary);
    background: rgba(99, 102, 241, 0.08);
}

.tab-panel { display: none; }
.tab-panel.active { display: block; }

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

.form-group label {
    display: block;
    font-size: 14px;
    font-weight: 600;
    color: var(--text-primary);
    margin-bottom: 8px;
}

.form-group input {
    width: 100%;
    padding: 14px 16px;
    border: 1px solid var(--border);
    border-radius: 10px;
    font-size: 15px;
    background: var(--surface-secondary);
    color: var(--text-primary);
    transition: border-color 0.15s ease, box-shadow 0.15s ease;
}

.form-group input:focus {
    outline: none;
    border-color: var(--accent);
    box-shadow: 0 0 0 3px rgba(99, 102, 241, 0.15);
}

.form-group input::placeholder {
    color: var(--text-secondary);
    opacity: 0.7;
}

.btn {
    width: 100%;
    padding: 14px 24px;
    background: var(--accent);
    color: var(--accent-contrast);
    border: none;
    border-radius: 10px;
    font-size: 15px;
    font-weight: 600;
    cursor: pointer;
    transition: transform 0.15s ease, box-shadow 0.15s ease;
    box-shadow: 0 8px 16px rgba(79, 70, 229, 0.25);
    margin-top: 4px;
}

.btn:hover {
    transform: translateY(-1px);
    box-shadow: 0 12px 20px rgba(79, 70, 229, 0.35);
}

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

.btn:disabled {
    opacity: 0.6;
    cursor: not-allowed;
    transform: none;
    box-shadow: none;
}

.btn-link {
    background: none;
    border: none;
    color: var(--accent);
    cursor: pointer;
    font-size: 14px;
    font-weight: 600;
    padding: 0;
    text-decoration: none;
    transition: opacity 0.2s;
}

.btn-link:hover {
    opacity: 0.8;
    text-decoration: underline;
}

.alert {
    padding: 12px 16px;
    border-radius: 10px;
    font-size: 13px;
    line-height: 1.5;
    margin-bottom: 16px;
    display: none;
}

.alert.visible { display: block; }

.alert-success {
    background: rgba(22, 163, 74, 0.1);
    color: var(--badge-good);
    border: 1px solid rgba(22, 163, 74, 0.2);
}

.alert-error {
    background: rgba(239, 68, 68, 0.1);
    color: var(--badge-error);
    border: 1px solid rgba(239, 68, 68, 0.2);
}

.alert-info {
    background: rgba(14, 165, 233, 0.1);
    color: var(--badge-info);
    border: 1px solid rgba(14, 165, 233, 0.2);
}

.email-notice {
    display: flex;
    align-items: flex-start;
    gap: 10px;
    padding: 12px 16px;
    border-radius: 10px;
    background: rgba(14, 165, 233, 0.08);
    border: 1px solid rgba(14, 165, 233, 0.15);
    color: var(--text-secondary);
    font-size: 13px;
    line-height: 1.5;
    margin-bottom: 16px;
}

.email-notice-icon {
    font-size: 18px;
    flex-shrink: 0;
    margin-top: 1px;
}

.verification-sent {
    text-align: center;
    padding: 12px 0;
}

.verification-sent .icon {
    font-size: 48px;
    margin-bottom: 16px;
}

.verification-sent h3 {
    font-size: 1.2em;
    margin-bottom: 8px;
}

.verification-sent p {
    color: var(--text-secondary);
    font-size: 14px;
    line-height: 1.6;
    margin-bottom: 16px;
}

.resend-row {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 6px;
    font-size: 14px;
    color: var(--text-secondary);
    margin-top: 16px;
}

.form-footer {
    text-align: center;
    margin-top: 20px;
    font-size: 14px;
    color: var(--text-secondary);
}

.spinner-small {
    display: inline-block;
    width: 16px;
    height: 16px;
    border: 2px solid rgba(255, 255, 255, 0.3);
    border-top-color: #fff;
    border-radius: 50%;
    animation: spin 0.6s linear infinite;
    vertical-align: middle;
    margin-right: 8px;
}

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

.main-footer {
    position: fixed;
    bottom: 0;
    left: 0;
    right: 0;
    text-align: center;
    padding: 14px;
    color: var(--text-secondary);
    font-size: 12px;
}

.main-footer a {
    color: var(--text-secondary);
    text-decoration: none;
    transition: color 0.15s;
}

.main-footer a:hover {
    color: var(--accent);
}

@media (max-width: 520px) {
    body {
        padding: 16px;
        padding-bottom: 60px;
    }

    .auth-card {
        padding: 24px;
    }

    .auth-header h1 {
        font-size: 1.4em;
    }
}