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

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', 'Roboto', 'Oxygen',
        'Ubuntu', 'Cantarell', 'Fira Sans', 'Droid Sans', 'Helvetica Neue',
        sans-serif;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    min-height: 100vh;
    display: flex;
    align-items: center;
    justify-content: center;
    padding: 20px;
}

.container {
    width: 100%;
    max-width: 450px;
}

.auth-container {
    background: white;
    border-radius: 16px;
    box-shadow: 0 20px 60px rgba(0, 0, 0, 0.3);
    overflow: hidden;
    animation: slideUp 0.5s ease-out;
}

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

.auth-header {
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    color: white;
    padding: 40px 30px 30px;
    text-align: center;
    position: relative;
}

.auth-lang-switch {
    position: absolute;
    top: 16px;
    right: 16px;
    padding: 6px 12px;
    background: rgba(255, 255, 255, 0.15);
    border: 1px solid rgba(255, 255, 255, 0.25);
    border-radius: 8px;
    color: white;
    font-size: 13px;
    cursor: pointer;
    transition: all 0.3s ease;
}

.auth-lang-switch:hover {
    background: rgba(255, 255, 255, 0.25);
}

.auth-header h1 {
    font-size: 28px;
    font-weight: 600;
    margin-bottom: 30px;
    letter-spacing: 0.5px;
}

.tab-buttons {
    display: flex;
    gap: 10px;
    background: rgba(255, 255, 255, 0.2);
    border-radius: 10px;
    padding: 5px;
}

.tab-btn {
    flex: 1;
    padding: 12px 20px;
    border: none;
    background: transparent;
    color: rgba(255, 255, 255, 0.7);
    font-size: 16px;
    font-weight: 500;
    cursor: pointer;
    border-radius: 8px;
    transition: all 0.3s ease;
}

.tab-btn:hover {
    color: white;
    background: rgba(255, 255, 255, 0.1);
}

.tab-btn.active {
    background: white;
    color: #667eea;
    font-weight: 600;
}

.form-container {
    display: none;
    padding: 40px 30px;
    animation: fadeIn 0.3s ease-in;
}

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

@keyframes fadeIn {
    from {
        opacity: 0;
    }
    to {
        opacity: 1;
    }
}

.form-group {
    margin-bottom: 24px;
}

.form-group label {
    display: block;
    margin-bottom: 8px;
    color: #333;
    font-weight: 500;
    font-size: 14px;
}

.form-group input,
.form-group select {
    width: 100%;
    padding: 14px 16px;
    border: 2px solid #e0e0e0;
    border-radius: 8px;
    font-size: 15px;
    transition: all 0.3s ease;
    background: #f9f9f9;
    font-family: inherit;
}

.form-group input:focus,
.form-group select:focus {
    outline: none;
    border-color: #667eea;
    background-color: white;
    box-shadow: 0 0 0 3px rgba(102, 126, 234, 0.1);
}

.form-group input::placeholder {
    color: #999;
}

.password-field {
    position: relative;
}

.password-field input {
    padding-right: 48px;
}

.password-toggle {
    position: absolute;
    right: 10px;
    top: 50%;
    transform: translateY(-50%);
    display: flex;
    align-items: center;
    justify-content: center;
    width: 32px;
    height: 32px;
    border: none;
    border-radius: 6px;
    background: transparent;
    color: #888;
    cursor: pointer;
    transition: color 0.2s ease, background-color 0.2s ease;
}

.password-toggle:hover {
    color: #667eea;
    background: rgba(102, 126, 234, 0.08);
}

.password-toggle svg {
    width: 20px;
    height: 20px;
}

.password-toggle .icon-eye-off {
    display: none;
}

.password-toggle.is-visible .icon-eye {
    display: none;
}

.password-toggle.is-visible .icon-eye-off {
    display: block;
}

.form-group select {
    cursor: pointer;
    appearance: none;
    background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='12' height='12' viewBox='0 0 12 12'%3E%3Cpath fill='%23667eea' d='M6 9L1 4h10z'/%3E%3C/svg%3E");
    background-repeat: no-repeat;
    background-position: right 16px center;
    padding-right: 40px;
}

.form-group select:hover {
    border-color: #d0d0d0;
}

.form-group select option {
    padding: 10px;
    background: white;
}

.btn {
    width: 100%;
    padding: 14px;
    border: none;
    border-radius: 8px;
    font-size: 16px;
    font-weight: 600;
    cursor: pointer;
    transition: all 0.3s ease;
    text-transform: uppercase;
    letter-spacing: 0.5px;
}

.btn-primary {
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    color: white;
}

.btn-primary:hover {
    transform: translateY(-2px);
    box-shadow: 0 8px 20px rgba(102, 126, 234, 0.4);
}

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

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

.message {
    margin-top: 16px;
    padding: 12px 16px;
    border-radius: 8px;
    font-size: 14px;
    text-align: center;
    display: none;
    animation: slideDown 0.3s ease-out;
}

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

.message.show {
    display: block;
}

.message.success {
    background: #d4edda;
    color: #155724;
    border: 1px solid #c3e6cb;
}

.message.error {
    background: #f8d7da;
    color: #721c24;
    border: 1px solid #f5c6cb;
}

.message.info {
    background: #d1ecf1;
    color: #0c5460;
    border: 1px solid #bee5eb;
}

.demo-hint {
    margin-top: 12px;
    font-size: 13px;
    color: #666;
    text-align: center;
    line-height: 1.5;
}

/* 响应式设计 */
@media (max-width: 480px) {
    .auth-header {
        padding: 30px 20px 20px;
    }

    .auth-header h1 {
        font-size: 24px;
        margin-bottom: 20px;
    }

    .form-container {
        padding: 30px 20px;
    }

    .tab-btn {
        padding: 10px 16px;
        font-size: 14px;
    }
}