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

:root {
    --primary-color: #3b82f6;
    --primary-dark: #2563eb;
    --primary-light: #60a5fa;
    --secondary-color: #64748b;
    --bg-primary: #ffffff;
    --bg-secondary: #f8fafc;
    --bg-tertiary: #f1f5f9;
    --bg-dark: #0f172a;
    --text-primary: #0f172a;
    --text-secondary: #475569;
    --text-tertiary: #64748b;
    --border-color: #e2e8f0;
    --shadow-sm: 0 1px 2px 0 rgba(0, 0, 0, 0.05);
    --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.1);
    --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.1);
    --shadow-xl: 0 20px 25px -5px rgba(0, 0, 0, 0.1);
    --error-color: #ef4444;
    --success-color: #10b981;
    --warning-color: #f59e0b;
    --transition: all 0.2s ease;
}

/* Dark Mode Support */
[data-theme="dark"] {
    --primary-color: #60a5fa;
    --primary-dark: #3b82f6;
    --primary-light: #93c5fd;
    --bg-primary: #1e293b;
    --bg-secondary: #0f172a;
    --bg-tertiary: #334155;
    --text-primary: #f1f5f9;
    --text-secondary: #cbd5e1;
    --text-tertiary: #94a3b8;
    --border-color: #334155;
}

body {
    font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', 'Roboto', sans-serif;
    background-color: var(--bg-secondary);
    min-height: 100vh;
    display: flex;
    align-items: center;
    justify-content: center;
    padding: 20px;
    color: var(--text-primary);
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
    transition: background-color 0.3s ease, color 0.3s ease;
}

.login-container {
    width: 100%;
    max-width: 450px;
    animation: fadeIn 0.6s ease-out;
}

@keyframes fadeIn {
    from {
        opacity: 0;
        transform: translateY(-20px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

.login-box,
.register-box {
    background: var(--bg-primary);
    border-radius: 16px;
    padding: 40px;
    box-shadow: var(--shadow-lg);
    border: 1px solid var(--border-color);
    transition: var(--transition);
}

.login-box:hover,
.register-box:hover {
    box-shadow: var(--shadow-xl);
}

.logo {
    text-align: center;
    margin-bottom: 20px;
}

.logo img {
    width: 60px;
    height: 60px;
    animation: rotate 20s linear infinite;
}

@keyframes rotate {
    from {
        transform: rotate(0deg);
    }
    to {
        transform: rotate(360deg);
    }
}

h1 {
    text-align: center;
    color: var(--text-primary);
    font-size: 32px;
    font-weight: 700;
    margin-bottom: 10px;
    letter-spacing: -0.02em;
}

.subtitle {
    text-align: center;
    color: var(--text-secondary);
    margin-bottom: 30px;
    font-size: 16px;
}

.login-form {
    display: flex;
    flex-direction: column;
    gap: 20px;
}

.form-group {
    display: flex;
    flex-direction: column;
    gap: 8px;
}

.form-group label {
    color: var(--text-primary);
    font-weight: 500;
    font-size: 14px;
    display: flex;
    align-items: center;
    gap: 8px;
}

.form-group label i {
    color: var(--primary-color);
}

.form-group input {
    padding: 12px 16px;
    border: 1px solid var(--border-color);
    border-radius: 8px;
    font-size: 15px;
    font-family: inherit;
    transition: var(--transition);
    outline: none;
    background-color: var(--bg-primary);
    color: var(--text-primary);
}

.form-group input:focus {
    border-color: var(--primary-color);
    box-shadow: 0 0 0 3px rgba(59, 130, 246, 0.1);
}

.password-input {
    position: relative;
    display: flex;
    align-items: center;
}

.password-input input {
    width: 100%;
    padding-right: 45px;
}

.toggle-password {
    position: absolute;
    right: 12px;
    background: none;
    border: none;
    color: var(--text-secondary);
    cursor: pointer;
    padding: 8px;
    display: flex;
    align-items: center;
    justify-content: center;
    transition: var(--transition);
}

.toggle-password:hover {
    color: var(--primary-color);
}

.form-options {
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.remember-me {
    display: flex;
    align-items: center;
    gap: 8px;
    cursor: pointer;
    font-size: 14px;
    color: var(--text-secondary);
}

.remember-me input[type="checkbox"] {
    width: 18px;
    height: 18px;
    cursor: pointer;
    accent-color: var(--primary-color);
}

.error-message {
    display: none;
    padding: 12px;
    background: rgba(239, 68, 68, 0.1);
    border: 1px solid var(--error-color);
    border-radius: 8px;
    color: var(--error-color);
    font-size: 14px;
    text-align: center;
    animation: shake 0.5s ease;
}

.error-message.show {
    display: block;
}

@keyframes shake {
    0%, 100% { transform: translateX(0); }
    25% { transform: translateX(-10px); }
    75% { transform: translateX(10px); }
}

.login-btn {
    background: var(--primary-color);
    color: white;
    border: none;
    padding: 14px 24px;
    border-radius: 8px;
    font-size: 16px;
    font-weight: 600;
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 10px;
    transition: var(--transition);
    margin-top: 10px;
    font-family: inherit;
}

.login-btn:hover {
    background: var(--primary-dark);
    transform: translateY(-2px);
    box-shadow: var(--shadow-lg);
}

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

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

.login-info {
    margin-top: 25px;
    padding: 15px;
    background: var(--bg-secondary);
    border-radius: 10px;
    border: 1px solid var(--border-color);
    text-align: center;
    font-size: 13px;
    color: var(--text-secondary);
}

.login-info p {
    margin: 5px 0;
}

.login-info i {
    color: var(--primary-color);
    margin-right: 5px;
}

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

.register-link a {
    color: var(--primary-color);
    text-decoration: none;
    font-weight: 600;
    transition: var(--transition);
}

.register-link a:hover {
    color: var(--primary-dark);
    text-decoration: underline;
}

.register-box {
    display: none;
}

/* Theme Toggle Button */
.theme-toggle-btn {
    position: fixed;
    top: 20px;
    right: 20px;
    width: 40px;
    height: 40px;
    background: var(--bg-primary);
    border: 1px solid var(--border-color);
    border-radius: 8px;
    display: flex;
    align-items: center;
    justify-content: center;
    cursor: pointer;
    color: var(--text-primary);
    font-size: 18px;
    transition: var(--transition);
    z-index: 1000;
}

.theme-toggle-btn:hover {
    background: var(--primary-color);
    color: white;
    border-color: var(--primary-color);
    transform: rotate(15deg);
}

/* Responsive Design */
@media (max-width: 480px) {
    .login-box,
    .register-box {
        padding: 30px 25px;
    }
    
    h1 {
        font-size: 26px;
    }
    
    .subtitle {
        font-size: 14px;
    }
    
    .theme-toggle-btn {
        top: 15px;
        right: 15px;
        width: 36px;
        height: 36px;
        font-size: 16px;
    }
}