:root{--color-primary:#6366f1;--color-primary-dark:#4f46e5;--color-primary-light:#818cf8;--color-secondary:#8b5cf6;--color-success:#10b981;--color-error:#ef4444;--color-warning:#f59e0b;--color-bg:#f9fafb;--color-bg-secondary:#fff;--color-bg-tertiary:#f3f4f6;--color-text:#1f2937;--color-text-secondary:#6b7280;--color-text-tertiary:#9ca3af;--color-border:#e5e7eb;--color-border-dark:#d1d5db;--spacing-md:1rem;--spacing-lg:1.5rem;--shadow-sm:0 1px 2px 0 #0000000d;--font-size-2xl:1.5rem;--font-weight-bold:700;--header-height:60px;--sidebar-width:250px;--max-width:1400px}body{background-color:#f4f4f4;justify-content:center;align-items:center;min-height:100vh;margin:0;font-family:Arial,sans-serif;display:flex}.container{background-color:#fff;border-radius:8px;width:400px;padding:20px 30px;box-shadow:0 0 10px #0000001a}.header{background-color:var(--color-bg-secondary);border-bottom:1px solid var(--color-border);box-shadow:var(--shadow-sm);z-index:100;position:sticky;top:0}.header-content{max-width:var(--max-width);padding:0 var(--spacing-lg);height:var(--header-height);justify-content:space-between;align-items:center;margin:0 auto;display:flex}.app-title{font-size:var(--font-size-2xl);font-weight:var(--font-weight-bold);color:var(--color-primary)}.header-nav{gap:var(--spacing-md);align-items:center;display:flex}li{text-decoration:none;list-style-type:none}h1{text-align:center;color:#333}.form-group{margin-bottom:15px}.form-group label{margin-bottom:5px;font-weight:700;display:block}.form-group input[type=text],.form-group input[type=email],.form-group input[type=password]{box-sizing:border-box;border:1px solid #ddd;border-radius:4px;width:calc(100% - 22px);padding:10px}.form-group input:invalid{border-color:#e74c3c}.form-group .error-message{color:#e74c3c;min-height:1em;margin-top:5px;font-size:.9em;display:block}.form-group small{color:#777;margin-top:3px;font-size:.8em;display:block}button[type=submit]{color:#fff;cursor:pointer;background-color:#3498db;border:none;border-radius:4px;width:100%;padding:10px;font-size:16px}button[type=submit]:hover{background-color:#2980b9}